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Interstellar Hydrides
Neufeld, David A.; Gerin, Maryvonne; Goicoechea, Javier R.
Interstellar hydrides—that is, molecules containing a single heavy element atom with one or more hydrogen atoms—were among the first molecules detected outside the solar system. They lie at the root of interstellar chemistry, being among the first species to form in initially atomic gas, along with molecular hydrogen and its associated ions. Becau…
The Connection Between Reddening, Gas Covering Fraction, and the Escape of Ionizing Radiation at High Redshift
Pettini, Max; Shapley, Alice E.; Steidel, Charles C. +2 more
Using a large sample of spectroscopically confirmed z∼ 3 galaxies, we establish an empirical relationship between reddening (E(B-V)), neutral gas covering fraction ({f}{{cov}}({{H}} {{I}})), and the escape of ionizing (Lyman continuum, LyC) photons. Our sample includes 933 galaxies at z∼ 3,121 of which have deep spectroscopic observatio…
Detection of the kinematic Sunyaev-Zel'dovich effect with DES Year 1 and SPT
Benoit-Lévy, A.; Efstathiou, G.; D'Andrea, C. B. +82 more
We detect the kinematic Sunyaev-Zel'dovich (kSZ) effect with a statistical significance of 4.2σ by combining a cluster catalogue derived from the first year data of the Dark Energy Survey with cosmic microwave background temperature maps from the South Pole Telescope Sunyaev-Zel'dovich Survey. This measurement is performed with a differential stat…
Eliminating the optical depth nuisance from the CMB with 21 cm cosmology
Sherwin, Blake D.; Liu, Adrian; Pritchard, Jonathan R. +3 more
Amongst standard model parameters that are constrained by cosmic microwave background (CMB) observations, the optical depth τ stands out as a nuisance parameter. While τ provides some crude limits on reionization, it also degrades constraints on other cosmological parameters. Here we explore how 21 cm cosmology—as a direct probe of reionization—ca…
A census of dense cores in the Taurus L1495 cloud from the Herschel
White, G. J.; André, Ph.; Könyves, V. +17 more
We present a catalogue of dense cores in a ∼4° × 2° field of the Taurus star-forming region, inclusive of the L1495 cloud, derived from Herschel SPIRE and PACS observations in the 70 µm, 160 µm, 250 µm, 350 µm, and 500 µm continuum bands. Estimates of mean dust temperature and total mass are derived using modified bla…
A New Population of Compton-thick AGNs Identified Using the Spectral Curvature above 10 keV
Harrison, F. A.; Stern, D.; Alexander, D. M. +19 more
We present a new metric that uses the spectral curvature (SC) above 10 keV to identify Compton-thick active galactic nuclei (AGNs) in low-quality Swift/Burst Alert Telescope (BAT) X-ray data. Using NuSTAR, we observe nine high SC-selected AGNs. We find that high-sensitivity spectra show that the majority are Compton-thick (78% or 7/9) and the rema…
Globular Clusters Indicate That Ultra-diffuse Galaxies Are Dwarfs
Beasley, Michael A.; Trujillo, Ignacio
We present an analysis of archival HST/ACS imaging in the F475W (g 475), F606W (V 606), and F814W (I 814) bands of the globular cluster (GC) system of a large (3.4 kpc effective radius) ultra-diffuse galaxy (DF17) believed to be located in the Coma Cluster of galaxies. We detect 11 GCs down to the 5σ completeness l…
A Universal Density Structure for Circumgalactic Gas
Stern, Jonathan; Hennawi, Joseph F.; Prochaska, J. Xavier +1 more
We develop a new method to constrain the physical conditions in the cool (∼104 K) circumgalactic medium (CGM) from measurements of ionic column densities by assuming that the cool CGM spans a large range of gas densities and that small high-density clouds are hierarchically embedded in large low-density clouds. The new method combines t…
Regulation of black-hole accretion by a disk wind during a violent outburst of V404 Cygni
Ponti, G.; Charles, P. A.; Rodriguez, J. +7 more
Accretion of matter onto black holes is universally associated with strong radiative feedback and powerful outflows. In particular, black-hole transients have outflows whose properties are strongly coupled to those of the accretion flow. This includes X-ray winds of ionized material, expelled from the accretion disk encircling the black hole, and …
Balloon-Borne Submillimeter Polarimetry of the Vela C Molecular Cloud: Systematic Dependence of Polarization Fraction on Column Density and Local Polarization-Angle Dispersion
Ward-Thompson, Derek; Fissel, Laura M.; Nakamura, Fumitaka +27 more
We present results for Vela C obtained during the 2012 flight of the Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry. We mapped polarized intensity across almost the entire extent of this giant molecular cloud, in bands centered at 250, 350, and 500 µm. In this initial paper, we show our 500 µm data smoothed to a r…