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100 results on '"Paerels, F. B. S."'

51. Clusters of Galaxies: Beyond the Thermal View

Author

Kaastra, J. S., primary, Bykov, A. M., additional, Schindler, S., additional, Bleeker, J. A. M., additional, Borgani, S., additional, Diaferio, A., additional, Dolag, K., additional, Durret, F., additional, Nevalainen, J., additional, Ohashi, T., additional, Paerels, F. B. S., additional, Petrosian, V., additional, Rephaeli, Y., additional, Richter, P., additional, Schaye, J., additional, and Werner, N., additional

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57. Tentative detection of warm intervening gas towards PKS 0548-322 with XMM-Newton

Author

Barcons, Xavier, Paerels, F. B. S., Carrera, Francisco J., Ceballos, María Teresa, Sako, M., Barcons, Xavier, Paerels, F. B. S., Carrera, Francisco J., Ceballos, María Teresa, and Sako, M.

Abstract

We present the results of a long (~93 ksec) XMM-Newton observation of the bright BL-Lac object PKS 0548-322 (z=0.069). Our Reflection Grating Spectrometer (RGS) spectrum shows a single absorption feature at an observed wavelength lambda=23.33 A, which we interpret as OVI Ka absorption at z=0.058, i.e., ~3000 km/s from the background object. The observed equivalent width of the absorption line ~30 mA, coupled with the lack of the corresponding absorption edge in the EPIC pn data, implies an OVI column density ~ 2x10^{16} cm-2 and turbulence with a Doppler velocity parameter b>100 km/s. Within the limitations of our RGS spectrum, no OVII or OV Ka absorption are detected. Under the assumption of ionisation equilibrium by both collisions and the extragalactic background, this is only marginally consistent if the gas temperature is ~250,000 K, with significantly lower or higher values being excluded by our limits on OV or OVII. If confirmed, this would be the first X-ray detection of a large amount of intervening warm absorbing gas through OVI absorption. The existence of such a high column density absorber, much stronger than any previously detected one in OVI, would place stringent constraints on the large-scale distribution of baryonic gas in the Universe.

Published
2005

63. Clusters of Galaxies: Beyond the Thermal View

Author

Kaastra, J. S., primary, Bykov, A. M., additional, Schindler, S., additional, Bleeker, J. A. M., additional, Borgani, S., additional, Diaferio, A., additional, Dolag, K., additional, Durret, F., additional, Nevalainen, J., additional, Ohashi, T., additional, Paerels, F. B. S., additional, Petrosian, V., additional, Rephaeli, Y., additional, Richter, P., additional, Schaye, J., additional, and Werner, N., additional

Published
2008
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65. Calibration and in-orbit performance of the reflection grating spectrometer onboard XMM-Newton.

Author

de Vries, C. P., den Herder, J. W., Gabriel, C., Gonzalez-Riestra, R., Ibarra, A., Kaastra, J. S., Pollock, A. M. T., Raassen, A. J. J., and Paerels, F. B. S.

Subjects
SPECTROMETERS, ORBITS (Astronomy), WAVELENGTH measurement, ABSORPTION, CALIBRATION
Abstract

Context. XMM-Newton was launched on 10 December 1999 and has been operational since early 2000. One of the instruments onboard XMM-Newton is the reflection grating spectrometer (RGS). Two identical RGS instruments are available, with each RGS combining a reflection grating assembly and a camera with charge-coupled devices to record the spectra. Aims. We describe the calibration and in-orbit performance of the RGS instrument. By combining the preflight calibration with appropriate inflight calibration data including the changes in detector performance over time, we aim at profound knowledge about the accuracy in the calibration. This will be crucial for any correct scientific interpretation of spectral features for a wide variety of objects. Methods. Ground calibrations alone are not able to fully characterize the instrument. Dedicated inflight measurements and constant monitoring are essential for a full understanding of the instrument and the variations of the instrument response over time. Physical models of the instrument are tuned to agree with calibration measurements and are the basis from which the actual instrument response can be interpolated over the full parameter space. Results. Uncertainties in the instrument response have been reduced to <10% for the effective area and <6 mÅ for the wavelength scale (in the range from 8 Å to 34 Å). The remaining systematic uncertainty in the detection of weak absorption features has been estimated to be 1.5%. Conclusions. Based on a large set of inflight calibration data and comparison with other instruments onboard XMM-Newton, the calibration accuracy of the RGS instrument has been improved considerably over the preflight calibrations. [ABSTRACT FROM AUTHOR]

