A Deep Search For Faint Galaxies Associated With Very Low-redshift C IV Absorbers: III. The Mass- and Environment-dependent Circumgalactic Medium

Using Hubble Space Telescope Cosmic Origins Spectrograph observations of 89 QSO sightlines through the Sloan Digital Sky Survey footprint, we study the relationships between C IV absorption systems and the properties of nearby galaxies as well as large-scale environment. To maintain sensitivity to very faint galaxies, we restrict our sample to 0.0015 < z < 0.015, which defines a complete galaxy survey to L > 0.01 L* or stellar mass log M_* > 8 Msun. We report two principal findings. First, for galaxies with impact parameter rho < 1 rvir, C IV detection strongly depends on the luminosity/stellar mass of the nearby galaxy. C IV is preferentially associated with galaxies with log M_* > 9.5 Msun; lower mass galaxies rarely exhibit significant C IV absorption (covering fraction f = 9 +12-6% for 11 galaxies with log M_* < 9.5 Msun). Second, C IV detection within the log M_* > 9.5 Msun population depends on environment. Using a fixed-aperture environmental density metric for galaxies with rho < 160 kpc at z < 0.055, we find that 57+/-12% (8/14) of galaxies in low-density regions (regions with fewer than seven L > 0.15 L* galaxies within 1.5 Mpc) have affiliated C IV absorption; however, none (0/7) of the galaxies in denser regions show C IV. Similarly, the C IV detection rate is lower for galaxies residing in groups with dark-matter halo masses of log Mhalo > 12.5 Msun. In contrast to C IV, H I is pervasive in the CGM without regard to mass or environment. These results indicate that C IV absorbers with log N(C IV) > 13.5 cm^-2 trace the halos of log M_* > 9.5 Msun galaxies but also reflect larger scale environmental conditions.Comment: 26 pages, 13 figures. ApJ, in pres

A deep search for faint galaxies associated with very low-redshift C iv absorbers: A case with cold-accretion characteristics

Studies of QSO absorber–galaxy connections are often hindered by inadequate information on whether faint/dwarf galaxies are located near the QSO sight lines. To investigate the contribution of faint galaxies to QSO absorber populations, we are conducting a deep galaxy redshift survey near low-z Civ absorbers. Here we report a blindly detected C iv absorption system (zabs = 0.00348) in the spectrum of PG1148+549 that appears to be associated either with an edge-on dwarf galaxy with an obvious disk (UGC 6894, zgal = 0.00283) at an impact parameter of ρ = 190 kpc or with a very faint dwarf irregular galaxy at ρ = 23 kpc, which is closer to the sightline but has a larger redshift difference (zgal = 0.00107, i.e., δv = 724 km s−1). We consider various gas/galaxy associations, including infall and outflows. Based on current theoretical models, we conclude that the absorber is most likely tracing (1) the remnants of an outflow from a previous epoch, a so-called “ancient outflow”, or (2) intergalactic gas accreting onto UGC 6894, “cold mode” accretion. The latter scenario is supported by Hi synthesis imaging data that shows the rotation curve of the disk being codirectional with the velocity offset between UGC 6894 and the absorber, which is located almost directly along the major axis of the edge-on disk.Web of Scienc

Sexual health promotion and contraceptive services in local authorities: a systematic review of economic evaluations 2010-2015

