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31 results on '"Stefan Rosén"'

1. Mutual Neutralization in Li++H−/D− and Na++H−/D− Collisions: Implications of Experimental Results for Non-LTE Modeling of Stellar Spectra

Author

Anish M. Amarsi, Henning T. Schmidt, Henrik Cederquist, Jon Grumer, Paul S. Barklem, Stefan Rosén, Gustav Eklund, MingChao Ji, and Henning Zettergren

Subjects
Physics, Atomic Physics (physics.atom-ph), Stellar atmosphere, FOS: Physical sciences, Astronomy and Astrophysics, Astronomical spectroscopy, Neutralization, Physics - Atomic Physics, Ion, Reaction rate, Astrophysics - Solar and Stellar Astrophysics, Computer Science::Systems and Control, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, Atomic physics, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

Advances in merged-beams instruments have allowed experimental studies of the mutual neutralisation (MN) processes in collisions of both Li$^+$ and Na$^+$ ions with D$^-$ at energies below 1 eV. These experimental results place constraints on theoretical predictions of MN processes of Li$^+$ and Na$^+$ with H$^-$, important for non-LTE modelling of Li and Na spectra in late-type stars. We compare experimental results with calculations for methods typically used to calculate MN processes, namely the full quantum (FQ) approach, and asymptotic model approaches based on the linear combination of atomic orbitals (LCAO) and semi-empirical (SE) methods for deriving couplings. It is found that FQ calculations compare best overall with the experiments, followed by the LCAO, and the SE approaches. The experimental results together with the theoretical calculations, allow us to investigate the effects on modelled spectra and derived abundances and their uncertainties arising from uncertainties in the MN rates. Numerical experiments in a large grid of 1D model atmospheres, and a smaller set of 3D models, indicate that neglect of MN can lead to abundance errors of up to 0.1 dex (26\%) for Li at low metallicity, and 0.2 dex (58\%) for Na at high metallicity, while the uncertainties in the relevant MN rates as constrained by experiments correspond to uncertainties in abundances of much less than 0.01~dex (2\%). This agreement for simple atoms gives confidence in the FQ, LCAO and SE model approaches to be able to predict MN with the accuracy required for non-LTE modelling in stellar atmospheres., Comment: Accepted by ApJ

Published
2021

2. X-ray-selected broad absorption line quasi-stellar objects

Author

Silvia Mateos, Stefan Rosén, A. Corral, María Teresa Ceballos, J. Ebrero, M. G. Watson, Jonathan Tedds, Francisco J. Carrera, Axel Schwope, M. Symeonidis, M. J. Page, Alina Streblyanska, Mirko Krumpe, P. Esquej, German Research Foundation, European Commission, Ministerio de Economía y Competitividad (España), and Science and Technology Facilities Council (UK)

Subjects
Physics, absorption lines [Quasars], 010308 nuclear & particles physics, Young stellar object, Member states, Library science, Quasars: absorption lines, Astronomy and Astrophysics, 01 natural sciences, galaxies [X-rays], law.invention, Telescope, X-rays: galaxies, Space and Planetary Science, law, 0103 physical sciences, 010303 astronomy & astrophysics
Abstract

We study a sample of six X-ray-selected broad absorption line (BAL) quasi-stellar objects (QSOs) from the XMM-Newton Wide Angle Survey. All six objects are classified as BALQSOs using the classic balnicity index, and together they form the largest sample of X-ray-selected BALQSOs. We find evidence for absorption in the X-ray spectra of all six objects. An ionized absorption model applied to an X-ray spectral shape that would be typical for non-BAL QSOs (a power law with energy index ¿ = 0.98) provides acceptable fits to the X-ray spectra of all six objects. The optical to X-ray spectral indices, ¿OX, of the X-ray-selected BALQSOs, have a mean value of = 1.69 ± 0.05, which is similar to that found for X-ray-selected and optically selected non-BAL QSOs of a similar ultraviolet luminosity. In contrast, optically selected BALQSOs typically have much larger ¿OX and so are characterized as being X-ray weak. The results imply that X-ray selection yields intrinsically X-ray bright BALQSOs, but their X-ray spectra are absorbed by a similar degree to that seen in optically selected BALQSO samples; X-ray absorption appears to be ubiquitous in BALQSOs, but X-ray weakness is not. We argue that BALQSOs sit at one end of a spectrum of X-ray absorption properties in QSOs related to the degree of ultraviolet absorption in C IV 1550 Å., MJP acknowledges financial support from the UK Science and Technology Facilities Council. FJC and SM acknowledge financial support through grant AYA2015-64346-C2-1-P (MINECO/FEDER). MTC acknowledges support by the Spanish Programma Nacional de Astronomia y Astrofisica under grant AYA2009-08059. MK acknowledges support by DFG grant KR 3338/3-1.

Published
2016

3. The measurement errors in the Swift-UVOT and XMM-OM

Author

N. P. M. Kuin and Stefan Rosén

Subjects
Physics, Photon, Observational error, Swift Gamma-Ray Burst Mission, Astrophysics::High Energy Astrophysical Phenomena, Instrumentation, Detector, Physics::Optics, Astronomy and Astrophysics, Astrophysics, Poisson distribution, Photon counting, Binomial distribution, symbols.namesake, Space and Planetary Science, symbols
Abstract

The probability of photon measurement in some photon counting instrumentation, such as the Optical Monitor on the XMM-Newton satellite, and the UVOT on the Swift satellite, does not follow a Poisson distribution due to the detector characteristics, but a Binomial distribution. For a single-pixel approximation, an expression was derived for the incident countrate as a function of the measured count rate by Fordham, Moorhead and Galbraith (2000). We show that the measured countrate error is binomial, and extend their formalism to derive the error in the incident count rate. The error on the incident count rate at large count rates is larger than the Poisson-error of the incident count rate.

Published
2007

4. Swift observations of GRB 050712

Author

Neil Gehrels, M. J. Page, Shiho Kobayashi, Dirk Grupe, P. W. A. Roming, K. O. Mason, J. A. Nousek, M. de Pasquale, A. A. Breeveld, T. S. Poole, David N. Burrows, Silvia Zane, Bing Zhang, Stefan Rosén, and H. A. Krimm

Subjects
Physics, Swift, Line-of-sight, Epoch (reference date), Astrophysics::High Energy Astrophysical Phenomena, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, law.invention, Space and Planetary Science, law, Astrophysics::Solar and Stellar Astrophysics, Gamma-ray burst, Ejecta, Absorption (electromagnetic radiation), computer, computer.programming_language, Flare
Abstract

We present the results of X-ray and optical observations of GRB050712 performed by Swift. The X-ray lightcurve of this burst exhibits episodes of flares in the first 1000s, the same epoch at which the UVOT detected an optical counterpart. A shallow X-ray decay, with a decay slope of -0.73, followed and lasted ~70ks. This behaviour can be explained in terms of activity of GRB 'inner engine', with the possibility of that the last flare is caused by the interaction of the ejecta with the surrounding medium. We also find interesting spectral parameters for the X-ray emission. In particular, data suggest the presence of an intrinsic absorption in the first 1000s, which can be explained if circumbust medium clouds lie along the line of sight.

Published
2006

5. Dissociative recombination of C$_{\sf 2}{{\sf H}_{\sf 3}}\!^+$

Author

J. Semaniak, Stefan Rosén, Mats Larsson, S. Kalhori, M. af Ugglas, Albert A. Viggiano, Susan T. Arnold, and A. M. Derkatch

Subjects
Physics, Range (particle radiation), Electron energy, Space and Planetary Science, Branching fraction, Astronomy and Astrophysics, Atomic physics, Dissociative recombination, Ion
Abstract

We have studied the vibrationally relaxed C2H + ion in the heavy - ion storage ring CRYRING in Stockholm. We measured the dissociative recombination absolute cross section over center-of-mass energies in the range between 0 and 0.1 eV by scanning the electron energy. The rate of dierent neutral product channels of dissociative recombination was measured. We found the three-body chan- nel C2H + H + H, with a branching ratio of 59%, to be the dominant one. Finally, we compare C2H + and C2H + (Derkatch et al. 1999) results.

Published
2002

6. Searching for highly obscured AGN in the XMM-Newton serendipitous source catalog

Author

Piero Ranalli, K. L. Page, John P. Pye, G. C. Stewart, M. G. Watson, Giorgio Lanzuisi, I. Georgantopoulos, G. Mountrichas, Elias Koulouridis, Amalia Corral, Stefan Rosén, A. Akylas, Corral, A, Georgantopoulos, I., Watson, M.G., Rosen, S.R., Koulouridis, E., Page, K.L., Ranalli, P., Lanzuisi, G., Mountrichas, G., Akylas, A., Stewart, G.C., and Pye, J.P.

Subjects
Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Active galactic nucleus, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, Quasar, Galaxies: active, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astronomy and Astrophysic, X-rays: general, Redshift, Spectral line, Wavelength, Space and Planetary Science, Astrophysics - High Energy Astrophysical Phenomena, Survey, X-rays: diffuse background, Equivalent width, Luminosity function, Astrophysics::Galaxy Astrophysics, Line (formation)
Abstract

The majority of active galactic nuclei (AGN) are obscured by large amounts of absorbing material that makes them invisible at many wavelengths. X-rays, given their penetrating power, provide the most secure way for finding these AGN. The XMM-Newton serendipitous source catalog is the largest catalog of X-ray sources ever produced; it contains about half a million detections. These sources are mostly AGN. We have derived X-ray spectral fits for very many 3XMM-DR4 sources ($\gtrsim$ 114 000 observations, corresponding to $\sim$ 77 000 unique sources), which contain more than 50 source photons per detector. Here, we use a subsample of $\simeq$ 1000 AGN in the footprint of the SDSS area (covering 120 deg$^2$) with available spectroscopic redshifts. We searched for highly obscured AGN by applying an automated selection technique based on X-ray spectral analysis that is capable of efficiently selecting AGN. The selection is based on the presence of either a) flat rest-frame spectra; b) flat observed spectra; c) an absorption turnover, indicative of a high rest-frame column density; or d) an Fe K$��$ line with an equivalent width > 500 eV. We found 81 highly obscured candidate sources. Subsequent detailed manual spectral fits revealed that 28 of them are heavily absorbed by column densities higher than 10$^{23}$ cm$^{-2}$. Of these 28 AGN, 15 are candidate Compton-thick AGN on the basis of either a high column density, consistent within the 90% confidence level with N$_{\rm H}$ $>$10$^{24}$ cm$^{-2}$, or a large equivalent width (>500 eV) of the Fe K$��$ line. Another six are associated with near-Compton-thick AGN with column densities of $\sim$ 5$\times$10$^{23}$ cm$^{-2}$. A combination of selection criteria a) and c) for low-quality spectra, and a) and d) for medium- to high-quality spectra, pinpoint highly absorbed AGN with an efficiency of 80%., 18 pages, 10 figures, accepted for publication in A&A

Published
2014
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7. Dissociative Recombination of HCNH + : Absolute Cross‐Sections and Branching Ratios

Author

A. M. Derkatch, M. Larsson, A. Neau, Fredrik Hellberg, Stefan Rosén, Richard D. Thomas, Boris F. Minaev, Jacek Semaniak, M. af Ugglas, Håkan Danared, and A. Paál

Subjects
Physics, Thermal equilibrium, Space and Planetary Science, Elementary reaction, Analytical chemistry, Astronomy and Astrophysics, Heavy ion, Complete active space, Methods laboratory, Atomic physics, Branching (polymer chemistry), Dissociative recombination, Dissociation (chemistry)
Abstract

The dissociative recombination (DR) of HCNH+ has been studied at the heavy ion storage ring CRYRING. The absolute cross-sections have been measured between 0.01 meV and 0.2 eV collision energy. The DR thermal rate coefficients, which can be directly applied to modeling environments in thermal equilibrium, have been found to be 2.8 × 10-7(300/T)0.65 at temperatures T < 1000 K. The DR branching fractions have been measured for different dissociation channels: HCN(HNC)+H (0.67), CN+H2 (0.0), and CN+H+H (0.33) at collision energy of 0 eV. The results show that DR of HCNH+ is an efficient process leading to formation of HCN or HNC isomers, whereas CN production is dominated by three-body fragmentation. The multireference self-consistent calculations in a complete active space have been used as a common background for all studied species and reaction paths. Three-body fragmentation CN+H+H has been considered in one concerted elementary reaction step.

