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3. Predictions for the 21cm-galaxy cross-power spectrum observable with SKA and future galaxy surveys

Author

Dijana Vrbanec, Benedetta Ciardi, Vibor Jelić, Garrelt Mellema, Saleem Zaroubi, Hannes Jensen, Ilian T. Iliev, and Astronomy

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), first stars, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, galaxies: high-redshift, intergalactic medium, dark ages, reionization, cosmology: observations, Astrophysics - Cosmology and Nongalactic Astrophysics, 0103 physical sciences, Radiative transfer, dark ages, reionization, first stars, LARGE SCALES, 010303 astronomy & astrophysics, Spectrograph, Reionization, TEMPERATURE, Astrophysics::Galaxy Astrophysics, Wide Field Infrared Survey Telescope, Physics, EPOCH, 010308 nuclear & particles physics, SIMULATING COSMIC REIONIZATION, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, LOFAR, 21 CM FOREST, Galaxy, Redshift, SIGNAL, Space and Planetary Science, Dark Ages, HIGH-REDSHIFT, EMISSION
Abstract

In this paper we use radiative transfer + N-body simulations to explore the feasibility of measurements of cross-correlations between the 21cm field observed by the Square Kilometer Array (SKA) and high-z Lyman Alpha Emitters (LAEs) detected in galaxy surveys with the Subaru Hyper Supreme Cam (HSC), Subaru Prime Focus Spectrograph (PFS) and Wide Field Infrared Survey Telescope (WFIRST). 21cm-LAE cross-correlations are in fact a powerful probe of the epoch of reionization as they are expected to provide precious information on the progress of reionization and the typical scale of ionized regions at different redshifts. The next generation observations with SKA will have a noise level much lower than those with its precursor radio facilities, introducing a significant improvement in the measurement of the cross-correlations. We find that an SKA-HSC/PFS observation will allow to investigate scales below ~10 Mpc/h and ~60 Mpc/h at z=7.3 and 6.6, respectively. WFIRST will allow to access also higher redshifts, as it is expected to observe spectroscopically ~900 LAEs per square degree and unit redshift in the range 7.5, Comment: 8 pages, 8 figures, accepted for publication in MNRAS

Published
2020

4. Erratum: 'The Spectral Evolution of the First Galaxies. III. Simulated James Webb Space Telescope Spectra of Reionization-epoch Galaxies with Lyman-continuum Leakage' (2017, ApJ, 836, 78)

Author

Christian Binggeli, Hannes Jensen, Akio K. Inoue, Sadegh Khochfar, Claudio Dalla Vecchia, Nickolay Y. Gnedin, Genoveva Micheva, Erik Zackrisson, J. P. Paardekooper, Ikkoh Shimizu, and Kristian Finlator

Subjects
Physics, Spectral evolution, Space and Planetary Science, Epoch (reference date), Continuum (design consultancy), James Webb Space Telescope, Astronomy and Astrophysics, Astrophysics, Reionization, Spectral line, Galaxy
Published
2021
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5. Polarization leakage in epoch of reionization windows - I. Low Frequency Array observations of the 3C196 field

Author

Vishambhar Pandey, Abhik Ghosh, Emma Chapman, S. van der Tol, Saleem Zaroubi, Hannes Jensen, Harish Vedantham, Rajat M. Thomas, Ilian T. Iliev, A. G. de Bruyn, Vibor Jelić, O. Martinez-Rubi, K. M. B. Asad, F. B. Abdalla, Luitje Koopmans, Sarod Yatawatta, S. Daiboo, Gianni Bernardi, Garrelt Mellema, A. R. Offringa, Geraint Harker, Maaijke Mevius, Michiel A. Brentjens, Elizabeth Fernandez, Joop Schaye, B. Ciardi, A. H. Patil, S. Bus, ITA, GBR, FRA, DEU, NLD, Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], UMR Peuplement Végétaux et Bioagresseurs en Milieu Tropical (UMR PVBMT - INRA), Institut National de la Recherche Agronomique (INRA), Department of Physics and Astronomy [Ghent], Ghent University [Belgium] (UGENT), University College of London [London] (UCL), Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University [Cambridge]-Smithsonian Institution, Netherlands Institute for Radio Astronomy (ASTRON), Max-Planck-Institut für Astrophysik (MPA), Max-Planck-Gesellschaft, Howard Hugues Medical Institute, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Department of Physics and Astronomy [UCL London], Department of Biochemistry and Microbiology, Plovdiv University 'Paisii Hilendarski, Stockholm University, AlbaNova University Center, Spatial Ecology and Epidemiology Group, University of Oxford [Oxford], Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Peuplements végétaux et bioagresseurs en milieu tropical (UMR PVBMT), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Université de La Réunion (UR), Universiteit Gent = Ghent University [Belgium] (UGENT), Howard Hughes Medical Institute (HHMI), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Universiteit Gent = Ghent University (UGENT), Harvard University-Smithsonian Institution, Plovdiv University 'Paisii Hilendarski', University of Oxford, Universiteit Leiden, Kapteyn Astronomical Institute, and Astronomy

Subjects
first stars, Field of view, polarization, instrumentation: polarimeters, intergalactic medium, cosmo-logy: observations, dark ages, reionization, Low frequency, 01 natural sciences, symbols.namesake, Optics, 0103 physical sciences, Stokes parameters, 010303 astronomy & astrophysics, Reionization, ComputingMilieux_MISCELLANEOUS, QB, Leakage (electronics), Physics, [PHYS]Physics [physics], 010308 nuclear & particles physics, business.industry, Spectral density, Astronomy and Astrophysics, LOFAR, Polarization (waves), Space and Planetary Science, symbols, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

Detection of the 21-cm signal coming from the epoch of reionization (EoR) is challenging especially because, even after removing the foregrounds, the residual Stokes I maps contain leakage from polarized emission that can mimic the signal. Here, we discuss the instrumental polarization of Low Frequency Array (LOFAR) and present realistic simulations of the leakages between Stokes parameters. From the LOFAR observations of polarized emission in the 3C196 field, we have quantified the level of polarization leakage caused by the nominal model beam of LOFAR, and compared it with the EoR signal using power spectrum analysis. We found that at 134-166 MHz, within the central 4° of the field the (Q, U) → I leakage power is lower than the EoR signal at k < 0.3 Mpc-1. The leakage was found to be localized around a Faraday depth of 0, and the rms of the leakage as a fraction of the rms of the polarized emission was shown to vary between 0.2 and 0.3 per cent, both of which could be utilized in the removal of leakage. Moreover, we could define an `EoR window' in terms of the polarization leakage in the cylindrical power spectrum above the point spread function (PSF)-induced wedge and below k∥ ̃ 0.5 Mpc-1, and the window extended up to k∥ ̃ 1 Mpc-1 at all k⊥ when 70 per cent of the leakage had been removed. These LOFAR results show that even a modest polarimetric calibration over a field of view of ≲ 4° in the future arrays like Square Kilometre Array will ensure that the polarization leakage remains well below the expected EoR signal at the scales of 0.02-1 Mpc-1.

Published
2015
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6. Lyman continuum leakage versus quenching with the James Webb Space Telescope : the spectral signatures of quenched star formation activity in reionization-epoch galaxies

Author

Ikko Shimizu, Kristiaan Pelckmans, Ruben Cubo, Christian Binggeli, Hannes Jensen, and Erik Zackrisson

Subjects
first stars, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Spectral line, Astronomi, astrofysik och kosmologi, 0103 physical sciences, high-redshilt [galaxies], Astronomy, Astrophysics and Cosmology, dark ages, 010303 astronomy & astrophysics, Reionization, Astrophysics::Galaxy Astrophysics, Physics, Quenching, Spectral signature, 010308 nuclear & particles physics, Star formation, James Webb Space Telescope, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Galaxy, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Dark Ages, reionization, Astrophysics::Earth and Planetary Astrophysics
Abstract

In this paper, we study the effects of a recent drop in star formation rate (SFR) on the spectra of epoch of reionization (EoR) galaxies, and the resulting degeneracy with the spectral features produced by extreme Lyman continuum leakage. In order to study these effects in the wavelength range relevant for the upcoming James Webb Space Telescope (JWST), we utilize synthetic spectra of simulated EoR galaxies from cosmological simulations together with synthetic spectra of partially quenched mock galaxies. We find that rapid declines in the SFR of EoR galaxies could seriously affect the applicability of methods that utilize the equivalent width of Balmer lines and the ultraviolet spectral slope to assess the escape fraction of EoR galaxies. In order to determine if the aforementioned degeneracy can be avoided by using the overall shape of the spectrum, we generate mock NIRCam observations and utilize a classification algorithm to identify galaxies that have undergone quenching. We find that while there are problematic cases, JWST/NIRCam or NIRSpec should be able to reliably identify galaxies with redshifts $z\sim 7$ that have experienced a significant decrease in the SFR (by a factor 10-100) in the past 50-100 Myr with a success rate $\gtrsim 85\%$. We also find that uncertainties in the dust-reddening effects on EoR galaxies significantly affect the performance of the results of the classification algorithm. We argue that studies that aim to characterize the dust extinction law most representative in the EoR would be extremely useful., 10 pages, 7 figures. Accepted for publication in MNRAS

Published
2018

7. On the use of seminumerical simulations in predicting the 21-cm signal from the epoch of reionization

Author

Suman Majumdar, T. Roy Choudhury, Garrelt Mellema, Kanan K. Datta, Martina M. Friedrich, Somnath Bharadwaj, and Hannes Jensen

Subjects
Physics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Dark matter, FOS: Physical sciences, Spectral density, Astronomy and Astrophysics, Observable, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Computational physics, Space and Planetary Science, Ionization, Dark Ages, Radiative transfer, Multipole expansion, Reionization, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present a detailed comparison of three different simulations of the epoch of reionization (EoR). The radiative transfer simulation (${\rm C}^2$-RAY) among them is our benchmark. Radiative transfer codes can produce realistic results, but are computationally expensive. We compare it with two semi-numerical techniques: one using the same halos as ${\rm C}^2$-RAY as its sources (Sem-Num), and one using a conditional Press-Schechter scheme (CPS+GS). These are vastly more computationally efficient than ${\rm C}^2$-RAY, but use more simplistic physical assumptions. We evaluate these simulations in terms of their ability to reproduce the history and morphology of reionization. We find that both Sem-Num and CPS+GS can produce an ionization history and morphology that is very close to ${\rm C}^2$-RAY, with Sem-Num performing slightly better compared to CPS+GS. We also study different redshift space observables of the 21-cm signal from EoR: the variance, power spectrum and its various angular multipole moments. We find that both semi-numerical models perform reasonably well in predicting these observables at length scales relevant for present and future experiments. However, Sem-Num performs slightly better than CPS+GS in producing the reionization history, which is necessary for interpreting the future observations., 20 pages, 14 figures, 1 table. Accepted for publication in MNRAS. Replaced to match the accepted version

Published
2014
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8. The spectral evolution of the first Galaxies. III. Simulated James Webb Space Telescope spectra of reionization-epoch galaxies with Lyman continuum leakage

