Effect of cosmic rays and ionizing radiation on observational ultraviolet plasma diagnostics in the circumgalactic medium

The relevance of some galactic feedback mechanisms, in particular cosmic ray feedback and the hydrogen ionizing radiation field, has been challenging to definitively describe in a galactic context, especially far outside the galaxy in the circumgalactic medium (CGM). Theoretical and observational uncertainties prevent conclusive interpretations of multiphase CGM properties derived from ultraviolet (UV) diagnostics. We conduct three dimensional magnetohydrodynamic simulations of a section of a galactic disk with star formation and feedback, including radiative heating from stars, a UV background, and cosmic ray feedback. We utilize the temperature phases present in our simulations to generate Cloudy models to derive spatially and temporally varying synthetic UV diagnostics. We find that radiative effects without additional heating mechanisms are not able to produce synthetic diagnostics in the observed ranges. For low cosmic ray diffusivity $\kappa_{\rm{cr}}=10^{28} \rm{cm}^2 \rm{s}^{-1}$, cosmic ray streaming heating in the outflow helps our synthetic line ratios roughly match observed ranges by producing transitional temperature gas ($T \sim 10^{5-6}$ K). High cosmic ray diffusivity $\kappa_{\rm{cr}}=10^{29} \rm{cm}^2 \rm{s}^{-1}$, with or without cosmic ray streaming heating, produced transitional temperature gas. The key parameter controlling the production of this gas phase remains unclear, as the different star formation history and outflow evolution itself influences these diagnostics. Our work demonstrates the use of UV plasma diagnostics to differentiate between galactic/circumgalactic feedback models.Comment: Published in MNRA

Quality of life of chronic stable angina patients 4 years after coronary angioplasty or coronary artery bypass surgery

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72244/1/j.1365-2796.2001.00782.x.pd

Metal Transport to the Gaseous Outskirts of Galaxies

We present a search for outlying H II regions in the extended gaseous outskirts of nearby ( D < 40 Mpc) galaxies and subsequent multi-slit spectroscopy used to obtain the H II region nebular oxygen abundances. The galaxies in our sample have extended H I disks and/or interaction-related H I features that extend well beyond their primary stellar components. We report oxygen abundance gradients out to 2.5 times the optical radius for these galaxies which span a range of morphologies and masses. We analyze the underlying stellar and neutral H I gas distributions in the vicinity of the H II regions to understand the physical processes that give rise to the observed metal distributions in galaxies. These measurements, for the first time, convincingly show flat abundance distributions out to large radii in a wide variety of systems and have broad implications for galaxy chemodynamical evolution.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90754/1/0004-637X_735_2_71.pd

The Metal-Enriched Outer Disk of NGC 2915

We present optical emission-line spectra for outlying HII regions in the extended neutral gas disk surrounding the blue compact dwarf galaxy NGC 2915. Using a combination of strong-line R23 and direct oxygen abundance measurements, we report a flat, possibly increasing, metallicity gradient out to 1.2 times the Holmberg radius. We find the outer-disk of NGC 2915 to be enriched to a metallicity of 0.4 Z_solar. An analysis of the metal yields shows that the outer disk of NGC 2915 is overabundant for its gas fraction, while the central star-foming core is similarly under-abundant for its gas fraction. Star formation rates derived from very deep ~14 ks GALEX FUV exposures indicate that the low-level of star formation observed at large radii is not sufficient to have produced the measured oxygen abundances at these galactocentric distances. We consider 3 plausible mechanisms that may explain the metal-enriched outer gaseous disk of NGC 2915: radial redistribution of centrally generated metals, strong galactic winds with subsequent fallback, and galaxy accretion. Our results have implications for the physical origin of the mass-metallicity relation for gas-rich dwarf galaxies.Comment: 11 pages, 4 figures, accepted to ApJ April 8th, 201