Published
2001

8. Multiwavelength monitoring of QS Tel

Author

J. P. D. Mittaz, D. de Martino, Steve B. Howell, Matthew R. Burleigh, Martin M. Sirk, J. F. Rainger, D. A. H. Buckley, Richard Lieu, and Stefan Rosén

Subjects
Physics, Brightness, Zeeman effect, Astronomy, White dwarf, Magnetosphere, Astronomy and Astrophysics, Astrophysics, Effective temperature, Light curve, symbols.namesake, Space and Planetary Science, Extreme ultraviolet, ROSAT, symbols
Abstract

Multiwavelength monitoring observations of the AM Her system, QS Tel, are presented, the centrepiece being a coordinated campaign with the ASCA, EUVE and HST satellites and optical observations on 1996 September 28–29. The star was initially observed in an intermediate brightness, single pole state in 1996 April by ROSAT. However two EUVE snapshots of the system in August found it in a deep low state, the light curves appearing to retain a bright and faint phase morphology although the bright interval showed significant phase drifts compared with the earlier ROSAT data. At this time, the system appeared optically bright, while polarimetry pointed to one active pole. A modest recovery of intensity, albeit accompanied by an apparently chaotic extreme ultraviolet (EUV) light curve, was subsequently recorded during the coordinated run in late September. This brightening was confirmed by a second ROSAT pointing in early October, although the EUV brightening is matched by a marked decay in its optical output. These observations, all of which found the system in a fainter EUV state than seen in 1993, add to the catalogue of accretion mode behaviour in QS Tel. However, as yet, the data base of observations does not allow us to establish whether the accretion mode is dictated by accretion-rate dependent penetration of the magnetosphere or asynchronous rotation. The ASCA spectrum obtained during the coordinated observation is adequately described by a thermal spectrum with a temperature of about 4.4 keV and an absorbing column density of less than 8×1020 cm−2. At the same time, the 1150–2600 A UV HST spectrum shows a strong, broad Lyα absorption profile which we attribute to the white dwarf. We infer an effective temperature of 16 000–19 000 K and a mass between 0.5 and 0.93 M⊙ for the white dwarf, at least some of the uncertainty arising because the profile is very probably contaminated and broadened by Zeeman features. The orbital variation seen by HST can be matched by a blackbody-like spectrum with a temperature above 24 000 K. The near UV part of the spectrum contains evidence of phase-variable cyclotron harmonics.

Published
2001

9. Branching Fractions in Dissociative Recombination of \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $\mathrm{CH}\,^{+}_{2}$ \end{document}

Author

Gordon H. Dunn, Stefan Rosén, Sheldon Datz, N. Djurić, Robert Peverall, A. Le Padellec, M. Larsson, Åsa Larson, Håkan Danared, Jacek Semaniak, and C. Strömholm

Subjects
chemistry.chemical_classification, Physics, Molecular cloud, Analytical chemistry, Astronomy and Astrophysics, Electron, Dissociation (chemistry), Cosmochemistry, chemistry, Space and Planetary Science, Compounds of carbon, Atomic physics, Recombination, Dissociative recombination, Excitation
Abstract

The absolute cross section and branching ratios for dissociative recombination of CH -->+2 with electrons have been measured by means of the heavy-ion storage ring CRYRING. Contrary to what has been previously believed, recombination of CH -->+2 is dominated by the three-body channel C + H + H (63%), whereas breakup into the CH + H and C + H2 channels occurs with branching ratios of 25% and 12%, respectively. The thermal rate coefficient for dissociative recombination at 300 K is 6.4 × 10-7 cm3 s-1, which is higher by a factor of 2.5 than the value used in modeling dark molecular clouds. The low CH production and the high production of energetic carbon atoms could be favorable factors for the turbulence model to explain the large abundance of interstellar CH+. The cross section for dissociative excitation was also measured and found to be in good agreement with results from a crossed electron-ion beam experiment.

Published
1998

10. Phase-resolved Hubble Space Telescope ultraviolet spectroscopy of V795 Her

Author

Steve B. Howell, Stefan Rosén, Keith O. Mason, Janet E. Drew, and Raman K. Prinja

Subjects
Physics, Ultraviolet visible spectroscopy, Space and Planetary Science, Hubble space telescope, Phase (waves), Astronomy, Astronomy and Astrophysics, Astrophysics
Abstract

‘The definitive version is available at www.blackwell-synergy.com.’ Copyright Blackwell Publishing. DOI: 10.1046/j.1365-8711.1998.01844.x [Full text of this article is not available in the UHRA]

Published
1998

11. Dissociative Recombination and Excitation of \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $\mathrm{CH}\,^{+}_{5}$ \end{document} : Absolute Cross Sections and Branching Fractions

Author

A. Le Padellec, M. Larsson, Håkan Danared, N. Djurić, Gordon H. Dunn, C. Strömholm, Sheldon Datz, Stefan Rosén, Jacek Semaniak, Åsa Larson, and Robert Peverall

Subjects
Physics, Interstellar cloud, Astronomy and Astrophysics, Branching (polymer chemistry), Dissociation (chemistry), Afterglow, symbols.namesake, Space and Planetary Science, symbols, Langmuir probe, Atomic physics, Recombination, Excitation, Dissociative recombination
Abstract

The heavy-ion storage ring CRYRING was used to measure the absolute dissociative recombination and dissociative excitation cross sections for collision energies below 50 eV. Deduced thermal rates coefficients are consistent with previous beams data but are lower by a factor of 3 than the rates measured by means of the flowing afterglow Langmuir probe technique. A resonant structure in dissociative recombination cross section was found at 9 eV. We have determined the branching fractions in DR of CH+5 below 0.2 eV. The branching is dominated by three-body CH3 + H + H and CH2 + H2 + H dissociation channels, which occur with branching ratios of ≈ 0.7 and ≈ 0.2, respectively; thus methane is a minor species among dissociation products. Both the measured absolute cross sections and branching in dissociative recombination of CH+5 can have important implications for the models of dense interstellar clouds and abundance of CH2, CH3 and CH4 in these media.

Published
1998

12. Spin and beat phenomena in time-resolved Hubble Space Telescope UV spectroscopy of PQ Gem

Author

Stefan Rosén, K. O. Mason, D. Stavroyiannopoulos, M. G. Watson, and Steve B. Howell

Subjects
Physics, Spectral power distribution, Faint Object Spectrograph, Astronomy, Beat (acoustics), White dwarf, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Light curve, Wavelength, Intermediate polar, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, Emission spectrum, Astrophysics::Galaxy Astrophysics
Abstract

Results of the first low-resolution (6 A), time-resolved Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) observation of the prototypical strong-field intermediate polar system, PQ Gem, are presented. The AAl150-2600 continuum light curve is dominated by the 13.9-min rotational signature of the white dwarf at all UV wavelengths covered, with a broadly constant fractional modulation depth. The rotational profile contains a dip which is deepest in the far-UVand which we believe, like its X-ray counterpart, is caused by stream occultation of the white dwarf. The continuum and emission-line fluxes are also modulated on the 14.5-min beat period but, remarkably, vary in antiphase. This complex behaviour facilitates the identification and partial isolation of two spin­ modulated spectral components and a beat component. One spin component has a blue spectral distribution whose temperature is :$ 50000 K if no allowance is made for the absorbing effects of the stream, but may be much hotter (consistent with earlier X-ray estimates) if, as seems likely, the absorber is not completely optically thick. The other spin-modulated component has a red spectral distribution whose temperature (:$ 10000 K) and luminosity probably associate it with the magnetospheric accretion flow itself. The beat continuum component has a temperature in the region of 17 000 K and appears to be radiated by a region whose size is comparable to that of the white dwarf. The beat pulsation in the emission lines may also originate from a region of similar dimensions. We consider one- and two-site hypotheses to explain the antiphased line and continuum beat modulations, but are unable to arrive at a convincing solution.

Published
1997

13. The intricate optical line behaviour of the nova-like system V795 Herculis

Author

Stefan Rosén, Andrew J. King, R. J. Dickinson, Coel Hellier, Raman K. Prinja, and Keith Horne

Subjects
Physics, Accretion (meteorology), Astrophysics::High Energy Astrophysical Phenomena, Newtonian telescope, Astronomy, Cataclysmic variable star, Balmer series, White dwarf, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Redshift, law.invention, symbols.namesake, Intermediate polar, Space and Planetary Science, law, symbols, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Emission spectrum, Astrophysics::Galaxy Astrophysics
Abstract

The optical emission-line properties of the nova-like cataclysmic variable V795 Her are studied using high-resolution Isaac Newton Telescope [Intermediate Dispersion Spectrograph (IDS) and Faint-Object Spectrograph (FOS)] data secured during 1994 June. The observed Balmer and He emission lines, and He I lambda 4471 absorption, modulate on the 2.6-h orbital period of this system. The detailed nature of these changes is complex, however, with the incidence of separate low- and high-velocity fluctuations. Low-intensity 'S'-wave features are apparent in the blue and red outer wings of the Balmer lines, extending to similar to +/- 1600 km s(-1). These phased changes are seen as two synchronized components with net blueshift and redshift. The Balmer profiles are also affected by absorption which dominates during the first part of the cycle. We propose an empirical interpretation of this behaviour in terms of a single broad emission feature which follows a high-velocity 'S' wave, plus a superimposed, sympathetically phased, absorption component. The associated physical interpretation is that of a gas stream (seen in absorption) that overflows the outer accretion disc and re-impacts on the inner disc regions.The 'double-peaked' inner cores of the Balmer lines have relatively fixed central velocities, and do not reveal an obvious 'S'-wave variation. This inner-core emission likely arises from material located in the outer regions of the accretion disc. An similar to 10 per cent variation is present in the continuum flux of V795 Her, restricted to less than 25 per cent of the system orbit. We find some correspondence between the overall optical emission changes and those found by us in the UV resonance lines of V795 Her in a separate study based on Hubble Space Telescope data.We discuss our observational results in terms of magnetic white dwarf and disc-overflow gas stream scenarios. Constraints are presented that argue against recently proposed models for V795 Her which invoke channelled accretion columns flowing on to a synchronously rotating white dwarf. Disc-overflow model simulations are presented which quantitatively account for several of the observed dynamical properties of V795 Her. There remain some discrepancies, however, which call for a more detailed physical model.