Background Since 2013, health commissioners in England’s local authorities have been responsible for sexual health services, including contraception, HIV testing, STI testing and treatment, health education and specialist sexual health services. Effective commissioning requires information to indicate which interventions may, or may not, be cost-effective. However, current UK guidance and recent research on the cost-effectiveness of sexual health services provides patchy and fragmented evidence. This study aims systematically to review the evidence available on the cost-effectiveness of OECD-based interventions relevant to UK local authority-commissioned sexual health services. Methods Key informants, bibliographic database searches and reference lists of guidance documents and included studies were searched for potentially relevant research. Guided by key stakeholders, we sought economic evaluations of sexual health interventions within the responsibility of local authorities, and focused in the UK, on contraception and on health promotion, published between 2010 and 2015 in English. Eligible studies were full economic evaluations based in an OECD country. Studies were classified using a specifically developed tool and assessed for methodological risk of bias using one of three design-specific assessment tools. Descriptive frequencies of codes were analysed to provide a ‘map’ of research that informed stakeholder discussions to focus the subsequent synthesis. The characteristics of studies, quality ratings and cost outcomes from each included study were extracted into tables and findings summarised narratively. Studies were assessed for their relative cost-saving or cost-effectiveness according to NICE guidance. Results In total, 17,705 references were screened; of these, 29 met our inclusion criteria and were included in the synthesis. Nine studies were undertaken in the UK; the remainder were US based. Fifteen studies examined the economics of contraception and 14 evaluated health promotion. Overall, studies were of medium methodological quality. In general, economic evaluations of contraception reported cost-effectiveness or cost savings for ulipristal acetate (UPA) as emergency contraception, long-acting reversible contraceptives (LARCs) for regular, post-natal and post-abortion contraception, and targeting to high risk groups; none, however, reported costs per quality-adjusted life year (QALY) within NICE thresholds. Economic evaluations of sexual health promotion interventions indicated more mixed results. Only three interventions were found to be cost-effective according to the NICE thresholds for HIV or sexually transmitted infection (STI) outcomes: nurse-led rapid testing and tailored counselling; condom negotiations skills training for female sex workers; and a teacher-led STI prevention and skills training intervention. UK studies focused on health promotion and contraception, and supported the above findings. In general, there has been a reasonable amount of economic research into sexual health interventions since 2010, and these support current NICE sexual health guidance. Abstract Sexual health promotion and contraceptive services in local authorities: a systematic review of economic evaluations 2010-2015 vi Conclusions The broad nature of the research question posed in this systematic review resulted in the inclusion of a dataset very diverse in terms of populations, interventions, outcomes and types of economic evaluation designs. In considering the cost-effectiveness of these strategies in relation to their own commissioning climate, policy and decision makers should consider carefully the fit between their context and that of individual studies. Use of longer-term outcomes in trials used in economic evaluations would strengthen estimates of effects such as QALYs, as would the routine use of longitudinal cohort data

The COS Absorption Survey of Baryon Harbors (CASBaH): Warm-hot Circumgalactic Gas Reservoirs Traced by Ne VIII Absorption

We survey the highly ionized circumgalactic media (CGM) of 29 blindly selected galaxies at 0.49 < z_(gal) < 1.44 based on high-S/N ultraviolet spectra of z > 1 QSOs and the galaxy database from the COS Absorption Survey of Baryon Harbors (CASBaH). We detect the Ne VIII doublet in nine of the galaxies, and for gas with N(Ne VIII) > 10^13.3 cm^-2 (> 10^13.5 cm^-2), we derive a Ne VIII covering fraction f_c = 75 +15/-25% (44 +22/-20%) within impact parameter (rho) < 200 kpc of M_* = 10^(9.5-11.5) Msol galaxies and f_c = 70 +16/-22% (f_c = 42 +20/-17%) within rho < 1.5 virial radii. We estimate the mass in Ne VIII-traced gas to be M_gas(Ne VIII) > 10^9.5 Msol (Z/Zsol)^-1, or 6-20% of the expected baryonic mass if the Ne VIII absorbers have solar metallicity. Ionizing Ne VII to Ne VIII requires 207 eV, and photons with this energy are scarce in the CGM. However, for the median halo mass and redshift of our sample, the virial temperature is close to the peak temperature for the Ne VIII ion, and the Ne VIII-bearing gas is plausibly collisionally ionized near this temperature. Moreover, we find that photoionized Ne VIII requires cool and low-density clouds that would be highly underpressured (by approximately two orders of magnitude) relative to the putative, ambient virialized medium, complicating scenarios where such clouds could survive. Thus, more complex (e.g., non-equilibrium) models may be required; this first statistical sample of Ne VIII absorber/galaxy systems will provide stringent constraints for future CGM studies.Comment: Published in ApJL, Volume 877, Issue 2, Article L2