arXiv subjects

Axel Schwope

Publications and source records attributed to Axel Schwope.

58 records · Page 4Linked to original sources

arXiv2010

eROSITA on SRG

eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the core instrument on the Russian Spektrum-Roentgen-Gamma (SRG) mission which is scheduled for launch in late 2012. eROSITA is fully approved and funded by the German Space Agency DLR and the Max-Planck-Society.The design driving science is the detection of 50-100 thousands Clusters of Galaxies up to redshift z~1.3 in order to study the large scale structure in the Universe and test cosmological models, especially Dark Energy. This will be accomplished by an all-sky survey lasting for four years plus a phase of pointed observations. eROSITA consists of seven Wolter-I telescope modules, each equipped with 54 Wolter-I shells having an outer diameter of 360 mm. This would provide and effective area at 1.5 keV of ~1500 cm2 and an on axis PSF HEW of 15" which would provide an effective angular resolution of 25"-30". In the focus of each mirror module, a fast frame-store pn-CCD will provide a field of view of 1deg in diameter for an active FOV of ~0.83 deg2. At the time of writing the instrument development is currently in phase C/D.

astro-ph.CO↗

arXiv2009

Multi-wavelength observations of a rich galaxy cluster at z ~ 1: the HST/ACS colour-magnitude diagram

XMMU J1229+0151 is a rich galaxy cluster with redshift z=0.975, that was serendipitously detected in X-rays within the scope of the XMM-Newton Distant Cluster Project. HST/ACS observations in the i775 and z850 passbands, as well as VLT/FORS2 spectroscopy were further obtained, in addition to follow-up Near-Infrared (NIR) imaging in J- and Ks-bands with NTT/SOFI. We investigate the photometric, structural and spectral properties of the early-type galaxies in the high-redshift cluster XMMU J1229+0151. Source detection and aperture photometry are performed in the optical and NIR imaging. Galaxy morphology is inspected visually and by means of Sersic profile fitting to the 21 spectroscopically confirmed cluster members in the ACS field of view. The i775-z850 colour-magnitude relation (CMR) is derived with a method based on galaxy magnitudes obtained by fitting the surface brightness of the galaxies with Sersic models. The i775-z850 CMR of the spectroscopic members shows a very tight red-sequence with a zero point of 0.86+-0.04 mag and intrinsic scatter equal to 0.039 mag. The CMR obtained with the galaxy models has similar parameters. Stellar masses and formation ages of the cluster galaxies are derived by fitting the observed spectral energy distributions (SED) with models based on Bruzual & Charlot 2003. We obtain a star formation weighted age of 4.3 Gyr for a median mass of 7.4e10 Msun. Instead of an unambiguous brightest cluster galaxy (BCG), we find three bright galaxies with a similar z850 magnitude, which are, in addition, the most massive cluster members, with ~ 2e11 Msun. Our results strengthen the current evidence for a lack of significant evolution of the scatter and slope of the red-sequence out to z~1.

astro-ph.CO↗

arXiv2008

2XMM J100451.6+411627: A cool core cluster at z=0.82

- Aims: Gas cooling in the centre of massive galaxy clusters is believed to feed the most powerful active galactic nuclei in the Universe. How often clusters at high redshift show such cool cores has still to be explored by current and upcoming X-ray telescopes. - Methods: We correlated extended X-ray emissions from the second XMM-Newton source catalogue with SDSS data to particularly identify distant clusters. 2XMM J100451.6+411627 is a candidate luminous enough to obtain its redshift and temperature from the X-ray spectrum. We also determine the surface luminosity profile and estimate the temperature in a few spherical bins. The analysis is complemented by a Subaru g'r'i'-image. - Results: 2XMM J100451.6+411627 has a redshift a redshift of z=0.82+-0.02 and a temperature of k_BT = 4.2+-0.4 keV. A double-beta profile fit yields a highly concentrated surface brightness, c_SB = 0.32, i.e. the clusters hosts very likely a strong cool core. This is supported by the relaxed morphology of the cluster and an central temperature decrease.

astro-ph↗

arXiv2003

X-rays from Cataclysmic Variables

Cataclysmic Variables are a distinct class of interacting binaries, transferring mass from a donor star to a degenerate accretor, a white dwarf. We here review X-ray observations of these systems, with some emphasis on what has been achieved in the last decade.

astro-ph↗