Published
1997

14. Infrared spectroscopy of cataclysmic variables -- II. Intermediate polars

Author

Stefan Rosén, S. R. Duck, T. R. Marsh, and V. S. Dhillon

Subjects
Physics, Infrared, Astrophysics (astro-ph), Cyclotron, FOS: Physical sciences, Infrared spectroscopy, Astronomy, Astronomy and Astrophysics, Astrophysics, Spectral line, law.invention, Magnetic field, Intermediate polar, Space and Planetary Science, law, Emission spectrum, Circular polarization
Abstract

We present infrared (0.97-2.45 micron) spectra of the intermediate polars PQ Gem (RE0751+14), BG CMi and EX Hya. The spectra show strong Paschen, Brackett and HeI emission lines from the accretion disc/stream. The infrared continua of PQ Gem and BG CMi can be represented by blackbodies of temperatures 4500 K and 5100 K, respectively, or by power-laws of the form f_nu \propto nu^(0.6,0.9), respectively, and show no evidence of secondary star features. The continuum of EX Hya is doiminated by water bands from the red-dwarf secondary star, which has a spectral type of ~M3. Despite showing circular polarization, PQ Gem and BG CMi show no evidence for cyclotron humps and hence we are unable to measure their magnetic field strengths; any cyclotron emission present must contribute less than ~3 per cent of the infrared continuum flux., 7 pages, 2 figures