Published
2015
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68. Simultaneous X-ray and UV spectroscopy of the Seyfert galaxy NGC 5548

Author

Steenbrugge, K. C., primary, Kaastra, J. S., additional, Crenshaw, D. M., additional, Kraemer, S. B., additional, Arav, N., additional, George, I. M., additional, Liedahl, D. A., additional, van der Meer, R. L. J., additional, Paerels, F. B. S., additional, Turner, T. J., additional, and Yaqoob, T., additional

Published
2005
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71. Chandra LETGS and XMM-Newton observations of NGC 4593

Author

Steenbrugge, K. C., primary, Kaastra, J. S., additional, Blustin, A. J., additional, Branduardi-Raymont, G., additional, Sako, M., additional, Behar, E., additional, Kahn, S. M., additional, Paerels, F. B. S., additional, and Walter, R., additional

Published
2003
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72. Simultaneous Ultraviolet and X‐Ray Spectroscopy of the Seyfert 1 Galaxy NGC 5548. I. Physical Conditions in the Ultraviolet Absorbers

Author

Crenshaw, D. M., primary, Kraemer, S. B., additional, Gabel, J. R., additional, Kaastra, J. S., additional, Steenbrugge, K. C., additional, Brinkman, A. C., additional, Dunn, J. P., additional, George, I. M., additional, Liedahl, D. A., additional, Paerels, F. B. S., additional, Turner, T. J., additional, and Yaqoob, T., additional

Published
2003
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77. High resolution soft X-ray spectroscopy of M 87 with the reflection grating spectrometers on $\vec{XMM-Newton}$

Author

Sakelliou, I., primary, Peterson, J. R., additional, Tamura, T., additional, Paerels, F. B. S., additional, Kaastra, J. S., additional, Belsole, E., additional, Böhringer, H., additional, Branduardi-Raymont, G., additional, Ferrigno, C., additional, den Herder, J. W., additional, Kennea, J., additional, Mushotzky, R. F., additional, Vestrand, W. T., additional, and Worrall, D. M., additional

Published
2002
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79. X-ray imaging-spectroscopy of Abell 1835

Author

Peterson, J. R., primary, Paerels, F. B. S., additional, Kaastra, J. S., additional, Arnaud, M., additional, Reiprich, T. H., additional, Fabian, A. C., additional, Mushotzky, R. F., additional, Jernigan, J. G., additional, and Sakelliou, I., additional

Published
2001
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80. First light measurements with the XMM-Newton reflection grating spectrometers: Evidence for an inverse first ionisation potential effect and anomalous Ne abundance in the Coronae of HR 1099

Author

Brinkman, A. C., primary, Behar, E., additional, Güdel, M., additional, Audard, M., additional, den Boggende, A. J. F., additional, Branduardi-Raymont, G., additional, Cottam, J., additional, Erd, C., additional, den Herder, J. W., additional, Jansen, F., additional, Kaastra, J. S., additional, Kahn, S. M., additional, Mewe, R., additional, Paerels, F. B. S., additional, Peterson, J. R., additional, Rasmussen, A. P., additional, Sakelliou, I., additional, and de Vries, C., additional

Published
2001
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82. Simultaneous X-ray and ultraviolet spectroscopy of the Seyfert galaxy NGC 5548

Author

Kaastra, J. S., Steenbrugge, K. C., Crenshaw, D. M., Kraemer, S. B., Arav, N., George, I. M., Liedahl, D. A., van der Meer, R. L. J., Paerels, F. B. S., Turner, T. J., Yaqoob, T., Kaastra, J. S., Steenbrugge, K. C., Crenshaw, D. M., Kraemer, S. B., Arav, N., George, I. M., Liedahl, D. A., van der Meer, R. L. J., Paerels, F. B. S., Turner, T. J., and Yaqoob, T.

Abstract

The Seyfert 1 galaxy NGC 5548 was observed for a week by Chandra using both the HETGS and LETGS spectrometers. In this paper we study the time variability of the continuum radiation. During our observation, the source showed a gradual increase in flux over four days, followed by a rapid decrease and flattening of the light curve afterwards. Superimposed upon these relatively slow variations several short duration bursts or quasi-periodic oscillations occured with a typical duration of several hours and separation between 0.6–0.9 days. The bursts show a delay of the hard X-rays with respect to the soft X-rays of a few hours. We interpret these bursts as occurring due to a rotating, fluctuating hot spot at approximately 10 gravitational radii; the time delay of the hard X-rays from the bursts agrees with the canonical picture of Inverse Compton scattering of the soft accretion disk photons on a hot medium that is relatively close to the central black hole.

