We explore the connection between different classes of active galactic nuclei (AGNs) and the evolution of their host galaxies, by deriving host galaxy properties, clustering, and Eddington ratios of AGNs selected in the radio, X-ray, and infrared (IR) wavebands. We study a sample of 585 AGNs at 0.25 < z < 0.8 using redshifts from the AGN and Galaxy Evolution Survey (AGES). We select AGNs with observations in the radio at 1.4 GHz from the Westerbork Synthesis Radio Telescope, X-rays from the Chandra XBoötes Survey, and mid-IR from the Spitzer IRAC Shallow Survey. The radio, X-ray, and IR AGN samples show modest overlap, indicating that to the flux limits of the survey, they represent largely distinct classes of AGNs. We derive host galaxy colors and luminosities, as well as Eddington ratios, for obscured or optically faint AGNs. We also measure the two-point cross-correlation between AGNs and galaxies on scales of 0.3-10 h −1 Mpc, and derive typical dark matter halo masses. We find that: (1) radio AGNs are mainly found in luminous red sequence galaxies, are strongly clustered (with M halo ∼ 3 × 10 13 h −1 M ⊙ ), and have very low Eddington ratios (λ 10 −3 ); (2) X-rayselected AGNs are preferentially found in galaxies that lie in the "green valley" of color-magnitude space and are clustered similar to typical AGES galaxies (M halo ∼ 10 13 h −1 M ⊙ ), with 10 −3 λ 1; (3) IR AGNs reside in slightly bluer, slightly less luminous galaxies than X-ray AGNs, are weakly clustered (M halo 10 12 h −1 M ⊙ ), and have λ > 10 −2 . We interpret these results in terms of a simple model of AGN and galaxy evolution, whereby a "quasar" phase and the growth of the stellar bulge occurs when a galaxy's dark matter halo reaches a critical mass between ∼10 12 and 10 13 M ⊙ . After this event, star formation ceases and AGN accretion shifts from radiatively efficient (optical-and IR-bright) to radiatively inefficient (optically faint, radio-bright) modes.

Objective This study evaluates the long-term outcomes, biliary complication rates, and risk factors for biliary complications after liver transplantation from donation after cardiac death (DCD) donors. Summary Background Data Recent enthusiasm toward increased use of DCD donor livers is mitigated by high biliary complication rates. Predictive risk factors for the development of biliary complications after DCD liver transplantation remain incompletely defined. Methods We performed a retrospective review of 1157 donation after brain death (DBD) and 87 DCD liver transplants performed between January 1, 1993 and December 31, 2008. Patient and graft survivals, and complication rates within the first year of transplantation were compared between DBD and DCD groups. Cox proportional hazards models were used to assess the influence of potential risk factors. Results Patient survival was significantly lower in the DCD group compared to the DBD group at 1, 5, 10 and 15 years (DCD: 84%, 68%, 54%, 54% vs. DBD: 91%, 81%, 67%, 58%, p<0.01). Graft survival was also significantly lower in the DCD group compared to the DBD group at 1, 5, 10 and 15 years (DCD: 69%, 56%, 43%, 43% vs. DBD: 86%, 76%, 60%, 51%, p<0.001). Rates of overall biliary complications (OBC) (DCD: 47% vs. DBD: 26%, p<0.01) and ischemic cholangiopathy (IC) (DCD: 34% vs. DBD: 1%, p<0.01) were significantly higher in the DCD group. Donor age (HR: 1.04, p<0.01) and donor age >40 years (HR: 3.13, p < 0.01) were significant risk factors for the development of OBC. Multivariate analysis revealed cold ischemic time (CIT) >8 hours (HR: 2.46, p=0.05), donor age >40 (HR: 2.90, p< 0.01) significantly increased the risk of IC. Conclusions Long-term patient and graft survival after DCD liver transplantation remain significantly lower but acceptable when compared to DBD liver transplants. Donor age and CIT >8 hours are the strongest predictors for the development of ischemic cholangiopathy. Careful selection of younger DCD donors and minimizing CIT may limit the incidence of severe biliary complications and improve the successful utilization of DCD donor livers.

Galaxies are missing most of their baryons, and many models predict these baryons lie in a hot halo around galaxies. We establish observationally motivated constraints on the mass and radii of these haloes using a variety of independent arguments. First, the observed dispersion measure of pulsars in the Large Magellanic Cloud allows us to constrain the hot halo around the Milky Way: if it obeys the standard NFW profile, it must contain less than 4-5% of the missing baryons from the Galaxy. This is similar to other upper limits on the Galactic hot halo, such as the soft X-ray background and the pressure around high velocity clouds. Second, we note that the X-ray surface brightness of hot haloes with NFW profiles around large isolated galaxies is high enough that such emission should be observed, unless their haloes contain less than 10-25% of their missing baryons. Third, we place constraints on the column density of hot haloes using nondetections of OVII absorption along AGN sightlines: in general they must contain less than 70% of the missing baryons or extend to no more than 40 kpc. Flattening the density profile of galactic hot haloes weakens the surface brightness constraint so that a typical L * galaxy may hold half its missing baryons in its halo, but the OVII constraint remains unchanged, and around the Milky Way a flattened profile may only hold 6 − 13% of the missing baryons from the Galaxy (2 − 4 × 10 10 M ⊙ ). We also show that AGN and supernovae at low to moderate redshift -the theoretical sources of winds responsible for driving out the missing baryons -do not produce the expected correlations with the baryonic Tully-Fisher relationship and so are insufficient to explain the missing baryons from galaxies. We conclude that most of missing baryons from galaxies do not lie in hot haloes around the galaxies, and that the missing baryons never fell into the potential wells of protogalaxies in the first place. They may have been expelled from the galaxies as part of the process of galaxy formation.

