Search Publications
Low-Level Nuclear Activity in Nearby Spiral Galaxies
Fiore, Fabrizio; Mathur, Smita; Ferrarese, Laura +1 more
We are conducting a search for supermassive black holes (SMBHs) with masses below ~107 M⊙ by looking for signs of extremely low-level nuclear activity in nearby galaxies that are not known to be AGNs. Our survey has the following characteristics: (1) X-ray selection using the Chandra X-Ray Observatory, since X-rays are a ubiq…
VLT Spectroscopy of Globular Clusters in Low Surface Brightness Dwarf Galaxies
Puzia, Thomas H.; Sharina, Margarita E.
We present VLT/FORS2 spectroscopic observations of globular clusters (GCs) in five low surface brightness dwarf galaxies: KK 211 and KK 221, both dwarf spheroidal satellites (dSph) of NGC 5128; dSph KK 84 located close to the isolated S0 galaxy NGC 3115; and two isolated dwarf irregular (dIrr) galaxies, UGC 3755 and ESO 490-17. Our sample is selec…
Self-Regulated Fueling of Galaxy Centers: Evidence for Star Formation Feedback in IC 342's Nucleus
Meier, David S.; Böker, Torsten; Calzetti, Daniela +1 more
Using new, high-resolution interferometric observations of the CO and HCN molecules, we directly compare the molecular and ionized components of the interstellar medium in the center of the nearby spiral galaxy IC 342, on spatial scales of ≈10 pc. The morphology of the tracers suggests that the molecular gas flow caused by a large-scale stellar ba…
The Solar Magnetic Field and Coronal Dynamics of the Eruption on 2007 May 19
Luhmann, J. G.; Li, Y.; Lynch, B. J. +5 more
The solar eruption on 2007 May 19, from AR 10956 near solar disk center, consisted of a B9.5 flare (12:48 UT), a filament eruption, an EUV dimming, a coronal wave, and a multifront CME. The eruption was observed by the twin STEREO spacecraft at a separation angle of 8.5°. We report analysis of the source region photospheric magnetic field and its …
BAT X-Ray Survey. I. Methodology and X-Ray Identification
Greiner, J.; Strong, A. W.; Ajello, M. +3 more
We applied the maximum likelihood (ML) method, as an image reconstruction algorithm, to the BAT X-Ray Survey (BXS). This method was specifically designed to preserve the full statistical information in the data and to avoid mosaicking of many exposures with different pointing directions, thus reducing systematic errors when co-adding images. We re…
Strongly Blueshifted Phenomena Observed with Hinode EIS in the 2006 December 13 Solar Flare
Culhane, J. L.; Hara, Hirohisa; Narukage, Noriyuki +5 more
We present a detailed examination of strongly blueshifted emission lines observed with the EUV Imaging Spectrometer on board the Hinode satellite. We found two kinds of blueshifted phenomenon associated with the X3.4 flare that occurred on 2006 December 13. One was related to a plasmoid ejection seen in soft X-rays. It was very bright in all the l…
HST ACS Imaging of M82: A Comparison of Mass and Size Distribution Functions of the Younger Nuclear and Older Disk Clusters
Luna, A.; Mayya, Y. D.; Rosa-González, D. +3 more
We present the results obtained from an objective search for stellar clusters, both in the currently active nuclear starburst region, and in the poststarburst disk of M82. Images obtained with the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST) in F435W (B), F555W (V), and F814W (I) filters were used in the search for t…
A Search for Molecular Gas in the Nucleus of M87 and Implications for the Fueling of Supermassive Black Holes
Beuther, Henrik; Walter, Fabian; Tan, Jonathan C. +1 more
Supermassive black holes in giant elliptical galaxies are remarkably faint given their expected accretion rates. This motivates models of radiatively inefficient accretion due to either ion-electron thermal decoupling, generation of outflows that inhibit accretion, or settling of gas to a gravitationally unstable disk that forms stars in preferenc…
Emission from Very Small Grains and PAH Molecules in Monte Carlo Radiation Transfer Codes: Application to the Edge-On Disk of Gomez's Hamburger
Wood, Kenneth; Robitaille, Thomas; Draine, Bruce T. +1 more
We have modeled optical to far-infrared images, photometry, and spectroscopy of the object known as Gomez's Hamburger. We reproduce the images and spectrum with an edge-on disk of mass 0.3 M⊙ and radius 1600 AU, surrounding an A0 III star at a distance of 280 pc. Our mass estimate is in excellent agreement with recent CO observations. H…
A New FUSE Survey of Interstellar HD
Snow, Theodore P.; Destree, Joshua D.; Rachford, Brian L. +5 more
We have used archival FUSE data to complete a survey of interstellar HD in 41 lines of sight with a wide range of extinctions. This follow-up to an earlier survey was made to further assess the utility of HD as a cosmological probe; to analyze the HD formation process; and to see what trends with other interstellar properties were present in the d…