Search Publications
The Yellow Supergiant Progenitor of the Type II Supernova 2011dh in M51
Sollerman, J.; Smartt, S. J.; Kotak, R. +11 more
We present the detection of the putative progenitor of the Type IIb SN 2011dh in archival pre-explosion Hubble Space Telescope images. Using post-explosion Adaptive Optics imaging with Gemini NIRI+ALTAIR, the position of the supernova (SN) in the pre-explosion images was determined to within 23 mas. The progenitor candidate is consistent with an F…
On the Evolution of the Molecular Gas Fraction of Star-Forming Galaxies
Smail, Ian; Moran, Sean M.; MacArthur, Lauren A. +3 more
We present IRAM Plateau de Bure interferometric detections of CO (J = 1 → 0) emission from a 24 µm-selected sample of star-forming galaxies at z = 0.4. The galaxies have polycyclic aromatic hydrocarbon 7.7 µm-derived star formation rates of SFR ~30-60 M sun yr-1 and stellar masses M sstarf ~ 1011
Globular Clusters in the Outer Galactic Halo: New Hubble Space Telescope/Advanced Camera for Surveys Imaging of Six Globular Clusters and the Galactic Globular Cluster Age-metallicity Relation
Anderson, Jay; Dotter, Aaron; Sarajedini, Ata
Color-magnitude diagrams (CMDs) derived from Hubble Space Telescope (HST) Advanced Camera for Surveys F606W, F814W photometry of six globular clusters (GCs) are presented. The six GCs form two loose groupings in Galactocentric distance (R GC): IC 4499, NGC 6426, and Ruprecht 106 at ~15-20 kpc and NGC 7006, Palomar 15, and Pyxis at ~40 k…
Observing Flux Rope Formation During the Impulsive Phase of a Solar Eruption
Liu, Y.; Cheng, X.; Ding, M. D. +1 more
Magnetic flux ropes are believed to be an important structural component of coronal mass ejections (CMEs). While there exists much observational evidence of flux ropes after the eruption, e.g., as seen in remote-sensing coronagraph images or in situ solar wind data, the direct observation of flux ropes during CME impulsive phase has been rare. In …
What Drives the Expansion of Giant H II Regions?: A Study of Stellar Feedback in 30 Doradus
Ramirez-Ruiz, Enrico; Prochaska, J. Xavier; Bolatto, Alberto D. +2 more
Observations show that star formation is an inefficient and slow process. This result can be attributed to the injection of energy and momentum by stars that prevents free-fall collapse of molecular clouds. The mechanism of this stellar feedback is debated theoretically; possible sources of pressure include the classical warm H II gas, the hot gas…
Sizes and Temperature Profiles of Quasar Accretion Disks from Chromatic Microlensing
Schechter, Paul L.; Pooley, David; Blackburne, Jeffrey A. +1 more
Microlensing perturbations to the flux ratios of gravitationally lensed quasar images can vary with wavelength because of the chromatic dependence of the accretion disk's apparent size. Multiwavelength observations of microlensed quasars can thus constrain the temperature profiles of their accretion disks, a fundamental test of an important astrop…
Testing the Unification Model for Active Galactic Nuclei in the Infrared: Are the Obscuring Tori of Type 1 and 2 Seyferts Different?
Pérez García, A. M.; Díaz-Santos, T.; Packham, C. +7 more
We present new mid-infrared imaging data for three Type-1 Seyfert galaxies obtained with T-ReCS on the Gemini-South Telescope at subarcsecond resolution. Our aim is to enlarge the sample studied in a previous work to compare the properties of Type-1 and Type-2 Seyfert tori using clumpy torus models and a Bayesian approach to fit the infrared (IR) …
The Spin of the Supermassive Black Hole in NGC 3783
Nandra, K.; Iwasawa, K.; Fabian, A. C. +9 more
The Suzaku AGN Spin Survey is designed to determine the supermassive black hole spin in six nearby active galactic nuclei (AGNs) via deep Suzaku stares, thereby giving us our first glimpse of the local black hole spin distribution. Here, we present an analysis of the first target to be studied under the auspices of this Key Project, the Seyfert ga…
Pan-STARRS1 Discovery of Two Ultraluminous Supernovae at z ≈ 0.9
Price, P. A.; Berger, E.; Kirshner, R. P. +29 more
We present the discovery of two ultraluminous supernovae (SNe) at z ≈ 0.9 with the Pan-STARRS1 Medium Deep Survey. These SNe, PS1-10ky and PS1-10awh, are among the most luminous SNe ever discovered, comparable to the unusual transients SN 2005ap and SCP 06F6. Like SN 2005ap and SCP 06F6, they show characteristic high luminosities (M bol…
The Impact of Galaxy Interactions on Active Galactic Nucleus Activity in zCOSMOS
Finoguenov, A.; Jahnke, K.; Silverman, J. D. +52 more
Close encounters between galaxies are expected to be a viable mechanism, as predicted by numerical simulations, by which accretion onto supermassive black holes can be initiated. To test this scenario, we construct a sample of 562 galaxies (M * > 2.5 × 1010 M ⊙) in kinematic pairs over the redshift range 0.25 &l…