K-band Imaging of strong CaII-absorber host galaxies at z~1

We present K-band imaging of fields around 30 strong CaII absorption line systems, at 0.7<z<1.1, three of which are confirmed Damped Lyman-alpha systems. A significant excess of galaxies is found within 6"0 (~50kpc) from the absorber line-of-sight. The excess galaxies are preferentially luminous compared to the population of field galaxies. A model in which field galaxies possess a luminosity-dependent cross-section for CaII absorption of the form (L/L*)^0.7 reproduces the observations well. The luminosity-dependent cross-section for the CaII absorbers appears to be significantly stronger than the established (L/L*)^0.4 dependence for MgII absorbers. The associated galaxies lie at large physical distances from the CaII-absorbing gas; we find a mean impact parameter of 24kpc (H0=70km\s\Mpc). Combined with the observed number density of CaII absorbers the large physical separations result in an inferred filling factor of only ~10 per cent. The physical origin of the strong CaII absorption remains unclear, possible explanations vary from very extended disks of the luminous galaxies to associated dwarf galaxy neighbours, remnants of outflows from the luminous galaxies, or tidal debris from cannibalism of smaller galaxies.Comment: 18 pages, 5 figures. Accepted by MNRAS. Version with full resolution figures available at http://www.mpa-garching.mpg.de/~vwild/CaII/CaII_ukirt.pd

Evidence for dust reddening in DLAs identified through CaII H&K absorption

We present a new sample of 31 CaII(H&K) 3935,3970 absorption line systems with 0.84<z_abs<1.3 discovered in the spectra of Sloan Digital Sky Survey (SDSS) Data Release 3 quasars, together with an analysis of their dust content. The presence of Calcium absorption together with measurements of the MgII 2796, FeII 2600 and MgI 2853 lines lead to the conclusion that the majority of our systems are Damped Ly-alpha (DLA) absorbers. The composite spectrum in the rest frame of the absorber shows clear evidence for reddening. Large and Small Magellanic Cloud extinction curves provide satisfactory fits, with a best-fit E(B-V) of 0.06, while the Galactic dust extinction curve provides a poor fit due to the lack of a strong 2175A feature. A trend of increasing dust content with equivalent width of CaII is present. Monte Carlo techniques demonstrate that the detection of reddening is significant at >99.99% confidence. The discovery of significant amounts of dust in a subsample of DLAs has direct implications for studies of the metallicity evolution of the universe and the nature of DLAs in relation to high redshift galaxies. The gas:dust ratio is discussed. Our results suggest that at least ~40% of the CaII absorption systems are excluded from the magnitude-limited SDSS quasar sample as a result of the associated extinction, a fraction similar to the upper limit deduced at higher redshifts from radio-selected surveys.Comment: 5 pages, 2 figures, accepted MNRAS Letter

Peering through the OH Forest: public release of sky-residual subtracted spectra for SDSS DR7

The Sloan Digital Sky Survey (SDSS) automated spectroscopic reduction pipeline provides >1.5 million intermediate resolution, R~2000, moderate signal-to-noise ratio (SNR), SNR~15, astronomical spectra of unprecedented homogeneity that cover the wavelength range 3800-9200AA. However, there remain significant systematic residuals in many spectra due to the sub-optimal subtraction of the strong OH sky emission lines longward of 6700AA. The OH sky lines extend over almost half the wavelength range of the SDSS spectra, and the SNR over substantial wavelength regions in many spectra is reduced by more than a factor two over that expected from photon counting statistics. Following the OH line subtraction procedure presented in Wild & Hewett (2005), we make available to the community sky-residual subtracted spectra for the Sloan Digital Sky Survey Data Relase 7. Here we summarise briefly the method, including minor changes in the implementation of the procedure with respect to WH05. The spectra are suitable for many science applications but we highlight some limitations for certain investigations. Details of the data model for the sky-residual subtracted spectra and instructions on how to access the spectra are provided.Comment: 11 pages, 5 figures. Spectra may be downloaded from the JHU SDSS server http://www.sdss.jhu.edu/skypca/spSpec, additionally the QSOs can be found on the DR7 Value Added Catalogue web page: http://www.sdss.org/dr7/products/value_added/index.html#quasar

The star formation rate of CaII and damped Lyman-alpha absorbers at 0.4<z<1.3

[abridged] Using stacked Sloan Digital Sky Survey spectra, we present the detection of [OII]3727,3730 nebular emission from galaxies hosting CaII and MgII absorption line systems. Both samples of absorbers, 345 CaII systems and 3461 MgII systems, span the redshift interval 0.4 < z < 1.3; all of the former and half the latter sample are expected to be bona-fide damped Lyman-alpha (DLA) absorbers. The measured star formation rate (SFR) per absorber from light falling within the SDSS fibre apertures (corresponding to physical radii of 6-9 h^-1 kpc) is 0.11-0.14 Msol/yr for the MgII-selected DLAs and 0.11-0.48 Msol/yr for the CaII absorbers. These results represent the first estimates of the average SFR in an absorption-selected galaxy population from the direct detection of nebular emission. Adopting the currently favoured model in which DLAs are large, with radii >9h^-1 kpc, and assuming no attenuation by dust, leads to the conclusion that the SFR per unit area of MgII-selected DLAs falls an order of magnitude below the predictions of the Schmidt law, which relates the SFR to the HI column density at z~0. The contribution of both DLA and CaII absorbers to the total observed star formation rate density in the redshift range 0.4 < z < 1.3, is small, <10% and <3% respectively. The result contrasts with the conclusions of Hopkins et al. that DLA absorbers can account for the majority of the total observed SFR density in the same redshift range. Our results effectively rule out a picture in which DLA absorbers are the sites in which a large fraction of the total SFR density at redshifts z < 1 occurs.Comment: Accepted for publication in MNRAS, 13 pages, 6 figure

