Search Publications
Disentangling Overlapping Astronomical Sources Using Spatial and Spectral Information
van Dyk, David A.; Kashyap, Vinay L.; Jones, David E.
We present a powerful new algorithm that combines both spatial information (event locations and the point-spread function) and spectral information (photon energies) to separate photons from overlapping sources. We use Bayesian statistical methods to simultaneously infer the number of overlapping sources, to probabilistically separate the photons …
The Role of Bulge Formation in the Homogenization of Stellar Populations at z~2 as revealed by Internal Color Dispersion in CANDELS
Giavalisco, M.; Papovich, C.; Koekemoer, A. M. +13 more
We use data from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey to study how the spatial variation in the stellar populations of galaxies relates to the formation of galaxies at 1.5\lt z\lt 3.5. We use the internal color dispersion (ICD), measured between the rest-frame UV and optical bands, which is sensitive to age (and dust …
The Stellar Mass-Halo Mass Relation for Low-mass X-Ray Groups At 0.5< z< 1 in the CDFS With CSI
Kelson, Daniel D.; McCarthy, Patrick J.; Dressler, Alan +4 more
Since z∼ 1, the stellar mass density locked in low-mass groups and clusters has grown by a factor of ∼8. Here, we make the first statistical measurements of the stellar mass content of low-mass X-ray groups at 0.5\lt z\lt 1, enabling the calibration of stellar-to-halo mass scales for wide-field optical and infrared surveys. Groups are selected fro…
Modeling of Hot Plasma in the Solar Active Region Core
Schmelz, J. T.; Pathak, S.; Imada, S. +2 more
Magnetically confined plasma with temperatures ≥slant 5 {MK} are a feature of hot coronal loops observed in the core of active regions. In this paper, using observations and MHD modeling of coronal loops, we investigate whether wave heating (Alternating Current) models can describe the high temperature loops observed in the active region of 2012 S…
Two Candidate Optical Counterparts of M82 X-1 from HST Observations
Liu, Jifeng; Bai, Yu; Wang, Song +1 more
Optical counterparts can provide significant constraints on the physical nature of ultraluminous X-ray sources (ULXs). In this Letter, we identify six point sources in the error circle of a ULX in M82, namely M82 X-1, by registering Chandra positions onto Hubble Space Telescope images. Two objects are considered as optical counterpart candidates o…
Mass and Energy of Erupting Solar Plasma Observed with the X-Ray Telescope on Hinode
Moon, Yong-Jae; Reeves, Katharine K.; Raymond, John C. +2 more
We investigate seven eruptive plasma observations by Hinode/XRT. Their corresponding EUV and/or white light coronal mass ejection features are visible in some events. Five events are observed in several passbands in X-rays, which allows for the determination of the eruptive plasma temperature using a filter ratio method. We find that the isotherma…
The High-velocity System: Infall of a Giant Low-surface-brightness Galaxy toward the Center of the Perseus Cluster
Ohyama, Youichi; Broadhurst, T.; Lim, Jeremy +2 more
The high-velocity system (HVS) lies just north-west of the center and is moving at a speed of 3000 km s-1 toward NGC 1275, the central giant elliptical galaxy in the Perseus cluster. We report imaging spectroscopy of the HVS in Hα and [N ii] that resolves both the nature of this galaxy and its physical relationship with NGC 1275. The HV…
The Young Stellar Object Population in the Vela-D Molecular Cloud
Elia, D.; Pezzuto, S.; Molinari, S. +7 more
We investigate the young stellar population in the Vela Molecular Ridge, Cloud-D, a star-forming region observed by both the Spitzer/NASA and Herschel/ESA space telescopes. The point-source, band-merged, Spitzer-IRAC catalog complemented with MIPS photometry previously obtained is used to search for candidate young stellar objects (YSOs), also inc…
The Evolved Main-sequence Channel: HST and LBT Observations of CSS120422:111127+571239
Szkody, P.; Garnavich, P.; Kennedy, M. +3 more
The “evolved main-sequence (EMS)” channel is thought to contribute significantly to the population of AM CVn-type systems in the Galaxy, and also to the number of cataclysmic variables (CVs) detected below the period minimum for hydrogen rich systems. CSS 120422:J111127+571239 was discovered by the Catalina Sky Survey in 2012 April. Its period was…
LEGUS Discovery of a Light Echo Around Supernova 2012aw
Van Dyk, Schuyler D.; Anderson, Jay; Grebel, Eva K. +9 more
We have discovered a luminous light echo around the normal Type II-Plateau Supernova (SN) 2012aw in Messier 95 (M95; NGC 3351), detected in images obtained approximately two years after explosion with the Wide Field Channel 3 on board the Hubble Space Telescope by the Legacy ExtraGalactic Ultraviolet Survey. The multi-band observations span from t…