Author

Erik Zackrisson, Kristian Finlator, J. P. Paardekooper, Ikkoh Shimizu, Sadegh Khochfar, Akio K. Inoue, Christian Binggeli, Hannes Jensen, Claudio Dalla Vecchia, Nickolay Y. Gnedin, and Genoveva Micheva

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), first stars, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Spectral line, Spectral evolution, 0103 physical sciences, dark ages, 010303 astronomy & astrophysics, Reionization, Astrophysics::Galaxy Astrophysics, Physics, Continuum (measurement), 010308 nuclear & particles physics, James Webb Space Telescope, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Redshift, Galaxy, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Dark Ages, reionization, spectroscopic [techniques], Astrophysics::Earth and Planetary Astrophysics, high-redshift [galaxies], Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Using four different suites of cosmological simulations, we generate synthetic spectra for galaxies with different Lyman continuum escape fractions (fesc) at redshifts z=7-9, in the rest-frame wavelength range relevant for the James Webb Space Telescope (JWST) NIRSpec instrument. By investigating the effects of realistic star formation histories and metallicity distributions on the EW(Hb)-beta diagram (previously proposed as a tool for identifying galaxies with very high fesc), we find that neither of these effects are likely to jeopardize the identification of galaxies with extreme Lyman continuum leakage. Based on our models, we expect essentially all z=7-9 galaxies that exhibit rest-frame EW(Hb)< 30 �� to have fesc>0.5. Incorrect assumptions concerning the ionizing fluxes of stellar populations or the dust properties of z>6 galaxies can in principle bias the selection, but substantial model deficiencies of this type will at the same time reveal themselves as an offset between the observed and simulated distribution of z>6 galaxies in the EW(Hb)-beta diagram. Such offsets would thereby allow JWST/NIRSpec measurements of these observables to serve as input for further model refinement., 12 pages, 8 figures, v.2: ApJ, accepted. Model grids are available from http://www.astro.uu.se/~ez/lycan/lycan.html

Published
2016
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9. Predictions for the 21 cm-galaxy cross-power spectrum observable with LOFAR and Subaru

Author

Elizabeth Fernandez, Abhik Ghosh, Benedetta Ciardi, Saleem Zaroubi, Dijana Vrbanec, Hannes Jensen, Ilian T. Iliev, Vibor Jelić, Garrelt Mellema, Koki Kakiichi, Léon V. E. Koopmans, and Astronomy

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), Photon, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, galaxies: high-redshift, intergalactic medium, cosmology: observations, 0103 physical sciences, Radiative transfer, 010303 astronomy & astrophysics, Cross-spectrum, Reionization, QB, Physics, 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, Observable, LOFAR, Redshift, Galaxy, Space and Planetary Science, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The 21 cm-galaxy cross-power spectrum is expected to be one of the promising probes of the Epoch of Reionization (EoR), as it could offer information about the progress of reionization and the typical scale of ionized regions at different redshifts. With upcoming observations of 21 cm emission from the EoR with the Low Frequency Array (LOFAR), and of high-redshift Ly α emitters with Subaru's Hyper Suprime-Cam (HSC), we investigate the observability of such cross-power spectrum with these two instruments, which are both planning to observe the ELAIS-N1 field at z = 6.6. In this paper, we use N-body + radiative transfer (both for continuum and Ly α photons) simulations at redshift 6.68, 7.06 and 7.3 to compute the 3D theoretical 21 cm-galaxy cross-power spectrum and cross-correlation function, as well as to predict the 2D 21 cm-galaxy cross-power spectrum and cross- correlation function expected to be observed by LOFAR and HSC. Once noise and projection effects are accounted for, our predictions of the 21 cm-galaxy cross-power spectrum show clear anti-correlation on scales larger than ˜60 h-1 Mpc (corresponding to k ˜ 0.1 h Mpc-1), with levels of significance p = 0.003 at z = 6.6 and p = 0.08 at z = 7.3. On smaller scales, instead, the signal is completely contaminated. On the other hand, our 21 cm-galaxy cross-correlation function is strongly contaminated by noise on all scales, since the noise is no longer being separated by its k modes.

Published
2016

10. A machine-learning approach to measuring the escape of ionizing radiation from galaxies in the reionization epoch

Author

Hannes Jensen, Erik Zackrisson, Kristiaan Pelckmans, Kristiina Ausmees, Christian Binggeli, and Ulrika Lundholm

Subjects
Physics, 010308 nuclear & particles physics, Epoch (reference date), Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Galaxy, Ionizing radiation, Methods statistical, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Physics::Atomic and Molecular Clusters, Dark Ages, Physics::Atomic Physics, Astrophysics::Earth and Planetary Astrophysics, 010303 astronomy & astrophysics, Reionization, Astrophysics::Galaxy Astrophysics
Abstract

Recent observations of galaxies at $z \gtrsim 7$, along with the low value of the electron scattering optical depth measured by the Planck mission, make galaxies plausible as dominant sources of ionizing photons during the epoch of reionization. However, scenarios of galaxy-driven reionization hinge on the assumption that the average escape fraction of ionizing photons is significantly higher for galaxies in the reionization epoch than in the local Universe. The NIRSpec instrument on the James Webb Space Telescope (JWST) will enable spectroscopic observations of large samples of reionization-epoch galaxies. While the leakage of ionizing photons will not be directly measurable from these spectra, the leakage is predicted to have an indirect effect on the spectral slope and the strength of nebular emission lines in the rest-frame ultraviolet and optical. Here, we apply a machine learning technique known as lasso regression on mock JWST/NIRSpec observations of simulated $z=7$ galaxies in order to obtain a model that can predict the escape fraction from JWST/NIRSpec data. Barring systematic biases in the simulated spectra, our method is able to retrieve the escape fraction with a mean absolute error of $\Delta f_{\mathrm{esc}} \approx 0.12$ for spectra with $S/N\approx 5$ at a rest-frame wavelength of 1500 {\AA} for our fiducial simulation. This prediction accuracy represents a significant improvement over previous similar approaches., Comment: 13 pages, 11 figures. Accepted for publication in ApJ

Published
2016
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11. Effects of the sources of reionization on 21-cm redshift-space distortions

Author

Elizabeth Fernandez, Vibor Jelić, Garrelt Mellema, Benedetta Ciardi, Kai-Yan Lee, Filipe B. Abdalla, Saleem Zaroubi, Kanan K. Datta, Hannes Jensen, Suman Majumdar, Léon V. E. Koopmans, Ilian T. Iliev, Keri L. Dixon, Emma Chapman, and Astronomy

Subjects
PECULIAR VELOCITIES, Cosmology and Nongalactic Astrophysics (astro-ph.CO), first stars, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astronomy & Astrophysics, 01 natural sciences, methods: numerical, OBSERVATIONS COSMOLOGICAL INTERPRETATION, Redshift-space distortions, LOW-MASS GALAXIES, 0103 physical sciences, dark ages, reionization, first stars, dark ages, LARGE SCALES, Anisotropy, 010303 astronomy & astrophysics, Reionization, QB, Physics, Science & Technology, Line-of-sight, 010308 nuclear & particles physics, SIMULATING COSMIC REIONIZATION, Astrophysics::Instrumentation and Methods for Astrophysics, Spectral density, Astronomy, CM POWER SPECTRUM, HYDROGEN REIONIZATION, Astronomy and Astrophysics, LOFAR, reionization, 0201 Astronomical And Space Sciences, LOFAR OBSERVATIONS, Space and Planetary Science, Physical Sciences, HI DISTRIBUTION, Quadrupole, Dark Ages, INTERGALACTIC MEDIUM, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The observed 21-cm signal from the epoch of reionization will be distorted along the line-of-sight by the peculiar velocities of matter particles. These redshift-space distortions will affect the contrast in the signal and will also make it anisotropic. This anisotropy contains information about the cross-correlation between the matter density field and the neutral hydrogen field, and could thus potentially be used to extract information about the sources of reionization. In this paper, we study a collection of simulated reionization scenarios assuming different models for the sources of reionization. We show that the 21-cm anisotropy is best measured by the quadrupole moment of the power spectrum. We find that, unless the properties of the reionization sources are extreme in some way, the quadrupole moment evolves very predictably as a function of global neutral fraction. This predictability implies that redshift-space distortions are not a very sensitive tool for distinguishing between reionization sources. However, the quadrupole moment can be used as a model-independent probe for constraining the reionization history. We show that such measurements can be done to some extent by first-generation instruments such as LOFAR, while the SKA should be able to measure the reionization history using the quadrupole moment of the power spectrum to great accuracy., Comment: 17 pages, 12 figures, 1 table. Accepted for publication in MNRAS. Replaced to match the accepted version

Published
2016
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12. The wedge bias in reionization 21-cm power spectrum measurements

Author

Suman Majumdar, Keri L. Dixon, Hannes Jensen, Adam Lidz, Garrelt Mellema, and Ilian T. Iliev

Subjects
PECULIAR VELOCITIES, Cosmology and Nongalactic Astrophysics (astro-ph.CO), IMPRINTS, IMPACT, LINE, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astronomy & Astrophysics, 01 natural sciences, Wedge (geometry), Spectral line, methods: numerical, REDSHIFT-SPACE DISTORTION, 0103 physical sciences, dark ages, reionization, first stars, Anisotropy, 010303 astronomy & astrophysics, Reionization, Astrophysics::Galaxy Astrophysics, QB, EPOCH, Physics, Science & Technology, 010308 nuclear & particles physics, COSMIC DAWN, Spectral density, Astronomy and Astrophysics, 21 CM SIGNAL, SIMULATIONS, Redshift, 0201 Astronomical And Space Sciences, Space and Planetary Science, Frequency domain, Physical Sciences, astro-ph.CO, Dark Ages, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

A proposed method for dealing with foreground emission in upcoming 21-cm observations from the epoch of reionization is to limit observations to an uncontaminated window in Fourier space. Foreground emission can be avoided in this way, since it is limited to a wedge-shaped region in $k_{\parallel}, k_{\perp}$ space. However, the power spectrum is anisotropic owing to redshift-space distortions from peculiar velocities. Consequently, the 21-cm power spectrum measured in the foreground avoidance window---which samples only a limited range of angles close to the line-of-sight direction---differs from the full spherically-averaged power spectrum which requires an average over \emph{all} angles. In this paper, we calculate the magnitude of this "wedge bias" for the first time. We find that the bias is strongest at high redshifts, where measurements using foreground avoidance will over-estimate the power spectrum by around 100 per cent, possibly obscuring the distinctive rise and fall signature that is anticipated for the spherically-averaged 21-cm power spectrum. In the later stages of reionization, the bias becomes negative, and smaller in magnitude ($\lesssim 20$ per cent). The effect shows only a weak dependence on spatial scale and reionization topology., Accepted for publication in MNRAS

Published
2015

13. Linear polarization structures in LOFAR observations of the interstellar medium in the 3C 196 field

Author

Vibor Jelić, K. M. B. Asad, Luitje Koopmans, Harish Vedantham, Maaijke Mevius, A. R. Offringa, Sarod Yatawatta, M. Haverkorn, G. Mellema, Elizabeth Fernandez, I. T. Iliev, Geraint Harker, Hannes Jensen, A. G. de Bruyn, S. Kazemi, A. H. Patil, Emma Chapman, Vishambhar Pandey, B. Ciardi, S. Zaroubi, S. Bus, Michiel A. Brentjens, F. B. Abdalla, Abhik Ghosh, Kapteyn Astronomical Institute, and Astronomy

