We present a study of extended galaxy halo gas through H I and O VI absorption over two decades in projected distance at z approximate to 0.2. The study is based on a sample of 95 galaxies from a highly complete (> 80 per cent) survey of faint galaxies (L > 0.1L(*)) with archival quasar absorption spectra and 53 galaxies from the literature. A clear anticorrelation is found between H I (O VI) column density and virial radius normalized projected distance, d/R-h. Strong H I (O VI) absorption systems with column densities greater than 10(14.0) (10(13.5)) cm(-2) are found for 48 of 54 (36 of 42) galaxies at d < R-h indicating a mean covering fraction of = 0.89 ( = 0.86). O VI absorbers are found at d approximate to R-h, beyond the extent observed for lower ionization species. At d/R-h = 1-3 strong H I (O VI) absorption systems are found for only 7 of 43 (5 of 34) galaxies ( = 0.16 and = 0.15). Beyond d = 3 R-h, the H I and O VI covering fractions decrease to levels consistent with coincidental systems. The high completeness of the galaxy survey enables an investigation of environmental dependence of extended gas properties. Galaxies with nearby neighbours exhibit a modest increase in O VI covering fraction at d > R-h compared to isolated galaxies (kappa(O) (VI) approximate to 0.13 versus 0.04) but no excess H I absorption. These findings suggest that environmental effects play a role in distributing heavy elements beyond the enriched gaseous haloes of individual galaxies. Finally, we find that differential H I and O VI absorption between early-and late-type galaxies continues from d < R-h to d approximate to 3 R-h.

We present a study of extended galaxy halo gas through H I and O VI absorption over two decades in projected distance at z approximate to 0.2. The study is based on a sample of 95 galaxies from a highly complete (> 80 per cent) survey of faint galaxies (L > 0.1L(*)) with archival quasar absorption spectra and 53 galaxies from the literature. A clear anticorrelation is found between H I (O VI) column density and virial radius normalized projected distance, d/R-h. Strong H I (O VI) absorption systems with column densities greater than 10(14.0) (10(13.5)) cm(-2) are found for 48 of 54 (36 of 42) galaxies at d < R-h indicating a mean covering fraction of = 0.89 ( = 0.86). O VI absorbers are found at d approximate to R-h, beyond the extent observed for lower ionization species. At d/R-h = 1-3 strong H I (O VI) absorption systems are found for only 7 of 43 (5 of 34) galaxies ( = 0.16 and = 0.15). Beyond d = 3 R-h, the H I and O VI covering fractions decrease to levels consistent with coincidental systems. The high completeness of the galaxy survey enables an investigation of environmental dependence of extended gas properties. Galaxies with nearby neighbours exhibit a modest increase in O VI covering fraction at d > R-h compared to isolated galaxies (kappa(O) (VI) approximate to 0.13 versus 0.04) but no excess H I absorption. These findings suggest that environmental effects play a role in distributing heavy elements beyond the enriched gaseous haloes of individual galaxies. Finally, we find that differential H I and O VI absorption between early-and late-type galaxies continues from d < R-h to d approximate to 3 R-h.

We present a study of extended galaxy halo gas through H I and O VI absorption over two decades in projected distance at z approximate to 0.2. The study is based on a sample of 95 galaxies from a highly complete (> 80 per cent) survey of faint galaxies (L > 0.1L(*)) with archival quasar absorption spectra and 53 galaxies from the literature. A clear anticorrelation is found between H I (O VI) column density and virial radius normalized projected distance, d/R-h. Strong H I (O VI) absorption systems with column densities greater than 10(14.0) (10(13.5)) cm(-2) are found for 48 of 54 (36 of 42) galaxies at d < R-h indicating a mean covering fraction of = 0.89 ( = 0.86). O VI absorbers are found at d approximate to R-h, beyond the extent observed for lower ionization species. At d/R-h = 1-3 strong H I (O VI) absorption systems are found for only 7 of 43 (5 of 34) galaxies ( = 0.16 and = 0.15). Beyond d = 3 R-h, the H I and O VI covering fractions decrease to levels consistent with coincidental systems. The high completeness of the galaxy survey enables an investigation of environmental dependence of extended gas properties. Galaxies with nearby neighbours exhibit a modest increase in O VI covering fraction at d > R-h compared to isolated galaxies (kappa(O) (VI) approximate to 0.13 versus 0.04) but no excess H I absorption. These findings suggest that environmental effects play a role in distributing heavy elements beyond the enriched gaseous haloes of individual galaxies. Finally, we find that differential H I and O VI absorption between early-and late-type galaxies continues from d < R-h to d approximate to 3 R-h.

Aims. We present the detection, identification and calibration of extended sources in the deepest X-ray dataset to date, the Extended Chandra Deep Field South (ECDF-S).

Aims. We present the detection, identification and calibration of extended sources in the deepest X-ray dataset to date, the Extended Chandra Deep Field South (ECDF-S).

Aims. We present the detection, identification and calibration of extended sources in the deepest X-ray dataset to date, the Extended Chandra Deep Field South (ECDF-S).

