Search Publications
GALEX Far-ultraviolet Color Selection of UV-bright High-redshift Quasars
Worseck, Gábor; Prochaska, J. Xavier
We study the small population of high-redshift (z em>2.7) quasars detected by the Galaxy Evolution Explorer(GALEX), whose far-UV emission is not extinguished by intervening H I Lyman limit systems. These quasars are of particular importance to detect intergalactic He II absorption along their sight lines. We correlate almost all veri…
Discovery of Two Millisecond Pulsars in Fermi Sources with the Nançay Radio Telescope
Abdo, A. A.; Ballet, J.; Camilo, F. +29 more
We report the discovery of two millisecond pulsars in a search for radio pulsations at the positions of Fermi-Large Area Telescope sources with no previously known counterparts, using the Nançay Radio Telescope. The two millisecond pulsars, PSRs J2017+0603 and J2302+4442, have rotational periods of 2.896 and 5.192 ms and are both in binary systems…
Multiphase Gas in Galaxy Halos: The O VI Lyman-limit System toward J1009+0713
Sembach, K. R.; Prochaska, J. X.; Tripp, T. M. +6 more
We have serendipitously detected a strong O VI-bearing Lyman-limit system (LLS) at z abs = 0.3558 toward the quasi-stellar object (QSO) J1009+0713 (z em = 0.456) in our survey of low-redshift galaxy halos with the Hubble Space Telescope's (HST) Cosmic Origins Spectrograph. Its total rest-frame equivalent width of Wr
A Low Escape Fraction of Ionizing Photons of L > L* Lyman Break Galaxies at z = 3.3
Fiore, F.; Castellano, M.; Pentericci, L. +12 more
We present an upper limit for the relative escape fraction (f rel esc) of ionizing radiation at z ~ 3.3 using a sample of 11 Lyman break galaxies (LBGs) with deep imaging in the U band obtained with the Large Binocular Camera, mounted on the prime focus of the Large Binocular Telescope. We selected 11 LBGs with secure redshif…
Chromospheric Jet and Growing "Loop" Observed by Hinode: New Evidence of Fan-spine Magnetic Topology Resulting from Flux Emergence
Liu, Wei; Berger, Thomas E.; Tarbell, Theodore D. +2 more
We present observations of a chromospheric jet and growing "loop" system that show new evidence of a fan-spine topology resulting from magnetic flux emergence. This event, occurring in an equatorial coronal hole on 2007 February 9, was observed by the Hinode Solar Optical Telescope in the Ca II H line in unprecedented detail. The predecessor of th…
Hubble Space Telescope Observations of the Double-peaked Emission Lines in the Seyfert Galaxy Markarian 78: Mass Outflows from a Single Active Galactic Nucleus
Kraemer, S. B.; Crenshaw, D. M.; Schmitt, H. R. +3 more
Previous ground-based observations of the Seyfert 2 galaxy Mrk 78 revealed a double set of emission lines, similar to those seen in several active galactic nuclei (AGNs) from recent surveys. Are the double lines due to two AGNs with different radial velocities in the same galaxy, or are they due to mass outflows from a single AGN? We present a stu…
The Mass-loss Return from Evolved Stars to the Large Magellanic Cloud. IV. Construction and Validation of a Grid of Models for Oxygen-rich AGB Stars, Red Supergiants, and Extreme AGB Stars
Meixner, M.; Sargent, Benjamin A.; Srinivasan, S.
To measure the mass loss from dusty oxygen-rich (O-rich) evolved stars in the Large Magellanic Cloud (LMC), we have constructed a grid of models of spherically symmetric dust shells around stars with constant mass-loss rates using 2Dust. These models will constitute the O-rich model part of the "Grid of Red supergiant and Asymptotic giant branch s…
Population Parameters of Intermediate-age Star Clusters in the Large Magellanic Cloud. III. Dynamical Evidence for a Range of Ages Being Responsible for Extended Main-sequence Turnoffs
Chandar, Rupali; Goudfrooij, Paul; Puzia, Thomas H. +1 more
We present a new analysis of 11 intermediate-age (1-2 Gyr) star clusters in the Large Magellanic Cloud based on Hubble Space Telescope imaging data. Seven of the clusters feature main-sequence turnoff (MSTO) regions that are wider than can be accounted for by a simple stellar population, whereas their red giant branches (RGBs) indicate a single va…
Surface Chemistry and Particle Shape: Processes for the Evolution of Aerosols in Titan's Atmosphere
Lavvas, P.; Sander, M.; Kraft, M. +1 more
We use a stochastic approach in order to investigate the production and evolution of aerosols in Titan's atmosphere. The simulation initiates from the benzene molecules observed in the thermosphere and follows their evolution to larger aromatic structures through reaction with gas-phase radical species. Aromatics are allowed to collide and provide…
Effect of a Dark Matter Halo on the Determination of Black Hole Masses
Gebhardt, Karl; Schulze, Andreas
Stellar dynamical modeling is a powerful method to determine the mass of black holes in quiescent galaxies. However, in previous work the presence of a dark matter halo has been ignored in the modeling. Gebhardt & Thomas in 2009 showed that accounting for a dark matter halo increased the black hole mass of the massive galaxy M87 by a factor of…