Subjects
Physics, Linear polarization, Astronomy, Image (category theory), ISM: structure, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, LOFAR, Galactic plane, Astrophysics - Astrophysics of Galaxies, ISM, general / ISM, magnetic fields / ISM, structure / radio continuum, ISM / techniques, interferometric / techniques, polarimetric, Interstellar medium, techniques: polarimetric, Local Bubble, radio continuum: ISM, Space and Planetary Science, techniques: interferometric, Astrophysics of Galaxies (astro-ph.GA), Brightness temperature, ISM: magnetic fields, Reionization, QB, ISM: general
Abstract

This study aims to characterize linear polarization structures in LOFAR observations of the interstellar medium (ISM) in the 3C196 field, one of the primary fields of the LOFAR-Epoch of Reionization key science project. We have used the high band antennas (HBA) of LOFAR to image this region and Rotation Measure (RM) synthesis to unravel the distribution of polarized structures in Faraday depth. The brightness temperature of the detected Galactic emission is $5-15~{\rm K}$ in polarized intensity and covers the range from -3 to +8 ${\rm rad~m^{-2}}$ in Faraday depth. The most interesting morphological feature is a strikingly straight filament at a Faraday depth of $+0.5~{\rm rad~m^{-2}}$ running from north to south, right through the centre of the field and parallel to the Galactic plane. There is also an interesting system of linear depolarization canals conspicuous in an image showing the peaks of Faraday spectra. We used the Westerbork Synthesis Radio Telescope (WSRT) at 350 MHz to image the same region. For the first time, we see some common morphology in the RM cubes made at 150 and 350~{\rm MHz}. There is no indication of diffuse emission in total intensity in the interferometric data, in line with results at higher frequencies and previous LOFAR observations. Based on our results, we determined physical parameters of the ISM and proposed a simple model that may explain the observed distribution of the intervening magneto-ionic medium. The mean line-of-sight magnetic field component, $B_\parallel$, is determined to be $0.3\pm0.1~{\rm \mu G}$ and its spatial variation across the 3C196 field is $0.1~{\rm \mu G}$. The filamentary structure is probably an ionized filament in the ISM, located somewhere within the Local Bubble. This filamentary structure shows an excess in thermal electron density ($n_e B_\parallel>6.2~{\rm cm^{-3}\mu G}$) compared to its surroundings., Comment: 16 pages, 10 figures, aceppted for publication in A&A

Published
2015

14. Lunar occultation of the diffuse radio sky: LOFAR measurements between 35 and 80 MHz

Author

Vibor Jelić, Martin Bell, Gottfried Mann, Michael W. Wise, Gianni Bernardi, Wilfred Frieswijk, Jörg R. Hörandel, Garrelt Mellema, J. W. Broderick, J. Anderson, E. de Geus, George Heald, Y. Tang, K. M. B. Asad, M. J. Norden, Heino Falcke, Michiel A. Brentjens, Luitje Koopmans, V. I. Kondratiev, Arthur Corstanje, de Antonius Bruyn, A. Renting, Michel Tagger, Ben Stappers, Elizabeth Fernandez, F. de Gasperin, S. Kazemi, Emanuela Orrú, O. Martinez-Rubi, Rob Fender, A. Nelles, Oleg Smirnov, Stefan J. Wijnholds, P. Lambropoulos, A. R. Offringa, Annalisa Bonafede, Emma Chapman, Hannes Jensen, E. Juette, D. Engels, Sera Markoff, C. Toribio, Abhik Ghosh, F. B. Abdalla, Rebecca McFadden, Roberto Pizzo, Marco Iacobelli, Sarod Yatawatta, S. Daiboo, Satyendra Thoudam, W. Reich, D. McKay-Bukowski, Dominik J. Schwarz, D. D. Mulcahy, A. H. Patil, Frank Breitling, Jochen Eislöffel, B. Ciardi, Maaijke Mevius, Mark J. Bentum, C. Tasse, V. Veligatla, A. G. Polatidis, Matthias Steinmetz, S. Bus, Vishambhar Pandey, M. Kuniyoshi, Philippe Zarka, S. ter Veen, Adam Deller, Chiara Ferrari, A. W. Gunst, Ashish Asgekar, Matthias Hoeft, Philip Best, A. Shulevski, John D. Swinbank, H. Munk, Marcus Brüggen, Geraint Harker, Jean-Mathias Grießmeier, Tim Hassall, Christian Vocks, Saleem Zaroubi, Rajat M. Thomas, John McKean, Harvey Butcher, M. Pandey-Pommier, S. Duscha, Harish Vedantham, Richard Fallows, M. A. Garrett, H. J. A. Röttgering, Olaf Wucknitz, G. Kuper, Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], UMR Peuplement Végétaux et Bioagresseurs en Milieu Tropical (UMR PVBMT - INRA), Institut National de la Recherche Agronomique (INRA), Netherlands Institute for Radio Astronomy (ASTRON), University College of London [London] (UCL), Laboratoire de Mécanique des Contacts et des Structures [Villeurbanne] (LaMCoS), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Mécanique multiphysique pour les matériaux et les procédés (MULTIMAP), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Howard Hugues Medical Institute, Max Planck Institute for Astrophysics, Max-Planck-Gesellschaft, Departamento de Geologıa, Universidad de Santiago de Chile [Santiago] (USACH), Advanced Computing and Microelectronics Unit [Kolkata] (ACMU), Indian Statistical Institute [Kolkata], Department of Physics and Astronomy [UCL London], Stockholm University, Department of process and energy, Delft University of Technology (TU Delft), Department of Physics, University of Crete [Heraklion] (UOC), Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas (FORTH), Stockholm Observatory Department of Astronomy, Department of Physics and Astronomy [Ghent], Ghent University [Belgium] (UGENT), Spatial Ecology and Epidemiology Group, University of Oxford [Oxford], Plant Ind, Hort Unit, Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Institute for Mathematics Applied to Geoscience, National Center for Atmospheric Research [Boulder] (NCAR), CSIRO Astronomy and Space Science, University of Edinburgh, Jacobs University [Bremen], Leibniz-Institut für Astrophysik Potsdam (AIP), University of Southampton, Radboud university [Nijmegen], Hamburger Sternwarte/Hamburg Observatory, Universität Hamburg (UHH), Metacohorts Consortium, Thüringer Landessternwarte Tautenburg (TLS), Département de Géologie, Université de Montréal [Montréal], Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Unité Scientifique de la Station de Nançay (USN), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Ruhr-Universität Bochum [Bochum], Max-Planck-Institut für Radioastronomie (MPIFR), Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), University of Oulu, Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Centre de Recherche Astrophysique de Lyon (CRAL), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Interactions Son Musique Mouvement, Sciences et Technologies de la Musique et du Son (STMS), Université Pierre et Marie Curie - Paris 6 (UPMC)-IRCAM-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-IRCAM-Centre National de la Recherche Scientifique (CNRS), Rhodes University, Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH / Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures (DSMZ), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Department of Astrophysics [Nijmegen], Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud university [Nijmegen]-Radboud university [Nijmegen], Argelander-Institut für Astronomie (AlfA), Rheinische Friedrich-Wilhelms-Universität Bonn, Observatoire de Paris - Site de Paris (OP), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), European Project: 258942,EC:FP7:ERC,ERC-2010-StG_20091028,FIRSTLIGHT(2010), Howard Hughes Medical Institute (HHMI), Universiteit Gent = Ghent University (UGENT), University of Oxford, Radboud University [Nijmegen], Université de Montréal (UdeM), Universiteit Leiden, Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche et Coordination Acoustique/Musique (IRCAM)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche et Coordination Acoustique/Musique (IRCAM)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Rhodes University, Grahamstown, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Radboud University [Nijmegen]-Radboud University [Nijmegen], Agence Nationale de la Recherche (ANR-09-JCJC-0001-01), Peuplements végétaux et bioagresseurs en milieu tropical (UMR PVBMT), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Université de La Réunion (UR), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Pierre et Marie Curie - Paris 6 (UPMC), Universiteit Gent = Ghent University [Belgium] (UGENT), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Vedantham, H.K., Koopmans, L.V.E., de Bruyn, A.G., Wijnholds, S.J., Brentjens, M., Abdalla, F.B., Asad, K.M.B., Bernardi, G., Bus, S., Chapman, E., Ciardi, B., Daiboo, S., Fernandez, E.R., Ghosh, A., Harker, G., Jelic, V., Jensen, H., Kazemi, S., Lambropoulos, P., Martinez-Rubi, O., Mellema, G., Mevius, M., Offringa, A.R., Pandey, V.N., Patil, A.H., Thomas, R.M., Veligatla, V., Yatawatta, S., Zaroubi, S., Anderson, J., Asgekar, A., Bell, M.E., Bentum, M.J., Best, P., Bonafede, A., Breitling, F., Broderick, J., Brüggen, M., Butcher, H.R., Corstanje, A., De Gasperin, F., De Geus, E., Deller, A., Duscha, S., Eislöffel, J., Engels, D., Falcke, H., Fallows, R.A., Fender, R., Ferrari, C., Frieswijk, W., Garrett, M.A., Grießmeier, J., Gunst, A.W., Hassall, T.E., Heald, G., Hoeft, M., Hörandel, J., Iacobelli, M., Juette, E., Kondratiev, V.I., Kuniyoshi, M., Kuper, G., Mann, G., Markoff, S., McFadden, R., McKay-Bukowski, D., McKean, J.P., Mulcahy, D.D., Munk, H., Nelles, A., Norden, M.J., Orru, E., Pandey-Pommier, M., Pizzo, R., Polatidis, A.G., Reich, W., Renting, A., Röttgering, H., Schwarz, D., Shulevski, A., Smirnov, O., Stappers, B.W., Steinmetz, M., Swinbank, J., Tagger, M., Tang, Y., Tasse, C., Ter Veen, S., Thoudam, S., Toribio, C., Vocks, C., Wise, M.W., Wucknitz, O., Zarka, P., Astronomy, Kapteyn Astronomical Institute, ITA, GBR, FRA, DEU, NLD, and High Energy Astrophys. & Astropart. Phys (API, FNWI)

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, Astronomy, first stars, observational [methods], FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, methods: observational, techniques: interferometric, Moon, dark ages, reionization, methods: observational – techniques: interferometric – Moon – cosmology: dark ages, Occultation, IR-98655, Reionization, Instrumentation and Methods for Astrophysics (astro-ph.IM), media_common, EWI-26150, Astroparticle physics, Physics, Epoch (reference date), Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, LOFAR, Astronomy and Astrophysic, Universe, interferometric [techniques], Dark ages, reionization, first star, Sky, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Physics::Space Physics, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, Dark Ages, Astrophysics::Earth and Planetary Astrophysics, METIS-314921, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present radio observations of the Moon between $35$ and $80$ MHz to demonstrate a novel technique of interferometrically measuring large-scale diffuse emission extending far beyond the primary beam (global signal) for the first time. In particular, we show that (i) the Moon appears as a negative-flux source at frequencies $35z>12$) and the Epoch of Reionization ($12>z>5$)., Comment: 15 pages, 11 figures, 1 table

