Search Publications
Uncovering Red and Dusty Ultraluminous X-Ray Sources with Spitzer
Gehrz, Robert D.; Fürst, Felix; Walton, Dominic J. +9 more
We present a mid-infrared (IR) sample study of nearby ultraluminous X-ray sources (ULXs) using multiepoch observations with the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. Spitzer/IRAC observations taken after 2014 were obtained as part of the Spitzer Infrared Intensive Transients Survey. Our sample includes 96 ULXs located within…
The Detection of [O III] λ4363 in a Lensed, Dwarf Galaxy at z = 2.59: Testing Metallicity Indicators and Scaling Relations at High Redshift and Low Mass
Richard, Johan; Siana, Brian; Freeman, William R. +6 more
We present Keck/MOSFIRE (Multi-Object Spectrometer for InfraRed Exploration) and Keck/LRIS (Low Resolution Imaging Spectrometer) spectroscopy of A1689-217, a lensed (magnification ∼7.9), star-forming (SFR ∼ 16 M ⊙ yr-1), dwarf (log(M */M ⊙) = 8.07-8.59) Lyα emitter (EW0 ∼ 138 Å) at z = 2.5918.…
Simulations of Ice Chemistry in Cometary Nuclei
Garrod, Robin T.
The first computational model of solid-phase chemistry in cometary nuclear ices is presented. An astrochemical kinetics model, the Model for Astrophysical Gas and Ice Chemical Kinetics And Layering, is adapted to trace the chemical evolution in multiple layers of cometary ice, over a representative period of 5 Gyr. Physical conditions are chosen a…
Discovery of an X-Ray Quasar Wind Driving the Cold Gas Outflow in the Ultraluminous Infrared Galaxy IRAS F05189-2524
Veilleux, Sylvain; Tombesi, Francesco; Lohfink, Anne M. +2 more
We present new XMM-Newton and NuSTAR observations of the galaxy merger IRAS F05189-2524, which is classified as an ultraluminous infrared galaxy and optical Seyfert 2 at z = 0.0426. We test a variety of spectral models that yield a best fit consisting of an absorbed power law with emission and absorption features in the Fe K band. Remarkably, we f…
Modeling Mg II During Solar Flares. I. Partial Frequency Redistribution, Opacity, and Coronal Irradiation
Kerr, Graham S.; Carlsson, Mats; Allred, Joel C.
The Interface Region Imaging Spectrograph has routinely observed the flaring Mg II near-ultraviolet (NUV) spectrum, offering excellent diagnostic potential and a window into the location of energy deposition. A number of studies have forward-modeled both the general properties of these lines and specific flare observations. Generally these have fo…
Characteristics of the Two Sequences Seen in the High-velocity Hertzsprung-Russell Diagram in Gaia DR2
Casagrande, Luca; Feltzing, Sofia; Sahlholdt, Christian L.
In this study we use a sample of about 9 million SkyMapper stars with metallicities to investigate the properties of the two stellar populations seen in the high-velocity (V T > 200 km s-1) Gaia DR2 Hertzsprung-Russell diagram. Based on 10,000 red giant branch (RGB) stars (out of 75,000 with high velocity), we find that th…
The Nitrogen Carrier in Inner Protoplanetary Disks
Banzatti, Andrea; Walsh, Catherine; Pontoppidan, Klaus M. +4 more
The dominant reservoirs of elemental nitrogen in protoplanetary disks have not yet been observationally identified. Likely candidates are HCN, NH3, and N2. The relative abundances of these carriers determine the composition of planetesimals as a function of disk radius due to strong differences in their volatility. A signific…
Kinetic Energy Transfer from X-Ray Ultrafast Outflows to Millimeter/Submillimeter Cold Molecular Outflows in Seyfert Galaxies
Kohno, Kotaro; Mizumoto, Misaki; Izumi, Takuma
UltraFast Outflows (UFOs), seen as X-ray blueshifted absorption lines in active galactic nuclei (AGNs), are considered to be a key mechanism for AGN feedback. In this scenario, UFO kinetic energy is transferred into the cold and extended molecular outflow observed at the millimeter/submillimeter wavelength, which blows away the gas and suppresses …
The Green Bank Ammonia Survey: A Virial Analysis of Gould Belt Clouds in Data Release 1
Caselli, Paola; Chen, Mike; Di Francesco, James +14 more
We perform a virial analysis of starless dense cores in three nearby star-forming regions: L1688 in Ophiuchus, NGC 1333 in Perseus, and B18 in Taurus. Our analysis takes advantage of comprehensive kinematic information for the dense gas in all of these regions made publicly available through the Green Bank Ammonia Survey Data Release 1, which is u…
Large-amplitude Quasiperiodic Pulsations as Evidence of Impulsive Heating in Hot Transient Loop Systems Detected in the EUV with SDO/AIA
Testa, Paola; Petralia, Antonino; Reale, Fabio +1 more
Short heat pulses can trigger plasma pressure fronts inside closed magnetic tubes in the corona. The alternation of condensations and rarefactions from the pressure modes drive large-amplitude pulsations in the plasma emission. Here we show the detection of such pulsations along magnetic tubes that brighten transiently in the hot 94 Å EUV channel …