Search Publications
The Gas Dynamics of NGC 4472 Revealed by XMM-Newton
Hardcastle, M. J.; Sivakoff, G. R.; Sarazin, C. L. +6 more
We present results from a 100 ks XMM-Newton observation of the hot gas in the Virgo cluster elliptical galaxy NGC 4472. We find a surface brightness discontinuity ~21 kpc north of the nucleus, consistent with being a contact discontinuity between two moving fluids. We also detect a >60 kpc long ram-pressure stripped tail. The pressure across th…
The Far-ultraviolet "Continuum" in Protoplanetary Disk Systems. II. Carbon Monoxide Fourth Positive Emission and Absorption
Herczeg, Gregory J.; Valenti, Jeff A.; Harper, Graham M. +21 more
We exploit the high sensitivity and moderate spectral resolution of the Hubble Space Telescope Cosmic Origins Spectrograph to detect far-ultraviolet (UV) spectral features of carbon monoxide (CO) present in the inner regions of protoplanetary disks for the first time. We present spectra of the classical T Tauri stars HN Tau, RECX-11, and V4046 Sgr…
Discovery of Strong Iron Kα Emitting Compton Thick Quasars at z = 2.5 and 2.9
Daddi, E.; Alexander, D. M.; Fiore, F. +3 more
We report the detection of the 6.4 keV iron Kα emission line in two infrared-luminous, massive, star-forming BzK galaxies at z = 2.578 and z = 2.90 in the CDF-S. The Chandra 4 Ms spectra of BzK 4892 and BzK 8608 show a reflection-dominated continuum with strong iron lines, with rest-frame equivalent widths EW ~ 2.3 keV and 1.2 keV, respectively, d…
The Effect of Helium-enhanced Stellar Populations on the Ultraviolet-upturn Phenomenon of Early-type Galaxies
Chung, Chul; Yoon, Suk-Jin; Lee, Young-Wook
Recent observations and modeling of globular clusters (GCs) with multiple populations strongly indicate the presence of super-helium-rich subpopulations in old stellar systems. Motivated by this, we have constructed new population synthesis models with and without helium-enhanced subpopulations to investigate their impact on the UV-upturn phenomen…
What do Spectral Line Profile Asymmetries Tell us About the Solar Atmosphere?
Martínez-Sykora, Juan; De Pontieu, Bart; Hansteen, Viggo +1 more
Recently, analysis of solar spectra obtained with the EUV Imaging Spectrograph (EIS) onboard the Hinode satellite has revealed the ubiquitous presence of asymmetries in transition region (TR) and coronal spectral line profiles. These asymmetries have been observed especially at the footpoints of coronal loops and have been associated with strong u…
Probing the GC-LMXB Connection in NGC 1399: A Wide-field Study with the Hubble Space Telescope and Chandra
Kundu, Arunav; Zepf, Stephen E.; Maccarone, Thomas J. +5 more
We present a wide-field study of the globular cluster (GC)/low-mass X-ray binary (LMXB) connection in the giant elliptical NGC 1399. The large field of view of the Advanced Camera for Surveys/WFC, combined with Hubble Space Telescope and Chandra high resolution, allow us to constrain the LMXB formation scenarios in elliptical galaxies. We confirm …
Nonlinear Color-Metallicity Relations of Globular Clusters. III. On the Discrepancy in Metallicity between Globular Cluster Systems and Their Parent Elliptical Galaxies
Peng, Eric W.; Blakeslee, John P.; Sohn, Sangmo T. +7 more
One of the conundrums in extragalactic astronomy is the discrepancy in observed metallicity distribution functions (MDFs) between the two prime stellar components of early-type galaxies—globular clusters (GCs) and halo field stars. This is generally taken as evidence of highly decoupled evolutionary histories between GC systems and their parent ga…
The Photometric and Spectral Evolution of the 2008 Luminous Optical Transient in NGC 300
Walter, Frederick M.; Bond, Howard E.; Humphreys, Roberta M. +5 more
The 2008 optical transient in NGC 300 is one of a growing class of intermediate-luminosity transients that brighten several orders of magnitude from a previously optically obscured state. The origin of their eruptions is not understood. Our multi-wavelength photometry and spectroscopy from maximum light to more than a year later provide a record o…
Four IRAC Sources with an Extremely Red H - [3.6] Color: Passive or Dusty Galaxies at z > 4.5?
Wang, T.; Rigopoulou, D.; Fazio, G. G. +3 more
We report the detection of four IRAC sources in the GOODS-South field with an extremely red color of H - [3.6] > 4.5. The four sources are not detected in the deep Hubble Space Telescope WFC3 H-band image with H limit = 28.3 mag. We find that only three types of SED templates can produce such a red H - [3.6] color: a very dusty SED w…
A Powerful AGN Outburst in RBS 797
McNamara, B. R.; Nulsen, P. E. J.; Gitti, M. +4 more
Utilizing ~50 ks of Chandra X-Ray Observatory imaging, we present an analysis of the intracluster medium (ICM) and cavity system in the galaxy cluster RBS 797. In addition to the two previously known cavities in the cluster core, the new and deeper X-ray image has revealed additional structure associated with the active galactic nucleus (AGN). The…