Search Publications
The Hubble Diagram to Redshift >6 from 69 Gamma-Ray Bursts
Schaefer, Bradley E.
One of the few ways to measure the properties of dark energy is to extend the Hubble diagram (HD) to higher redshifts with gamma-ray bursts (GRBs). GRBs have at least five properties (their spectral lag, variability, spectral peak photon energy, time of the jet break, and the minimum rise time) that have correlations to the luminosity of varying q…
The X-Ray Properties of the Most Luminous Quasars from the Sloan Digital Sky Survey
Brandt, W. N.; Garmire, G. P.; Chartas, G. +4 more
Utilizing 21 new Chandra observations as well as archival Chandra, ROSAT, and XMM-Newton data, we study the X-ray properties of a representative sample of 59 of the most optically luminous quasars in the universe (Mi~-29.3 to -30.2) spanning a redshift range of z~1.5-4.5. Our full sample consists of 32 quasars from the Sloan Digital Sky…
What Do We Learn from IRAC Observations of Galaxies at 2 < z < 3.5?
van Dokkum, Pieter G.; Franx, Marijn; Labbé, Ivo +9 more
We analyze very deep HST, VLT, and Spitzer photometry of galaxies at 2<z<3.5 in the Hubble Deep Field-South. The sample is selected from the deepest public K-band imaging currently available. We show that the rest-frame U-V versus V-J color-color diagram is a powerful diagnostic of the stellar populations of distant galaxies. Galaxies with r…
Tip of the Red Giant Branch Distances. II. Zero-Point Calibration
Dolphin, Andrew E.; Shaya, Edward J.; Tully, R. Brent +4 more
The luminosity of the tip of the red giant branch (TRGB) provides an excellent measure of galaxy distances and is easily determined in the resolved images of nearby galaxies observed with Hubble Space Telescope. There is now a large amount of archival data that are relevant to the TRGB methodology and offer comparisons with other distance estimato…
Resolved Galaxies in the Hubble Ultra Deep Field: Star Formation in Disks at High Redshift
Ravindranath, Swara; Elmegreen, Bruce G.; Elmegreen, Debra Meloy +1 more
The photometric redshift distributions, spectral types, Sérsic indices, and sizes of all resolved galaxies in the Hubble Space Telescope Ultra Deep Field (UDF) are studied in order to understand the environment and nature of star formation in the early universe. Clumpy disk galaxies that are bright at short wavelengths (rest-frame λ<5000 Å) dom…
The Infrared Luminosity Function of Galaxies at Redshifts z = 1 and z ~ 2 in the GOODS Fields
Le Floc'h, E.; Dole, H.; Helou, G. +6 more
We present the rest-frame 8 µm LF at redshifts z=1 and ~2, computed from Spitzer 24 µm-selected galaxies in the GOODS fields over an area of 291 arcmin2. Using classification criteria based on X-ray data and IRAC colors, we identify the AGNs in our sample. The rest-frame 8 µm LFs for star-forming galaxies at redshifts …
A Characteristic Magnetic Field Pattern Associated with All Major Solar Flares and Its Use in Flare Forecasting
Schrijver, Carolus J.
Solar flares result from some electromagnetic instability that occurs within regions of relatively strong magnetic field in the Sun's atmosphere. The processes that enable and trigger these flares remain topics of intense study and debate. I analyze observations of 289 X- and M-class flares and over 2500 active region magnetograms to discover (1) …
Combining Strong and Weak Gravitational Lensing in Abell 1689
Richard, Johan; Smith, Graham P.; Smail, Ian +14 more
We present a reconstruction of the mass distribution of galaxy cluster Abell 1689 at z=0.18 using detected strong lensing features from deep ACS observations and extensive ground based spectroscopy. Earlier analyses have reported up to 32 multiply imaged systems in this cluster, of which only 3 were spectroscopically confirmed. In this work, we pr…
On the Progenitor of SN 2005gl and the Nature of Type IIn Supernovae
Cenko, S. B.; Filippenko, Alexei V.; Aldering, G. +9 more
We present a study of the Type IIn supernova (SN) 2005gl, in the relatively nearby (d~66 Mpc) galaxy NGC 266. Photometry and spectroscopy of the SN indicate that it is a typical member of its class. Pre-explosion Hubble Space Telescope (HST) imaging of the location of the SN, along with a precise localization of this event using the laser guide st…
A Complete Sample of 12 Very X-Ray Luminous Galaxy Clusters at z > 0.5
Edge, A. C.; Ebeling, H.; Ma, C. -J. +3 more
We present the statistically complete and cosmologically most relevant subset of the 12 most distant galaxy clusters detected at z>0.5 by the Massive Cluster Survey (MACS). Ten of these systems are new discoveries; only two (MACS J0018.5+1626, aka Cl 0016+1609, and MACS J0454.1-0300, aka MS 0451.6-0305) were previously known. We provide fundame…