Astrophysics - Cosmology and Nongalactic Astrophysics

Late-time Radio Emission from X-Ray-selected Tidal Disruption Events

We present new observations with the Karl G. Jansky Very Large Array of seven X-ray-selected tidal disruption events (TDEs). The radio observations were carried out between 9 and 22 years after the initial X-ray discovery, and thus probe the …

Discovery and Early Multi-wavelength Measurements of the Energetic Type Ic Supernova PTF12gzk: A Massive-star Explosion in a Dwarf Host Galaxy

We present the discovery and extensive early-time observations of the Type Ic supernova (SN) PTF12gzk. Our light curves show a rise of 0.8 mag within 2.5 hr. Power-law fits (f(t)vprop(t - t $_0$)$^ n $) to these data constrain the explosion date to …

Automating Discovery and Classification of Transients and Variable Stars in the Synoptic Survey Era

The rate of image acquisition in modern synoptic imaging surveys has already begun to outpace the feasibility of keeping astronomers in the real-time discovery and classification loop. Here we present the inner workings of a framework, based on …

An empirical relation between sodium absorption and dust extinction

Dust extinction and reddening are ubiquitous in astronomical observations and are often a major source of systematic uncertainty. We present here a study of the correlation between extinction in the Milky Way and the equivalent width of the Na I D …

Berkeley Supernova Ia Program - I. Observations, data reduction and spectroscopic sample of 582 low-redshift Type Ia supernovae

In this first paper in a series, we present 1298 low-redshift (z łesssim 0.2) optical spectra of 582 Type Ia supernovae (SNe Ia) observed from 1989 to 2008 as part of the Berkeley Supernova Ia Program (BSNIP). 584 spectra of 199 SNe Ia have …

Calcium-rich Gap Transients in the Remote Outskirts of Galaxies

From the first two seasons of the Palomar Transient Factory, we identify three peculiar transients (PTF 09dav, PTF 10iuv, and PTF 11bij) with five distinguishing characteristics: peak luminosity in the gap between novae and supernovae (M$_R$ ≈ -15.5 …

PTF 11kx: A Type Ia Supernova with a Symbiotic Nova Progenitor

There is a consensus that type Ia supernovae (SNe Ia) arise from the thermonuclear explosion of white dwarf stars that accrete matter from a binary companion. However, direct observation of SN Ia progenitors is lacking, and the precise nature of the …

Analysis of the Early-time Optical Spectra of SN 2011fe in M101

The nearby Type Ia supernova (SN Ia) SN 2011fe in M101 (cz = 241 km s$^-1$) provides a unique opportunity to study the early evolution of a ``normal'' SN Ia, its compositional structure, and its elusive progenitor system. We present 18 high …

Evidence for a Compact Wolf-Rayet Progenitor for the Type Ic Supernova PTF 10vgv

We present the discovery of PTF 10vgv, a Type Ic supernova (SN) detected by the Palomar Transient Factory, using the Palomar 48 inch telescope (P48). R-band observations of the PTF 10vgv field with P48 probe the SN emission from its very early phases …

The dark GRB 080207 in an extremely red host and the implications for gamma-ray bursts in highly obscured environments

We present comprehensive X-ray, optical, near- and mid-infrared and submm observations of GRB 080207 and its host galaxy. The afterglow was undetected in the optical and near-infrared (nIR) implying an X-ray-to-optical spectral slope less than 0.3, …