Published
2004
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83. Spatially resolved X-ray spectroscopy of cooling clusters of galaxies

Author

Kaastra, J. S., Tamura, T., Peterson, J. R., Bleeker, J. A. M., Ferrigno, C., Kahn, S. M., Paerels, F. B. S., Piffaretti, R., Branduardi-Raymont, G., Böhringer, H., Kaastra, J. S., Tamura, T., Peterson, J. R., Bleeker, J. A. M., Ferrigno, C., Kahn, S. M., Paerels, F. B. S., Piffaretti, R., Branduardi-Raymont, G., and Böhringer, H.

Abstract

We present spatially resolved X-ray spectra taken with the EPIC cameras of XMM-Newton of a sample of 17 cooling clusters and three non-cooling clusters for comparison. The deprojected spectra are analyzed with a multi-temperature model, independent of any a priori assumptions about the physics behind the cooling and heating mechanisms. All cooling clusters show a central decrement of the average temperature, most of them of a factor of ${\sim} 2$. Three clusters (Sérsic 159-3, MKW 3s and Hydra A) only show a weak temperature decrement, while two others (A 399 and A 2052) have a very strong temperature decrement. All cooling clusters show a weak pressure gradient in the core. More important, at each radius within the cooling region the gas is not isothermal. The differential emission measure distribution shows a strong peak near the maximum (ambient) temperature, with a steep decline towards lower temperatures, approximately proportional to T3, or alternatively a cut-off at about a quarter to half of the maximum temperature. In general, we find a poor correlation between radio flux of the central galaxy and the temperature decrement of the cooling flow. This is interpreted as evidence that except for a few cases (like the Hydra A cluster) heating by a central AGN is not the most common cause of weak cooling flows. We investigate the role of heat conduction by electrons and find that the theoretically predicted conductivity rates are not high enough to balance radiation losses. The differential emission measure distribution has remarkable similarities with the predictions from coronal magnetic loop models. Also the physical processes involved (radiative cooling, thermal conduction along the loops, gravity) are similar for clusters loops and coronal loops. If coronal loop models apply to clusters, we find that a few hundred loops per scale height should be present. The typical loop sizes deduced from the observed emission measure distribution are consistent with the characteristic magnetic field sizes deduced from Faraday rotation measurements.

Published
2004
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84. XMM-Newton confirmation of soft X-ray excess emission in clusters of galaxies – The discovery of O VII emission from an extended warm baryonic component

Author

Kaastra, J. S., Lieu, R., Tamura, T., Paerels, F. B. S., den Herder, J. W., Kaastra, J. S., Lieu, R., Tamura, T., Paerels, F. B. S., and den Herder, J. W.

Abstract

We investigate a sample of 14 clusters of galaxies observed with XMM-Newton in a search for soft X-ray excess emission. In five of these clusters a significant soft excess is evident. This soft X-ray excess is compared with the thermal emission from both the hot intracluster gas and any cooling (flow) gas that may be present. A warm ($kT=0.2$keV), extended (several Mpc), plasma component is particularly clear in the outer parts of the cluster, where the normal cluster X-ray emission is weak. This warm component causes both a thermal soft X-ray excess at low energies (below 0.4–0.5 keV), as well as $\ion{O}{vii}$line emission with a redshift consistent with a cluster origin, and not easily interpreted as Galactic foreground emission. The intensity of this component is commensurate with what has been measured before with the ROSAT PSPC in the 1/4 keV band. We attribute this component to emission from intercluster filaments of the Warm-Hot Intergalactic Medium in the vicinity of these clusters. For the central regions of clusters the detection of lines in the soft X-ray spectrum is more difficult, due to the predominance of the X-ray emitting hot plasma there, hence we cannot discriminate between the thermal and nonthermal origin of the soft excess, leaving several options open. These include thermal emission from warm filaments seen in projection in front of or behind the cluster center, thermal or nonthermal emission in the cluster core itself related to magnetic reconnection, or Inverse Compton emission from the cosmic microwave background on relativistic electrons.

Published
2003
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85. X-ray spectroscopy of the cluster of galaxies Abell 1795with XMM-Newton

Author

Tamura, T., Kaastra, J. S., Peterson, J. R., Paerels, F. B. S., Mittaz, J. P. D., Trudolyubov, S. P., Stewart, G., Fabian, A. C., Mushotzky, R. F., Lumb, D. H., Ikebe, Y., Tamura, T., Kaastra, J. S., Peterson, J. R., Paerels, F. B. S., Mittaz, J. P. D., Trudolyubov, S. P., Stewart, G., Fabian, A. C., Mushotzky, R. F., Lumb, D. H., and Ikebe, Y.