Published
2015
Full Text
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15. Constraining the epoch of reionization with the variance statistic: simulations of the LOFAR case

Author

K. M. B. Asad, Vibor Jelić, Gianni Bernardi, Garrelt Mellema, Sarod Yatawatta, S. Daiboo, Saleem Zaroubi, A. H. Patil, Rajat M. Thomas, Vamsikrishna Veligatla, Vishhambhar N. Pandey, Sander Bus, Harish Vedantham, A. G. de Bruyn, Oscar Martinez, Maaijke Mevius, Joop Schaye, Geraint Harker, Abhik Ghosh, S. Kazemi, A. R. Offringa, Emma Chapman, Elizabeth Fernandez, P. Labropoulos, Michiel A. Brentjens, Hannes Jensen, Filipe B. Abdalla, Léon V. E. Koopmans, Benedetta Ciardi, Stefan J. Wijnholds, Astronomy, and Kapteyn Astronomical Institute

Subjects
Physics, methods: statistical, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Estimation theory, techniques: interferometric, dark ages, reionization, first stars, Spectral density, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, LOFAR, Signal, Redshift, Standard deviation, Space and Planetary Science, Reionization, Parametrization, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Several experiments are underway to detect the cosmic redshifted 21-cm signal from neutral hydrogen from the Epoch of Reionization (EoR). Due to their very low signal-to-noise ratio, these observations aim for a statistical detection of the signal by measuring its power spectrum. We investigate the extraction of the variance of the signal as a first step towards detecting and constraining the global history of the EoR. Signal variance is the integral of the signal's power spectrum, and it is expected to be measured with a high significance. We demonstrate this through results from a simulation and parameter estimation pipeline developed for the Low Frequency Array (LOFAR)-EoR experiment. We show that LOFAR should be able to detect the EoR in 600 hours of integration using the variance statistic. Additionally, the redshift ($z_r$) and duration ($\Delta z$) of reionization can be constrained assuming a parametrization. We use an EoR simulation of $z_r = 7.68$ and $\Delta z = 0.43$ to test the pipeline. We are able to detect the simulated signal with a significance of 4 standard deviations and extract the EoR parameters as $z_r = 7.72^{+0.37}_{-0.18}$ and $\Delta z = 0.53^{+0.12}_{-0.23}$ in 600 hours, assuming that systematic errors can be adequately controlled. We further show that the significance of detection and constraints on EoR parameters can be improved by measuring the cross-variance of the signal by cross-correlating consecutive redshift bins., Comment: 13 pages, 14 figures, Accepted for publication in MNRAS

Published
2014

16. Light cone effect on the reionization 21-cm signal – II. Evolution, anisotropies and observational implications

Author

Yi Mao, Kanan K. Datta, Paul R. Shapiro, Garrelt Mellema, Kyungjin Ahn, Hannes Jensen, Ilian T. Iliev, and Suman Majumdar

Subjects
Physics, Line-of-sight, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010308 nuclear & particles physics, Bandwidth (signal processing), Spectral density, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Spectral line, Space and Planetary Science, Light cone, 0103 physical sciences, Dark Ages, Anisotropy, 010303 astronomy & astrophysics, Reionization, Astrophysics - Cosmology and Nongalactic Astrophysics, QB
Abstract

Measurements of the HI 21-cm power spectra from the reionization epoch will be influenced by the evolution of the signal along the line-of-sight direction of any observed volume. We use numerical as well as semi-numerical simulations of reionization in a cubic volume of 607 Mpc across to study this so-called light cone effect on the HI 21-cm power spectrum. We find that the light cone effect has the largest impact at two different stages of reionization: one when reionization is $\sim 20\%$ and other when it is $\sim 80\%$ completed. We find a factor of $\sim 4$ amplification of the power spectrum at the largest scale available in our simulations. We do not find any significant anisotropy in the 21-cm power spectrum due to the light cone effect. We argue that for the power spectrum to become anisotropic, the light cone effect would have to make the ionized bubbles significantly elongated or compressed along the line-of-sight, which would require extreme reionization scenarios. We also calculate the two-point correlation functions parallel and perpendicular to the line-of-sight and find them to differ. Finally, we calculate an optimum frequency bandwidth below which the light cone effect can be neglected when extracting power spectra from observations. We find that if one is willing to accept a $10 \%$ error due to the light cone effect, the optimum frequency bandwidth for $k= 0.056 \, \rm{Mpc}^{-1}$ is $\sim 7.5$ MHz. For $k = 0.15$ and $0.41 \, \rm{Mpc}^{-1}$ the optimum bandwidth is $\sim 11$ and $\sim 16$ MHz respectively., Comment: 17 pages, accepted for publication in MNRAS, minor changes

Published
2014

17. Initial LOFAR observations of epoch of reionization windows. II. Diffuse polarized emission in the ELAIS-N1 field

Author

F. de Gasperin, A. Horneffer, Jochen Eislöffel, M. A. Garrett, Geraint Harker, Michael Kramer, A. Nelles, J. van Leeuwen, Maaijke Mevius, Wilfred Frieswijk, Y. Tang, Anna M. M. Scaife, S. ter Veen, J. P. Hamaker, V. Veligatla, Marijke Haverkorn, G. Mann, A. W. Gunst, Chiara Ferrari, Rob Fender, D. Engels, Philip Best, Harish Vedantham, A. R. Offringa, John Conway, M. Iacobelli, M. Serylak, E. Juette, Hannes Jensen, James M. Anderson, C. Vocks, Annalisa Bonafede, Heino Falcke, Vibor Jelić, R. J. Dettmar, John McKean, Matthias Hoeft, A. H. Patil, J. W. Broderick, Saleem Zaroubi, P. Maat, Tim Hassall, Harvey Butcher, Aris Karastergiou, H. J. A. Röttgering, Rajat M. Thomas, M. J. Norden, V. I. Kondratiev, Olaf Wucknitz, M. Pandey-Pommier, H. Paas, Gianni Bernardi, Jörg R. Hörandel, Mark J. Bentum, Antonia Rowlinson, Michel Tagger, Garrelt Mellema, H. Munk, C. Tasse, O. Martinez-Rubi, W. Reich, J. D. Bregman, S. Kazemi, Abhik Ghosh, George Heald, Oleg Smirnov, Elizabeth Fernandez, S. Duscha, Dominik J. Schwarz, A. G. Polatidis, I. M. Avruch, Michiel A. Brentjens, W. N. Brouw, Roberto Pizzo, P. Labropoulos, Marcus Brüggen, Ralph A. M. J. Wijers, G. Pietka, Gerard H. Kuper, K. M. B. Asad, Martin Bell, Satyendra Thoudam, Jean-Mathias Griessmeier, Richard Fallows, A. Alexov, Emma Chapman, Ron Beck, A. G. de Bruyn, Luitje Koopmans, Vishambhar Pandey, Adam Deller, C. Toribio, F. B. Abdalla, P. Zarka, Matthias Steinmetz, F. Breitling, B. Ciardi, Jason W. T. Hessels, S. Bus, M. Kuniyoshi, R. Vermeulen, Stefan J. Wijnholds, E. de Geus, Sarod Yatawatta, S. Daiboo, Adam Stewart, A. J. van der Horst, R. J. van Weeren, D. McKay-Bukowski, Netherlands Institute for Radio Astronomy (ASTRON), University College of London [London] (UCL), Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE (UMR_7585)), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Max Planck Institute for Astrophysics, Max-Planck-Gesellschaft, University of Pennsylvania [Philadelphia], SRON Netherlands Institute for Space Research (SRON), Max-Planck-Institut für Radioastronomie (MPIFR), University of Southampton, University of Edinburgh, Jacobs University [Bremen], Leibniz-Institut für Astrophysik Potsdam (AIP), Thüringer Landessternwarte Tautenburg (TLS), Radboud university [Nijmegen], Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Jodrell Bank Centre for Astrophysics (JBCA), University of Manchester [Manchester], University of Amsterdam [Amsterdam] (UvA), Ruhr-Universität Bochum [Bochum], Vrije Universiteit Medical Centre (VUMC), Vrije Universiteit Amsterdam [Amsterdam] (VU), University of Oulu, Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), School of Physics and Astronomy [Southampton], Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Astronomical Institute Anton Pannekoek (AI PANNEKOEK), ANR-09-JCJC-0001,OPALES(2009), Jelić, V., De Bruyn, A.G., Mevius, M., Abdalla, F.B., Asad, K.M.B., Bernardi, G., Brentjens, M.A., Bus, S., Chapman, E., Ciardi, B., Daiboo, S., Fernandez, E.R., Ghosh, A., Harker, G., Jensen, H., Kazemi, S., Koopmans, L.V.E., Labropoulos, P., Martinez-Rubi, O., Mellema, G., Offringa, A.R., Pandey, V.N., Patil, A.H., Thomas, R.M., Vedantham, H.K., Veligatla, V., Yatawatta, S., Zaroubi, S., Alexov, A., Anderson, J., Avruch, I.M., Beck, R., Bell, M.E., Bentum, M.J., Best, P., Bonafede, A., Bregman, J., Breitling, F., Broderick, J., Brouw, W.N., Brüggen, M., Butcher, H.R., Conway, J.E., De Gasperin, F., De Geus, E., Deller, A., Dettmar, R.-J., Duscha, S., Eislöffel, J., Engels, D., Falcke, H., Fallows, R.A., Fender, R., Ferrari, C., Frieswijk, W., Garrett, M.A., Grießmeier, J., Gunst, A.W., Hamaker, J.P., Hassall, T.E., Haverkorn, M., Heald, G., Hessels, J.W.T., Hoeft, M., Hörandel, J., Horneffer, A., Van Der Horst, A., Iacobelli, M., Juette, E., Karastergiou, A., Kondratiev, V.I., Kramer, M., Kuniyoshi, M., Kuper, G., Van Leeuwen, J., Maat, P., Mann, G., McKay-Bukowski, D., McKean, J.P., Munk, H., Nelles, A., Norden, M.J., Paas, H., Pandey-Pommier, M., Pietka, G., Pizzo, R., Polatidis, A.G., Reich, W., Röttgering, H., Rowlinson, A., Scaife, A.M.M., Schwarz, D., Serylak, M., Smirnov, O., Steinmetz, M., Stewart, A., Tagger, M., Tang, Y., Tasse, C., Ter Veen, S., Thoudam, S., Toribio, C., Vermeulen, R., Vocks, C., Van Weeren, R.J., Wijers, R.A.M.J., Wijnholds, S.J., Wucknitz, O., Zarka, P., Astronomy, Kapteyn Astronomical Institute, University of Pennsylvania, Radboud University [Nijmegen], Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Universiteit Leiden, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), High Energy Astrophys. & Astropart. Phys (API, FNWI), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Jodrell Bank Centre for Astrophysics, Observatoire de Paris - Site de Paris (OP), PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and ANR-09-JCJC-0001,OPALES,nOn-thermal Processes in gALaxy cluStErs(2009)

