The Hamburg Identification Program of Rosat All-Sky Survey Sources

Bade, N.; Cordis, L.; Engels, D.; Reimers, D.; Voges, W.

doi:10.1007/978-94-009-1485-8_111

Cited by 46 publications

(67 citation statements)

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“…The object appears to be lensed by a galaxy cluster at z ¼ 0:7689 ( Burud et al 1998;Kneib et al 2000). The QSO itself is a mini-broad absorption line ( BAL) QSO ( Bade et al 1997); in the present data (see below) we detect triangular troughs at blueshifts of 18,700 km s À1 relative to the QSO's broad C iv emission peak ( Fig. 1).…”

Section: Rx J09114+0551supporting

confidence: 47%

“…This object was identified as a gravitationally lensed quasar by Bade et al (1997). The image configuration consists of four images in an ''animal paw'' pattern with mutual separations of up to 3B1 ( Burud et al 1998).…”

Section: Rx J09114+0551mentioning

confidence: 99%

“…The observations and data analysis are described in x 2, followed in x 3 by an analysis of the velocity differences between common absorption systems at the smallest ($1 kpc proper) scales as represented by the typical transverse separations between the beams to the gravitationally lensed QSO RXJ0911.4+0551 (z ¼ 2:79; Bade et al 1997). The cross-correlation function between the two Ly forest sight lines is derived, and an alternative method is presented that measures the difference between the line-of-sight velocities of individual, manually selected absorption systems common to two adjacent sight lines.…”

Section: Introductionmentioning

confidence: 99%

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Expansion and Collapse in the Cosmic Web

Rauch

Becker

Viel

et al. 2005

ApJ

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We study the kinematics of the gaseous cosmic web at high redshift using Ly forest absorption in multiple QSO sight lines. Observations of the projected velocity shifts between Ly absorbers common to the lines of sight to a gravitationally lensed QSO and three more widely separated QSO pairs are used to directly measure the expansion of the cosmic web in units of the Hubble velocity, as a function of redshift and spatial scale. The lines of sight used span a redshift range from about 2 to 4.5 and represent transverse scales from the subkiloparsec range to about 300 h À1 70 physical kpc. Using a simple analytic model and a cosmological hydrodynamic simulation, we constrain the underlying three-dimensional distribution of expansion velocities from the observed line-of-sight distribution of velocity shear across the plane of the sky. The shape of the shear distribution and its width (14.9 km s À1 rms for a physical transverse separation of 61 h À1 70 kpc at z ¼ 2, 30.0 km s À1 for 261 h À1 70 kpc at z ¼ 3:6) are found to be in good agreement with the IGM undergoing large-scale motions dominated by the Hubble flow, making this one of the most direct observations possible of the expansion of the universe. However, modeling the Ly clouds with a simple ''expanding pancake'' model, the average expansion velocity of the gaseous structures causing the Ly forest in the lower redshift (z $ 2) smaller separation (61 kpc) sample appears about 20% lower than the local Hubble expansion velocity.In order to understand the observed velocity distribution further we investigated the statistical distribution of expansion velocities in cosmological Ly forest simulations. The mean expansion velocity in the (z $ 2, separation $ 60 kpc) simulation is indeed somewhat smaller than the Hubble velocity, as found in the real data. We interpret this finding as tentative evidence for some Ly forest clouds breaking away from the Hubble flow and undergoing the early stages of gravitational collapse. However, the distribution of velocities is highly skewed, and the majority of Ly forest clouds at all redshifts from 2 to 3.8 expand with super-Hubble velocities, typically about 5%-20% faster than the Hubble flow. This behavior is explained if most Ly forest clouds in the column density range typically detectable are expanding filaments that stretch and drain into more massive nodes. The significant difference seen in the velocity distributions between the high-and low-redshift samples may conceivably reflect actual peculiar deceleration, the differences in spatial scale, or our selecting higher densities at lower redshift for a given detection threshold for Ly forest lines.We also investigate the alternative possibility that the velocity structure of the general Ly forest could have an entirely different, local origin, as expected if the Ly forest were produced or at least significantly modified by galactic feedback, e.g., winds from star-forming galaxies at high redshift. However, we find no evidence that the observed distribution of veloc...

