Search Publications
The Mass of the Central Black Hole in the Seyfert Galaxy NGC 4151
Peterson, Bradley M.; Onken, Christopher A.; Metzroth, Kyle G.
In order to improve the reverberation-mapping-based estimate of the mass of the central supermassive black hole in the Seyfert 1 galaxy NGC 4151, we have reanalyzed archival ultraviolet monitoring spectra from two campaigns undertaken with the International Ultraviolet Explorer. We measure emission-line time delays for four lines, C IV λ1549, He I…
The Physical and Photometric Properties of High-Redshift Galaxies in Cosmological Hydrodynamic Simulations
Papovich, C.; Davé, R.; Finlator, K. +1 more
We study the physical and photometric properties of galaxies at z=4 in cosmological hydrodynamic simulations of a ΛCDM universe. We focus on galaxies satisfying the ``B dropout'' criteria of the Great Observatories Origins DEEP Survey (GOODS). Our simulations predict that high-redshift galaxies show strong correlations in star formation rate (SFR)…
The Pure Noncollisional Blue Straggler Population in the Giant Stellar System ω Centauri
Pancino, E.; Bellazzini, M.; Origlia, L. +3 more
We have used high spatial resolution data from the Hubble Space Telescope (HST) and wide-field ground-based observations to search for blue straggler stars (BSSs) over the entire radial extent of the large stellar system ω Centauri. We have detected the largest population of BSSs ever observed in any stellar system. Even though the sample is restr…
A Radio Study of the Seyfert Galaxy Markarian 6: Implications for Seyfert Life Cycles
O'Dea, C. P.; Xu, C.; Baum, S. A. +2 more
We have carried out an extensive radio study with the Very Large Array on the Seyfert 1.5 galaxy Mrk 6 and imaged a spectacular radio structure in the source. The radio emission occurs on three different spatial scales: ~7.5 kpc bubbles, ~1.5 kpc bubbles lying nearly orthogonal to them, and a ~1 kpc radio jet lying orthogonal to the kiloparsec-sca…
The Eclipsing Binary V1061 Cygni: Confronting Stellar Evolution Models for Active and Inactive Solar-Type Stars
Torres, Guillermo; Lacy, Claud H.; Marschall, Laurence A. +2 more
We present spectroscopic and photometric observations of the eclipsing system V1061 Cyg (P=2.35 days). A third star is visible in the spectrum, and the system is a hierarchical triple. We combine the radial velocities for the three stars, times of eclipse, and intermediate astrometric data from the Hipparcos mission (abscissa residuals) to establi…
Hierarchical Star Formation in the Spiral Galaxy NGC 628
Chandar, Rupali; Elmegreen, Bruce G.; Whitmore, Brad +2 more
The distributions of size and luminosity for star-forming regions in the nearby spiral galaxy NGC 628 are studied over a wide range of scales using progressively blurred versions of an image from the Hubble Space Telescope Advanced Camera for Surveys. Four optical filters are considered for the central region, including Hα. Two filters are used fo…
A 70 Kiloparsec X-Ray Tail in the Cluster A3627
Forman, W.; Sun, M.; Nulsen, P. E. J. +3 more
We present the discovery of a 70 kpc X-ray tail behind the small late-type galaxy ESO 137-001, in the nearby, hot (T=6.5 keV) merging cluster A3627, from both Chandra and XMM-Newton observations. The tail has a length-to-width ratio of ~10. It is luminous (L0.5-2keV~1041 ergs s-1), with a temperature of ~0.7 keV an…
Radiatively Inefficient Accretion Flow in the Nucleus of NGC 1097
Eracleous, Michael; Terashima, Yuichi; Storchi-Bergmann, Thaisa +3 more
We present a model for the accretion flow around the supermassive black hole in the LINER nucleus of NGC 1097 that fits the optical to X-ray spectral energy distribution (SED). The X-ray segment of the SED is based on observations with the Chandra X-Ray Observatory, which are reported here for the first time. The inner part of the flow is modeled …
Satellites of the Largest Kuiper Belt Objects
Brown, M. E.; Rabinowitz, D. L.; Trujillo, C. A. +12 more
We have searched the four brightest objects in the Kuiper Belt for the presence of satellites using the newly commissioned Keck Observatory Laser Guide Star Adaptive Optics system. Satellites are seen around three of the four objects: Pluto (whose satellite Charon is well-known and whose recently discovered smaller satellites are too faint to be d…
The X-Ray Synchrotron Emission of RCW 86 and the Implications for Its Age
Vink, Jacco; Bamba, Aya; Yamazaki, Ryo +3 more
We report X-ray imaging spectroscopy observations of the northeastern shell of the supernova remnant RCW 86 using Chandra and XMM-Newton. Along this part of the shell, the dominant X-ray radiation mechanism changes from thermal to synchrotron emission. We argue that both the presence of X-ray synchrotron radiation and the width of the synchrotron-…