Published
1997

15. Introducing the CTA concept

Author

A. Mathieu, R. G. Wagner, K. Panagiotidis, S Rosier Lees, Julien Rousselle, M. Gómez Berisso, Michela Uslenghi, Stephen Maxfield, R. C. Shellard, Ivica Puljak, T. Le Flour, Thomas Schanz, Tobias C. Walther, Juanan Aguilar, Pierre Colin, M. Chikawa, N. Fouque, Mosè Mariotti, G. Fontaine, Merja Tornikoski, V. Diez-Blanco, Enrico Giro, A. Krepps, G. Koss, J. M. Martin, Sergio Billotta, E. de Oña Wilhelmi, Keitaro Takahashi, S. Buson, P. Brook, S. Steiner, M. Dyrda, Joseph Silk, Sera Markoff, P. Lubinski, U. Schwanke, Sauvik Bhattacharyya, J. Ripken, T. Haubold, C. Zurbach, H. Wetteskind, R. Hermel, J. Darling, J. Nicolau-Kukliński, Konstancja Satalecka, M. Videla, Stefan Funk, P. Conconi, S. Bajtlik, Lukasz Stawarz, J. M. Paredes, K. Reitberger, Stefan Wagner, Teresa Mineo, David Kieda, G. Pareschi, Shigeto Kabuki, Makoto Sawada, Antonio Stamerra, Rodolfo Canestrari, N. Baby, G. Crimi, P. Kostka, J. Grube, R. Zanin, I. K. Kominis, L. Mc Comb, R. Sternberger, M. Fesquet, M. Tokarz, David Fink, Daniela Dorner, N. Hamer Heras, A. Moralejo Olaizola, M. de Naurois, Diego F. Torres, Claes Fransson, K. Nishijima, Yutaka Fujita, L. Fresnillo, B. García, R. Kossakowski, A. Masserot, H. von Gunten, Alkiviadis F. Bais, Ciro Bigongiari, A. Saggion, G. Papyan, I. Mrusek, K. Farakos, J. Michałowski, A. Franckowiak, Fernando Martinez, M. Doert, R. Wawrzaszek, Michele Doro, L. Sapozhnikov, Claudia Lavalley, D. Thuermann, A.A. Zdziarski, Cristina Knapic, Karen Byrum, N. Neyroud, Petr Schovanek, W. Domainko, D. Kastana, E. Birsin, Adrian Biland, F. Sánchez, Alexandre Marcowith, M. Errando, R. L. C. Starling, J. Schultze, A. Weinstein, B. B. Singh, Yassir Moudden, Jelena Aleksić, C. L. Naumann, V. Waegebaert, M. Shayduk, U. F. Katz, Gianpiero Tagliaferri, M. Schroedter, A. Vollhardt, O. Reimann, Hideyuki Ohoka, Vincenzo Testa, C. Jablonski, Tsuguya Naito, J. Schäfer, Stavros Maltezos, A. Wierzcholska, P. Wawer, L. Nellen, F. Mirabel, Tatsuo Yoshida, P. H. Carton, Nina Nowak, L. Platos, Riccardo Rando, P. P. Krueger, R. Wischnewski, W. Romaszkan, E. Fede, Martino Marisaldi, Markus Gaug, Richard Willingale, J. H. Buckley, U. De AlmeidaBarres, J. Knapp, Saverio Lombardi, D. della Volpe, A. Herrero, A. Bottani, E. Delagnes, Martin J. Hardcastle, C. Morello, Anna Lipniacka, T. Greenshaw, M. Renaud, Giancarlo Cusumano, Jonathan Biteau, M. Sowiński, J. R. T. de Mello Neto, T. B. Humensky, Michael G. Richer, G. Parks, G. Grasseau, H. Baba, Gino Tosti, Damir Lelas, H. Krawzcynski, David Paneque, M. Barcelo, R. Dickherber, P. Ferrando, Shinji Hara, D. Florin, Hideaki Katagiri, T. Shibata, Fuyuki Tokanai, N. A. McCubbin, J. Gomez-Ortega, D. Nakajima, A. Liolios, P. Laporte, Orjan Dale, A. Sillanpää, Dainis Dravins, Timothée Grégoire, Nu. Komin, A. Mihailidis, L. Sidoli, Shiu-Hang Lee, A. W. Chen, J. M. Illa, A. Kuznetsov, P. Munar-Adrover, D. Dominis Prester, Marcos Daniel Actis, Abraham D. Falcone, L. Journet, D. Hadasch, N. Galante, A. Murphy, C. J. Todero Peixoto, S. Wiesand, A. Aravantinos, A. C. Rovero, J. L. Dournaux, P. Romano, M. Hrabovsky, R. de los Reyes Lopez, M. Ostrowski, J. Pallota, Geza Gyuk, Petar Temnikov, R. Dubois, Jan Ebr, R. Koul, David J. Smith, S. Schwarzburg, P. Manigot, Chad Finley, Tarek M. Hassan, Giuseppe Sottile, Evgeni Ovcharov, P. J. Rajda, F. Krennrich, Peter L. Moore, W. B. Focke, W. Bednarek, Elena Amato, Kazunori Kohri, J. Gamez-Garcia, I. Oya, A. Shibuya, German Hermann, William H. Lee, Dorota Sobczyńska, X. Zhou, C. Balkowski, G. Vallejo, M. Hayashida, M. Bitossi, Loukas Vlahos, H. Lockart, N. Geffroy, L. Tibaldo, Marek Jamrozy, Luke O'c. Drury, Pratik Majumdar, P. Sutcliffe, S. Schlenstedt, M. Palatka, Christophe Champion, H. Ueno, M. Rupiński, P. Giommi, J. Schwarz, G. Pühlhofer, Takashi Saito, W. van Driel, C. van Eldik, Q. Xiong, Yasuo Fukui, A. Donat, A. Ibarra, R. S. Warwick, Michiko Ohishi, A. W. Smith, J.-P. Lenain, Aion Viana, Terry Ashton, Guillaume Dubus, Jacek Niemiec, K. Kodani, Luis Ángel Tejedor, A. Wörnlein, Takanori Yoshikoshi, Masahiro Teshima, W. Gäbele, Ll. Font, Olaf Reimer, J. F. Valdés-Galicia, Lucy Fortson, J. P. Osborne, Mattia Fornasa, Keith Bechtol, Masayuki Tanaka, Shigehiro Nagataki, M. Rataj, M. Ribordy, Emmanuel Moulin, I. de la Calle, K. Winiarski, C. Jeanney, I. Mognet, I. Vegas, C. Juffroy, Yutaka Ohira, A. Jacholkowska, Matthew Wood, A. E. Suárez, J. Bähr, K. M. Schure, J. Maya, M. Dafonseca, J. Tasan, R. Sugawara, M. Bourgeat, A. Mancilla, D. Pelat, Olga Botner, D. Nedbal, G. Depaola, Robert Wagner, T. Okuda, H. Arnaldi, Josep Martí, P. Corona, T. Bonev, D. Yelos, J. Sieiro, V. Scalzotto, Jacco Vink, D. Languignon, Marco Ajello, J. Vandenbrouke, Philipp Mertsch, M. Mordalska, P. Wegner, P. Ziółkowski, P. T. O'Brien, A. Nozato, Robert D. Preece, B. Huber, Matteo Balbo, J.R. Bogart, R. Kankanyan, K. Mori, T. Jogler, Seth Digel, Claudio Vuerli, Hiromitsu Takahashi, Thomas Lohse, K. Saito, A. W. Borgland, Elisa Prandini, Helene Sol, Ryan Heller, M. Bogdan, D. Dumas, M. Stodulski, Y. Awane, Piercarlo Bonifacio, Pedro L. Luque-Escamilla, Judith H. Croston, Fabio Pizzolato, P. M. Chadwick, M. K. Daniel, Riccardo Paoletti, Reiko Orito, Katsuaki Asano, R. Frei, G. Disset, Valerie Connaughton, Juhani Huovelin, Hiroyasu Tajima, S. Vercellone, F. Feinstein, G. Decerprit, Riccardo Smareglia, S. Spyrou, Gustavo E. Romero, J. Shi, J. Carr, N. Girard, Dirk L. Hoffmann, Andreas Zech, Markus Boettcher, Osvaldo Catalano, Akira Okumura, M. Dohmke, C. Föhr, Sabrina Casanova, R. A. Cameron, Jan Conrad, K. Umehara, K. K. Yadav, A. Paizis, John L. Quinn, L. Pogosyan, C. Farnier, William J. Potter, Domenico Impiombato, Tadashi Kifune, Jonathan Granot, Gernot Maier, M. Cieślar, S. Palanque, G.W. Fraser, J. Prast, R. Bose, Heidi Sandaker, G. Lamanna, Dusan Mandat, J.F. Glicenstein, J. Harris, D. Naumann, J. Ziolkowski, Michał Szanecki, C. Delgado, J. Kocot, W. Lustermann, Sabine Elles, J. Schmoll, L. Gérard, M. López, Norita Kawanaka, V. Gika, B. Lieunard, A. Pichel, Martin Pohl, Mariusz Sterzel, S. Vincent, Paolo De Coppi, J. Lande, O. Blanch Bigas, Gianluca Giavitto, Yusuke Konno, Julian Sitarek, M. Panter, P.-O. Petrucci, F. Henault, M. Prouza, Philip Kaaret, Josep Colomé, Luciano Nicastro, German Martinez, L. Gebremedhin, J. M. Yebras, Apostolos Mastichiadis, A. S. Madhavan, Thomas J. Maccarone, K. Berger, R. Buehler, P. Jean, N. Sartore, F. Toussenel, Aris Karastergiou, W. Kluźniak, A. Djannati-Ataï, S. J. Fegan, Louis Antonelli, A. González Muñoz, J. Berdugo, S. S. Upadhya, M. Sidz, F. Mottez, Patrick Vogler, F. Di Pierro, Wystan Benbow, B. Sacco, L. Chiappetti, J. Dumm, R. Firpo Curcoll, David Gascon, V. Boccone, J. Krause, J. P. Avernet, B. Peyaud, B. De Lotto, Ana Babić, T. O. B. Schmidt, I. M. McHardy, T. Schweizer, S. P. Wakely, Daniel Gall, Frank M. Rieger, E. Sant'Ambrogio, M. Kagaya, P. Vincent, R. C. Rannot, Sandro Mereghetti, A. De Angelis, M. Scarcioffolo, R. White, G. H. Sembroski, Takeshi Nakamori, C. Medina, M. A. De Oliveira Leigui, Subir Sarkar, A. Marszałek, Reshmi Mukherjee, K. Nakayama, A. Fiasson, S. Giarrusso, T. Bernardino, J. P. Finley, D. Neise, L. O. Takalo, F. Grañena, Nikola Godinovic, H. Sasaki, P. Zychowski, Francesco Dazzi, B. Courty, A. Basili, Vitaly Neustroev, B. Khélifi, T. Glanzman, M. Trifoglio, Regis Terrier, R. A. Ong, E. M. Santos, M. Minuti, Thomas Bretz, R. Moderski, J. Kushida, S. Royer, Emilio Molinari, Etienne Lyard, J. Houles, Juan Abel Barrio, T. Lerch, S. Rivoire, T. Kishimoto, M. Cailles, M. Casiraghi, Nikolaos Stergioulas, J. Gaweda, S. Koyama, Ingomar Allekotte, E. Ismailova, Elina Giannakaki, S. Schwemmer, Ryo Yamazaki, G. Fasola, Christoph Deil, Jose Luis Contreras, T. Bird, Miguel A. Sánchez-Conde, J. Dick, E. Edy, D. Parsons, R. Pyzioł, R. Mirzoyan, Manjuli R. Sharma, J. Borkowski, Jonathan S. Lapington, Cameron B Rulten, Rino Bandiera, Volker Beckmann, Jun Kakuwa, Dimitris Balis, Kenji Toma, Anna Barnacka, Andrea Santangelo, L. Padilla, Peter Eger, G. Decock, Karol Seweryn, N. Sakaki, Darko Veberič, Andrea Bulgarelli, B. Rudak, M. Pérez, H. Koppel, Felix Spanier, M. I. Martínez, D. Horville, Marco Molinaro, R. Walter, P. Ramon, S. Brau-Nogue, J. Camprecios, K. Kärcher, John H. Seiradakis, S. Criswell, D. J. Leopold, V. J. Guarino, R. Gredig, S. Vorobiov, Viktor Gruev, Gareth Hughes, Daniele Spiga, Quirin Weitzel, N. Håkansson, Susumu Inoue, U. Straumann, Juan Cortina, B. Behera, Jürgen Knödlseder, Daniel Nieto, Tomasz Szepieniec, H. Prokoph, Jerzy Grygorczuk, G. De La Vega, Jim Hinton, E. Chabanne, M. Mahabir, R. Krobot, M. Capalbi, Miroslav Pech, C. Díaz, J. Ludwin, F. Gianotti, Garret Cotter, Claudio Melioli, Hiroaki Yamamoto, C. Veyssiere, Kunihito Ioka, S. Sun, J. M. Parraud, L. Rob, Felix Aharonian, G. Maneva, D. Melkumyan, T. Schwab, J. Kasperek, J. M. Huet, E. Lorenz, S. Tanaka, Y. A. Gallant, S. Couturier, B.W. Favill, J. Boix Gargallo, Andrea Tiengo, Leszek Bogacz, Andreu Sanuy, Christian Fruck, J. Sykes, C. Martens, A. Yoshida, Marek Sikora, E. Racero, G. Rouaix, N. Bhat, A. Salini, A. S. Barber, Mauro Ghigo, Jan Ridky, K. Kosack, Konrad Bernlöhr, C. Tenzer, Alice Allafort, M. Torres, Catherine Boisson, Grzegorz Kowal, M. Karczewski, G. Agnetta, Victor Stamatescu, Anthony H. Gonzalez, S. Rousselle, Giovanni Bonanno, A. Zajczyk, A. Gadola, P. Martin, V. Zitelli, I. Manthos, N. Maragos, A. Dettlaff, F. Profeti, S. Colonges, S. Gunji, S. Cazaux, S. Colafrancesco, M. Paz Arribas, Rika Hagiwara, Darell Engelhaupt, Nestor Mirabal, Johann Cohen-Tanugi, S. Grunewald, Abby M. Green, I. D. Davids, D. Nosek, T. Yamamoto, Gagik Tovmassian, R. Sakonaka, Miguel Alcubierre, C. Baixeras, T. L. Usher, Kazufumi Torii, H. Lüdecke, L. Wiśniewski, B. Kellner-Leidel, P. Demange, F. Gonzalez, B. Moal, V. De Caprio, V. Golev, K. Katarzyński, V. Bugaev, A. Reimer, J. Koziol, G. Pojmanski, Alessandro Carosi, J. Bolmont, A. Nikolaidis, R. J. García López, V. A. Kudryavtsev, C. Stegmann, J.-P. Ernenwein, M. Fiorini, Ivone F. M. Albuquerque, Marco Tavani, P. Korohoda, A. Giuliani, E. Carmona, C. Bauer, Kostas D. Kokkotas, O. Tibolla, G. Deleglise, Pierre Brun, Dinko Dimitrov, I. Jung, R. Steenkamp, Marc Ribó, Kathrin Egberts, P. Reardon, Adriano Ghedina, Stefan Rosén, N. Hidaka, Trygve Buanes, A. Segreto, H. Huan, Juri Poutanen, Ruben Lopez-Coto, S. Cavazzani, Massimiliano Belluso, A. Kretzschmann, F. De Frondat, A. Riviere, J. F. Olive, Tsunefumi Mizuno, Serena Mattiazzo, M. González, D. Fantinel, Matteo Cerruti, S. Vergani, Sabrina Einecke, N. La Palombara, Reinhard Schlickeiser, P. Antoranz, Pol Bordas, D. Paillot, V. de Souza, Yasushi Fukazawa, Phil Evans, Werner Hofmann, Hugh Dickinson, F. Roy, Yvonne Becherini, E. O. Angüner, D. Corti, T. C. Arlen, Francesco Russo, V. R. Chitnis, D. Ross, R. Gabriele, Massimo Persic, E. Fokitis, A. Bonardi, D. Garrido, A. Niedźwiecki, L. Cossio, Hidetoshi Kubo, Y. de Oliveira, F. Mattana, Anna Szostek, M. Compin, S. Blake, F. Lucarelli, Petter Hofverberg, Felix Ryde, M. Gougerot, C. Boutonnet, Dimitrios Emmanoulopoulos, A. Mangano, P. Vallania, Jose Miguel Miranda, A. Manalaysay, M. Raue, A. Bouvier, Shohei Yanagita, Nektarios Vlahakis, Joni Tammi, M. Naumann-Godo, Kohta Murase, E. Fillin-Martino, Jiri Chudoba, K. Hatanaka, A. Lopatin, N. Otte, G. Rojas, Tomonori Totani, K. S. Gothe, J. P. Vialle, D. Kolitzus, K. Warda, Hironori Matsumoto, J. Rico, P. Ringegni, James Chiang, R. McKay, A. Bobkov, Aya Bamba, H. Takami, B. Giebels, O. Grimm, S. Basso, F. Dubois, Victor Zabalza, A. Förster, Pasquale Blasi, Alexandros Papayannis, A. G. Akhperjanian, Eckhard Kendziorra, James A. Anderson, Giuseppe Malaguti, R. Welsing, S. Pita, A. Ozieblo, Heide Costantini, D. Tezier, J.-H. Köhne, M. Tluczykont, Ll. Garrido, Alexander Varón Sandoval, Matthew R. Orr, Dominique Durand, F. Chollet, O. Luz, E. O. Saemann, Jun Kataoka, M. Proyetti, C. Barbier, Jürgen Barnstedt, L. Bouchet, Hiroshi Muraishi, Anton N. Baushev, L. A. Otero, Denis Bastieri, S. Incorvaia, Tihomir Surić, V. La Parola, Nathan Smith, Karl-Heinz Sulanke, F. Bernard, Luca Stringhetti, S. Paiano, S. Federici, Hector Flores, Karl Mannheim, Michael S. Briggs, Giovanna Pedaletti, E. M. de Gouveia Dal Pino, J. D. Smith, G. La Rosa, Alicia López-Oramas, M. Janiak, Gary Drake, G. Talbot, Petr Travnicek, Elisabetta Bissaldi, Mario Meucci, R. Northrop, V. Scapin, Vito Conforti, J. D. Ponz, T. Aghajani, J. J. Jimenez, A. D. Supanitsky, Hernán Asorey, M. Werner, Brian Reville, A. Haupt, C. Skole, Gilles Henri, Daniele Gardiol, V. Vassiliev, R. Platzer, Y. Saito, A. La Barbera, Allan Hallgren, C. Eleftheriadis, S. Cantu, G. Maurin, K. Lacombe, A. Le Padellec, F. Stinzing, T. Hayakawa, A. Cillis, M. Suchenek, I. Monteiro, V. Sahakian, A. Di Paola, Grzegorz Madejski, A. De Luca, Andreas Quirrenbach, P. A. Caraveo, N. A. Webb, Michael Zacharias, J. Vanderwalt, Dario Hrupec, K. Ziȩtara, T. Armstrong, A. Lorca, T. Krähenbühl, A. Etchegoyen, Stefano Covino, C. Kalkuhl, K. Kitamoto, Tomasz Bulik, R. Rohlfs, D. Allan, A. Zhao, Luisa Arrabito, B. S. Acharya, T. Johnson, C. Schultz, G. Vasileiadis, Eleen Shum, Daniel Ferenc, Paola Grandi, Maria Concetta Maccarone, E. Strazzeri, H. Kelly, E. J. Quel, H. Vankov, Ruben Alfaro, I. Telezhinsky, J. Becker Tjus, C. Dufour, F. Köck, Ilana M. Braun, Jamie Holder, Ryoji Enomoto, Luigi Lessio, Michael Punch, Stefano Gabici, I. Puerto-Gimenez, S. Karkar, P. Nayman, M. Grudzińska, E. Aliu, Yoshiyuki Inoue, Elina Lindfors, J. Becerra, Daniel Mazin, Yukikatsu Terada, André Schulz, Teresa Montaruli, G. Bonnoli, S. Renner, Dieter Horns, J. Dyks, V. Pelassa, Mark I. Wilkinson, Ricardo Graciani, I. Troyano, P. Ristori, Thomas Kihm, P. Micolon, S. J. Nolan, Torsten Bringmann, David A. Williams, Joachim Hahn, L. Brunetti, U. Roeser, Wolfgang Rhode, Kanaris Tsinganos, Stefan