Search Publications
M32 Analogs? A Population of Massive Ultra-compact Dwarf and Compact Elliptical Galaxies in Intermediate-redshift Clusters
Bell, Eric F.; Zhang, Yuanyuan
We report the discovery of relatively massive, M32-like ultra compact dwarf (UCD) and compact elliptical (CE) galaxy candidates in 0.2< z< 0.6 massive galaxy clusters imaged by the Cluster Lensing And Supernova survey with Hubble (CLASH) survey. Examining the nearly unresolved objects in the survey, we identify a sample of compact objects co…
Chandra Detection of Intracluster X-Ray sources in Virgo
Liu, Chengze; Peng, Eric W.; Li, Zhiyuan +1 more
We present a survey of X-ray point sources in the nearest and dynamically young galaxy cluster, Virgo, using archival Chandra observations that sample the vicinity of 80 early-type member galaxies. The X-ray source populations at the outskirts of these galaxies are of particular interest. We detect a total of 1046 point sources (excluding galactic…
ALMA Observations of SMM11 Reveal an Extremely Young Protostar in Serpens Main Cluster
Ohashi, Nagayoshi; Tomisaka, Kohji; Yen, Hsi-Wei +8 more
We report the discovery of an extremely young protostar, SMM11, located in the associated submillimeter condensation in the Serpens Main cluster using the Atacama Large Millimeter/submillimeter Array (ALMA) during its Cycle 3 at 1.3 mm and an angular resolution of ∼ 0\buildrel{\prime\prime}\over{.} 5∼ 210 {AU}. SMM11 is a Class 0 protostar without…
Probing Subsurface Flows in NOAA Active Region 12192: Comparison with NOAA 10486
Hill, F.; Tripathy, S. C.; Jain, Kiran
NOAA Active Region (AR) 12192 is the biggest AR observed in solar cycle 24 so far. This was a long-lived AR that survived for four Carrington rotations (CRs) and exhibited several unusual phenomena. We measure the horizontal subsurface flows in this AR in multiple rotations using the ring-diagram technique of local helioseismology and the Global O…
A Spitzer Spectral Atlas of Low-mass Active Galactic Nuclei
Ho, Luis C.; Barth, Aaron J.; Greene, Jenny E. +1 more
We present Spitzer low-resolution Infrared Spectrograph (IRS) spectra (5 µm ≲ λ ≲ 40 µm) of a sample of 41 Type 1 and Type 2 active galactic nuclei (AGNs) with estimated black hole masses of {M}{BH} ≲ {10}6 {M}⊙ , in order to probe the validity of unification models in this mass regime. We find that the…
Testing the Universality of the Stellar IMF with Chandra and HST
Lehmer, B. D.; Hornschemeier, A. E.; Maccarone, T. +8 more
The stellar initial mass function (IMF), which is often assumed to be universal across unresolved stellar populations, has recently been suggested to be “bottom-heavy” for massive ellipticals. In these galaxies, the prevalence of gravity-sensitive absorption lines (e.g., Na I and Ca II) in their near-IR spectra implies an excess of low-mass (m≲ 0.…
Star Formation in the Cluster Merger DLSCL J0916.2+2953
Dawson, W. A.; Lemaux, B. C.; Wittman, D. +3 more
We investigate star formation in DLSCL J0916.2+2953, a dissociative merger of two clusters at z = 0.53 that has progressed {1.1}-0.4+1.3 Gyr since the first pass-through. We attempt to reveal the effects a collision may have had on the evolution of the cluster galaxies by tracing their star formation history. We probe current…
Stagnant Shells in the Vicinity of the Dusty Wolf-Rayet-OB Binary WR 112
Moffat, A. F. J.; Schödel, R.; Ressler, M. E. +3 more
We present high spatial resolution mid-infrared images of the nebula around the late-type carbon-rich Wolf-Rayet (WC)-OB binary system WR 112 taken by the recently upgraded VLT spectrometer and imager for the mid-infrared (VISIR) with the PAH1, Ne ii_2, and Q3 filters. The observations reveal a morphology resembling a series of arc-like filaments …
Gas Sloshing in Abell 2204: Constraining the Properties of the Magnetized Intracluster Medium
Andrade-Santos, Felipe; Jones, Christine; Li, Zhiyuan +2 more
The rich galaxy cluster Abell 2204 exhibits edges in its X-ray surface brightness at ∼65 and 35 {kpc} west and east of its center, respectively. The presence of these edges, which were interpreted as sloshing cold fronts, implies that the intracluster medium (ICM) was recently disturbed. We analyze the properties of the ICM using multiple Chandra …
Isophote Shapes of Early-type Galaxies in Massive Clusters at z ∼ 1 and 0
Perlmutter, Saul; Morokuma, Tomoki; Doi, Mamoru +5 more
We compare the isophote shape parameter a4 of early-type galaxies (ETGs) between z ∼ 1 and 0 as a proxy for dynamics to investigate the epoch at which the dynamical properties of ETGs are established, using cluster ETG samples with stellar masses of {log}({M}* /{M}⊙ )≥slant 10.5 which have spectroscopic redshifts. …