Search Publications
NuSTAR Reveals an Intrinsically X-Ray Weak Broad Absorption Line Quasar in the Ultraluminous Infrared Galaxy Markarian 231
Rigby, J. R.; Veilleux, S.; Harrison, F. A. +24 more
We present high-energy (3-30 keV) NuSTAR observations of the nearest quasar, the ultraluminous infrared galaxy (ULIRG) Markarian 231 (Mrk 231), supplemented with new and simultaneous low-energy (0.5-8 keV) data from Chandra. The source was detected, though at much fainter levels than previously reported, likely due to contamination in the large ap…
Globular Cluster Systems in Brightest Cluster Galaxies: A Near-universal Luminosity Function?
Bailin, Jeremy; Whitmore, Bradley C.; Côté, Patrick +10 more
We present the first results from our Hubble Space Telescope brightest cluster galaxy (BCG) survey of seven central supergiant cluster galaxies and their globular cluster (GC) systems. We measure a total of 48,000 GCs in all seven galaxies, representing the largest single GC database. We find that a log-normal shape accurately matches the observed…
Observations of Environmental Quenching in Groups in the 11 GYR since z = 2.5: Different Quenching for Central and Satellite Galaxies
van Dokkum, Pieter G.; Franx, Marijn; Illingworth, Garth D. +16 more
We present direct observational evidence for star formation quenching in galaxy groups in the redshift range 0 < z < 2.5. We utilize a large sample of nearly 6000 groups, selected by fixed cumulative number density from three photometric catalogs, to follow the evolving quiescent fractions of central and satellite galaxies over roughly 11 Gy…
Measurement of Galaxy Clustering at z ~ 7.2 and the Evolution of Galaxy Bias from 3.8 < z < 8 in the XDF, GOODS-S, and GOODS-N
Trenti, M.; Oesch, P. A.; Carollo, C. M. +8 more
Lyman-break galaxy (LBG) samples observed during reionization (z >~ 6) with the Hubble Space Telescope's Wide Field Camera 3 are reaching sizes sufficient to characterize their clustering properties. Using a combined catalog from the Hubble eXtreme Deep Field and CANDELS surveys, containing N = 743 LBG candidates at z >= 6.5 at a mean redshi…
Evolution of Thermally Pulsing Asymptotic Giant Branch Stars. IV. Constraining Mass loss and Lifetimes of Low Mass, Low Metallicity AGB Stars
Williams, Benjamin F.; Dolphin, Andrew; Girardi, Léo +7 more
The evolution and lifetimes of thermally pulsating asymptotic giant branch (TP-AGB) stars suffer from significant uncertainties. In this work, we analyze the numbers and luminosity functions of TP-AGB stars in six quiescent, low metallicity ([Fe/H] <~ -0.86) galaxies taken from the ACS Nearby Galaxy Survey Treasury sample, using Hubble Space Te…
Carbon-rich Dust Past the Asymptotic Giant Branch: Aliphatics, Aromatics, and Fullerenes in the Magellanic Clouds
Sahai, R.; Zijlstra, A. A.; Peeters, E. +10 more
Infrared spectra of carbon-rich objects that have evolved off the asymptotic giant branch reveal a range of dust properties, including fullerenes, polycyclic aromatic hydrocarbons (PAHs), aliphatic hydrocarbons, and several unidentified features, including the 21 µm emission feature. To test for the presence of fullerenes, we used the positi…
The INTEGRAL High-energy Cut-off Distribution of Type 1 Active Galactic Nuclei
Bird, A. J.; Ubertini, P.; Malizia, A. +4 more
In this Letter we present the primary continuum parameters, the photon index Γ, and the high-energy cut-off E c of 41 type-1 Seyfert galaxies extracted from the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) complete sample of active galactic nuclei (AGNs). We performed broadband (0.3-100 keV) spectral analysis by simultaneo…
Disintegrating Asteroid P/2013 R3
Mutchler, Max; Jewitt, David; Agarwal, Jessica +3 more
Splitting of the nuclei of comets into multiple components has been frequently observed but, to date, no main-belt asteroid has been observed to break up. Using the Hubble Space Telescope, we find that main-belt asteroid P/2013 R3 consists of 10 or more distinct components, the largest up to 200 m in radius (assumed geometric albedo of 0.05) each …
The Light Curve of SN 1987A Revisited: Constraining Production Masses of Radioactive Nuclides
Seitenzahl, Ivo R.; Timmes, F. X.; Magkotsios, Georgios
We revisit the evidence for the contribution of the long-lived radioactive nuclides 44Ti, 55Fe, 56Co, 57Co, and 60Co to the UVOIR light curve of SN 1987A. We show that the V-band luminosity constitutes a roughly constant fraction of the bolometric luminosity between 900 and 1900 days, and we o…
NuSTAR and XMM-NEWTON Observations of NGC 1365: Extreme Absorption Variability and a Constant Inner Accretion Disk
Harrison, F. A.; Stern, D.; Zhang, W. W. +24 more
We present a spectral analysis of four coordinated NuSTAR+XMM-Newton observations of the Seyfert galaxy NGC 1365. These exhibit an extreme level of spectral variability, which is primarily due to variable line-of-sight absorption, revealing relatively unobscured states in this source for the first time. Despite the diverse range of absorption stat…