(2015) 'Unifying X-ray scaling relations from galaxies to clusters.', Monthly notices of the Royal Astronomical Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.

We summarize and reanalyze observations bearing upon missing galactic baryons, where we propose a consistent picture for halo gas in L L* galaxies. The hot X-ray emitting halos are detected to 50-70 kpc, where typically, M hot (< 50 kpc) ∼ 5 × 10 9 M , and with density n ∝ r −3/2 . When extrapolated to R 200 , the gas mass is comparable to the stellar mass, but about half of the baryons are still missing from the hot phase. If extrapolated to 1.9-3R 200 , the baryon to dark matter ratio approaches the cosmic value. Significantly flatter density profiles are unlikely for R < 50 kpc and they are disfavored but not ruled out for R > 50 kpc. For the Milky Way, the hot halo metallicity lies in the range 0.3-1 solar for R < 50 kpc. Planck measurements of the thermal Sunyaev-Zeldovich effect toward stacked luminous galaxies (primarily early-type) indicate that most of their baryons are hot, near the virial temperature, and extend beyond R 200 . This stacked SZ signal is nearly an order of magnitude larger than that inferred from the X-ray observations of individual (mostly spiral) galaxies with M * > 10 11.3 M . This difference suggests that the hot halo properties are distinct for early and late type galaxies, possibly due to different evolutionary histories. For the cooler gas detected in UV absorption line studies, we argue that there are two absorption populations: extended halos; and disks extending to ∼ 50 kpc, containing most of this gas, and with masses a few times lower than the stellar masses. Such extended disks are also seen in 21 cm HI observations and in simulations.

Hot gaseous halos are predicted around all large galaxies and are critically important for our understanding of galaxy formation, but they have never been detected at distances beyond a few kpc around a spiral galaxy. We used the Chandra ACIS-I instrument to search for diffuse X-ray emission around an ideal candidate galaxy: the isolated giant spiral NGC 1961. We observed four quadrants around the galaxy for 30 ks each, carefully subtracting background and point source emission, and found diffuse emission that appears to extend to 40-50 kpc. We fit β-models to the emission, and estimate a hot halo mass within 50 kpc of 5 × 10 9 M . When this profile is extrapolated to 500 kpc (the approximate virial radius), the implied hot halo mass is 1 − 3 × 10 11 M . These mass estimates assume a gas metallicity of Z = 0.5Z . This galaxy's hot halo is a large reservoir of gas, but falls significantly below observational upper limits set by pervious searches, and suggests that NGC 1961 is missing 75% of its baryons relative to the cosmic mean, which would tentatively place it below an extrapolation of the baryon Tully-Fisher relationship of less massive galaxies. The cooling rate of the gas is no more than 0.4 M /year, more than an order of magnitude below the gas consumption rate through star formation. We discuss the implications of this halo for galaxy formation models.

We conduct a comprehensive search for X-ray emission lines from sterile neutrino dark matter, motivated by recent claims of unidentified emission lines in the stacked X-ray spectra of galaxy clusters and the centers of the Milky Way and M31. Since the claimed emission lines lie around 3.5 keV, we focus on galaxies and galaxy groups (masking the central regions), since these objects emit very little radiation above ∼ 2 keV and offer a clean background against which to detect emission lines. We develop a formalism for maximizing the signal-to-noise of decaying dark matter emission lines by weighing each X-ray event according to the expected dark matter profile. In total, we examine 81 and 89 galaxies with Chandra and XMM-Newton respectively, totaling 15.0 and 14.6 Ms of integration time. We find no significant evidence of any emission lines, placing strong constraints on the mixing angle of sterile neutrinos with masses between 4.8-12.4 keV. In particular, if the 3.57 keV feature from Bulbul et al. (2014) were due to 7.1 keV sterile neutrino emission, we would have detected it at 4.4σ and 11.8σ in our two samples. The most conservative estimates of the systematic uncertainties reduce these constraints to 4.4σ and 7.8σ, or letting the line energy vary between 3.50 and 3.60 keV reduces these constraints to 2.7σ and 11.0σ respectively. Unlike previous constraints, our measurements do not depend on the model of the X-ray background or on the assumed logarithmic slope of the center of the dark matter profile.

We present our XMM-Newton observation of the fastest rotating spiral galaxy UGC 12591. We detect hot gas halo emission out to 80 kpc from the galaxy center, and constrain the halo gas mass to be smaller than 4.5 × 10 11 M . We also measure the temperature of the hot gas as T = 0.64 ± 0.03 keV. Combining our x-ray constraints and the near-infrared and radio measurements in the literature, we find a baryon mass fraction of 0.03-0.05 in UGC 12591, suggesting a missing baryon mass of 70% compared with the cosmological mean value. Combined with another recent measurement in NGC 1961, the result strongly argues that the majority of missing baryons in spiral galaxies do not reside in their hot halos. We also find that UGC 12591 lies significantly below the baryonic Tully-Fisher relationship. Finally, we find that the baryon fractions of massive spiral galaxies are similar to those of galaxy groups with similar masses, indicating that the baryon loss is ultimately controlled by the gravitational potential well. The cooling radius of this gas halo is small, similar to NGC 1961, which argues that the majority of the stellar mass of this galaxy is not assembled as a result of cooling of this gas halo.