Search Publications
The Anatomy of Star Formation in NGC 300
Helou, G.; Roussel, H.; Fazio, G. G. +19 more
The Spitzer Space Telescope was used to study the mid- to far-infrared properties of NGC 300 and to compare dust emission to Hα to elucidate the heating of the interstellar medium (ISM) and the star formation cycle at scales smaller than 100 pc. The new data allow us to discern clear differences in the spatial distribution of 8 µm dust emiss…
An Extended Scheme for Fitting X-Ray Data with Accretion Disk Spectra in the Strong Gravity Regime
Yaqoob, T.; Dovčiak, M.; Karas, V.
Accreting black holes are believed to emit X-rays, which then mediate information about strong gravity in the vicinity of the emission region. We report on a set of new routines for the XSPEC package for analyzing X-ray spectra of black-hole accretion disks. The new computational tool significantly extends the capabilities of the currently availab…
The Rest-Frame Optical Spectra of SCUBA Galaxies
Ivison, R. J.; Smail, Ian; Swinbank, A. M. +3 more
We present near-infrared spectroscopy and narrowband imaging at the wavelength of redshifted Hα for a sample of 30 high-redshift, far-infrared luminous galaxies. This sample is selected from surveys in the submillimeter, millimeter, and radio wave bands and has complete redshift coverage with a median redshift of z~2.4. We use our data to measure …
A Study of the Kinematic Evolution of Coronal Mass Ejections
Zhang, J.; Howard, R. A.; Dere, K. P. +1 more
We report the kinematic properties of a set of three coronal mass ejections (CMEs) observed with the LASCO (Large Angle and Spectrometric Coronagraph) on the Solar and Heliospheric Observatory (SOHO) spacecraft, which showed characteristics of impulsive, intermediate, and gradual acceleration, respectively. The first CME had a 30 minute long fast …
Constraining the population of cosmic ray protons in cooling flow clusters with γ-ray and radio observations: Are radio mini-halos of hadronic origin?
Enßlin, T. A.; Pfrommer, C.
We wish to constrain the cosmic-ray proton (CRp) population in galaxy clusters. By hadronic interactions with the thermal gas of the intra-cluster medium (ICM), the CRp produce γ-rays for which we develop an analytic formalism to deduce their spectral distribution. Assuming the CRp-to-thermal energy density ratio XCRp and the CRp spectr…
Galaxy Size Evolution at High Redshift and Surface Brightness Selection Effects: Constraints from the Hubble Ultra Deep Field
Bouwens, R. J.; Illingworth, G. D.; Blakeslee, J. P. +2 more
We use the exceptional depth of the Ultra Deep Field (UDF) and UDF-parallel Advanced Camera for Surveys fields to study the sizes of high-redshift (z~2-6) galaxies and address long-standing questions about possible biases in the cosmic star formation rate due to surface brightness dimming. Contrasting B-, V-, and i-dropout samples culled from the …
Cone model for halo CMEs: Application to space weather forecasting
Xie, Hong; Ofman, Leon; Lawrence, Gareth
In this study, we present an innovative analytical method to determine the angular width and propagation orientation of halo Coronal Mass Ejections (CMEs). The relation of CME actual speed with apparent speed and its components measured at different position angle has been investigated. The present work is based on the cone model proposed by [2002…
Constraining Solar Abundances Using Helioseismology
Basu, Sarbani; Antia, H. M.
Recent analyses of solar photospheric abundances suggest that the oxygen abundance in the solar atmosphere needs to be revised downward. In this study, we investigate the consequence of this revision on helioseismic analyses of the depth of the solar convection zone and the helium abundance in the solar envelope and find no significant effect. We …
Star formation history and dust content of galaxies drawn from ultraviolet surveys
Kong, X.; Brinchmann, J.; Charlot, S. +1 more
We compile a new sample of 115 nearby, non-Seyfert galaxies spanning a wide range of star formation activities, from starburst to nearly dormant, based on ultraviolet observations with various satellites. We combine these observations with infrared observations to study the relation between ratio of total far-infrared to ultraviolet luminosity and…
High-Redshift Supernova Rates
Ferguson, Henry C.; Giavalisco, Mauro; Fruchter, Andrew S. +10 more
We use a sample of 42 supernovae detected with the Advanced Camera for Surveys on board the Hubble Space Telescope as part of the Great Observatories Origins Deep Survey to measure the rate of core-collapse supernovae to z~0.7 and Type Ia supernovae to z~1.6. This significantly increases the redshift range at which supernova rates have been estima…