Ohm, J. L. Panazol, G. Busetto, B. S., Acharya, M., Acti, T., Aghajani, G., Agnetta, J., Aguilar, F., Aharonian, M., Ajello, A., Akhperjanian, M., Alcubierre, J., Aleksic, R., Alfaro, E., Aliu, A. J., Allafort, D., Allan, I., Allekotte, E., Amato, J., Anderson, E. O., Anguener, L. A., Antonelli, P., Antoranz, A., Aravantino, T., Arlen, T., Armstrong, H., Arnaldi, L., Arrabito, K., Asano, T., Ashton, H. G., Asorey, Y., Awane, H., Baba, A., Babic, N., Baby, J., Baehr, A., Bai, C., Baixera, S., Bajtlik, M., Balbo, D., Bali, C., Balkowski, A., Bamba, R., Bandiera, A., Barber, C., Barbier, M., Barcelo, A., Barnacka, J., Barnstedt, U. B., De, J. A., Barrio, A., Basili, S., Basso, D., Bastieri, C., Bauer, A., Baushev, J., Becerra, Y., Becherini, K. C., Bechtol, J. B., Tju, V., Beckmann, W., Bednarek, B., Behera, M., Belluso, W., Benbow, J., Berdugo, K., Berger, F., Bernard, T., Bernardino, K., Bernloehr, N., Bhat, S., Bhattacharyya, C., Bigongiari, A., Biland, S., Billotta, T., Bird, E., Birsin, Bissaldi, Elisabetta, J., Biteau, M., Bitossi, S., Blake, O. B., Biga, P., Blasi, A., Bobkov, V., Boccone, M., Boettcher, L., Bogacz, J., Bogart, M., Bogdan, C., Boisson, J. B., Gargallo, J., Bolmont, G., Bonanno, A., Bonardi, T., Bonev, P., Bonifacio, G., Bonnoli, P., Borda, A., Borgland, J., Borkowski, R., Bose, O., Botner, A., Bottani, L., Bouchet, M., Bourgeat, C., Boutonnet, A., Bouvier, S., Brau Nogue, I., Braun, T., Bretz, M., Brigg, T., Bringmann, P., Brook, P., Brun, L., Brunetti, T., Buane, J., Buckley, R., Buehler, V., Bugaev, A., Bulgarelli, T., Bulik, G., Busetto, S., Buson, K., Byrum, M., Caille, R., Cameron, J., Camprecio, R., Canestrari, S., Cantu, M., Capalbi, P., Caraveo, E., Carmona, A., Carosi, J., Carr, P. . ., H., S., Casanova, M., Casiraghi, O., Catalano, S., Cavazzani, S., Cazaux, M., Cerruti, E., Chabanne, P., Chadwick, C., Champion, A., Chen, J., Chiang, L., Chiappetti, M., Chikawa, V. R., Chitni, F., Chollet, J., Chudoba, M., Cieslar, A., Cilli, J., Cohen Tanugi, S., Colafrancesco, P., Colin, J., Calome, S., Colonge, M., Compin, P., Conconi, V., Conforti, V., Connaughton, J., Conrad, J. L., Contrera, P., Coppi, P., Corona, D., Corti, J., Cortina, L., Cossio, H., Costantini, G., Cotter, B., Courty, S., Couturier, S., Covino, G., Crimi, S. J., Criswell, J., Croston, G., Cusumano, M., Dafonseca, O., Dale, M., Daniel, J., Darling, I., David, F., Dazzi, A. D., Angeli, V. D., Caprio, F. D., Frondat, E. M., De, I. d., La, G. A., De, R. d., Lo, B. D., Lotto, A. D., Luca, J. R., T., M. d., Nauroi, Y. d., Oliveira, E. d., Ona, V. d., Souza, G., Decerprit, G., Decock, C., Deil, E., Delagne, G., Deleglise, C., Delgado, D. D., Volpe, P., Demange, G., Depaola, A., Dettlaff, A. D., Paola, F. D., Pierro, C., Diaz, J., Dick, R., Dickherber, H., Dickinson, V., Diez Blanco, S., Digel, D., Dimitrov, G., Disset, A., Djannati Atai, M., Doert, M., Dohmke, W., Domainko, D. D., Prester, A., Donat, D., Dorner, M., Doro, J. . ., L., G., Drake, D., Dravin, L., Drury, F., Duboi, R., Duboi, G., Dubu, C., Dufour, D., Duma, J., Dumm, D., Durand, J., Dyk, M., Dyrda, J., Ebr, E., Edy, K., Egbert, P., Eger, S., Einecke, C., Eleftheriadi, S., Elle, D., Emmanoulopoulo, D., Engelhaupt, R., Enomoto, J. . ., P., M., Errando, A., Etchegoyen, P., Evan, A., Falcone, D., Fantinel, K., Farako, C., Farnier, G., Fasola, B., Favill, E., Fede, S., Federici, S., Fegan, F., Feinstein, D., Ferenc, P., Ferrando, M., Fesquet, A., Fiasson, E., Fillin Martino, D., Fink, C., Finley, J. P., Finley, M., Fiorini, R. F., Curcoll, H., Flore, D., Florin, W., Focke, C., Foehr, E., Fokiti, L., Font, G., Fontaine, M., Fornasa, A., Foerster, L., Fortson, N., Fouque, A., Franckowiak, C., Fransson, G., Fraser, R., Frei, I. F., M., L., Fresnillo, C., Fruck, Y., Fujita, Y., Fukazawa, Y., Fukui, S., Funk, W., Gaebele, S., Gabici, R., Gabriele, A., Gadola, N., Galante, D., Gall, Y., Gallant, J., Gamez Garcia, B., Garcia, R. G., Lopez, D., Gardiol, D., Garrido, L., Garrido, D., Gascon, M., Gaug, J., Gaweda, L., Gebremedhin, N., Geffroy, L., Gerard, A., Ghedina, M., Ghigo, E., Giannakaki, F., Gianotti, S., Giarrusso, G., Giavitto, B., Giebel, V., Gika, P., Giommi, N., Girard, E., Giro, A., Giuliani, T., Glanzman, J. . ., F., N., Godinovic, V., Golev, M. G., Berisso, J., Gomez Ortega, M. M., Gonzalez, A., Gonzalez, F., Gonzalez, A. G., Munoz, K. S., Gothe, M., Gougerot, R., Graciani, P., Grandi, F., Granena, J., Granot, G., Grasseau, R., Gredig, A., Green, T., Greenshaw, T., Gregoire, O., Grimm, J., Grube, M., Grudzinska, V., Gruev, S., Gruenewald, J., Grygorczuk, V., Guarino, S., Gunji, G., Gyuk, D., Hadasch, R., Hagiwara, J., Hahn, N., Hakansson, A., Hallgren, N. H., Hera, S., Hara, M. J., Hardcastle, J., Harri, T., Hassan, K., Hatanaka, T., Haubold, A., Haupt, T., Hayakawa, M., Hayashida, R., Heller, F., Henault, G., Henri, G., Hermann, R., Hermel, A., Herrero, N., Hidaka, J., Hinton, D., Hoffmann, W., Hofmann, P., Hofverberg, J., Holder, D., Horn, D., Horville, J., Houle, M., Hrabovsky, D., Hrupec, H., Huan, B., Huber, J. . ., M., G., Hughe, T. B., Humensky, J., Huovelin, A., Ibarra, J. M., Illa, D., Impiombato, S., Incorvaia, S., Inoue, Y., Inoue, K., Ioka, E., Ismailova, C., Jablonski, A., Jacholkowska, M., Jamrozy, M., Janiak, P., Jean, C., Jeanney, J. J., Jimenez, T., Jogler, T., Johnson, L., Journet, C., Juffroy, I., Jung, P., Kaaret, S., Kabuki, M., Kagaya, J., Kakuwa, C., Kalkuhl, R., Kankanyan, A., Karastergiou, K., Kaercher, M., Karczewski, S., Karkar, A., Kasperek, D., Kastana, H., Katagiri, J., Kataoka, K., Katarzynski, U., Katz, N., Kawanaka, B., Kellner Leidel, H., Kelly, E., Kendziorra, B., Khelifi, D. B., Kieda, T., Kifune, T., Kihm, T., Kishimoto, K., Kitamoto, W., Kluzniak, C., Knapic, J. w., Knapp, J., Knoedlseder, F., Koeck, J., Kocot, K., Kodani, J. . ., H., K., Kohri, K., Kokkota, D., Kolitzu, N., Komin, I., Komini, Y., Konno, H., Koeppel, P., Korohoda, K., Kosack, G., Ko, R., Kossakowski, P., Kostka, R., Koul, G., Kowal, S., Koyama, J., Koziol, T., Kraehenbuehl, J., Krause, H., Krawzcynski, F., Krennrich, A., Krepp, A., Kretzschmann, R., Krobot, P., Krueger, H., Kubo, V. A., Kudryavtsev, J., Kushida, A., Kuznetsov, A. L., Barbera, N. L., Palombara, V. L., Parola, G. L., Rosa, K., Lacombe, G., Lamanna, J., Lande, D., Languignon, J., Lapington, P., Laporte, C., Lavalley, T. L., Flour, A. L., Padellec, S. . ., H., W. H., Lee, M. A., Leigui, D., Lela, D. J., Leopold, T., Lerch, L., Lessio, B., Lieunard, E., Lindfor, A., Liolio, A., Lipniacka, H., Lockart, T., Lohse, S., Lombardi, A., Lopatin, M., Lopez, R., Lopez Coto, A., Lopez Orama, A., Lorca, E., Lorenz, P., Lubinski, F., Lucarelli, H., Luedecke, J., Ludwin, P. L., Luque Escamilla, W., Lustermann, O., Luz, E., Lyard, M. C., Maccarone, T. J., Maccarone, G. M., Madejski, A., Madhavan, M., Mahabir, G., Maier, P., Majumdar, G., Malaguti, S., Maltezo, A., Manalaysay, A., Mancilla, D., Mandat, G., Maneva, A., Mangano, P., Manigot, K., Mannheim, I., Mantho, N., Marago, A., Marcowith, M., Mariotti, M., Marisaldi, S., Markoff, A., Marszalek, C., Marten, J., Marti, P., Martin, G., Martinez, F., Martinez, M., Martinez, A., Masserot, A., Mastichiadi, A., Mathieu, H., Matsumoto, F., Mattana, S., Mattiazzo, G., Maurin, S., Maxfield, J., Maya, D., Mazin, L. M., Comb, N., Mccubbin, I., Mchardy, R., Mckay, C., Medina, C., Melioli, D., Melkumyan, S., Mereghetti, P., Mertsch, M., Meucci, J., Michalowski, P., Micolon, A., Mihailidi, T., Mineo, M., Minuti, N., Mirabal, F., Mirabel, J. M., Miranda, R., Mirzoyan, T., Mizuno, B., Moal, R., Moderski, I., Mognet, E., Molinari, M., Molinaro, T., Montaruli, I., Monteiro, P., Moore, A. M., Olaizola, M., Mordalska, C., Morello, K., Mori, F., Mottez, Y., Moudden, E., Moulin, I., Mrusek, R., Mukherjee, P., Munar Adrover, H., Muraishi, K., Murase, A., Murphy, S., Nagataki, T., Naito, D., Nakajima, T., Nakamori, K., Nakayama, C., Naumann, D., Naumann, M., Naumann Godo, P., Nayman, D., Nedbal, D., Neise, L., Nellen, V., Neustroev, N., Neyroud, L., Nicastro, J., Nicolau Kuklinski, A., Niedzwiecki, J., Niemiec, D., Nieto, A., Nikolaidi, K., Nishijima, S., Nolan, R., Northrop, D., Nosek, N., Nowak, A., Nozato, P., O'Brien, Y., Ohira, M., Ohishi, S., Ohm, H., Ohoka, T., Okuda, A., Okumura, R. A., Ong, R., Orito, M., Orr, J., Osborne, M., Ostrowski, L. A., Otero, N., Otte, E., Ovcharov, I., Oya, A., Ozieblo, L., Padilla, S., Paiano, D., Paillot, A., Paizi, S., Palanque, M., Palatka, J., Pallota, K., Panagiotidi, D., Paneque, M., Panter, R., Paoletti, A., Papayanni, G., Papyan, J. M., Parede, G., Pareschi, G., Park, D., Parson, M. P., Arriba, M., Pech, G., Pedaletti, V., Pelassa, D., Pelat, M. D., C., M., Persic, P. . ., O., B., Peyaud, A., Pichel, S., Pita, F., Pizzolato, L., Plato, R., Platzer, L., Pogosyan, M., Pohl, G., Pojmanski, J. D., Ponz, W., Potter, J., Poutanen, E., Prandini, J., Prast, R., Preece, F., Profeti, H., Prokoph, M., Prouza, M., Proyetti, I., Puerto Gimenez, G., Puehlhofer, I., Puljak, M., Punch, R., Pyziol, E. J., Quel, J., Quinn, A., Quirrenbach, E., Racero, P. J., Rajda, P., Ramon, R., Rando, R. C., Rannot, M., Rataj, M., Raue, P., Reardon, O., Reimann, A., Reimer, O., Reimer, K., Reitberger, M., Renaud, S., Renner, B., Reville, W., Rhode, M., Ribo, M., Ribordy, M. G., Richer, J., Rico, J., Ridky, F., Rieger, P., Ringegni, J., Ripken, P. R., Ristori, A., Riviere, S., Rivoire, L., Rob, U., Roeser, R., Rohlf, G., Roja, P., Romano, W., Romaszkan, G. E., Romero, S., Rosen, S. R., Lee, D., Ro, G., Rouaix, J., Rousselle, S., Rousselle, A. C., Rovero, F., Roy, S., Royer, B., Rudak, C., Rulten, M., Rupinski, F., Russo, F., Ryde, B., Sacco, E. O., Saemann, A., Saggion, V., Safiakian, K., Saito, T., Saito, Y., Saito, N., Sakaki, R., Sakonaka, A., Salini, F., Sanchez, M., Sanchez Conde, A., Sandoval, H., Sandaker, E., Sant'Ambrogio, A., Santangelo, E. M., Santo, A., Sanuy, L., Sapozhnikov, S., Sarkar, N., Sartore, H., Sasaki, K., Satalecka, M., Sawada, V., Scalzotto, V., Scapin, M., Scarcioffolo, J., Schafer, T., Schanz, S., Schlenstedt, R., Schlickeiser, T., Schmidt, J., Schmoll, P., Schovanek, M., Schroedter, C., Schultz, J., Schultze, A., Schulz, K., Schure, T., Schwab, U., Schwanke, J., Schwarz, S., Schwarzburg, T., Schweizer, S., Schwemmer, A., Segreto, G. H., Sembroski, K., Seweryn, M., Sharma, M., Shayduk, R. C., Shellard, J., Shi, T., Shibata, A., Shibuya, E., Shum, L., Sidoli, M., Sidz, J., Sieiro, M., Sikora, J., Silk, A., Sillanpaa, B. B., Singh, J., Sitarek, C., Skole, R., Smareglia, A., Smith, D., Smith, J., Smith, N., Smith, D., Sobczynska, H., Sol, G., Sottile, M., Sowinski, F., Spanier, D., Spiga, S., Spyrou, V., Stamatescu, A., Stamerra, R., Starling, L., Stawarz, R., Steenkamp, C., Stegmann, S., Steiner, N., Stergioula, R., Sternberger, M., Sterzel, F., Stinzing, M., Stodulski, U., Straumann, E., Strazzeri, L., Stringhetti, A., Suarez, M., Suchenek, R., Sugawara, K. . ., H., S., Sun, A. D., Supanitsky, T., Suric, P., Sutcliffe, J., Syke, M., Szanecki, T., Szepieniec, A., Szostek, G., Tagliaferri, H., Tajima, H., Takahashi, K., Takahashi, L., Takalo, H., Takami, C., Talbot, J., Tammi, M., Tanaka, S., Tanaka, J., Tasan, M., Tavani, L. A., Tejedor, I., Telezhinsky, P., Temnikov, C., Tenzer, Y., Terada, R., Terrier, M., Teshima, V., Testa, D., Tezier, D., Thuermann, L., Tibaldo, O., Tibolla, A., Tiengo, M., Tluczykont, C. J., Todero, F., Tokanai, M., Tokarz, K., Toma, K., Torii, M., Tornikoski, D. F., Torre, M., Torre, G., Tosti, T., Totani, C., Toussenel, G., Tovmassian, P., Travnicek, M., Trifoglio, I., Troyano, K., Tsingano, H., Ueno, K., Umehara, S. S., Upadhya, T., Usher, M., Uslenghi, J. F., Valdes Galicia, P., Vallania, G., Vallejo, W. v., Driel, C. v., Eldik, J., Vandenbrouke, J., Vanderwalt, H., Vankov, G., Vasileiadi, V., Vassiliev, D., Veberic, I., Vega, S., Vercellone, S., Vergani, C., Veyssiere, J. P., Vialle, A., Viana, M., Videla, P., Vincent, S., Vincent, J., Vink, N., Vlahaki, L., Vlaho, P., Vogler, A., Vollhardt, H. . ., P., S., Vorobiov, C., Vuerli, V., Waegebaert, R., Wagner, R. G., Wagner, S., Wagner, S. P., Wakely, R., Walter, T., Walther, K., Warda, R., Warwick, P., Wawer, R., Wawrzaszek, N., Webb, P., Wegner, A., Weinstein, Q., Weitzel, R., Welsing, M., Werner, H., Wetteskind, R., White, A., Wierzcholska, S., Wiesand, M., Wilkinson, D. A., William, R., Willingale, K., Winiarski, R., Wischnewski, L., Wisniewski, M., Wood, A., Woernlein, Q., Xiong, K. K., Yadav, H., Yamamoto, T., Yamamoto, R., Yamazaki, S., Yanagita, J. M., Yebra, D., Yelo, A., Yoshida, T., Yoshida, T., Yoshikoshi, V., Zabalza, M., Zacharia, A., Zajczyk, R., Zanin, A., Zdziarski, A., Zech, A., Zhao, X., Zhou, K., Zietara, J., Ziolkowski, P., Ziolkowski, V., Zitelli, C., Zurbach, P., Zychowski, Laboratoire d'Annecy de Physique des Particules (LAPP/Laboratoire d'Annecy-le-Vieux de Physique des Particules), 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), AstroParticule et Cosmologie (APC (UMR_7164)), 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), APC - Astrophysique des Hautes Energies (APC - AHE), 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), Centre de Physique des Particules de Marseille (CPPM), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Aix Marseille Université (AMU), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, CTA, 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)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Laboratoire d'Annecy de Physique des Particules (LAPP), 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)-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), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), 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), 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), 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), and High Energy Astrophys. & Astropart. Phys (API, FNWI)