Subjects
Brightness, Astronomy, techniques, Astrophysics, Cosmology: observation, 01 natural sciences, EWI-25428, law.invention, law, polarimetric [techniques], dark ages, Faraday cage, 010303 astronomy & astrophysics, Physics, Line-of-sight, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Astrophysics::Instrumentation and Methods for Astrophysics, Polarization (waves), observations [cosmology], interferometric [techniques], radio continuum: ISM, techniques: interferometric, Brightness temperature, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, IR-93232, reionization, Astrophysics - Instrumentation and Methods for Astrophysics, techniques: polarimetric, cosmology: observations, diffuse radiation, first stars, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, ISM [radio continuum], Astrophysics::Cosmology and Extragalactic Astrophysics, Radio telescope, 0103 physical sciences, Instrumentation and Methods for Astrophysics (astro-ph.IM), Reionization, Astrophysics::Galaxy Astrophysics, 010308 nuclear & particles physics, Astronomy and Astrophysics, METIS-309730, LOFAR, Astronomy and Astrophysic, Astrophysics - Astrophysics of Galaxies, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Dark ages, reionization, first star, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), polarimetric
Abstract

This study aims to characterise the polarized foreground emission in the ELAIS-N1 field and to address its possible implications for the extraction of the cosmological 21-cm signal from the Low-Frequency Array - Epoch of Reionization (LOFAR-EoR) data. We use the high band antennas of LOFAR to image this region and RM-synthesis to unravel structures of polarized emission at high Galactic latitudes. The brightness temperature of the detected Galactic emission is on average 4 K in polarized intensity and covers the range from -10 to +13rad m^-2 in Faraday depth. The total polarized intensity and polarization angle show a wide range of morphological features. We have also used the Westerbork Synthesis Radio Telescope (WSRT) at 350 MHz to image the same region. The LOFAR and WSRT images show a similar complex morphology, at comparable brightness levels, but their spatial correlation is very low. The fractional polarization at 150 MHz, expressed as a percentage of the total intensity, amounts to 1.5%. There is no indication of diffuse emission in total intensity in the interferometric data, in line with results at higher frequencies. The wide frequency range, good angular resolution and good sensitivity make LOFAR an exquisite instrument for studying Galactic polarized emission at a resolution of 1-2 rad m^-2 in Faraday depth. The different polarised patterns observed at 150 MHz and 350 MHz are consistent with different source distributions along the line of sight wring in a variety of Faraday thin regions of emission. The presence of polarised foregrounds is a serious complication for Epoch of Reionization experiments. To avoid the leakage of polarized emission into total intensity, which can depend on frequency, we need to calibrate the instrumental polarization across the field of view to a small fraction of 1%., 12 pages, 9 figures, accepted for publication in A&A

Published
2014
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18. Studying reionization with the next generation of Ly-alpha emitter surveys

Author

Hannes Jensen, Ilian T. Iliev, Matthew Hayes, Garrelt Mellema, Erik Zackrisson, and Peter Laursen

Subjects
Physics, Number density, Cosmology and Nongalactic Astrophysics (astro-ph.CO), James Webb Space Telescope, Astronomy, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Redshift, Galaxy, 13. Climate action, Space and Planetary Science, Dark Ages, Galaxy formation and evolution, Reionization, Luminosity function (astronomy), QB, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We study the prospects for constraining the ionized fraction of the intergalactic medium (IGM) at $z>6$ with the next generation of large Ly$\alpha$ emitter surveys. We make predictions for the upcoming Subaru Hyper Suprime-Cam (HSC) Ly$\alpha$ survey and a hypothetical spectroscopic survey performed with the James Webb Space Telescope (JWST). Considering various scenarios where the observed evolution of the Ly$\alpha$ luminosity function of Ly$\alpha$ emitters at $z>6$ is explained partly by an increasingly neutral IGM and partly by intrinsic galaxy evolution, we show how clustering measurements will be able to distinguish between these scenarios. We find that the HSC survey should be able to detect the additional clustering induced by a neutral IGM if the global IGM neutral fraction is greater than $\sim$20 per cent at $z=6.5$. If measurements of the Ly$\alpha$ equivalent widths (EWs) are also available, neutral fractions as small as 10 per cent may be detectable by looking for correlation between the EW and the local number density of objects. In this case, if it should turn out that the IGM is significantly neutral at $z=6.5$ and the intrinsic EW distribution is relatively narrow, the observed EWs can also be used to construct a map of the locations and approximate sizes of the largest ionized regions. For the JWST survey, the results appear a bit less optimistic. Since such surveys probe a large range of redshifts, the effects of the IGM will be mixed up with any intrinsic galaxy evolution that is present, making it difficult to disentangle the effects. However, we show that a survey with the JWST will have a possibility of observing a large group of galaxies at $z\sim7$, which would be a strong indication of a partially neutral IGM., Comment: 14 pages, 11 figures. Accepted for publication in MNRAS

Published
2014
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19. Reionization and the Cosmic Dawn with the Square Kilometre Array

Author

Panos Labroupoulos, Jonathan R. Pritchard, Mario G. Santos, Vibor Jelić, Saleem Zaroubi, Sarod Yatawatta, S. Daiboo, Gianni Bernardi, Garrelt Mellema, Hans-Rainer Kloeckner, Heino Falcke, B. Semelin, Harish Vedantham, Hannes Jensen, R. C. Joseph, A. R. Offringa, Andrea Ferrara, Ger de Bruyn, Benedetta Ciardi, Andrei Mesinger, Avery Meiksin, Kanan K. Datta, Dominik J. Schwarz, Fabio Iocco, Filipe B. Abdalla, Vishambhar Pandey, Léon V. E. Koopmans, Ilian T. Iliev, Mellema, G., Koopmans, L. V. E., Abdalla, F. A., Bernardi, G., Ciardi, B., Daiboo, S., de Bruyn, A. G., Datta, K. K., Falcke, H., Ferrara, A., Iliev, I. T., Iocco, F., Jelic, V., Jensen, H., Joseph, R., Labroupoulos, P., Meiksin, A., Mesinger, A., Offringa, A. R., Pandey, V. N., Pritchard, J. R., Santos, M. G., Schwarz, D. J., Semelin, B., Vedantham, H., Yatawatta, S., Zaroubi, S., Astronomy, Kapteyn Astronomical Institute, Mellema, G, Bernardi, G, Ciardi, B, Daiboo, S, Falcke, H, Ferrara, Andrea, Iocco, F, Jelić, V, Jensen, H, Joseph, R, Labroupoulos, P, Meiksin, A, Mesinger, ANDREI ALBERT, Semelin, B, Vedantham, H, and Yatawatta, S

Subjects
21 CENTIMETER FLUCTUATIONS, MURCHISON-WIDEFIELD-ARRAY, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Structure formation, Diffuse radiation, Techniques: Interferometric, Astronomy, Dark age, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Cosmology: Observations, 01 natural sciences, Cosmology, law.invention, LY-ALPHA EMITTERS, Telescope, H-II REGIONS, Reionization, First star, law, 0103 physical sciences, Galaxy formation and evolution, Dark ages, First stars, Intergalactic medium, Radio lines: General, 010303 astronomy & astrophysics, QB, Physics, SOUTH-POLE TELESCOPE, COSMIC cancer database, 010308 nuclear & particles physics, REDSHIFTED 21-CM MAPS, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Redshift, SMALL-SCALE FLUCTUATIONS, ULTRA-DEEP-FIELD, Stars, Cosmology: Observation, Space and Planetary Science, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, INFRARED BACKGROUND EXCESS, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The Square Kilometre Array (SKA) will have a low frequency component (SKA-low) which has as one of its main science goals the study of the redshifted 21cm line from the earliest phases of star and galaxy formation in the Universe. This 21cm signal provides a new and unique window on both the formation of the first stars and accreting black holes and the later period of substantial ionization of the intergalactic medium. The signal will teach us fundamental new things about the earliest phases of structure formation, cosmology and even has the potential to lead to the discovery of new physical phenomena. Here we present a white paper with an overview of the science questions that SKA-low can address, how we plan to tackle these questions and what this implies for the basic design of the telescope., Comment: Accepted for publication in Experimental Astronomy, reformatted to 57 pages, some updated and improved figures and minor changes and updates to the text

Published
2013
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20. On the use of Lyα emitters as probes of reionization

Author

Jesper Sommer-Larsen, Paul R. Shapiro, Ilian T. Iliev, Peter Laursen, Hannes Jensen, and Garrelt Mellema

Subjects
Physics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010308 nuclear & particles physics, FOS: Physical sciences, Astronomy, Astronomy and Astrophysics, Observable, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Correlation function (astronomy), 01 natural sciences, Redshift, Luminosity, 13. Climate action, Space and Planetary Science, 0103 physical sciences, Radiative transfer, 010303 astronomy & astrophysics, Reionization, Equivalent width, Astrophysics::Galaxy Astrophysics, Luminosity function (astronomy), Astrophysics - Cosmology and Nongalactic Astrophysics, QB
Abstract

We use numerical simulations to study the effects of the patchiness of a partly reionized intergalactic medium (IGM) on the observability of Ly-alpha emitters (LAEs) at high redshifts (z ~ 6). We present a new model that divides the Ly-alpha radiative transfer into a (circum-)galactic and an extragalactic (IGM) part, and investigate how the choice of intrinsic line model affects the IGM transmission results. We use our model to study the impact of neutral hydrogen on statistical observables such as the Ly-alpha restframe equivalent width (REW) distribution, the LAE luminosity function and the two-point correlation function. We find that if the observed changes in LAE luminosity functions and equivalent width distributions between z ~ 6 and z ~ 7 are to be explained by an increased IGM neutral fraction alone, we require an extremely late and rapid reionization scenario, where the Universe was ~ 40 % ionized at z = 7, ~ 50 % ionized at z = 6.5 and ~ 100 % ionized at z = 6. This is in conflict with other observations, suggesting that intrinsic LAE evolution at z > 6 cannot be completely neglected. We show how the two-point correlation function can provide more robust constraints once future observations obtain larger LAE samples, and provide predictions for the sample sizes needed to tell different reionization scenarios apart., Accepted for publication in MNRAS

Published
2013

21. The spectral evolution of the first galaxies. II. Spectral signatures of Lyman continuum leakage from galaxies in the reionization epoch

Author

Erik Zackrisson, Hannes Jensen, and Akio K. Inoue

Subjects
Physics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Star formation, James Webb Space Telescope, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Galaxy, Spectral line, Space and Planetary Science, Emission spectrum, Astrophysics::Earth and Planetary Astrophysics, Equivalent width, Reionization, Galaxy cluster, Astrophysics::Galaxy Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The fraction of ionizing photons (fesc) that escape from z>6 galaxies is an important parameter when assessing the role of these objects in the reionization of the Universe, but the opacity of the intergalactic medium precludes a direct measurement of fesc for individual galaxies at these epochs. We argue, that since fesc regulates the impact of nebular emission on the spectra of galaxies, it should nonetheless be possible to indirectly probe fesc well into the reionization epoch. As a first step, we demonstrate that by combining measurements of the rest-frame UV slope beta with the equivalent width of the Hb emission line, galaxies with very high Lyman continuum escape fractions (fesc>0.5) should be identifiable up to z~9 through spectroscopy with the upcoming James Webb Space Telescope (JWST). By targeting strongly lensed galaxies behind low-redshift galaxy clusters, JWST spectra of sufficiently good quality can be obtained for M(1500), Comment: 12 pages, 10 figures, v.3 : version accepted for publication in ApJ (references added and extinction discussion expanded)