Urban Poverty and Health in Developing Countries: Household and Neighborhood Effects

In the U.S. and other high-income countries, where most of the population lives in urban areas, there is intense scholarly and program interest in the effects of household and neighborhood living standards on health. Yet very few studies of developing-country cities have examined these issues. This paper investigates whether in these cities, the health of women and young children is influenced by both household and neighborhood standards of living. Using data from the urban samples of some 85 Demographic and Health surveys, and modelling living standards using factor-analytic MIMIC methods, we find, first, that the neighborhoods of poor households are more heterogeneous than is often asserted. To judge from our results, it appears that as a rule, poor urban households do not tend to live in uniformly poor communities; indeed, about 1 in 10 of a poor household's neighbors is relatively affluent, belonging to the upper quartile of the urban distribution of living standards. Do household and neighborhood living standards influence health? Applying multivariate models with controls for other socioeconomic variables, we discover that household living standards have a substantial influence on three measures of health: unmet need for modern contraception; birth attendance by doctors, nurses, or trained midwives; and children's height for age. Neighborhood living standards exert significant additional influence on health in many of the surveys we examine, especially in birth attendance. There is considerable evidence, then, indicating that both household and neighborhood living standards can make a substantively important difference to health.poverty, health, developing countries, urban, factor analysis, neighborhood

The Adolescent Girls Empowerment Program: Lessons learned from the pilot test program

This document presents an evaluation of the Adolescent Girls Empowerment Program (AGEP), which is comprised of three major components: 1) safe spaces groups in which girls meet once a week over the course of two years for training on sexual and reproductive health, life skills and financial education. Groups are facilitated by a mentor, a young female from the same community as the girls; 2) a health voucher that girls can use at contracted private and public facilities for general wellness and sexual and reproductive health services; and 3) a saving account that has been designed to be girl-friendly. A randomized control trial (RCT) using a cluster design is being used to evaluate the impact of AGEP. The research aims to identify the impact of the intervention on the following key indicators: HIV prevalence, HSV-2 prevalence, age at first sex, age at first birth, contraceptive use, experience of gender-based violence, and educational attainment

Direct Observational Test Rules Out Small MgII Absorbers

Recent observations suggest the incidence of strong intervening MgII absorption systems along the line-of-sight to gamma ray burst (GRB) afterglows is significantly higher than expected from analogous quasar sightlines. One possible explanation is a geometric effect, arising because MgII absorbers only partially cover the quasar continuum regions, in which case MgII absorbers must be considerably smaller than previous estimates. We investigate the production of abnormal absorption profiles by partial coverage and conclude that the lack of any known anomalous profiles in observed systems, whilst constraining, cannot on its own rule out patchy MgII absorbers. In a separate test, we look for differences in the distribution function of MgII equivalent widths over quasar continuum regions and CIII] emission lines. We show that these anomalies should be observable in any scenario where MgII absorbers are very small, but they are not present in the data. We conclude that models invoking small MgII cloudlets to explain the excess of absorbers seen towards GRBs are ruled out.Comment: Accepted for publication in MNRAS Letters. 5 pages, 2 figure

Observational study of galaxy clustering

An observational study of the clustering of faint galaxies in the magnitude range 19.5< mj <22.0 is undertaken. High quality plate material from the United Kingdom Schmidt Telescope, and automated machine measures from the COSMOS facility at the Royal Observatory Edinburgh constitute the primary data. Particular attention is paid to quantifying the amplitude and nature of random, and systematic errors associated with the plate material and the measuring process. The details of calibration procedures and properties of the COSMOS scanning spot are found to be particularly important for a full understanding of the measurement process. New information concerning the success of automated image classification techniques is obtained, through the use of very deep plate material from the Anglo- Australian Telescope to "calibrate" the wide field plate material used in the investigation. Automated image classification using COSMOS parameters is found to be considerably less successful than previously claimed. Consideration of the methods used to estimate the covariance function from galaxy samples shows that some discrepancies between earlier work on the Zwicky and Lick catalogues, and more recent, deep machine measured samples are due to different estimation procedures, and not the data themselves.Data from five high galactic latitude fields in the south, subtending a total area of more than 100 square degrees, allows precise limits to be placed on the amplitude of spurious galaxy clustering due to small scale extinction fluctuations within the galaxy. Upper limits to the amplitude of extinction fluctuations are derived from the form of the stellar covariance function and the cross -correlation between the stellar, and deep galaxy samples. The observations are compared to a number of extinction models, and it is concluded that mean values of absorbtion at 2 the poles of A <0.1 magnitudes are favoured

Superclustering of damped Lyman-alpha absorption systems at redshifts above two

Two high redshift QSOs (z = 3.23 and z = 3.18) separated by 8 arcmin, and containing two strong Ly-alpha absorption systems each, were observed. In both cases, the velocities of the absorption systems between the lines of sight differ by only about 300 km/s. Low ionization metal lines are related to at least one of the absorption systems, and the neutral hydrogen column densities deduced from the profiles lie between 1.2 x 10 exp 18 and 1.2 x 10 exp 20/sq cm. The probability of observing both redshift coincidences is very low, about 0.0003. The probability of seeing the wavelength matches is increased if the absorbers are clustered. Giant gas clouds cover both lines of sight, they must have solar masses of more than 10 exp 11. These observations all hint at the presence of large dense structures in the early universe.P.J.F. is supported by a SERC/NATO advanced fellowship. Computing support was provided in part by the Starlink Project, which is funded by the UK SERC. We also thank the staff at the AAT for their invaluable assistance