Search Publications
NuSTAR, XMM-Newton, and Suzaku Observations of the Ultraluminous X-Ray Source Holmberg II X-1
Harrison, F. A.; Stern, D.; Fabian, A. C. +14 more
We present the first broadband 0.3-25.0 keV X-ray observations of the bright ultraluminous X-ray source (ULX) Holmberg II X-1, performed by NuSTAR, XMM-Newton, and Suzaku in 2013 September. The NuSTAR data provide the first observations of Holmberg II X-1 above 10 keV and reveal a very steep high-energy spectrum, similar to other ULXs observed by …
Spectroscopic Study of Star-forming Galaxies in Filaments and the Field at z ~ 0.5: Evidence for Environmental Dependence of Electron Density
Sobral, David; Shivaei, Irene; Mobasher, Bahram +3 more
We study the physical properties of a spectroscopic sample of 28 star-forming galaxies in a large filamentary structure in the COSMOS field at z ∼ 0.53, with spectroscopic data taken with the Keck/DEIMOS spectrograph, and compare them with a control sample of 30 field galaxies. We spectroscopically confirm the presence of a large galaxy filament (…
Elemental Depletions in the Magellanic Clouds and the Evolution of Depletions with Metallicity
Meixner, Margaret; Seale, Jonathan; Dwek, Eli +4 more
We present a study of the composition of gas and dust in the Large and Small Magellanic Clouds (LMC and SMC) using UV absorption spectroscopy. We measure P ii and Fe ii along 84 spatially distributed sightlines toward the MCs using archival Far Ultraviolet Spectroscopic Explorer observations. For 16 of those sightlines, we also measure Si ii, Cr i…
The VLT SINFONI Mg II Program for Line Emitters (SIMPLE). II. Background Quasars Probing Z ~ 1 Galactic Winds
Finley, Hayley; Bouché, Nicolas; Contini, Thierry +3 more
The physical properties of galactic winds are of paramount importance for our understanding of galaxy formation. Fortunately, they can be constrained using background quasars passing near star-forming galaxies (SFGs). From the 14 quasar-galaxy pairs in our Very Large Telescope (VLT)/SINFONI Mg ii Program for Line Emitters sample, we reobserved the…
Spectroscopic Confirmation of an Ultra Massive and Compact Galaxy at z = 3.35: a Detailed Look at an Early Progenitor of Local Giant Ellipticals
van Dokkum, Pieter G.; Muzzin, Adam; Labbé, Ivo +10 more
We present the first spectroscopic confirmation of an ultramassive galaxy at redshift z\gt 3 using data from Keck-NIRSPEC, VLT-X-shooter, and GTC-Osiris. We detect strong [O iii] and Lyα emission, and weak [O ii], C iv, and He ii, placing C1-23152 at a spectroscopic redshift of {{z}spec}=3.351. The modeling of the emission-line-correcte…
Broadband Radio Polarimetry and Faraday Rotation of 563 Extragalactic Radio Sources
Gaensler, B. M.; Franzen, T. M. O.; Anderson, C. S. +1 more
We present a broadband spectropolarimetric survey of 563 discrete, mostly unresolved radio sources between 1.3 and 2.0 GHz using data taken with the Australia Telescope Compact Array. We have used rotation-measure synthesis to identify Faraday-complex polarized sources, those objects whose frequency-dependent polarization behavior indicates the pr…
HST Rotational Spectral Mapping of Two L-type Brown Dwarfs: Variability in and out of Water Bands indicates High-altitude Haze Layers
Metchev, Stanimir; Showman, Adam P.; Apai, Dániel +13 more
We present time-resolved near-infrared spectroscopy of two L5 dwarfs, 2MASS J18212815+1414010 and 2MASS J15074759-1627386, observed with the Wide Field Camera 3 instrument on the Hubble Space Telescope (HST). We study the wavelength dependence of rotation-modulated flux variations between 1.1 µm and 1.7 µm. We find that the water absor…
On the Origin of Mid-latitude Fast Wind: Challenging the Two-state Solar Wind Paradigm
Landi, Enrico; Zurbuchen, Thomas H.; Lepri, Susan T. +2 more
The bimodal paradigm of solar wind describes a slow solar wind situated near the heliospheric current sheet while a fast wind overexpands from the poles to fill in the remainder of the heliosphere. In this paper, we challenge this paradigm and focus here on mid-latitude wind using three fast-latitude passes completed by the Ulysses spacecraft. Bas…
NuSTAR and XMM-Newton Observations of the Extreme Ultraluminous X-Ray Source NGC 5907 ULX1: A Vanishing Act
Harrison, F. A.; Stern, D.; Bachetti, M. +15 more
We present results obtained from two broadband X-ray observations of the extreme ultraluminous X-ray source (ULX) NGC 5907 ULX1, known to have a peak X-ray luminosity of ~5 × 1040 erg s-1. These XMM-Newton and NuSTAR observations, separated by only ~4 days, revealed an extreme level of short-term flux variability. In the firs…
New Ultraviolet Extinction Curves for Interstellar Dust in M31
Gordon, Karl D.; Fitzpatrick, Edward L.; Bohlin, R. C. +4 more
New low-resolution UV spectra of a sample of reddened OB stars in M31 were obtained with the Hubble Space Telescope/STIS to study the wavelength dependence of interstellar extinction and the nature of the underlying dust grain populations. Extinction curves were constructed for four reddened sightlines in M31 paired with closely matching stellar a…