Published
2013
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22. Probing reionization with LOFAR using 21-cm redshift space distortions

Author

Sarod Yatawatta, Michiel A. Brentjens, Paul R. Shapiro, Geraint Harker, Yi Mao, S. Kazemi, Saleem Zaroubi, Kanan K. Datta, Rajat M. Thomas, de Antonius Bruyn, Luitje Koopmans, B. Ciardi, Filipe B. Abdalla, Emma Chapman, Vibor Jelić, Vishambhar Pandey, Hannes Jensen, Gianni Bernardi, Ilian T. Iliev, Garrelt Mellema, Harish Vedantham, Joop Schaye, O. Martinez, A. R. Offringa, V. Veligatla, P. Labropoulos, Mario G. Santos, Astronomy, and Kapteyn Astronomical Institute

Subjects
21 CENTIMETER FLUCTUATIONS, Cosmology and Nongalactic Astrophysics (astro-ph.CO), CM TOMOGRAPHY, POWER SPECTRUM, Astrophysics::High Energy Astrophysical Phenomena, first stars, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, FOREGROUND REMOVAL, methods: numerical, Redshift-space distortions, Celestial pole, instrumentation: interferometers, dark ages, reionization, 0103 physical sciences, STAR-FORMING GALAXIES, dark ages, reionization, first stars, 010303 astronomy & astrophysics, Reionization, Astrophysics::Galaxy Astrophysics, BLIND SOURCE SEPARATION, Line (formation), Physics, EPOCH, 010308 nuclear & particles physics, Epoch (reference date), Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, LOFAR, Redshift, NEUTRAL HYDROGEN, Space and Planetary Science, NORTH CELESTIAL POLE, Dark Ages, Astrophysics - Cosmology and Nongalactic Astrophysics, COSMIC REIONIZATION
Abstract

One of the most promising ways to study the epoch of reionization (EoR) is through radio observations of the redshifted 21-cm line emission from neutral hydrogen. These observations are complicated by the fact that the mapping of redshifts to line-of-sight positions is distorted by the peculiar velocities of the gas. Such distortions can be a source of error if they are not properly understood, but they also encode information about cosmology and astrophysics. We study the effects of redshift space distortions on the power spectrum of 21-cm radiation from the EoR using large scale $N$-body and radiative transfer simulations. We quantify the anisotropy introduced in the 21-cm power spectrum by redshift space distortions and show how it evolves as reionization progresses and how it relates to the underlying physics. We go on to study the effects of redshift space distortions on LOFAR observations, taking instrument noise and foreground subtraction into account. We find that LOFAR should be able to directly observe the power spectrum anisotropy due to redshift space distortions at spatial scales around $k \sim 0.1$ Mpc$^{-1}$ after $\gtrsim$ 1000 hours of integration time. At larger scales, sample errors become a limiting factor, while at smaller scales detector noise and foregrounds make the extraction of the signal problematic. Finally, we show how the astrophysical information contained in the evolution of the anisotropy of the 21-cm power spectrum can be extracted from LOFAR observations, and how it can be used to distinguish between different reionization scenarios., Accepted for publication in MNRAS

Published
2013
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23. Hunting for dark halo substructure using submilliarcsecond-scale observations of macrolensed radio jets

Author

Hannes Jensen, Pat Scott, Martina M. Friedrich, Joel Johansson, Kanan K. Datta, Erik Zackrisson, Claes-Erik Rydberg, Saghar Asadi, Kaj Wiik, Andreas Sandberg, and Jakob Jonsson

Subjects
Physics, ta115, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Dark matter, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, FOS: Physical sciences, Astronomy and Astrophysics, Scale (descriptive set theory), Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Galaxy, Dark matter halo, Gravitational lens, Space and Planetary Science, 0103 physical sciences, Substructure, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Dark halo substructure may reveal itself through secondary, small-scale gravitational lensing effects on light sources that are macrolensed by a foreground galaxy. Here, we explore the prospects of using Very Long Baseline Interferometry (VLBI) observations of multiply-imaged quasar jets to search for submilliarcsecond-scale image distortions produced by various forms of dark substructures in the 1e3-1e8 Msolar mass range. We present lensing simulations relevant for the angular resolutions attainable with the existing European VLBI Network (EVN), the global VLBI array, and an upcoming observing mode in which the Atacama Large Millimeter Array (ALMA) is connected to the global VLBI array. While observations of this type would not be sensitive to standard cold dark matter subhalos, they can be used to detect more compact forms of halo substructure predicted in alternative structure formation scenarios. By mapping ~5 strongly lensed systems, it should be possible to detect or robustly rule out primordial black holes in the 1e3-1e6 Msolar mass range if they constitute >1% percent of the dark matter in these lenses. Ultracompact minihalos are harder to detect using this technique, but 1e6-1e8 Msolar ultracompact minihalos could in principle be detected if they constitute >10% of the dark matter., 13 pages, 8 figures; v.2 accepted for publication in MNRAS

Published
2012
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24. Stellar Intensity Interferometry: Prospects for sub-milliarcsecond optical imaging

Author

Dainis Dravins, Paul D. Nuñez, Stephan LeBohec, and Hannes Jensen

Subjects
media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, 01 natural sciences, 010309 optics, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Image resolution, Instrumentation and Methods for Astrophysics (astro-ph.IM), Cherenkov radiation, Solar and Stellar Astrophysics (astro-ph.SR), media_common, Physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, Cherenkov Telescope Array, Interferometry, Wavelength, Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Sky, Spatial frequency, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Physics - Optics, Optics (physics.optics)
Abstract

Using kilometric arrays of air Cherenkov telescopes, intensity interferometry may increase the spatial resolution in optical astronomy by an order of magnitude, enabling images of rapidly rotating stars with structures in their circumstellar disks and winds, or mapping out patterns of nonradial pulsations across stellar surfaces. Intensity interferometry (pioneered by Hanbury Brown and Twiss) connects telescopes only electronically, and is practically insensitive to atmospheric turbulence and optical imperfections, permitting observations over long baselines and through large airmasses, also at short optical wavelengths. The required large telescopes with very fast detectors are becoming available as arrays of air Cherenkov telescopes, distributed over a few square km. Digital signal handling enables very many baselines to be synthesized, while stars are tracked with electronic time delays, thus synthesizing an optical interferometer in software. Simulated observations indicate limiting magnitudes around m(v)=8, reaching resolutions ~30 microarcsec in the violet. The signal-to-noise ratio favors high-temperature sources and emission-line structures, and is independent of the optical passband, be it a single spectral line or the broad spectral continuum. Intensity interferometry provides the modulus (but not phase) of any spatial frequency component of the source image; for this reason image reconstruction requires phase retrieval techniques, feasible if sufficient coverage of the interferometric (u,v)-plane is available. Experiments are in progress; test telescopes have been erected, and trials in connecting large Cherenkov telescopes have been carried out. This paper reviews this interferometric method in view of the new possibilities offered by arrays of air Cherenkov telescopes, and outlines observational programs that should become realistic already in the rather near future., Comment: New Astronomy Reviews, in press; 101 pages, 11 figures, 185 references

Published
2012
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25. Stellar Intensity Interferometry: Astrophysical targets for sub-milliarcsecond imaging

Author

Stephan LeBohec, Hannes Jensen, Dainis Dravins, and Paul D. Nuñez

Subjects
Physics, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy, 01 natural sciences, Spectral line, law.invention, Telescope, Interferometry, Stars, Wavelength, law, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Passband, Image resolution, Cherenkov radiation, Astrophysics::Galaxy Astrophysics
Abstract

Intensity interferometry permits very long optical baselines and the observation of sub-milliarcsecond structures. Using planned kilometric arrays of air Cherenkov telescopes at short wavelengths, intensity interferometry may increase the spatial resolution achieved in optical astronomy by an order of magnitude, inviting detailed studies of the shapes of rapidly rotating hot stars with structures in their circumstellar disks and winds, or mapping out patterns of nonradial pulsations across stellar surfaces. Signal-to-noise in intensity interferometry favors high-temperature sources and emission-line structures, and is independent of the optical passband, be it a single spectral line or the broad spectral continuum. Prime candidate sources have been identified among classes of bright and hot stars. Observations are simulated for telescope configurations envisioned for large Cherenkov facilities, synthesizing numerous optical baselines in software, confirming that resolutions of tens of microarcseconds are feasible for numerous astrophysical targets., 12 pages, 4 figures; presented at the SPIE conference "Optical and Infrared Interferometry II", San Diego, CA, USA (June 2010)

Published
2010

26. Stellar Intensity Interferometry: Imaging capabilities of air Cherenkov telescope arrays

Author

Dainis Dravins, Paul D. Nuñez, David Kieda, Hannes Jensen, Stephan LeBohec, and Richard Holmes

Subjects
Physics, business.industry, Phase (waves), Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Ranging, 01 natural sciences, law.invention, 010309 optics, Telescope, Stars, Interferometry, Optics, Astrophysics - Solar and Stellar Astrophysics, law, 0103 physical sciences, Angular resolution, business, Phase retrieval, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Cherenkov radiation, Astrophysics::Galaxy Astrophysics
Abstract

Sub milli-arcsecond imaging in the visible band will provide a new perspective in stellar astrophysics. Even though stellar intensity interferometry was abandoned more than 40 years ago, it is capable of imaging and thus accomplishing more than the measurement of stellar diameters as was previously thought. Various phase retrieval techniques can be used to reconstruct actual images provided a sufficient coverage of the interferometric plane is available. Planned large arrays of Air Cherenkov telescopes will provide thousands of simultaneously available baselines ranging from a few tens of meters to over a kilometer, thus making imaging possible with unprecedented angular resolution. Here we investigate the imaging capabilities of arrays such as CTA or AGIS used as Stellar Intensity Interferometry receivers. The study makes use of simulated data as could realistically be obtained from these arrays. A Cauchy-Riemann based phase recovery allows the reconstruction of images which can be compared to the pristine image for which the data were simulated. This is first done for uniform disk stars with different radii and corresponding to various exposure times, and we find that the uncertainty in reconstructing radii is a few percent after a few hours of exposure time. Finally, more complex images are considered, showing that imaging at the sub-milli-arc-second scale is possible., 10 pages, 6 figures; presented at the SPIE conference "Optical and Infrared Interferometry II", San Diego, CA, USA (June 2010)

Published
2010

27. Stellar intensity interferometry: Experimental steps toward long-baseline observations

Author

Hannes Jensen, Erez N. Ribak, Dainis Dravins, Edward Munford, David Kieda, Stephan LeBohec, Harold Simpson, Derrick Kress, J. Rose, Jeremy Smith, S. M. Bradbury, Ben Adams, Paul D. Nuñez, I. H. Bond, and Ryan Price