Abstract

The initial results from XMM-Newtonobservations of the rich cluster of galaxies Abell 1795are presented. The spatially-resolved X-ray spectra taken by the European Photon Imaging Cameras (EPIC) show a temperature drop at a radius of ~200 kpc from the cluster center, indicating that the ICM is cooling. Both the EPIC and the Reflection Grating Spectrometers (RGS) spectra extracted from the cluster center can be described by an isothermal model with a temperature of ~4 keV. The volume emission measure of any cool component ($< 1$keV) is less than a few % of the hot component at the cluster center. A strong OviiiLyman αline was detected with the RGS from the cluster core. The O abundance and its ratio to Fe at the cluster center is 0.2-0.5 and 0.5-1.5 times the solar value, respectively.

Published
2001
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87. EXOSAT observations of Cygnus X-2 continuum and line spectrum

Author

Chiappetti, L., primary, Treves, A., additional, Branduardi-Raymont, G., additional, Chiapi, A. L., additional, Ercan, E. N., additional, Freeman, P. E., additional, Kahn, S. M., additional, Maraschi, L., additional, Paerels, F. B. S., additional, and Tanzi, E. G., additional

Published
1990
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89. Soft X-ray excess in the cluster of galaxies Sérsic 159-03.

Author

de Plaa, J., Kaastra, J. S., Méndez, M., Tamura, T., Bleeker, J. A. M., Peterson, J., Paerels, F. B. S., Bonamente, M., and Lieu, R.

Abstract

We present the results from a new 120 ks XMM-Newton observation of Sérsic 159-03. A previous XMM-Newton observation of this cluster shows the presence of a soft X-ray excess in the outer parts of the cluster, which is possibly connected to the interaction between the cluster and the gas from the surrounding filaments. We exploit the long exposure time to constrain the excess emission and discuss the relation to the warm-hot intergalactic medium. Furthermore, we show a high-resolution RGS spectrum of the core of the cluster and radial profiles from EPIC, which allow us to constrain the internal temperature structure and elemental abundances.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html [ABSTRACT FROM PUBLISHER]

Published
2004
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91. Resonance scattering in the X-ray emission lines profiles of ζ Puppis

Author

Leutenegger, M. A., David Cohen, Kahn, S. M., Owocki, S. P., and Paerels, F. B. S.

Subjects
Astrophysics::High Energy Astrophysical Phenomena, ddc:520, Extern
Abstract

We present XMM-Newton Reflection Grating Spectrometer observations of pairs of X-ray emission line profiles from the O star ζ Pup that originate from the same He-like ion. The two profiles in each pair have different shapes and cannot both be consistently fit by models assuming the same wind parameters. We show that the differences in profile shape can be accounted for in a model including the effects of resonance scattering, which affects the resonance line in the pair but not the intercombination line. This implies that resonance scattering is also important in single resonance lines, where its effect is difficult to distinguish from a low effective continuum optical depth in the wind. Thus, resonance scattering may help reconcile X-ray line profile shapes with literature mass-loss rates.

92. The LOFT perspective on neutron star thermonuclear bursts

Author

In T Zand, J. J. M., Altamirano, D., Ballantyne, D. R., Bhattacharyya, S., Brown, E. F., Cavecchi, Y., Chakrabarty, D., Chenevez, J., Cumming, A., Degenaar, N., Falanga, M., Galloway, D. K., Heger, A., José, J., Keek, L., Linares, M., Mahmoodifar, S., Malone, C. M., Méndez, M., Miller, M. C., Paerels, F. B. S., Juri Poutanen, Rózanska, A., Schatz, H., Serino, M., Strohmayer, T. E., Suleimanov, V. F., Thielemann, F. -K, Watts, A. L., Weinberg, N. N., Woosley, S. E., Yu, W., Zhang, S., Zingale, M., and Astronomy

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Astrophysics::High Energy Astrophysical Phenomena, Physics::Space Physics, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract

This is a White Paper in support of the mission concept of the Large Observatory for X-ray Timing (LOFT), proposed as a medium-sized ESA mission. We discuss the potential of LOFT for the study of thermonuclear X-ray bursts on accreting neutron stars. For a summary, we refer to the paper., Comment: White Paper in Support of the Mission Concept of the Large Observatory for X-ray Timing

