Search Publications
IC 3599 Did It Again: A Second Outburst of the X-Ray Transient Seyfert 1.9 Galaxy
Komossa, S.; Saxton, Richard; Grupe, Dirk
We report on the Swift discovery of a second high-amplitude (factor 100) outburst of the Seyfert 1.9 galaxy IC 3599, and discuss implications for outburst scenarios. Swift detected this active galactic nucleus (AGN) again in 2010 February in X-rays at a level of (1.50 ± 0.11) × {{10}36} W (0.2-2.0 keV), which is nearly as luminous as th…
The Origin of the Spurious Iron Spread in the Globular Cluster NGC 3201
Massari, D.; Mucciarelli, A.; Ferraro, F. R. +2 more
NGC 3201 is a globular cluster suspected to have an intrinsic spread in the iron content. We re-analyzed a sample of 21 cluster stars observed with UVES-FLAMES at the Very Large Telescope and for which Simmerer et al. found a 0.4 dex wide [Fe/H] distribution with a metal-poor tail. We confirmed that when spectroscopic gravities are adopted, the de…
CME Propagation: Where does Aerodynamic Drag 'Take Over'?
Vourlidas, Angelos; Subramanian, Prasad; Sachdeva, Nishtha +1 more
We investigate the Sun-Earth dynamics of a set of eight well observed solar coronal mass ejections (CMEs) using data from the Solar Terrestrial Relations Observatory spacecraft. We seek to quantify the extent to which momentum coupling between these CMEs and the ambient solar wind (i.e., the aerodynamic drag) influences their dynamics. To this end…
The Link between the Formation Rates of Clusters and Stars in Galaxies
Whitmore, Bradley C.; Fall, S. Michael; Chandar, Rupali
The goal of this paper is to test whether the formation rate of star clusters is proportional to the star formation rate (SFR) in galaxies. As a first step, we present the mass functions of compact clusters younger than 10 Myr in seven star-forming galaxies of diverse masses, sizes, and morphologies: the Large and Small Magellanic Clouds, NGC 4214…
Probing the Dark Flow Signal in WMAP 9 -Year and Planck Cosmic Microwave Background Maps
Kocevski, D.; Atrio-Barandela, F.; Ebeling, H. +2 more
The “dark flow” dipole is a statistically significant dipole found at the position of galaxy clusters in filtered maps of Cosmic Microwave Background (CMB) temperature anisotropies. The dipole measured in WMAP 3-, 5-, and 7- year data releases was (1) mutually consistent, (2) roughly aligned with the all-sky CMB dipole, and (3) correlated with clu…
Galaxy Cluster Scaling Relations between Bolocam Sunyaev-Zel'dovich Effect and Chandra X-Ray Measurements
Pierpaoli, E.; Moustakas, L. A.; Umetsu, K. +11 more
We present scaling relations between the integrated Sunyaev-Zel’dovich effect (SZE) signal, {{Y}SZ}, its X-ray analogue, {{Y}X} ≡ {{M}gas} {{T}X}, and total mass, {{M}tot}, for the 45 galaxy clusters in the Bolocam X-ray SZ (BOXSZ) sample. All parameters are integrated within {{r}2500
Bicep2 III: Instrumental Systematics
Ade, P. A. R.; Bock, J. J.; Hildebrandt, S. R. +42 more
In a companion paper, we have reported a >5σ detection of degree scale B-mode polarization at 150 GHz by the Bicep2 experiment. Here we provide a detailed study of potential instrumental systematic contamination to that measurement. We focus extensively on spurious polarization that can potentially arise from beam imperfections. We present a he…
Radial Distributions of Sub-Populations in the Globular Cluster M15: A More Centrally Concentrated Primordial Population
Brodie, Jean P.; Strader, Jay; Larsen, Søren S. +3 more
We examine the radial distributions of stellar populations in the globular cluster (GC) M15, using Hubble Space Telescope/Wide Field Camera 3 (WFC3) photometry of red giants in the nitrogen-sensitive F343N-F555W color. Surprisingly, we find that giants with “primordial” composition (i.e., N abundances similar to those in field stars) are the most …
What Are Little Worlds Made Of? Stellar Abundances and the Building Blocks of Planets
Gaidos, Eric
If the photospheres of solar-type stars represent the composition of circumstellar disks from which any planets formed, spectroscopic determinations of stellar elemental abundances offer information on the composition of those planets, including smaller, rocky planets. In particular, the C/O ratio is proposed to be a key determinant of the composi…
Hubble Space Telescope Observations of Sub-damped Lyα Absorbers at z < 0.5, and Implications for Galaxy Chemical Evolution
York, Donald G.; Kulkarni, Varsha P.; Lauroesch, James T. +5 more
We report observations of four sub-damped Lyα (sub-DLA) quasar absorbers at z\lt 0.5 obtained with the Hubble Space Telescope Cosmic Origins Spectrograph. We measure the available neutrals or ions of C, N, O, Si, P, S, Ar, Mn, Fe, and/or Ni. Our data have doubled the sub-DLA metallicity samples at z\lt 0.5 and improved constraints on sub-DLA chemi…