Search Publications
Population Parameters of Intermediate-age Star Clusters in the Large Magellanic Cloud. II. New Insights from Extended Main-sequence Turnoffs in Seven Star Clusters
Chandar, Rupali; Goudfrooij, Paul; Puzia, Thomas H. +1 more
We discuss new photometry from high-resolution images of seven intermediate-age (1-2 Gyr) star clusters in the Large Magellanic Cloud taken with the Advanced Camera for Surveys on board the Hubble Space Telescope. We fit color-magnitude diagrams (CMDs) with several different sets of theoretical isochrones and determine systematic uncertainties for…
The Globular Cluster NGC 2419: A Crucible for Theories of Gravity
Dalessandro, E.; Bellazzini, M.; Chapman, S. C. +3 more
We present the analysis of a kinematic data set of stars in the globular cluster NGC 2419, taken with the DEep Imaging Multi-Object Spectrograph at the Keck II telescope. Combined with a reanalysis of deep Hubble Space Telescope and Subaru Telescope imaging data, which provide an accurate luminosity profile of the cluster, we investigate the valid…
AEGIS: Demographics of X-ray and Optically Selected Active Galactic Nuclei
Koekemoer, Anton M.; Weiner, Benjamin J.; Nandra, Kirpal +19 more
We develop a new diagnostic method to classify galaxies into active galactic nucleus (AGN) hosts, star-forming galaxies, and absorption-dominated galaxies by combining the [O III]/Hβ ratio with rest-frame U - B color. This can be used to robustly select AGNs in galaxy samples at intermediate redshifts (z < 1). We compare the result of this opti…
Quantitative Examination of a Large Sample of Supra-arcade Downflows in Eruptive Solar Flares
Savage, Sabrina L.; McKenzie, David E.
Sunward-flowing voids above post-coronal mass ejection flare arcades were first discovered using the soft X-ray telescope aboard Yohkoh and have since been observed with TRACE (extreme ultraviolet (EUV)), SOHO/LASCO (white light), SOHO/SUMER (EUV spectra), and Hinode/XRT (soft X-rays). Supra-arcade downflow (SAD) observations suggest that they are…
Probing Very Bright End of Galaxy Luminosity Function at z >~ 7 Using Hubble Space Telescope Pure Parallel Observations
Koekemoer, Anton M.; Fan, Xiaohui; McCarthy, Patrick J. +8 more
We report the first results from the Hubble Infrared Pure Parallel Imaging Extragalactic Survey, which utilizes the pure parallel orbits of the Hubble Space Telescope to do deep imaging along a large number of random sightlines. To date, our analysis includes 26 widely separated fields observed by the Wide Field Camera 3, which amounts to 122.8 ar…
Plasma Motions and Heating by Magnetic Reconnection in a 2007 May 19 Flare
Harra, Louise K.; Hara, Hirohisa; Young, Peter R. +2 more
Based on scanning spectroscopic observations with the Hinode EUV imaging spectrometer, we have found a loop-top hot source, a fast jet nearby, and an inflow structure flowing to the hot source that appeared in the impulsive phase of a long-duration flare at the disk center on 2007 May 19. The hot source observed in Fe XXIII and Fe XXIV emission li…
The Discovery and Nature of the Optical Transient CSS100217:102913+404220
Drake, A. J.; Djorgovski, S. G.; Anderson, J. +32 more
We report on the discovery and observations of the extremely luminous optical transient CSS100217:102913+404220 (CSS100217 hereafter). Spectroscopic observations showed that this transient was coincident with a galaxy at redshift z = 0.147 and reached an apparent magnitude of V ~ 16.3. After correcting for foreground Galactic extinction we determi…
The Star-formation-rate-Density Relation at 0.6 < z < 0.9 and the Role of Star-forming Galaxies
Franx, Marijn; Kelson, Daniel D.; Illingworth, Garth D. +2 more
We study the star formation rates (SFRs) of galaxies as a function of local galaxy density at 0.6 < z < 0.9. We used a low-dispersion prism in IMACS on the 6.5 m Baade (Magellan I) telescope to obtain spectra and measured redshifts to a precision of σ z /(1 + z) ~ 1% for galaxies with z AB < 23.3 mag. We utilized a s…
AKARI Observation of the Fluctuation of the Near-infrared Background
Lee, H. M.; Jeong, W. -S.; Matsuhara, H. +6 more
We report a search for fluctuations of the sky brightness toward the north ecliptic pole with the Japanese infrared astronomical satellite AKARI, at 2.4, 3.2, and 4.1 µm. We obtained circular maps with 10' diameter fields of view, which clearly show a spatial structure on the scale of a few hundred arcseconds. A power spectrum analysis shows…
Diffuse Emission Measurement with the SPectrometer on INTEGRAL as an Indirect Probe of Cosmic-Ray Electrons and Positrons
Jourdain, Elisabeth; Roques, Jean-Pierre; Bouchet, Laurent +3 more
Significant advances have been made in the understanding of the diffuse Galactic hard X-ray continuum emission using data from the INTEGRAL observatory. The diffuse hard power-law component seen with the SPectrometer on INTEGRAL (SPI) has been identified with inverse-Compton emission from relativistic (GeV) electrons on the cosmic microwave backgr…