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Time resolution, 01 natural sciences, 7. Clean energy, Salt lake, Intensity (physics), 010309 optics, Interferometry, Observatory, 0103 physical sciences, Astronomical interferometer, Environmental science, Astrophysics::Solar and Stellar Astrophysics, Baseline (configuration management), Astrophysics - Instrumentation and Methods for Astrophysics, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Cherenkov radiation, Remote sensing
Abstract

Experiments are in progress to prepare for intensity interferometry with arrays of air Cherenkov telescopes. At the Bonneville Seabase site, near Salt Lake City, a testbed observatory has been set up with two 3-m air Cherenkov telescopes on a 23-m baseline. Cameras are being constructed, with control electronics for either off- or online analysis of the data. At the Lund Observatory (Sweden), in Technion (Israel) and at the University of Utah (USA), laboratory intensity interferometers simulating stellar observations have been set up and experiments are in progress, using various analog and digital correlators, reaching 1.4 ns time resolution, to analyze signals from pairs of laboratory telescopes., Comment: 12 pages, 3 figure

Published
2010
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28. Design concepts for the Cherenkov Telescope Array CTA: an advanced facility for ground-based high-energy gamma-ray astronomy

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K. Ziȩtara, A. Konopelko, J. Rico, Philippe Laporte, Tatsuo Yoshida, A. Etchegoyen, Dennis Haefner, C. Morello, L. Garrido, Philip Kaaret, T. Yamamoto, F. Di Pierro, Wystan Benbow, B. Sacco, T. O. B. Schmidt, T. Krähenbühl, N. Geffroy, I. M. McHardy, Toru Tanimori, A. Salini, F. Grañena, A. Liolios, A. C. Rovero, A. Mendes, Etienne Lyard, Juan Abel Barrio, Jürgen Schmoll, R. Dubois, A. N. Otte, J. Bolmont, S. Rivoire, K. Berger, A. Nikolaidis, J.-P. Ernenwein, A. Bobkov, D. Allan, C. Schultz, Masayuki Tanaka, G. Deleglise, Oliver Grimm, Ł. Płatos, O. Tibolla, M. Gochna, S. Schwarzburg, H. Arnaldi, Hiromitsu Takahashi, Valerie Connaughton, Adriano Fontana, D. Nedbal, P. Jean, Alejandro Ibarra, S. Spyrou, Gustavo E. Romero, Judith H. Croston, F. Feinstein, L. Tibaldo, M. Benallou, Shinji Hara, D. Florin, A. E. Szymkowiak, J.L. Van der Walt, Stefano Covino, Shigehiro Nagataki, G. Busetto, P. Nayman, G. Lamanna, William J. Potter, Tadashi Kifune, O. Corpace, M. Bourgeat, N. Webb, J. K. Becker, K. Hultquist, P. Majumdar, Anna Szostek, M. Compin, Petter Hofverberg, Dimitrios Emmanoulopoulos, J. Ingjald, R. Kossakowski, A. Mangano, Kunihito Ioka, Jonathan Granot, S. Buson, P. Manigot, J. M. Paredes, M. Gómez Berisso, Massimiliano Belluso, A. Kretzschmann, M. Stodulski, L. Venter, Artemio Herrero, Nu. Komin, German Hermann, Dorota Sobczyńska, Reinhard Schlickeiser, Akira Okumura, Felix Spanier, Gareth Hughes, J. Carr, Antonio Stamerra, Norita Kawanaka, T. Shibata, R. C. Shellard, Dieter H. H. Hoffmann, B. Yoffo, T. Dettlaff, R. G. Talbot, L. Fresnillo, A. Manalaysay, I. Jung, Kohta Murase, Geza Gyuk, C. Farnier, J. C. Marin, Julian Sitarek, Francesco Dazzi, H. Ohka, C. Skole, C. Ghag, Patrick Vogler, M. Hauser, M. Cailles, K. Nishijima, Yutaka Fujita, J. Berdugo, Luke O'c. Drury, Naoto Sakaki, F. Köck, P. Sutcliffe, Luis Ángel Tejedor, Hugh Dickinson, Denis Bastieri, Q. Weitzel, Ryoji Enomoto, Josep Colomé, Luigi Lessio, B. Peyaud, C. L. Naumann, Michael Punch, S. Rodriguez, Lucy Fortson, J. P. Osborne, J. Kotula, Piero Giubilato, J. Dyks, W. Kluźniak, T. Schweizer, M. Rataj, Allan Hallgren, Matthew Wood, David Gascon, M. Doert, R. Wawrzaszek, Daniela Hadasch, H. Castarede, P. Wawer, M. Kapala, J.-M. Reymond, A.A. Zdziarski, E. De Cea del Pozo, K. Farakos, D. Corti, A. St. J. Murphy, Mosè Mariotti, Kazutaka Yamaoka, T. C. Arlen, Christian Fruck, Francesco Russo, Stefano Gabici, T. Bernardino, B. Khélifi, B. Huber, T. Glanzman, J. Michałowski, Mark I. Wilkinson, M. Suchenek, Massimo Persic, I. Monteiro, M. I. Martínez, V. Sahakian, R. Firpo, Seth Digel, V. La Parola, F. Roy, Regis Terrier, E. Fokitis, E. de Oña Wilhelmi, D. Melkumyan, E. Edy, Stefano Basso, J. Knapp, Cameron B Rulten, A. Niedźwiecki, Karol Seweryn, Karl-Heinz Sulanke, B. Rudak, V. Scapin, R. Wischnewski, Ricardo Graciani, Gianluca Giavitto, Matthias Beilicke, K. Nakayama, Thomas Schanz, A. Sillanpää, G. Motta, Yoshiyuki Inoue, Elina Lindfors, Hannes Jensen, Henric Krawczynski, Catherine Boisson, C. Medina, Dinko Dimitrov, Karen Byrum, M. Shayduk, Gianpiero Tagliaferri, Richard White, Kazunori Kohri, I. Oya, T. Greenshaw, C. Olivetto, Tomasz Szepieniec, R. D. Parsons, Fuyuki Tokanai, Jerzy Grygorczuk, V. Scalzotto, S. Rosier-Lees, Dainis Dravins, Jacco Vink, Włodzimierz Piechocki, F. Stinzing, Felix Ryde, P. Ristori, N. A. McCubbin, M. Hayashida, Martin J. Hardcastle, G.W. Fraser, S. Paiano, S. Blake, U. Barres de Almeida, S. Federici, M. Corlier, C. J. Todero Peixoto, Łukasz Stawarz, Michael S. Briggs, Yvonne Becherini, Martin Pohl, Daniel Mazin, B. Decerprit, Yukikatsu Terada, J. F. Huppert, P. J. Rajda, Justin Vandenbroucke, S. Schlenstedt, S. Renner, Ł. Wiśniewski, Dieter Horns, T. B. Humensky, Takeshi Nakamori, Andreas Quirrenbach, Asdrúbal Enrique Bottani, P. Vallania, B. García, H. von Gunten, Alkiviadis F. Bais, Takashi Saito, Marcos Daniel Actis, Jacek Niemiec, W. Gäbele, C. van Eldik, Olaf Reimer, P. Corona, Robert D. Preece, C. Reimann, Pierre Brun, Thomas Bretz, R. Moderski, Eric Delagnes, Gilles Henri, W. Domainko, P. H. Tam, J. Schultze, A. Weinstein, M. Schroedter, A. Vollhardt, Stavros Maltezos, A. Wierzcholska, P. M. Chadwick, Fabrice Mottez, S. Steiner, M. Dyrda, S. Sun, Victor Stamatescu, M. Bogdan, Felix Aharonian, Hajime Takami, M. Winde, Evgeni Ovcharov, M. Panter, Shohei Yanagita, T. Jogler, Thomas Kihm, P. Micolon, S. J. Nolan, David A. Williams, Joachim Hahn, Q. Xiong, Nikolaos Stergioulas, J. Gaweda, R. Mirzoyan, Nektarios Vlahakis, J. Becerra, N. Fouque, M. Ribordy, V. Vassiliev, Claes Fransson, R. L. C. Starling, J. M. Huet, J. Ruppel, J.-P. Lenain, Enrico Giro, J. Ripken, T. Haubold, A. Lopatin, Joseph Silk, J. Borkowski, P. Lubinski, T. Le Flour, R. Platzer, A. Di Paolo, Reiko Orito, O. C. de Jager, C. Eleftheriadis, A. Gonzalez, T. J. L. McComb, U. Schwanke, S. Brau-Nogue, Yutaka Ohira, Philipp Mertsch, Daniel Ferenc, Maria Concetta Maccarone, F. Gonzalez, V. Golev, Osvaldo Catalano, V. Bugaev, C. Clerc, Michał Szanecki, C. Delgado, L. Pogosyan, M. Renaud, G. Pivato, Sabine Elles, E. J. Quel, R. J. García López, M. Videla, Stefan Funk, H. Vankov, A. Le Padellec, Michele Doro, Saverio Lombardi, S. Pita, A. Wolczko, G. Disset, U. Roeser, Abraham D. Falcone, I. Telezhinsky, S. Artmann, Pierre Colin, M. Chikawa, Daniela Dorner, G. Fontaine, Wolfgang Rhode, C. Baixeras, K. Mori, H. Prokoph, Giancarlo Cusumano, J. L. Dournaux, F. Toussenel, C. Dufour, Ilana M. Braun, Riccardo Paoletti, A. R. Knappy, Sergio Billotta, F. Krennrich, S. Karkar, Anne M. Green, Takanori Yoshikoshi, I. de la Calle Perez, Masahiro Teshima, M. Janiak, C. Stegmann, H. Wetteskind, Marco Tavani, Kostas D. Kokkotas, C. Föhr, J. L. Panazol, S. Cantu, C. Tenzer, I. Vegas, M. Grudzińska, Elisabetta Bissaldi, S. Bajtlik, A. Jacholkowska, P. Małkiewicz, M. Ostrowski, Reshmi Mukherjee, Mario Meucci, Tarek M. Hassan, W. Bednarek, Rodolfo Canestrari, Stefan Wagner, Teresa Mineo, N. Karlsson, M. Tluczykont, A. E. Suárez, David Kieda, R. Steenkamp, Grzegorz Kowal, C. Gasq, Loukas Vlahos, Kathrin Egberts, K. Kosack, A. D. Supanitsky, Hernán Asorey, Adriano Ghedina, Frank M. Rieger, P. Zychowski, J. Bähr, P. Wegner, P. Ziółkowski, Shigeto Kabuki, G. Papyan, Dario Hrupec, P. T. O'Brien, Oscar Blanch, Tsunefumi Mizuno, Robert Wagner, Thomas Lohse, Susumu Inoue, U. Straumann, J. Kushida, Jose Luis Contreras, C. Maña, Matteo Cerruti, P. Antoranz, Ll. Font, R. Sugawara, M. Casiraghi, C. Kalkuhl, Subir Sarkar, Jelena Aleksić, Juan Cortina, J. Pallota, L. Brunetti, Petar Temnikov, Tomasz Bulik, L. O. Takalo, G. Vasileiadis, Riccardo Rando, J. H. Buckley, V. de Souza, Sera Markoff, G. Pareschi, P. Kostka, J. Grube, M. Tokarz, Manel Errando, David Fink, C. Barbier, Marek Sikora, J. P. Tavernet, Yasushi Fukazawa, Werner Hofmann, K. Takahashi, B. Wagner, David Paneque, M. Barcelo, L. Guglielmi, S. Royer, Rika Hagiwara, Nestor Mirabal, R. A. Cameron, R. Walter, G. De La Vega, Jim Hinton, Garret Cotter, M. Sofo Haro, Peter Walter, R. Gredig, S. Vorobiov, A. Bouvier, B. Lieunard, V. A. Kudryavtsev, Mauro Ghigo, John H. Seiradakis, Konrad Bernlöhr, M. de Naurois, A. Yoshida, F. Sánchez, K. Katarzyński, C. Veyssiere, Leszek Bogacz, B. Moal, A. Reimer, J. Koziol, Thomas J. Maccarone, G. Pojmanski, E. Carmona, C. Bauer, Andreu Sanuy, V. J. Guarino, Marc Ribó, Vincenzo Testa, H. Huan, C. Jablonski, Tsuguya Naito, C. Lavalley, M. Karczewski, G. Agnetta, Giovanni Bonanno, A. Zajczyk, C. Díaz, J. Kasperek, E. Lorenz, P. Vincent, K. Saito, S. Cazaux, S. Selmane, B. Kȩdziora, Y. A. Gallant, Serena Mattiazzo, Emilio Molinari, N. La Barbera, Hidetoshi Kubo, M. K. Daniel, Katsuaki Asano, Tanyu Bonev, A. Cillis, L. A. Otero, Gernot Maier, M. Cieślar, M. Ciesielska, Shuichi Gunji, E. Gianakaki, E. M. de Gouveia Dal Pino, Apostolos Mastichiadis, S. P. Wakely, G. La Rosa, C. Boutonnet, V. Zitelli, I. Ochoa, M. Raue, E. Fillin-Martino, Ingomar Allekotte, J. P. Vialle, G. Vallejo, Ryo Yamazaki, C. Tchernin, Anna Barnacka, Andrea Santangelo, P. Ringegni, James Chiang, Aya Bamba, B. Giebels, A. Förster, Heide Costantini, N. Galante, R. S. Warwick, Michiko Ohishi, O. Reimann, Guillaume Dubus, K. Kodani, Olga Botner, Andreas Zech, Paolo De Coppi, Louis Antonelli, A. Pepato, A. De Angelis, M. Scarcioffolo, E. M. Santos, Christoph Deil, T. Bird, T. Kneiske, Daniele Spiga, B. Behera, Jürgen Knödlseder, L. Rob, G. Pedaletti, P. Munar, J.F. Glicenstein, Aris Karastergiou, A. Djannati-Ataï, B. Courty, R. A. Ong, J. Dick, Paolo Conconi, S. Giarrusso, G. Maneva, E. Salazar, A. Saggion, E. Birsin, Adrian Biland, Markus Gaug, Gino Tosti, M. Á. Sánchez Conde, Abelardo Moralejo, Chad Finley, J. D. Ponz, Hideaki Katagiri, A. M. Lopez, G. Pühlhofer, M. Yonetani, Emmanuel Moulin, E. Aliu, R. Kankanyan, Hiroyasu Tajima, F. Mirabel, Jan Conrad, R. Sternberger, Diego F. Torres, P.H. Carton, P.-O. Petrucci, L. Sapozhnikov, A. Schulz, J. Krause, B. De Lotto, J. P. Finley, J. Boix, Volker Beckmann, S. Klepser, Jun Kakuwa, Dimitris Balis, Hironori Matsumoto, R. Welsing, Matthew R. Orr, Dominique Durand, O. Luz, Nina Nowak, J. M. Illa, A. Aravantinos, P. Romano, A. Oziȩbło, Alessandro Carosi, Keith Bechtol, Elisa Prandini, S. Cavazzani, A. Zagdański, Francesca Volpe, Helene Sol, Ryan Heller, S. Vercellone, A. Bonardi, D. Garrido, Jose Miguel Miranda, Jürgen Barnstedt, Hiroshi Muraishi, Nathan Smith, D. Naumann, German Martinez, F.C. Antico, Kenji Toma, B. Cerruti, S. Couturier, R. Bühler, A. Gadola, F. Guilloux, M. Paz Arribas, F. Dubois, Victor Zabalza, A. G. Akhperjanian, Eckhard Kendziorra, Tomonori Totani, Universitat de Barcelona, Laboratoire Leprince-Ringuet (LLR), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), APC - Astrophysique des Hautes Energies (APC - AHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Dipartimento di Astronomia, Universita degli Studi di Bologna, Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), CTA, High Energy Astrophys. & Astropart. Phys (API, FNWI), CTA Collaboration, Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Dipartimento di Astronomia, Universita degli Studi di Bologna, Università di Bologna [Bologna] (UNIBO)-Università di Bologna [Bologna] (UNIBO), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Aix Marseille Université (AMU), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Annecy de Physique des Particules (LAPP/Laboratoire d'Annecy-le-Vieux de Physique des Particules), M., Acti, G., Agnetta, F., Aharonian, A., Akhperjanian, J., Aleksic, E., Aliu, D., Allan, I., Allekotte, F., Antico, L. A., Antonelli, P., Antoranz, A., Aravantino, T., Arlen, H., Arnaldi, S., Artmann, K., Asano, H., Asorey, J., Baehr, A., Bai, C., Baixera, S., Bajtlik, D., Bali, A., Bamba, C., Barbier, M., Barcelo, A., Barnacka, J., Barnstedt, U. B., De, J. A., Barrio, S., Basso, D., Bastieri, C., Bauer, J., Becerra, Y., Becherini, K., Bechtol, J., Becker, V., Beckmann, W., Bednarek, B., Behera, M., Beilicke, M., Belluso, M., Benallou, W., Benbow, J., Berdugo, K., Berger, T., Bernardino, K., Bernloehr, A., Biland, S., Billotta, T., Bird, E., Birsin, Bissaldi, Elisabetta, S., Blake, O., Blanch, A. A., Bobkov, L., Bogacz, M., Bogdan, C., Boisson, J., Boix, J., Bolmont, G., Bonanno, A., Bonardi, T., Bonev, J., Borkowski, O., Botner, A., Bottani, M., Bourgeat, C., Boutonnet, A., Bouvier, S., Brau Nogue, I., Braun, T., Bretz, M. S., Brigg, P., Brun, L., Brunetti, H., Buckley, V., Bugaev, R., Buehler, T., Bulik, G., Busetto, S., Buson, K., Byrum, M., Caille, R., Cameron, R., Canestrari, S., Cantu, E., Carmona, A., Carosi, J., Carr, P. H., Carton, M., Casiraghi, H., Castarede, O., Catalano, S., Cavazzani, S., Cazaux, B., Cerruti, M., Cerruti, M., Chadwick, J., Chiang, M., Chikawa, M., Cieslar, M., Ciesielska, A., Cilli, C., Clerc, P., Colin, J., Colome, M., Compin, P., Conconi, V., Connaughton, J., Conrad, J. L., Contrera, P., Coppi, M., Corlier, P., Corona, O., Corpace, D., Corti, J., Cortina, H., Costantini, G., Cotter, B., Courty, S., Couturier, S., Covino, J., Croston, G., Cusumano, M. K., Daniel, F., Dazzi, A., Deangeli, E. d., Cea, E. M., De, O. d., Jager, I. d., La, G. D., La, B. D., Lotto, M. d., Nauroi, E. d., Ona, V. d., Souza, B., Decerprit, C., Deil, E., Delagne, G., Deleglise, C., Delgado, T., Dettlaff, A. D., Paolo, F. D., Pierro, C., Diaz, J., Dick, H., Dickinson, S. 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Subjects
Next generation Cherenkov telescopes, Ciencias Astronómicas, IACT, next generation Cherenkov telescopes, 01 natural sciences, 7. Clean energy, Design concepts, Ground based gamma ray astronomy, Observatory, Gamma ray astronomy, Instruments astronòmics, Ingeniería Aeronáutica, 010303 astronomy & astrophysics, media_common, Physics, Bursts, Radiation, Settore FIS/01 - Fisica Sperimentale, Astrophysics::Instrumentation and Methods for Astrophysics, Gamma-ray astronomy, Particles, Electrónica, Física nuclear, Magic Telescope, design concepts, Electricidad, Simulation, GAMMA-RAY PULSARS, Optical-System, [PHYS.ASTR.IM]Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], ATMOSPHERIC CHERENKOV TELESCOPE, VHE Gamma ray, QUASAR, cosmic rays, media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, Cosmic ray, Partícules (Física nuclear), 0103 physical sciences, Astronomia de raigs gamma, 14. Life underwater, 1St Detection, Cherenkov radiation, Particles (Nuclear physics), Astroparticle physics, Telescopis, 010308 nuclear & particles physics, Institut für Physik und Astronomie, Astronomy, Astronomical instruments, Astronomy and Astrophysics, ASTROFÍSICA, Cosmic-Rays, Cherenkov Telescope Array, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Induced Air-Showers, Space and Planetary Science, Sky, Next generation Cherenkov telescope, Tev, ground based gamma ray astronomy, Telescopes
Abstract

Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA., La lista completa de autores que integran el documento puede consultarse en el archivo., Departamento de Aeronáutica, Facultad de Ingeniería, Instituto Argentino de Radioastronomía, Facultad de Ciencias Astronómicas y Geofísicas

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29. The Spectral Evolution of the First Galaxies. III. Simulated James Webb Space Telescope Spectra of Reionization-epoch Galaxies with Lyman-continuum Leakage.

Author

Erik Zackrisson, Christian Binggeli, Kristian Finlator, Nickolay Y. Gnedin, Jan-Pieter Paardekooper, Ikkoh Shimizu, Akio K. Inoue, Hannes Jensen, Genoveva Micheva, Sadegh Khochfar, and Claudio Dalla Vecchia

Subjects
GALACTIC evolution, GALACTIC redshift, STELLAR populations, STELLAR evolution, IONIZATION (Atomic physics)
Abstract

Using four different suites of cosmological simulations, we generate synthetic spectra for galaxies with different Lyman-continuum escape fractions (fesc) at redshifts –9, in the rest-frame wavelength range relevant for the James Webb Space Telescope (JWST) NIRSpec instrument. By investigating the effects of realistic star formation histories and metallicity distributions on the EW(Hβ)–β diagram (previously proposed as a tool for identifying galaxies with very high fesc), we find that neither of these effects are likely to jeopardize the identification of galaxies with extreme Lyman-continuum leakage. Based on our models, we expect that essentially all galaxies that exhibit rest-frame Å to have . Incorrect assumptions concerning the ionizing fluxes of stellar populations or the dust properties of galaxies can in principle bias the selection, but substantial model deficiencies of this type should at the same time be evident from offsets in the observed distribution of galaxies in the EW(Hβ)–β diagram compared to the simulated distribution. Such offsets would thereby allow JWST/NIRSpec measurements of these observables to serve as input for further model refinement. [ABSTRACT FROM AUTHOR]

Published
2017
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