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Section: Rx J09114+0551supporting

confidence: 47%

Section: Rx J09114+0551mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Expansion and Collapse in the Cosmic Web

Rauch

Becker

Viel

et al. 2005

ApJ

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“…References. References for the redshifts of the lenses and sources: (a) Browne et al (1993); Stickel & Kuehr (1993);Carilli et al (1993); (b) Cohen et al (2003); (c) Lubin et al (2000); (d) Kochanek et al (1997); Oscoz et al (1997); (e) Kneib et al (2000); (f) Bade et al (1997); (g) Eigenbrod et al (2007); (h) Jakobsson et al (2005); (i) Lidman et al (2000); (j) Smette et al (1995); (k) Tonry (1998); (l) Weymann et al (1980); (m) Tonry (1998); (n) Patnaik et al (1992); (o) Auger et al (2008); (p) Chavushyan et al (1997); (q) Jaunsen & Hjorth (1997); Fassnacht & Cohen (1998); (r) Fassnacht & Cohen (1998); (s) Myers et al (1995); (t) Fassnacht et al (1996); (u) Eigenbrod et al (2007); (v) Wisotzki et al (1996). …”

Section: Datamentioning

confidence: 99%

COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses

Sluse

Chantry

Magain

et al. 2012

A&A

121

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Gravitationally lensed quasars can be used as powerful cosmological and astrophysical probes. We can (i) infer the Hubble constant H 0 based on the so-called time-delay technique, (ii) unveil substructures along the line-of-sight toward distant galaxies, and (iii) compare the shape and the slope of baryons and dark matter distributions in the inner regions of galaxies. To reach these goals, we need highaccuracy astrometry of the quasar images relative to the lensing galaxy and morphology measurements of the lens. In this work, we first present new astrometry for 11 lenses with measured time delays, namely, JVAS B0218+357, SBS 0909+532, RX J0911.4+0551, FBQS J0951+2635, HE 1104-1805, PG 1115+080, JVAS B1422+231, SBS 1520+530, CLASS B1600+434, CLASS B1608+656, and HE 2149-2745. These measurements proceed from the use of the Magain-Courbin-Sohy (MCS) deconvolution algorithm applied in an iterative way (ISMCS) to near-IR HST images. We obtain a typical astrometric accuracy of about 1-2.5 mas and an accurate shape measurement of the lens galaxy. Second, we combined these measurements with those of 14 other lensing systems, mostly from the COSMOGRAIL set of targets, to present new mass models of these lenses. The modeling of these 25 gravitational lenses led to the following results: 1) in four double-image quasars (HE0047-1746, J1226-006, SBS 1520+530, and HE 2149-2745), we show that the influence of the lens environment on the time delay can easily be quantified and modeled, hence putting these lenses with high priority for time-delay determination; 2) for quadruple-image quasars, the difficulty often encountered in reproducing the image positions to milli-arcsec accuracy (astrometric anomaly problem) is overcome by explicitly including the nearest visible galaxy/satellite in the lens model. However, one anomalous system (RXS J1131-1231) does not show any luminous perturber in its vicinity, and three others (WFI 2026-4536, WFI 2033, and B2045+265) have problematic modeling. These four systems are the best candidates for a pertubation by a dark matter substructure along the line-of-sight; 3) we revisit the correlation between the position angle (PA) and ellipticity of the light and of the mass distribution in lensing galaxies. As in previous studies, we find a significant correlation between the PA of the light and of the mass distributions. However, in contrast with these same studies, we find that the ellipticity of the light and of the mass also correlate well, suggesting that the overall spatial distribution of matter is not very different from the baryon distribution in the inner ∼5 kpc of lensing galaxies. This offers a new test for high-resolution hydrodynamical simulations.

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“…The ratio of X-ray to optical flux, log(f x /f v ), played an important role since the different types of Xray emitters were found in the EMSS to have different, well defined ranges (Gioia et al 1990). ROSAT observations confirmed these albeit with slight changes due to the different energy bands of the two satellites (Bade 1993).…”

Section: Introductionmentioning

confidence: 60%

Multiwavelength observations of the field HS 47.5/22 in Ursa Major

Molthagen

Wendker

Briel

1997

Astron. Astrophys. Suppl. Ser.

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Abstract. We present the X-ray source catalogue obtained from a ROSAT survey in the HQS field HS 47.5/22. The survey consists of 48 overlapping PSPC pointings which were first analysed individually, and then merged to increase the sensitivity. Both modes bring forth sources missed in the other, showing that both are necessary to detect all X-ray sources in the field. The final catalogue contains 574 X-ray sources. The identifications are mainly based on the HQS objective prism plate which allows object classification down to a magnitude m b < ∼ 18.m 5, and a rough distinction between red and blue objects more than a magnitude deeper. Follow-up observations were performed for a number of objects, mainly faint quasar candidates.

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The Hamburg Identification Program of Rosat All-Sky Survey Sources

Cited by 46 publications

References 0 publications

Expansion and Collapse in the Cosmic Web

Expansion and Collapse in the Cosmic Web

COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses

Multiwavelength observations of the field HS 47.5/22 in Ursa Major

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