Search Publications
Revisiting Putative Cool Accretion Disks in Ultraluminous X-Ray Sources
Fabian, A. C.; Miller, J. M.; Reis, R. C. +4 more
Soft, potentially thermal spectral components observed in some ultra-luminous X-ray sources (ULXs) can be fit with models for emission from cool, optically thick accretion disks. If that description is correct, the low temperatures that are observed imply accretion onto "intermediate-mass" black holes. Subsequent work has found that these componen…
Testing reflection features in 4U 1705-44 with XMM-Newton, BeppoSAX, and RXTE in the hard and soft states
Santangelo, A.; Belloni, T.; Robba, N. R. +10 more
We use data from the bright atoll source 4U 1705-44 taken with XMM-Newton, BeppoSAX, and RXTE both in the hard and in the soft state to perform a self-consistent study of the reflection component in this source. Although the data from these X-ray observatories are not simultaneous, the spectral decomposition is shown to be consistent among the dif…
Ultra-Deep Hubble Space Telescope Imaging of the Small Magellanic Cloud: The Initial Mass Function of Stars with M <~ 1 M ⊙
Anderson, Jay; Dotter, Aaron; Rich, R. Michael +7 more
We present a new measurement of the stellar initial mass function (IMF) based on ultra-deep, high-resolution photometry of >5000 stars in the outskirts of the Small Magellanic Cloud (SMC) galaxy. The Hubble Space Telescope (HST) Advanced Camera for Surveys observations reveal this rich, cospatial population behind the foreground globular cluste…
Deep luminosity functions and colour-magnitude relations for cluster galaxies at 0.2 < z < 0.6
Bremer, M. N.; De Propris, R.; Phillipps, S.
We derive deep I-band luminosity functions and colour-magnitude diagrams from Hubble Space Telescope imaging for eleven 0.2 < z < 0.6 clusters observed at various stages of merging, and a comparison sample of five more relaxed clusters at similar redshifts. The characteristic magnitude M* evolves passively out to z = 0.6, while the faint-end…
The size of the X-ray emitting region in SWIFT J2127.4+5654 via a broad line region cloud X-ray eclipse
Fabian, A. C.; Miller, J. M.; Miniutti, G. +4 more
We present results obtained from the time-resolved X-ray spectral analysis of the Narrow-Line-Seyfert 1 galaxy SWIFT J2127.4+5654 during a ∼130 ks XMM-Newton observation. We reveal large spectral variations, especially during the first ∼90 ks of the XMM-Newton exposure. The spectral variability can be attributed to a partial eclipse of the X-ray s…
A VLT/FLAMES Study of the Peculiar Intermediate-age Large Magellanic Cloud Star Cluster NGC 1846. I. Kinematics
Da Costa, G. S.; Yong, D.; Mackey, A. D. +1 more
In this paper we present high-resolution VLT/FLAMES observations of red giant stars in the massive intermediate-age Large Magellanic Cloud star cluster NGC 1846, which, on the basis of its extended main-sequence turnoff (EMSTO), possesses an internal age spread of ≈300 Myr. We describe in detail our target selection and data reduction procedures, …
A Resolved Debris Disk around the Candidate Planet-hosting Star HD 95086
Apai, D.; Pascucci, I.; Ábrahám, P. +11 more
Recently, a new planet candidate was discovered on direct images around the young (10-17 Myr) A-type star HD 95086. The strong infrared excess of the system indicates that, similar to HR8799, β Pic, and Fomalhaut, the star harbors a circumstellar disk. Aiming to study the structure and gas content of the HD 95086 disk, and to investigate its possi…
Tearing the Veil: Interaction of the Orion Nebula with its Neutral Environment
O'Dell, C. R.; van der Werf, Paul P.; Goss, W. M.
We present H I 21 cm observations of the Orion Nebula, obtained with the Karl G. Jansky Very Large Array, at an angular resolution of 7.''2 × 5.''7 and a velocity resolution of 0.77 km s-1. Our data reveal H I absorption in the Veil toward the radio continuum of the H II region, and H I emission arising from the Orion Bar photon-dominat…
What are the Progenitors of Compact, Massive, Quiescent Galaxies at z = 2.3? The Population of Massive Galaxies at z > 3 from NMBS and CANDELS
Marchesini, Danilo; Stefanon, Mauro; Whitaker, Katherine E. +2 more
Using public data from the NEWFIRM Medium-Band Survey (NMBS) and the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS), we investigate the population of massive galaxies at z > 3. The main aim of this work is to identify the potential progenitors of z ~ 2 compact, massive, quiescent galaxies (CMQGs), furthering our unders…
Near-infrared spectral monitoring of Pluto's ices: Spatial distribution and secular evolution
Olkin, C. B.; Buie, M. W.; Young, E. F. +2 more
We report results from monitoring Pluto's 0.8 to 2.4 µm reflectance spectrum with IRTF/SpeX on 65 nights over the dozen years from 2001 to 2012. The spectra show vibrational absorption features of simple molecules CH4, CO, and N2 condensed as ices on Pluto's surface. These absorptions are modulated by the planet's 6.39 …