Search Publications
Short GRB 130603B: Discovery of a Jet Break in the Optical and Radio Afterglows, and a Mysterious Late-time X-Ray Excess
Berger, E.; Foley, R. J.; Chornock, R. +13 more
We present radio, optical/NIR, and X-ray observations of the afterglow of the short-duration Swift and Konus-Wind GRB 130603B, and uncover a break in the radio and optical bands at ≈0.5 day after the burst, best explained as a jet break with an inferred jet opening angle of ≈4°-8°. GRB 130603B is only the third short GRB with a radio afterglow det…
Charting the Evolution of the Ages and Metallicities of Massive Galaxies since z = 0.7
Bell, Eric F.; Brinchmann, Jarle; Kelson, Daniel D. +2 more
Detailed studies of the stellar populations of intermediate-redshift galaxies can shed light onto the processes responsible for the growth of the massive galaxy population in the last 8 billion years. We here take a step toward this goal by means of deep, multiobject rest-frame optical spectroscopy, performed with the Inamori Magellan Areal Camera…
Spectroscopic Confirmation of the Rich z = 1.80 Galaxy Cluster JKCS 041 using the WFC3 Grism: Environmental Trends in the Ages and Structure of Quiescent Galaxies
Treu, Tommaso; Trinchieri, Ginevra; Ellis, Richard S. +3 more
We present Hubble Space Telescope imaging and grism spectroscopy in the field of the distant galaxy cluster JKCS 041 using the Wide Field Camera 3. We confirm that JKCS 041 is a rich cluster and derive a redshift z = 1.80 via the spectroscopic identification of 19 member galaxies, of which 15 are quiescent. These are centered upon diffuse X-ray em…
Geometry of Star-forming Galaxies from SDSS, 3D-HST, and CANDELS
Ferguson, H. C.; Giavalisco, M.; Brammer, G. +18 more
We determine the intrinsic, three-dimensional shape distribution of star-forming galaxies at 0 < z < 2.5, as inferred from their observed projected axis ratios. In the present-day universe, star-forming galaxies of all masses 109-1011 M ⊙ are predominantly thin, nearly oblate disks, in line with previous stud…
The Star Formation Histories of Local Group Dwarf Galaxies. II. Searching For Signatures of Reionization
Dolphin, Andrew E.; Skillman, Evan D.; Williams, Benjamin F. +4 more
We search for signatures of reionization in the star formation histories (SFHs) of 38 Local Group dwarf galaxies (104 < M sstarf < 109 M ⊙). The SFHs are derived from color-magnitude diagrams using archival Hubble Space Telescope/Wide Field Planetary Camera 2 imaging. Only five quenched galaxies (A…
Magnetic Fields in Relativistic Collisionless Shocks
Santana, Rodolfo; Barniol Duran, Rodolfo; Kumar, Pawan
We present a systematic study on magnetic fields in gamma-ray burst (GRB) external forward shocks (FSs). There are 60 (35) GRBs in our X-ray (optical) sample, mostly from Swift. We use two methods to study epsilon B (fraction of energy in magnetic field in the FS): (1) for the X-ray sample, we use the constraint that the observed flux …
CANDELS+3D-HST: Compact SFGs at z ~ 2-3, the Progenitors of the First Quiescent Galaxies
Wuyts, S.; Giavalisco, M.; Papovich, C. +34 more
We analyze the star-forming and structural properties of 45 massive (log(M/M ⊙) >10) compact star-forming galaxies (SFGs) at 2 < z < 3 to explore whether they are progenitors of compact quiescent galaxies at z ~ 2. The optical/NIR and far-IR Spitzer/Herschel colors indicate that most compact SFGs are heavily obscured. Nearly ha…
Nuclear Star Formation Activity and Black Hole Accretion in Nearby Seyfert Galaxies
Esquej, P.; Hernán-Caballero, A.; Hönig, S. F. +10 more
Recent theoretical and observational works indicate the presence of a correlation between the star-formation rate (SFR) and active galactic nucleus (AGN) luminosity (and, therefore, the black hole accretion rate, \dot{M}_BH) of Seyfert galaxies. This suggests a physical connection between the gas-forming stars on kpc scales and the gas on sub-pc s…
Power Asymmetry in WMAP and Planck Temperature Sky Maps as Measured by a Local Variance Estimator
Banday, A. J.; Eriksen, H. K.; Górski, K. M. +4 more
We revisit the question of hemispherical power asymmetry in the WMAP and Planck temperature sky maps by measuring the local variance over the sky and on disks of various sizes. For the 2013 Planck sky map we find that none of the 1000 available isotropic Planck "Full Focal Plane" simulations have a larger variance asymmetry than that estimated fro…
HD 106906 b: A Planetary-mass Companion Outside a Massive Debris Disk
Mamajek, Eric; Weinberger, Alycia J.; Reiter, Megan +14 more
We report the discovery of a planetary-mass companion, HD 106906 b, with the new Magellan Adaptive Optics (MagAO) + Clio2 system. The companion is detected with Clio2 in three bands: J, KS , and L', and lies at a projected separation of 7.''1 (650 AU). It is confirmed to be comoving with its 13 ± 2 Myr F5 host using Hubble Space Telesco…