Search Publications
The Megasecond Chandra X-Ray Visionary Project Observation of NGC 3115: Witnessing the Flow of Hot Gas within the Bondi Radius
Bregman, Joel N.; Wong, Ka-Wah; Irwin, Jimmy A. +3 more
Observational confirmation of hot accretion model predictions has been hindered by the challenge to resolve spatially the Bondi radii of black holes with X-ray telescopes. Here, we use the Megasecond Chandra X-ray Visionary Project observation of the NGC 3115 supermassive black hole to place the first direct observational constraints on the spatia…
Neutral interstellar He parameters in front of the heliosphere 1994-2007
Bzowski, M.; Witte, M.; Banaszkiewicz, M. +3 more
Context. A recent analysis of IBEX measurements of the neutral interstellar He flux showed that the inflow velocity vector is different from the results of an earlier analysis of observations from the GAS instrument onboard Ulysses. A recently published compilation of published results on the helium inflow direction from the past ~40 years suggest…
Herschel-ATLAS: properties of dusty massive galaxies at low and high redshifts
Smail, I.; Ivison, R. J.; Ibar, E. +16 more
We present a comparison of the physical properties of a rest-frame 250-µm-selected sample of massive, dusty galaxies from 0 < z < 5.3. Our sample comprises 29 high-redshift submillimetre galaxies (SMGs) from the literature and 843 dusty galaxies at z < 0.5 from the Herschel-Astrophysical TeraHertz Large Area Survey (H-ATLAS), select…
On the lack of X-ray bright Type IIP supernovae
Dwarkadas, V. V.
Type IIP supernovae (SNe) are expected to arise from red supergiant stars (RSGs). These stars have observed mass-loss rates that span more than two orders of magnitude, from less than 10^{-6} M_{⊙} yr-1 to almost 10^{-4} M_{⊙} yr-1. Thermal bremsstrahlung X-ray emission from at least some IIPs should reflect the larger end of…
Hubble Space Telescope and Ground-based Observations of the Type Iax Supernovae SN 2005hk and SN 2008A
Filippenko, Alexei V.; Schneider, Donald P.; Foley, Ryan J. +24 more
We present Hubble Space Telescope (HST) and ground-based optical and near-infrared observations of SN 2005hk and SN 2008A, typical members of the Type Iax class of supernovae (SNe). Here we focus on late-time observations, where these objects deviate most dramatically from all other SN types. Instead of the dominant nebular emission lines that are…
A search for flares and mass ejections on young late-type stars in the open cluster Blanco-1
Lammer, H.; Guenther, E. W.; Khodachenko, M. L. +5 more
We present a search for stellar activity (flares and mass ejections) in a sample of 28 stars in the young open cluster Blanco-1. We use optical spectra obtained with European Southern Observatory's Visible Multi-Object Spectrograph installed on the Very Large Telescope. From the total observing time of ∼5 h, we find four Hα flares but no distinct …
Extended [C II] Emission in Local Luminous Infrared Galaxies
Elbaz, D.; Veilleux, S.; Sanders, D. B. +20 more
We present Herschel/PACS observations of extended [C II] 157.7 µm line emission detected on ~1-10 kpc scales in 60 local luminous infrared galaxies (LIRGs) from the Great Observatories All-sky LIRG Survey. We find that most of the extra-nuclear emission show [C II]/FIR ratios >=4 × 10-3, larger than the mean ratio seen in the n…
Cosmological constraints on neutrinos after BICEP2
Zhang, Jing-Fei; Zhang, Xin; Li, Yun-He
Since the B-mode polarization of the cosmic microwave background (CMB) was detected by the BICEP2 experiment and an unexpectedly large tensor-to-scalar ratio,
Predicted Space Motions for Hypervelocity and Runaway Stars: Proper Motions and Radial Velocities for the Gaia Era
Geller, Margaret J.; Brown, Warren R.; Kenyon, Scott J. +1 more
We predict the distinctive three-dimensional space motions of hypervelocity stars (HVSs) and runaway stars moving in a realistic Galactic potential. For nearby stars with distances less than 10 kpc, unbound stars are rare; proper motions alone rarely isolate bound HVSs and runaways from indigenous halo stars. At large distances of 20-100 kpc, unbo…
The Knotted Sky II: does BICEP2 require a nontrivial primordial power spectrum?
Aslanyan, Grigor; Easther, Richard; Price, Layne C. +1 more
An inflationary gravitational wave background consistent with BICEP2 is difficult to reconcile with a simple power-law spectrum of primordial scalar perturbations. Tensor modes contribute to the temperature anisotropies at multipoles with l≲ 100, and this effect - together with a prior on the form of the scalar perturbations - was the source of pr…