Fast radio bursts (FRBs) are one of the most tantalizing mysteries of the radio sky; their progenitors and origins remain unknown and until now no rapid multiwavelength follow-up of an FRB has been possible. New instrumentation has decreased the time between observation and discovery from years to seconds, and enables polarimetry to be performed on FRBs for the first time. We have discovered an FRB (FRB 140514) in real-time on 2014 May 14 at 17:14:11.06 UTC at the Parkes radio telescope and triggered follow-up at other wavelengths within hours of the event. FRB 140514 was found with a dispersion measure (DM) of 562.7(6) cm(-3) pc, giving an upper limit on source redshift of z less than or similar to 0.5. FRB 140514 was found to be 21 +/- 7 per cent (3 sigma) circularly polarized on the leading edge with a 1 sigma upper limit on linear polarization <10 per cent. We conclude that this polarization is intrinsic to the FRB. If there was any intrinsic linear polarization, as might be expected from coherent emission, then it may have been depolarized by Faraday rotation caused by passing through strong magnetic fields and/or high-density environments. FRB 140514 was discovered during a campaign to re-observe known FRB fields, and lies close to a previous discovery, FRB 110220; based on the difference in DMs of these bursts and time-on-sky arguments, we attribute the proximity to sampling bias and conclude that they are distinct objects. Follow-up conducted by 12 telescopes observing from X-ray to radio wavelengths was unable to identify a variable multiwavelength counterpart, allowing us to rule out models in which FRBs originate from nearby (z < 0.3) supernovae and long duration gamma-ray bursts.

We study the evolution of the total star formation (SF) activity, total stellar mass (Sigma M-*) and halo occupation distribution (HOD) in massive haloes by using one of the largest X-ray selected sample of galaxy groups with secure spectroscopic identification in the major blank field surveys (ECDFS, CDFN, COSMOS, AEGIS). We provide an accurate measurement of star formation rate (SFR) for the bulk of the star-forming galaxies using very deep mid-infrared Spitzer MIPS and far-infrared Herschel PACS observations. For undetected IR sources, we provide a well-calibrated SFR from spectral energy distribution (SED) fitting. We observe a clear evolution in the level of SF activity in galaxy groups. The total SF activity in the high-redshift groups (0.5 < z < 1.1) is higher with respect to the low-redshift (0.15 < z < 0.5) sample at any mass by 0.8 +/- 0.12 dex. A milder difference (0.35 +/- 0.1 dex) is observed between the low-redshift bin and the groups at z similar to 0. We show that the level of SF activity is declining more rapidly in the more massive haloes than in the more common lower mass haloes. We do not observe any evolution in the HOD and total stellar mass-halo mass relations in groups. The picture emerging from our findings suggests that the galaxy population in the most massive systems is evolving faster than galaxies in lower mass haloes, consistently with a 'halo downsizing' scenario.

We study the evolution of the total star formation (SF) activity, total stellar mass (Sigma M-*) and halo occupation distribution (HOD) in massive haloes by using one of the largest X-ray selected sample of galaxy groups with secure spectroscopic identification in the major blank field surveys (ECDFS, CDFN, COSMOS, AEGIS). We provide an accurate measurement of star formation rate (SFR) for the bulk of the star-forming galaxies using very deep mid-infrared Spitzer MIPS and far-infrared Herschel PACS observations. For undetected IR sources, we provide a well-calibrated SFR from spectral energy distribution (SED) fitting. We observe a clear evolution in the level of SF activity in galaxy groups. The total SF activity in the high-redshift groups (0.5 < z < 1.1) is higher with respect to the low-redshift (0.15 < z < 0.5) sample at any mass by 0.8 +/- 0.12 dex. A milder difference (0.35 +/- 0.1 dex) is observed between the low-redshift bin and the groups at z similar to 0. We show that the level of SF activity is declining more rapidly in the more massive haloes than in the more common lower mass haloes. We do not observe any evolution in the HOD and total stellar mass-halo mass relations in groups. The picture emerging from our findings suggests that the galaxy population in the most massive systems is evolving faster than galaxies in lower mass haloes, consistently with a 'halo downsizing' scenario.

We study the evolution of the total star formation (SF) activity, total stellar mass (Sigma M-*) and halo occupation distribution (HOD) in massive haloes by using one of the largest X-ray selected sample of galaxy groups with secure spectroscopic identification in the major blank field surveys (ECDFS, CDFN, COSMOS, AEGIS). We provide an accurate measurement of star formation rate (SFR) for the bulk of the star-forming galaxies using very deep mid-infrared Spitzer MIPS and far-infrared Herschel PACS observations. For undetected IR sources, we provide a well-calibrated SFR from spectral energy distribution (SED) fitting. We observe a clear evolution in the level of SF activity in galaxy groups. The total SF activity in the high-redshift groups (0.5 < z < 1.1) is higher with respect to the low-redshift (0.15 < z < 0.5) sample at any mass by 0.8 +/- 0.12 dex. A milder difference (0.35 +/- 0.1 dex) is observed between the low-redshift bin and the groups at z similar to 0. We show that the level of SF activity is declining more rapidly in the more massive haloes than in the more common lower mass haloes. We do not observe any evolution in the HOD and total stellar mass-halo mass relations in groups. The picture emerging from our findings suggests that the galaxy population in the most massive systems is evolving faster than galaxies in lower mass haloes, consistently with a 'halo downsizing' scenario.

We study the evolution of the total star formation (SF) activity, total stellar mass (Sigma M-*) and halo occupation distribution (HOD) in massive haloes by using one of the largest X-ray selected sample of galaxy groups with secure spectroscopic identification in the major blank field surveys (ECDFS, CDFN, COSMOS, AEGIS). We provide an accurate measurement of star formation rate (SFR) for the bulk of the star-forming galaxies using very deep mid-infrared Spitzer MIPS and far-infrared Herschel PACS observations. For undetected IR sources, we provide a well-calibrated SFR from spectral energy distribution (SED) fitting. We observe a clear evolution in the level of SF activity in galaxy groups. The total SF activity in the high-redshift groups (0.5 < z < 1.1) is higher with respect to the low-redshift (0.15 < z < 0.5) sample at any mass by 0.8 +/- 0.12 dex. A milder difference (0.35 +/- 0.1 dex) is observed between the low-redshift bin and the groups at z similar to 0. We show that the level of SF activity is declining more rapidly in the more massive haloes than in the more common lower mass haloes. We do not observe any evolution in the HOD and total stellar mass-halo mass relations in groups. The picture emerging from our findings suggests that the galaxy population in the most massive systems is evolving faster than galaxies in lower mass haloes, consistently with a 'halo downsizing' scenario.

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).