99. Clusters of Galaxies: Beyond the Thermal View

Author

Takaya Ohashi, Jelle Kaastra, F. Durret, Norbert Werner, Vahé Petrosian, Johan A. M. Bleeker, Yoel Rephaeli, Joop Schaye, Stefano Borgani, Jukka Nevalainen, Andrei M. Bykov, Sabine Schindler, Frits Paerels, Philipp Richter, Klaus Dolag, Antonaldo Diaferio, Kaastra, J. S., Bykov, A. M., Schindler, S., Bleeker, J. A. M., Borgani, Stefano, Diaferio, A., Dolag, K., Durret, F., Nevalainen, J., Ohashi, T., Paerels, F. B. S., Petrosian, V., Rephaeli, Y., Richter, P., Schaye, J., Werner, N., Astrophysics, and Dep Natuurkunde

Subjects
Structure formation, media_common.quotation_subject, Large-scale structure of universe, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, clusters: general [Galaxies], 01 natural sciences, 0103 physical sciences, 010303 astronomy & astrophysics, galaxy clusters [X-rays], Galaxies: clusters: general, Intergalactic medium, X-rays: galaxy clusters, Astrophysics::Galaxy Astrophysics, media_common, Physics, Teamwork, 010308 nuclear & particles physics, Astrophysics (astro-ph), Astronomy, Subject (documents), Astronomy and Astrophysics, Thermal emission, Galaxy, Field (geography), Space and Planetary Science, Space Science
Abstract

We present the work of an international team at the International Space Science Institute (ISSI) in Bern that worked together to review the current observational and theoretical status of the non-virialised X-ray emission components in clusters of galaxies. The subject is important for the study of large-scale hierarchical structure formation and to shed light on the "missing baryon" problem. The topics of the team work include thermal emission and absorption from the warm-hot intergalactic medium, non-thermal X-ray emission in clusters of galaxies, physical processes and chemical enrichment of this medium and clusters of galaxies, and the relationship between all these processes. One of the main goals of the team is to write and discuss a series of review papers on this subject. These reviews are intended as introductory text and reference for scientists wishing to work actively in this field. The team consists of sixteen experts in observations, theory and numerical simulations., Comment: 6 pages, 1 figure, accepted for publication in Space Science Reviews, special issue "Clusters of galaxies: beyond the thermal view", Editor J.S. Kaastra, Chapter 1; work done by an international team at the International Space Science Institute (ISSI), Bern, organised by J.S. Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeker

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100. Shocks and Non-thermal Particles in Clusters of Galaxies

Author

Franco Vazza, Frits Paerels, A. M. Bykov, J. A. Kropotina, K. P. Levenfish, Bykov, A. M., Vazza, F., Kropotina, J. A., Levenfish, K. P., and Paerels, F. B. S.

Subjects
010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, Population, FOS: Physical sciences, Cosmic ray, Astrophysics, Electron, Astrophysics::Cosmology and Extragalactic Astrophysics, 7. Clean energy, 01 natural sciences, Intracluster medium, 0103 physical sciences, Clusters of galaxies · Shocks · Cosmic rays, education, 010303 astronomy & astrophysics, Galaxy cluster, 0105 earth and related environmental sciences, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), education.field_of_study, Astronomy and Astrophysics, Galaxy, Particle acceleration, 13. Climate action, Space and Planetary Science, Astrophysics - High Energy Astrophysical Phenomena, Fermi Gamma-ray Space Telescope
Abstract

Galaxy clusters grow by gas accretion, mostly from mergers of substructures, which release powerful shock waves into cosmic plasmas and convert a fraction of kinetic energy into thermal energy, amplification of magnetic fields and into the acceleration of energetic particles. The modeling of the radio signature of cosmic shocks, combined with the lack of detected gamma-rays from cosmic ray (CR) protons, poses challenges to our understanding of how cosmic rays get accelerated and stored in the intracluster medium. Here we review the injection of CRs by cosmic shocks of different strengths, combining the detailed "microscopic" view of collisionless processes governing the creation of non-thermal distributions of electrons and protons in cluster shocks (based on analytic theory and particle-in-cell simulations), with the "macroscopic" view of the large-scale distribution of cosmic rays, suggested by modern cosmological simulations. We discuss time dependent non-linear kinetic models of particle acceleration by multiple internal shocks with large scale compressible motions of plasma. The models produce soft CR spectra containing a noticeable energy density in the super-thermal protons of energies below a few GeV which are difficult to constrain by Fermi observations. We consider the effect of plasma composition on CR injection and super-thermal particle population in the hot intracluster matter which can be constrained by fine high resolution X-ray spectroscopy of Fe ions., Comment: Space Science Reviews, in print

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