Subjects
Next generation Cherenkov telescopes, Ciencias Físicas, 01 natural sciences, 7. Clean energy, TeV GAMMA-RAY ASTRONOMY, Observatory, Air showers, HESS, Cherenkov Telescopes, 010303 astronomy & astrophysics, MISSION, SUPERNOVA REMNANT W44, TELESCOPE, ASTRONOMY, EMISSION, Physics, ta213, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Settore FIS/01 - Fisica Sperimentale, Astrophysics::Instrumentation and Methods for Astrophysics, TeV gamma-ray astronomy, ddc:540, CIENCIAS NATURALES Y EXACTAS, [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], [PHYS.ASTR.IM]Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Air shower, AIR SHOWERS, Astrophysics::High Energy Astrophysical Phenomena, 0103 physical sciences, Preparatory phase, ta115, TeV gamma-ray astronomy Air showers Cherenkov Telescopes, 010308 nuclear & particles physics, business.industry, CHERENKOV TELESCOPES, Física, Astronomy, Institut für Physik und Astronomie, Astronomy and Astrophysics, ASTROFÍSICA, Cherenkov Telescope Array, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Astronomía, Design study, Telecommunications, business
Abstract

The Cherenkov Telescope Array (CTA) is a new observatory for very high-energy (VHE) gamma rays. CTA has ambitions science goals, for which it is necessary to achieve full-sky coverage, to improve the sensitivity by about an order of magnitude, to span about four decades of energy, from a few tens of GeV to above 100 TeV with enhanced angular and energy resolutions over existing VHE gamma-ray observatories. An international collaboration has formed with more than 1000 members from 27 countries in Europe, Asia, Africa and North and South America. In 2010 the CTA Consortium completed a Design Study and started a three-year Preparatory Phase which leads to production readiness of CTA in 2014. In this paper we introduce the science goals and the concept of CTA, and provide an overview of the project., La lista completa de autores puede consultarse en el documento o en la página web de la revista., Facultad de Ingeniería

Published
2013

16. Optical properties of the new polar RXJ1940.2–1025

Author

B. Warner, Stefan Rosén, G. M. Madejski, Chris Done, D. A. H. Buckley, M. G. Watson, D. O'Donoghue, T. F. Ramseyer, and Coel Hellier

Subjects
Physics, Space and Planetary Science, Astronomy, Polar, Astronomy and Astrophysics
Published
1995

17. The orbital period of the pre-cataclysmic binary RE 2013+400 and a study of the atmosphere of the DAO white dwarf primary

Author

Stefan Rosén, Jay B. Holberg, R. G. M. Rutten, R. W. Tweedy, Matthew R. Burleigh, Gary Wegner, Martin A. Barstow, M. C. Marsh, Thomas A. Fleming, Detlev Koester, and Shoko Sakai

Subjects
Atmosphere, Physics, Stars, Space and Planetary Science, Primary (astronomy), White dwarf, Binary number, Astronomy, Astronomy and Astrophysics, Astrophysics, Circumbinary planet, Orbital period
Published
1995

19. Spin-resolved optical CCD spectroscopy of GK-Persei

Author

M. A. Garlick, Keith O. Mason, Stefan Rosén, and J. P. D. Mittaz

Subjects
Physics, Intermediate polar, Space and Planetary Science, Polar, Astronomy and Astrophysics, Astrophysics, Atomic physics, Spectroscopy, Spin-½
Published
1994