A Gaseous Group with Unusual Remote Star Formation

We present VLA 21-cm observations of the spiral galaxy ESO 481-G017 to determine the nature of remote star formation traced by an HII region found 43 kpc and ~800 km s^-1 from the galaxy center (in projection). ESO 481-G017 is found to have a 120 kpc HI disk with a mass of 1.2x10^10 Msun and UV GALEX images reveal spiral arms extending into the gaseous disk. Two dwarf galaxies with HI masses close to 10^8 Msun are detected at distances of ~200 kpc from ESO 481-G017 and a HI cloud with a mass of 6x10^7 Msun is found near the position and velocity of the remote HII region. The HII region is somewhat offset from the HI cloud spatially and there is no link to ESO 481-G017 or the dwarf galaxies. We consider several scenarios for the origin of the cloud and HII region and find the most likely is a dwarf galaxy that is undergoing ram pressure stripping. The HI mass of the cloud and Halpha luminosity of the HII region (10^38.1 erg s^-1) are consistent with dwarf galaxy properties, and the stripping can trigger the star formation as well as push the gas away from the stars.Comment: 19 pages, 4 figures, accepted by PAS

Isolated OB Associations in Stripped HI Gas Clouds

HST ACS/HRC images in UV (F250W), V (F555W), and I (F814W) resolve three isolated OB associations that lie up to 30 kpc from the stellar disk of the S0 galaxy NGC 1533. Previous narrow-band Halpha imaging and optical spectroscopy showed these objects as unresolved intergalactic HII regions having Halpha luminosities consistent with single early-type O stars. These young stars lie in stripped HI gas with column densities ranging from 1.5 - 2.5 * 10^20 cm^-2 and velocity dispersions near 30 km s^-1. Using the HST broadband colors and magnitudes along with previously-determined Halpha luminosities, we place limits on the masses and ages of each association, considering the importance of stochastic effects for faint (M_V >-8) stellar populations. The upper limits to their stellar masses range from 600 M_sun to 7000 M_sun, and ages range from 2 - 6 Myrs. This analysis includes an updated calculation of the conversion factor between the ionizing luminosity and the total number of main sequence O stars contained within an HII region. The photometric properties and sizes of the isolated associations and other objects in the HRC fields are consistent with those of Galactic stellar associations, open clusters and/or single O and B stars. We interpret the age-size sequence of associations and clustered field objects as an indication that these isolated associations are most likely rapidly dispersing. Furthermore, we consider the possibility that these isolated associations represent the first generation of stars in the HI ring surrounding NGC 1533. This work suggests star formation in the unique environment of a galaxy's outermost gaseous regions proceeds similarly to that within the Galactic disk and that star formation in tidal debris may be responsible for building up a younger halo component.Comment: 21 pages, 9 figures, 6 tables; accepted for publication in Ap

Implications of genetic variation of common drug metabolizing enzymes and ABC transporters among the Pakistani population

Genetic polymorphism of drug metabolizing enzymes and transporters may influence drug response. The frequency varies substantially between ethnicities thus having implications on appropriate selection and dosage of various drugs in different populations. The distribution of genetic polymorphisms in healthy Pakistanis has so far not been described. In this study, 155 healthy adults (98 females) were included from all districts of Karachi. DNA was extracted from saliva and genotyped for relevant SNVs in CYP1A1, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP3A4 and CYP3A5 as well as ALDH3A1, GSTA1, ABCB1 and ABCC2. About 64% of the participants were born to parents who were unrelated to each other. There was generally a higher prevalence (p \u3c 0.05) of variant alleles of CYP450 1A2, 2B6, 2C19, 3A5, ALDH3A1, GSTM1 as well as ABCB1 and ABCC2 in this study cohort than in other ethnicities reported in the HapMap database. In contrast, the prevalence of variant alleles was lower in GSTA1. Therefore, in the Pakistani population sample from Karachi a significantly different prevalence of variant drug metabolizing enzymes and ABC transporters was observed as compared to other ethnicities, which could have putative clinical consequences on drug efficacy and safety