Search Publications
Photometric Determination of the Mass Accretion Rates of Pre-main-sequence Stars. I. Method and Application to the SN 1987A Field
Panagia, Nino; De Marchi, Guido; Romaniello, Martino
We have developed and successfully tested a new self-consistent method to reliably identify pre-main-sequence (PMS) objects actively undergoing mass accretion in a resolved stellar population, regardless of their age. The method does not require spectroscopy and combines broadband V and I photometry with narrowband Hα imaging to (1) identify all s…
Dark Matter Search Using Chandra Observations of Willman 1 and a Spectral Feature Consistent with a Decay Line of a 5 keV Sterile Neutrino
Loewenstein, Michael; Kusenko, Alexander
We report the results of a search for an emission line from radiatively decaying dark matter in the Chandra X-ray Observatory spectrum of the ultra-faint dwarf spheroidal galaxy Willman 1. 99% confidence line flux upper limits over the 0.4-7 keV Chandra bandpass are derived and mapped to an allowed region in the sterile neutrino mass-mixing angle …
Kernel Phase in Fizeau Interferometry
Martinache, Frantz
The detection of high contrast companions at small angular separation appears feasible in conventional direct images using the self-calibration properties of interferometric observable quantities. The friendly notion of closure phase, which is key to the recent observational successes of non-redundant aperture masking interferometry used with adap…
MOIRCS Deep Survey. VI. Near-infrared Spectroscopy of K-Selected Star-forming Galaxies at z ~ 2
Koekemoer, Anton M.; Tanaka, Ichi; Yamada, Toru +13 more
We present the results of near-infrared multi-object spectroscopic observations for 37 BzK-color-selected star-forming galaxies conducted with MOIRCS on the Subaru Telescope. The sample is drawn from the Ks -band-selected catalog of the MOIRCS Deep Survey in the GOODS-N region. About half of our samples are selected from the publicly av…
Tidal Disruption, Global Mass Function, and Structural Parameter Evolution in Star Clusters
Vesperini, Enrico; Trenti, Michele; Pasquato, Mario
We present a unified picture for the evolution of star clusters on the two-body relaxation timescale. We use direct N-body simulations of star clusters in a galactic tidal field starting from different multimass King models, up to 10% of primordial binaries and up to N tot = 65, 536 particles. An additional run also includes a central I…
Hubble Space Telescope Far-ultraviolet Observations of Brightest Cluster Galaxies: The Role of Star Formation in Cooling Flows and BCG Evolution
Baum, Stefi A.; O'Dea, Christopher P.; Donahue, Megan +8 more
Quillen et al. and O'Dea et al. carried out a Spitzer study of a sample of 62 brightest cluster galaxies (BCGs) from the ROSAT brightest cluster sample, which were chosen based on their elevated Hα flux. We present Hubble Space Telescope Advanced Camera for Surveys far-ultraviolet (FUV) images of the Lyα and continuum emission of the luminous emis…
A Spectroscopic Search for Leaking Lyman Continuum at z ~ 0.7
Ferguson, Henry C.; Giavalisco, Mauro; Brown, Thomas M. +11 more
We present the results of rest-frame, UV slitless spectroscopic observations of a sample of 32 z ~ 0.7 Lyman break galaxy (LBG) analogs in the COSMOS field. The spectroscopic search was performed with the Solar Blind Channel on the Hubble Space Telescope. We report the detection of leaking Lyman continuum (LyC) radiation from an active galactic nu…
Discovery of a Second Transient Low-Mass X-ray Binary in the Globular Cluster Ngc 6440
Altamirano, D.; Wijnands, R.; Knigge, C. +11 more
We have discovered a new transient low-mass X-ray binary, NGC 6440 X-2, with Chandra/ACIS, RXTE/PCA, and Swift/XRT observations of the globular cluster NGC 6440. The discovery outburst (2009 July 28-31) peaked at LX ~ 1.5 × 1036 erg s-1 and lasted for <4 days above LX = 1035 erg s-1
Multiple Component Outflows in an Active Region Observed with the EUV Imaging Spectrometer on Hinode
Young, P. R.; Doschek, G. A.; Bryans, P.
We have used the Extreme Ultraviolet Imaging Spectrometer on the Hinode spacecraft to observe large areas of outflow near an active region. These outflows are seen to persist for at least 6 days. The emission line profiles suggest that the outflow region is composed of multiple outflowing components, Doppler-shifted with respect to each other. We …
Hot Gas Halos in Early-type Field Galaxies
Mulchaey, John S.; Jeltema, Tesla E.
We use Chandra and XMM-Newton to study the hot gas content in a sample of field early-type galaxies. We find that the L X-L K relationship is steeper for field galaxies than for comparable galaxies in groups and clusters. The low hot gas content of field galaxies with L K lap L sstarf suggests that inter…