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Reproducing the kinematics of damped Lyman α systems
We examine the kinematic structure of Damped Lyman-alpha Systems (DLAs) in a
series of cosmological hydrodynamic simulations using the AREPO code. We are
able to match the distribution of velocity widths of associated low ionisation
metal absorbers substantially better than earlier work. Our simulations produce
a population of DLAs dominated by halos with virial velocities around 70 km/s,
consistent with a picture of relatively small, faint objects. In addition, we
reproduce the observed correlation between velocity width and metallicity and
the equivalent width distribution of SiII. Some discrepancies of moderate
statistical significance remain; too many of our spectra show absorption
concentrated at the edge of the profile and there are slight differences in the
exact shape of the velocity width distribution. We show that the improvement
over previous work is mostly due to our strong feedback from star formation and
our detailed modelling of the metal ionisation state
The Fundamental Plane of Damped Lyα Systems
Using a sample of 100 H I-selected damped Lyα (DLA) systems, observed with the High Resolution Echelle Spectrometer on the Keck I telescope, we present evidence that the scatter in the well-studied correlation between the redshift and metallicity of a DLA is largely due to the existence of a mass-metallicity relationship at each redshift. To describe the fundamental relations that exist between redshift, metallicity, and mass, we use a fundamental plane description, which is described by the following equation: [M/H] = (– 1.9 ± 0.5) + (0.74 ± 0.21) centerdot logΔv_90 – (0.32 ± 0.06) centerdot z. Here, we assert that the velocity width, Δv_90, which is defined as the velocity interval containing 90% of the integrated optical depth, traces the mass of the underlying dark matter halo. This description provides two significant improvements over the individual descriptions of the mass-metallicity correlation and metallicity-redshift correlation. Firstly, the fundamental equation reduces the scatter around both relationships by about 20%, providing a more stringent constraint on numerical simulations modeling DLAs. Secondly, it confirms that the dark matter halos that host DLAs satisfy a mass-metallicity relationship at each redshift between redshifts 2 through 5
Massive, Absorption-selected Galaxies at Intermediate Redshifts
The nature of absorption-selected galaxies and their connection to the
general galaxy population have been open issues for more than three decades,
with little information available on their gas properties. Here we show, using
detections of carbon monoxide (CO) emission with the Atacama Large
Millimeter/submillimeter Array (ALMA), that five of seven high-metallicity,
absorption-selected galaxies at intermediate redshifts, ,
have large molecular gas masses, and high molecular gas fractions (. Their modest star
formation rates (SFRs), yr, then
imply long gas depletion timescales, Gyr. The
high-metallicity absorption-selected galaxies at appear
distinct from populations of star-forming galaxies at both ,
during the peak of star formation activity in the Universe, and lower
redshifts, . Their relatively low SFRs, despite the large
molecular gas reservoirs, may indicate a transition in the nature of star
formation at intermediate redshifts, .Comment: 8 pages, 3 figures; accepted for publication in Astrophysical Journal
Letters. Minor changes to match the version in press in ApJ
Dynamical Characterization of Galaxies at z~4-6 via Tilted Ring Fitting to ALMA [CII] Observations
Until recently, determining the rotational properties of galaxies in the
early universe (z>4, Universe age <1.5Gyr) was impractical, with the exception
of a few strongly lensed systems. Combining the high resolution and sensitivity
of ALMA at (sub-) millimeter wavelengths with the typically high strength of
the [CII] 158um emission line from galaxies and long-developed dynamical
modeling tools raises the possibility of characterizing the gas dynamics in
both extreme starburst galaxies and normal star forming disk galaxies at z~4-7.
Using a procedure centered around GIPSY's ROTCUR task, we have fit tilted ring
models to some of the best available ALMA [CII] data of a small set of
galaxies: the MS galaxies HZ9 & HZ10, the Damped Lyman-alpha Absorber (DLA)
host galaxy ALMA J0817+1351, the submm galaxies AzTEC/C159 and COSMOS
J1000+0234, and the quasar host galaxy ULAS J1319+0950. This procedure directly
derives rotation curves and dynamical masses as functions of radius for each
object. In one case, we present evidence for a dark matter halo of O(10^11)
solar masses. We present an analysis of the possible velocity dispersions of
AzTEC/C159 and ULAS J1319+0950 based on matching simulated observations to the
integrated [CII] line profiles. Finally, we test the effects of observation
resolution and sensitivity on our results. While the conclusions remain limited
at the resolution and signal-to-noise ratios of these observations, the results
demonstrate the viability of the modeling tools at high redshift, and the
exciting potential for detailed dynamical analysis of the earliest galaxies, as
ALMA achieves full observational capabilities.Comment: 20 pages, 6 figures, Accepted for publication in Ap
The association between neuroticism and self-reported common somatic symptoms in a population cohort
OBJECTIVE: To test the hypotheses that (1) neuroticism is associated with self-reported somatic symptoms; (2) this association is especially found with regard to psychosomatic symptoms; and (3) it is not solemnly explained by somatic reflections of psychological distress. METHODS: We studied the cross-sectional association between neuroticism (as measured by EPQ-RSS-N), psychological distress (as measured by GHQ-12 sum score), and the occurrence of 22 common somatic symptoms by linear and logistic regression analyses in a population cohort of 6894 participants. RESULTS: Neuroticism is more strongly associated with the total number of somatic symptoms reported (beta=.32) than GHQ-12 sum score (beta=.15) and well-established risk markers such as gender (beta=.11) and age (beta=.04). Neuroticism was associated with all symptoms in individual logistic regressions controlled for age, gender, and psychological distress. Neuroticism is significantly more strongly related to psychosomatic symptoms (beta=.36) than to infectious/allergic symptoms (beta=.28). CONCLUSION: In a large, population-based cohort, we confirmed that neuroticism is associated with self-reported somatic symptoms. The associations were not attributable to somatic reflections of psychological distress associated with neuroticism and were relatively strong with respect to psychosomatic symptoms. Future studies should include both objective and subjective measures of health to study the mechanisms that connect neuroticism and ill health
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