Previous observations of quasar host haloes at z approximate to 2 have uncovered large quantities of cool gas that exceed what is found around inactive galaxies of both lower and higher masses. To better understand the source of this excess cool gas, we compiled an exhaustive sample of 195 quasars at z approximate to 1 with constraints on chemically enriched, cool gas traced by MgII absorption in background quasar spectra from the Sloan Digital Sky Survey. This quasar sample spans a broad range of luminosities from L-bol = 10(44.4) to 10(46.8) erg s(-1) and allows an investigation of whether halo gas properties are connected with quasar properties. We find a strong correlation between luminosity and cool gas covering fraction. In particular, low-luminosity quasars exhibit a mean gas covering fraction comparable to inactive galaxies of similar masses, but more luminous quasars exhibit excess cool gas approaching what is reported previously at z approximate to 2. Moreover, 30-40 per cent of the Mg II absorption occurs at radial velocities of vertical bar Delta nu vertical bar > 300 km s(-1) from the quasar, inconsistent with gas bound to a typical quasar host halo. The large velocity offsets and observed luminosity dependence of the cool gas near quasars can be explained if the gas arises from: (1) neighbouring haloes correlated through large-scale structure at Mpc scales, (2) feedback from luminous quasars or (3) debris from the mergers thought to trigger luminous quasars. The first of these scenarios is in tension with the lack of correlation between quasar luminosity and clustering while the latter two make distinct predictions that can be tested with additional observations.

Previous observations of quasar host haloes at z approximate to 2 have uncovered large quantities of cool gas that exceed what is found around inactive galaxies of both lower and higher masses. To better understand the source of this excess cool gas, we compiled an exhaustive sample of 195 quasars at z approximate to 1 with constraints on chemically enriched, cool gas traced by MgII absorption in background quasar spectra from the Sloan Digital Sky Survey. This quasar sample spans a broad range of luminosities from L-bol = 10(44.4) to 10(46.8) erg s(-1) and allows an investigation of whether halo gas properties are connected with quasar properties. We find a strong correlation between luminosity and cool gas covering fraction. In particular, low-luminosity quasars exhibit a mean gas covering fraction comparable to inactive galaxies of similar masses, but more luminous quasars exhibit excess cool gas approaching what is reported previously at z approximate to 2. Moreover, 30-40 per cent of the Mg II absorption occurs at radial velocities of vertical bar Delta nu vertical bar > 300 km s(-1) from the quasar, inconsistent with gas bound to a typical quasar host halo. The large velocity offsets and observed luminosity dependence of the cool gas near quasars can be explained if the gas arises from: (1) neighbouring haloes correlated through large-scale structure at Mpc scales, (2) feedback from luminous quasars or (3) debris from the mergers thought to trigger luminous quasars. The first of these scenarios is in tension with the lack of correlation between quasar luminosity and clustering while the latter two make distinct predictions that can be tested with additional observations.

Previous observations of quasar host haloes at z approximate to 2 have uncovered large quantities of cool gas that exceed what is found around inactive galaxies of both lower and higher masses. To better understand the source of this excess cool gas, we compiled an exhaustive sample of 195 quasars at z approximate to 1 with constraints on chemically enriched, cool gas traced by MgII absorption in background quasar spectra from the Sloan Digital Sky Survey. This quasar sample spans a broad range of luminosities from L-bol = 10(44.4) to 10(46.8) erg s(-1) and allows an investigation of whether halo gas properties are connected with quasar properties. We find a strong correlation between luminosity and cool gas covering fraction. In particular, low-luminosity quasars exhibit a mean gas covering fraction comparable to inactive galaxies of similar masses, but more luminous quasars exhibit excess cool gas approaching what is reported previously at z approximate to 2. Moreover, 30-40 per cent of the Mg II absorption occurs at radial velocities of vertical bar Delta nu vertical bar > 300 km s(-1) from the quasar, inconsistent with gas bound to a typical quasar host halo. The large velocity offsets and observed luminosity dependence of the cool gas near quasars can be explained if the gas arises from: (1) neighbouring haloes correlated through large-scale structure at Mpc scales, (2) feedback from luminous quasars or (3) debris from the mergers thought to trigger luminous quasars. The first of these scenarios is in tension with the lack of correlation between quasar luminosity and clustering while the latter two make distinct predictions that can be tested with additional observations.

Previous observations of quasar host haloes at z approximate to 2 have uncovered large quantities of cool gas that exceed what is found around inactive galaxies of both lower and higher masses. To better understand the source of this excess cool gas, we compiled an exhaustive sample of 195 quasars at z approximate to 1 with constraints on chemically enriched, cool gas traced by MgII absorption in background quasar spectra from the Sloan Digital Sky Survey. This quasar sample spans a broad range of luminosities from L-bol = 10(44.4) to 10(46.8) erg s(-1) and allows an investigation of whether halo gas properties are connected with quasar properties. We find a strong correlation between luminosity and cool gas covering fraction. In particular, low-luminosity quasars exhibit a mean gas covering fraction comparable to inactive galaxies of similar masses, but more luminous quasars exhibit excess cool gas approaching what is reported previously at z approximate to 2. Moreover, 30-40 per cent of the Mg II absorption occurs at radial velocities of vertical bar Delta nu vertical bar > 300 km s(-1) from the quasar, inconsistent with gas bound to a typical quasar host halo. The large velocity offsets and observed luminosity dependence of the cool gas near quasars can be explained if the gas arises from: (1) neighbouring haloes correlated through large-scale structure at Mpc scales, (2) feedback from luminous quasars or (3) debris from the mergers thought to trigger luminous quasars. The first of these scenarios is in tension with the lack of correlation between quasar luminosity and clustering while the latter two make distinct predictions that can be tested with additional observations.