20. Spin-resolved optical CCD spectroscopy and photometry of BG Canis Minoris

Author

D. de Martino, Keith O. Mason, Stefan Rosén, J. P. D. Mittaz, and M. A. Garlick

Subjects
Physics, Astronomy, Cataclysmic variable star, White dwarf, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Ephemeris, Photometry (optics), Intermediate polar, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Emission spectrum, Spectroscopy, Equivalent width, Astrophysics::Galaxy Astrophysics
Abstract

We report spin-resolved optical photometry and spectroscopy of the intermediate polar BG Canis Minoris. New 913-s pulsation ephemerides are derived. We find that a cubic fit provides a better description of the O-C values than the hitherto assumed quadratic ephemeris at a confidence level of 97.3 per cent. From the spectroscopy, we find that the violet-to-red (V/R) ratio of the emission lines varies with the 913-s period but not at the alternative period of 847 s detected in the X-ray band. This suggests that 913 s is the most probable spin period of the white dwarf. However, we do find evidence that the emission line intensities and equivalent widths are modulated at 847 s

Published
1994

21. RE0751 + 14, the first 'intermediate' polar?

Author

Stefan Rosén, J. P. D. Mittaz, and P. J. Hakala

Subjects
Physics, Rotation period, 010504 meteorology & atmospheric sciences, White dwarf, Cataclysmic variable star, Astronomy, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Light curve, 01 natural sciences, Radial velocity, Photometry (optics), Intermediate polar, Space and Planetary Science, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Emission spectrum, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences
Abstract

We present optical spectroscopy, multicolour photometry and polarimetry of the new intermediate polar, RE0751+14, discovered during the ROSAT WFC survey. The wings of its emission lines exhibit radial velocity motion with a period ∼13.9 min, confirming that this is the rotation period of the white dwarf. Intriguingly, the R- and I-band photometric light curves reveal a double-peaked profile at the rotation period. In contrast, the B-band light curve, at least in our longest (∼5 h) time-series in that colour, is apparently dominated by a 14.5-min, broadly sinusoidal pulsation. There is supporting evidence from a short NOT observation at an earlier epoch that a modulation with a slightly longer period than the rotation period makes an increasing contribution at blue wavelengths

Published
1993

22. ROSAT studies of the composition and structure of DA white dwarf atmospheres

Author

Stefan Rosén, Detlev Koester, Jay B. Holberg, Anne E. Sansom, Martin A. Barstow, Thomas A. Fleming, David S. Finley, C. J. Diamond, K. Kidder, and M. C. Marsh

Subjects
Physics, Space and Planetary Science, ROSAT, Baton rouge, Stellar atmosphere, Astronomy, White dwarf, Composition (visual arts), Astronomy and Astrophysics, Astrophysics, Effective temperature, Planetary nebula, Luminosity function (astronomy)
Abstract

We have made a detailed study of a sample of 28 hot DA white dwarfs detected in the ROSAT EUV and soft X-ray all-sky-survey.

Published
1993

23. ROSAT observations of UZ For: evidence of a structured X-ray emission region

Author

M. G. Watson, Stefan Rosén, Gavin Ramsay, Mark Cropper, and Keith O. Mason

Subjects
Physics, Infrared astronomy, Stars, Space and Planetary Science, ROSAT, Binary star, Astronomy, White dwarf, Astronomy and Astrophysics, Astrophysics, Variable star, Light curve, Luminosity
Abstract

We present the results of ROSAT X-ray and EUV observations of the eclipsing AM Her star UZ For. Data have been obtained during faint and bright phases and, most interestingly, during the rise interval when the emission region appears over the limb of the white dwarf. The source is seen weakly in the X-ray telescope during the faint phase. We find that the rise to the bright phase is resolved, which is direct evidence of a spatially extended soft X-ray emission region and which places constraints on the size of the emission region. Using the bright-phase spectrum and constraints on the flux per unit area on the white dwarf, we find 19 eV < kT(bb) < 25 eV, 7 x 10(19) cm-2 < N(H) < 1.7 x 10(20) cm-2 and a lower limit to the bolometric blackbody luminosity of 1.5 x 10(31) erg s-1 cm-2 d100(2), where d100 is the distance in units of 100 pc. We also show evidence that the blackbody temperature in the rise interval is approximately 10 per cent lower than in the bright phase. The soft X-ray excess is at least a factor of 7.

Published
1993

24. The ROSAT Wide Field Camera all-sky survey of extreme-ultraviolet sources – I. The Bright Source Catalogue

Author

A. M. Cruise, David Allan, Coel Hellier, A. P. Willmore, Steven Sembay, Trevor J. Ponman, I. Georgantopoulos, Stefan Rosén, R. J. Vallance, Alan A. Wells, T. J. Sumner, G. E. Bromage, M. J. Ricketts, P. A. McGale, Anne E. Sansom, John P. Pye, J. L. Culhane, D. Bertram, Richard Lieu, Richard Willingale, S. T. Hodgkin, Martin A. Barstow, E. M. Puchnarewicz, G. A. Willoughby, D. Wonnacott, Graziella Branduardi-Raymont, E. Dunford, D. O. Donoghue, M. Denby, C. Lloyd, Clive G. Page, B. C. Stewart, R. D. Jeffries, C. V. Goodall, Barry Kellett, Richard E. Cole, G. E. C. Brebner, David A. H. Buckley, M. G. Watson, R. S. Warwick, G. S. Pankiewicz, M. Courtier, A. W. Harris, C. R. Barber, S. D. Sidher, Ken Pounds, B. J. Kent, Keith O. Mason, Mark R. Sims, J. J. Quenby, J. A. Gourlay, P. M. Gondhalekar, L. Matthews, B. J. M. Hassall, J. P. D. Mittaz, and C. D. Pike

Subjects
Physics, Active galactic nucleus, media_common.quotation_subject, SIMBAD, Astronomy, White dwarf, Astronomy and Astrophysics, Astrophysics, Astronomical spectroscopy, Stars, Space and Planetary Science, Ultraviolet astronomy, Sky, ROSAT, media_common
Abstract

The first all-sky survey for cosmic sources of extreme-ultraviolet radiation has been carried out with the UK Wide Field Camera on ROSAT. A first reduction of the survey data has yielded a catalogue of 383 relatively bright EUV sources, forming the WFC Bright Source Catalogue. This represents a 30-fold increase in the number of astrophysical objects detected in the ∼ 60-200 eV energy band and covers a flux range, in each of the two survey bands, of more than 2000. A search of the (typically ∼ 1-arcmin) error circles of the WFC sources, using a variety of catalogues and the SIMBAD data base, has identified probable optical counterparts of ∼73 per cent, including many active stars, white dwarf stars and a variety of other galactic and extragalactic objects

Published
1993

25. Further calibration of the Swift ultraviolet/optical telescope

Author

W. B. Landsman, P. W. A. Roming, A. J. Blustin, Stefan Immler, Patricia Schady, Katherine E. McGowan, Vladimir Yershov, T. S. Poole, H. E. Huckle, M. Ivanushkina, T. Kennedy, M. de Pasquale, Patrick S. Broos, P. A. Curran, E. A. Hoversten, M. H. Siegel, C. Gronwall, B. Hancock, N. P. M. Kuin, M. M. Chester, K. O. Mason, M. J. Page, Martin Still, S. T. Holland, A. A. Breeveld, Adam N. Morgan, M. Carter, D. E. vanden Berk, S. Koch, Philip J. Smith, Stefan Rosén, F. E. Marshall, S. R. Oates, P. T. Boyd, and Peter Brown

Subjects
Physics, Point spread function, Instrumentation, Astronomy and Astrophysics, Photometer, Astrometry, Optical telescope, Coincidence, law.invention, Space and Planetary Science, Observatory, law, Calibration, Remote sensing
Abstract

The Ultraviolet/Optical Telescope (UVOT) is one of three instruments onboard theSwift observatory. The photometric calibration has been published, and this paperfollows up with details on other aspects of the calibration including a measurement ofthe point spread function with an assessment of the orbital variation and the effect onphotometry. A correction for large scale variations in sensitivity over the field of viewis described, as well as a model of the coincidence loss which is used to assess the coin-cidence correction in extended regions. We have provided a correction for the detectordistortion and measured the resulting internal astrometric accuracy of the UVOT,also giving the absolute accuracy with respect to the International Celestial ReferenceSystem. We have compiled statistics on the background count rates, and discuss thesources of the background, including instrumental scattered light. In each case we de-scribe any impact on UVOT measurements, whether any correction is applied in thestandard pipeline data processing or whether further steps are recommended.Keywords: instrumentation:photometers – instrumentation:detectors – astrometry

Published
2010

26. The XMM-Newton serendipitous survey IV. The AXIS X-ray source counts and angular clustering

Author

M. J. Page, R. Della Ceca, Michael Freyberg, Yoshihiro Ueda, Jonathan Tedds, Franz E. Bauer, Hermann Brunner, Silvia Mateos, Xavier Barcons, Francisco J. Carrera, J. Ebrero, T. Maccacaro, G. Lamer, Stefan Rosén, A. Corral, María Teresa Ceballos, and M. G. Watson

Subjects
Physics, media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), X-ray, Extrapolation, International survey, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Galaxy, Space and Planetary Science, Sky, Source counts, No detection, Cluster analysis, media_common
Abstract

AXIS (An XMM-Newton International Survey) is a survey of 36 high Galactic latitude XMM-Newton observations covering 4.8 deg2 and containing 1433 serendipitous X-ray sources detected with 5-sigma significance. We have studied the X-ray source counts in four energy bands soft (0.5-2 keV), hard (2-10 keV), XID (0.5-4.5 keV) and ultra-hard (4.5-7.5 keV). We have combined this survey with shallower and deeper surveys. Our source counts results are compatible with most previous samples in the soft, XID, ultra-hard and hard bands. The fractions of the XRB resolved in the surveys used in this work are 87%, 85%, 60% and 25% in the soft, hard, XID and ultra-hard bands, respectively. Extrapolation of our source counts to zero flux are not enough to saturate the XRB intensity. Only galaxies and/or absorbed AGN may be able contribute the remaining unresolved XRB intensity. Our results are compatible, within the errors, with recent revisions of the XRB intensity in the soft and hard bands. The maximum fractional contribution to the XRB comes from fluxes within about a decade of the break in the source counts (~1e-14 cgs), reaching ~50% of the total in the soft and hard bands. Using only AXIS sources, we have studied the angular correlation in those bands using a novel robust technique. Angular clustering (widely distributed over the sky and not confined to a few deep fields) is detected at 99-99.9% significance in the soft and XID bands, with no detection in the hard and ultra-hard band (probably due to the smaller number of sources). We cannot confirm the detection of significantly stronger clustering in the hard-spectrum hard sources. Medium depth surveys such as AXIS are essential to determine the evolution of the X-ray emission in the Universe below 10 keV., 28 pages, 10 figures, A&A accepted

