Search Publications
Resolving the Far-IR Line Deficit: Photoelectric Heating and Far-IR Line Cooling in NGC 1097 and NGC 4559
Helou, G.; Roussel, H.; Murphy, E. J. +30 more
The physical state of interstellar gas and dust is dependent on the processes which heat and cool this medium. To probe heating and cooling of the interstellar medium over a large range of infrared surface brightness, on sub-kiloparsec scales, we employ line maps of [C II] 158 µm, [O I] 63 µm, and [N II] 122 µm in NGC 1097 and NG…
The Swift Burst Alert Telescope Detected Seyfert 1 Galaxies: X-Ray Broadband Properties and Warm Absorbers
Veilleux, Sylvain; Kallman, T. R.; McKernan, Barry +1 more
We present results from an analysis of the broadband, 0.3-195 keV, X-ray spectra of 48 Seyfert 1-1.5 sources detected in the very hard X-rays with the Swift Burst Alert Telescope (BAT). This sample is selected in an all-sky survey conducted in the 14-195 keV band. Therefore, our sources are largely unbiased toward both obscuration and host galaxy …
A HST/WFC3-IR Morphological Survey of Galaxies at z = 1.5-3.6. II. The Relation between Morphology and Gas-phase Kinematics
Erb, Dawn K.; Shapley, Alice E.; Steidel, Charles C. +3 more
We analyze rest-frame optical morphologies and gas-phase kinematics as traced by rest-frame far-UV and optical spectra for a sample of 204 star-forming galaxies in the redshift range z ~ 2-3 drawn from the Keck Baryonic Structure Survey. We find that spectroscopic properties and gas-phase kinematics are closely linked to morphology: compact galaxi…
Field Topology Analysis of a Long-lasting Coronal Sigmoid
van Ballegooijen, A. A.; DeLuca, E. E.; Savcheva, A. S.
We present the first field topology analysis based on nonlinear force-free field (NLFFF) models of a long-lasting coronal sigmoid observed in 2007 February with the X-Ray Telescope on Hinode. The NLFFF models are built with the flux rope insertion method and give the three-dimensional coronal magnetic field as constrained by observed coronal loop …
The Extended Hubble Space Telescope Supernova Survey: The Rate of Core Collapse Supernovae to z ~ 1
Mobasher, Bahram; Riess, Adam G.; Strolger, Louis-Gregory +3 more
We use a sample of 45 core collapse supernovae detected with the Advanced Camera for Surveys on board the Hubble Space Telescope to derive the core collapse supernova rate in the redshift range 0.1 < z < 1.3. In redshift bins centered on langzrang = 0.39, langzrang = 0.73, and langzrang = 1.11, we find rates of 3.00+1.28 - 0.…
Low-mass X-Ray Binaries Indicate a Top-heavy Stellar Initial Mass Function in Ultracompact Dwarf Galaxies
Mieske, Steffen; Kroupa, Pavel; Pflamm-Altenburg, Jan +1 more
It has been shown before that the high mass-to-light ratios of ultracompact dwarf galaxies (UCDs) can be explained if their stellar initial mass function (IMF) was top-heavy, i.e., that the IMF was skewed toward high-mass stars. In this case, neutron stars (NSs) and black holes would provide unseen mass in the UCDs. In order to test this scenario …
The Pair Fraction of Massive Galaxies at 0 <= z <= 3
van der Wel, Arjen; Zirm, Andrew W.; Wuyts, Stijn +2 more
Using a mass-selected (M sstarf >= 1011 M ⊙) sample of 198 galaxies at 0 <= z <= 3.0 with Hubble Space Telescope/NICMOS H 160-band images from the COSMOS survey, we find evidence for the evolution of the pair fraction above z ~ 2, an epoch in which massive galaxies are believed to undergo signif…
The Contribution of TP-AGB and RHeB Stars to the Near-IR Luminosity of Local Galaxies: Implications for Stellar Mass Measurements of High-redshift Galaxies
Williams, Benjamin F.; Boyer, Martha L.; Girardi, Léo +9 more
Using high spatial resolution Hubble Space Telescope WFC3 and Advanced Camera for Surveys imaging of resolved stellar populations, we constrain the contribution of thermally pulsing asymptotic giant branch (TP-AGB) stars and red helium burning (RHeB) stars to the 1.6 µm near-infrared (NIR) luminosities of 23 nearby galaxies, including dwarfs…
A Study of the Dark Core in A520 with the Hubble Space Telescope: The Mystery Deepens
Dalcanton, J. J.; Capak, P.; Hoekstra, H. +4 more
We present a Hubble Space Telescope/Wide Field Planetary Camera 2 weak-lensing study of A520, where a previous analysis of ground-based data suggested the presence of a dark mass concentration. We map the complex mass structure in much greater detail, leveraging more than a factor of three increase in the number density of source galaxies availabl…
Hubble Space Telescope Measures of Mass Accretion Rates in the Orion Nebula Cluster
Lodato, G.; Robberto, M.; Da Rio, N. +4 more
The present observational understanding of the evolution of the mass accretion rates (\dot{M}_acc) in pre-main-sequence stars is limited by the lack of accurate measurements of \dot{M}_acc over homogeneous and large statistical samples of young stars. Such observational effort is needed to properly constrain the theory of star formation and disk e…