Published
2007

27. The XMM-SSC survey of hard-spectrum XMM-Newton sources - I. Optically bright sources

Author

S. Hess, A. D. Schwope, Francisco J. Carrera, Stefan Rosén, Paola Severgnini, Tom Dwelly, M. J. Page, Houri Ziaeepour, R. G. McMahon, G. Lamer, Th. Boller, Ingo Lehmann, N. S. Loaring, I. Matute, R. Della Ceca, M. G. Watson, Jonathan Tedds, Weimin Yuan, Istituto Nazionale di Astrofisica, Ministero dell'Istruzione, dell'Università e della Ricerca, and Ministerio de Educación y Ciencia (España)

Subjects
Physics, QSOS, education.field_of_study, active [Galaxies], Astrophysics::High Energy Astrophysical Phenomena, Population, Flux, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Galaxies: active, galaxies [X-rays], X-rays: galaxies, Space and Planetary Science, Absorbed power, education, Astrophysics::Galaxy Astrophysics
Abstract

We present optical and X-ray data for a sample of serendipitous XMM-Newton sources that are selected to have 0.5-2 versus 2-4.5 keV X-ray hardness ratios which are harder than the X-ray background. The sources have 2-4.5 keV X-ray flux ≥10-14 erg cm-2 s-1, and in this paper we examine a subsample of 42 optically bright (r < 21) sources; this subsample is 100 per cent spectroscopically identified. All but one of the optical counterparts are extragalactic, and we argue that the single exception, a Galactic M star, is probably a coincidental association rather than the correct identification of the X-ray source. The X-ray spectra of all the sources are consistent with heavily absorbed power laws (21.8 < log NH < 23.4), and all of them, including the two sources with 2-10 keV intrinsic luminosities of 1044 erg s-1, and two of these sources have optical spectra which are dominated by narrow emission lines, that is, are type 2 QSOs. Only a small fraction of the sources (7/42) show broad optical emission lines, and all of these have NH < 1023 cm-2. This implies that ratios of X-ray absorption to optical/ultraviolet extinction equivalent to >100 times the Galactic gas-to-dust ratio are rare in AGN absorbers (at most a few per cent of the population), and may be restricted to broad absorption line QSOs. Seven objects appear to have an additional soft X-ray component in addition to the heavily absorbed power law; all seven are narrow emission-line objects with z < 0.3 and 2-10 keV intrinsic luminosities 4 per cent of broad-line AGN (BLAGN) have ionized absorbers that attenuate their soft X-ray flux by >50 per cent. In at least one of the X-ray-absorbed BLAGN in our sample the X-ray spectrum requires an ionized absorber, consistent with this picture., FJC acknowledges financial support from the Spanish Ministerio de Educacion Ciencia, under projects ESP2003-00812 and ESP2006-13608-C02-01. RDC and PS acknowledge partial financial support by the MIUR (Cofin-03-02-23) and INAF.

Published
2007

28. Optical, Infrared, and Ultraviolet Observations of the X-Ray Flash GRB 050416A

Author

K. O. Mason, N. Gehrels, Martin Still, P. Laursen, Katherine E. McGowan, Stefan Rosén, Patricia Schady, V. Mangano, T. S. Poole, P. T. Boyd, J. P. U. Fynbo, W. B. Landsman, A. J. Blustin, B. Thomsen, P. W. A. Roming, Jens Hjorth, T. Augusteijn, A. A. Breeveld, Stephen T. Holland, M. J. Page, Alberto Moretti, M. de Pasquale, Caryl Gronwall, Javier Gorosabel, F. E. Marshall, S. D. Hunsberger, M. Ivanushkina, and C. B. Markwardt

Subjects
Physics, Infrared, Extinction (astronomy), Astrophysics (astro-ph), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Afterglow, Photometry (optics), Space and Planetary Science, GRB 030329, Spectral energy distribution, Small Magellanic Cloud, Gamma-ray burst
Abstract

We present ultraviolet, optical, and infrared photometry of the afterglow of the X-ray flash XRF 050416A taken between approximately 100 seconds and 36 days after the burst. We find an intrinsic spectral slope between 1930 and 22,200 Angstrom of beta = -1.14 +/- 0.20 and a decay rate of alpha = -0.86 +/- 0.15. There is no evidence for a change in the decay rate between approximately 0.7 and 4.7 days after the burst. Our data implies that there is no spectral break between the optical and X-ray bands between 0.7 and 4.7 days after the burst, and is consistent with the cooling break being redward of the K_s band (22,200 Angstrom) at 0.7 days. The combined ultraviolet/optical/infrared spectral energy distribution shows no evidence for a significant amount of extinction in the host galaxy along the line of sight to XRF 050416A. Our data suggest that the extragalactic extinction along the line of sight to the burst is only approximately A_V = 0.2 mag, which is significantly less than the extinction expected from the hydrogen column density inferred from $X$-ray observations of XRF 050416A assuming a dust-to-gas ratio similar to what is found for the Milky Way. The observed extinction, however, is consistent with the dust-to-gas ratio seen in the Small Magellanic Cloud. We suggest that XRF 050416A may have a two-component jet similar to what has been proposed for GRB 030329. If this is the case the lack of an observed jet break between 0.7 and 42 days is an illusion due to emission from the wide jet dominating the afterglow after approximately 1.5 days., 22 pages, 5 figures, LaTeX, AASTeX 5.2 Minor changes made in response to the referee's report

Published
2006

29. Swift and optical observations of GRB 050401

Author

Massimiliano De Pasquale, A. P. Beardmore, S. D. Barthelmy, Bing Zhang, K. L. Page, David N. Burrows, Stefan Rosén, N. Geherls, Jeffrey A. Rich, Shiho Kobayashi, J. Tueller, K. O. Mason, P. W. A. Roming, T. Sakamoto, Alan A. Wells, J. A. Nousek, Bruce A. Peterson, R. McNought, Silvia Zane, P. A. Price, R. Fink, D. M. Palmer, Houri Ziaeepour, P. T. Boyd, and B. P. Schimdt

Subjects
Physics, Swift Gamma-Ray Burst Mission, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), Extinction (astronomy), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Radiation, Light curve, Redshift, Afterglow, Space and Planetary Science, Gamma-ray burst, Ejecta, Astrophysics::Galaxy Astrophysics
Abstract

We present the results of the analysis of gamma-ray and X-ray data of GRB 050401 taken with the Swift satellite, together with a series of ground-based follow-up observations. The Swift X-ray light curve shows a clear break at about 4900 seconds after the GRB. The decay indices before and after the break are consistent with a scenario of continuous injection of radiation from the 'central engine' of the GRB to the fireball. Alternatively, this behaviour could result if ejecta are released with a range of Lorentz factors with the slower shells catching up the faster at the afterglow shock position. The two scenarios are observationally indistinguishable. The GRB 050401 afterglow is quite bright in the X-ray band but weak in the optical, with an optical to X-ray flux ratio similar to those of 'dark bursts'. We detect a significant amount of absorption in the X-ray spectrum, with N_H = (1.7 +/- 0.2) x 10^22 cm^-2 at a redshift of z=2.9, which is typical of a dense circumbust medium. Such high column density implies an unrealistic optical extinction of 30 magnitudes if we adopt the Galactic extinction law, which would not consistent with optical detection of the afterglow. This suggests that the extinction law is different from the Galactic one., 13 pages, 5 figures. MNRAS accepted

Published
2005

30. Very Early Optical Afterglows of Gamma-Ray Bursts: Evidence for Relative Paucity of Detection

Author

Bing Zhang, J. P. Osborne, James E. Rhoads, W. B. Landsman, P. W. A. Roming, T. S. Poole, P. T. Boyd, D. B. Fox, C. Gronwall, Peter Brown, Silvia Zane, P. Meszaros, Adam N. Morgan, E. Rol, Patricia Schady, J. A. Nousek, M. de Pasquale, A. Cucchiara, E. E. Fenimore, A. J. Blustin, David N. Burrows, Stefan Rosén, Shiho Kobayashi, Dirk Grupe, N. Gehrels, D. M. Palmer, Martin Still, V. Mangano, C. W. James, K. L. Page, K. O. Mason, D. E. vanden Berk, A. A. Breeveld, M. Ivanushkina, E. W. Liang, S. D. Barthelmy, Katherine E. McGowan, S. T. Holland, J. A. Kennea, M. R. Goad, and G. Tagliaferri

Subjects
Physics, Swift Gamma-Ray Burst Mission, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), Extinction (astronomy), FOS: Physical sciences, Flux, Astronomy and Astrophysics, Blanketing, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Redshift, Afterglow, Space and Planetary Science, Absorption (electromagnetic radiation), Gamma-ray burst, Astrophysics::Galaxy Astrophysics
Abstract

Very early observations with the Swift satellite of gamma-ray burst (GRB) afterglows reveal that the optical component is not detected in a large number of cases. This is in contrast to the bright optical flashes previously discovered in some GRBs (e.g. GRB 990123 and GRB 021211). Comparisons of the X-ray afterglow flux to the optical afterglow flux and prompt gamma-ray fluence is used to quantify the seemingly deficient optical, and in some cases X-ray, light at these early epochs. This comparison reveals that some of these bursts appear to have higher than normal gamma-ray efficiencies. We discuss possible mechanisms and their feasibility for explaining the apparent lack of early optical emission. The mechanisms considered include: foreground extinction, circumburst absorption, Ly-alpha blanketing and absorption due to high redshift, low density environments, rapid temporal decay, and intrinsic weakness of the reverse shock. Of these, foreground extinction, circumburst absorption, and high redshift provide the best explanations for most of the non-detections in our sample. There is tentative evidence of suppression of the strong reverse shock emission. This could be because of a Poynting-flux-dominated flow or a pure non-relativistic hydrodynamical reverse shock., 22 pages, 5 figures. Accepted for publication in ApJ

Published
2005

31. X-ray and UV observations of V751 Cygni in an optical high state

Author

Phil Evans, M. G. Watson, K. L. Page, Stefan Rosén, A. P. Beardmore, and J. P. Osborne

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Astrophysics::High Energy Astrophysical Phenomena, X-ray, FOS: Physical sciences, Flux, Astronomy and Astrophysics, Astrophysics, Nova (laser), Orbital period, Spectral line, law.invention, Telescope, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, law, Magnitude (astronomy), Astrophysics - High Energy Astrophysical Phenomena, Absorption (electromagnetic radiation), Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

Aims: The VY Scl system (anti-dwarf nova) V751 Cyg is examined following a claim of a super-soft spectrum in the optical low state. Methods: A serendipitous XMM-Newton X-ray observation and, 21 months later, Swift X-ray and UV observations, have provided the best such data on this source so far. These optical high-state datasets are used to study the flux and spectral variability of V751 Cyg. Results: Both the XMM-Newton and Swift data show evidence for modulation of the X-rays for the first time at the known 3.467 hr orbital period of V751 Cyg. In two Swift observations, taken ten days apart, the mean X-ray flux remained unchanged, while the UV source brightened by half a magnitude. The X-ray spectrum was not super-soft during the optical high state, but rather due to multi-temperature optically thin emission, with significant (10^{21-22} cm^-2) absorption, which was higher in the observation by Swift than that of XMM-Newton. The X-ray flux is harder at orbital minimum, suggesting that the modulation is related to absorption, perhaps linked to the azimuthally asymmetric wind absorption seen previously in H-alpha., 6 pages, 9 figures, accepted for publication in A&A

Published
2014

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