Search Publications
Coronal Rain as a Marker for Coronal Heating Mechanisms
Shibata, K.; Vissers, G.; Antolin, P.
Reported observations in Hα, Ca II H, and K or other chromospheric lines of coronal rain trace back to the days of the Skylab mission. Corresponding to cool and dense plasma, coronal rain is often observed falling down along coronal loops in active regions. A physical explanation for this spectacular phenomenon has been put forward thanks to numer…
Keck Spectroscopy of z > 1 Field Spheroidals: Dynamical Constraints on the Growth Rate of Red "Nuggets"
Treu, Tommaso; Ellis, Richard S.; Newman, Andrew B. +1 more
We present deep Keck spectroscopy for 17 morphologically selected field spheroidals in the redshift range 1.05 < z < 1.60 in order to investigate the continuity in physical properties between the claimed massive compact red galaxies ("nuggets") at z ~= 2 and well-established data for massive spheroidal galaxies below z ~= 1. By combining Kec…
A Deep Chandra X-Ray Spectrum of the Accreting Young Star TW Hydrae
Luna, G. J. M.; Cranmer, S. R.; Dupree, A. K. +2 more
We present X-ray spectral analysis of the accreting young star TW Hydrae from a 489 ks observation using the Chandra High Energy Transmission Grating. The spectrum provides a rich set of diagnostics for electron temperature Te , electron density Ne , hydrogen column density NH , relative elemental abundances, and v…
The Estimation of Star Formation Rates and Stellar Population Ages of High-redshift Galaxies from Broadband Photometry
Ferguson, Henry C.; Giavalisco, Mauro; Somerville, Rachel S. +2 more
We explore methods to improve the estimates of star formation rates and mean stellar population ages from broadband photometry of high-redshift star-forming galaxies. We use synthetic spectral templates with a variety of simple parametric star formation histories to fit broadband spectral energy distributions. These parametric models are used to i…
The Atacama Cosmology Telescope: Physical Properties and Purity of a Galaxy Cluster Sample Selected via the Sunyaev-Zel'dovich Effect
Hilton, Matt; Hasselfield, Matthew; Bond, J. Richard +48 more
We present optical and X-ray properties for the first confirmed galaxy cluster sample selected by the Sunyaev-Zel'dovich effect (SZE) from 148 GHz maps over 455 deg2 of sky made with the Atacama Cosmology Telescope (ACT). These maps, coupled with multi-band imaging on 4 m class optical telescopes, have yielded a sample of 23 galaxy clus…
Observational Evidence of Back Reaction on the Solar Surface Associated with Coronal Magnetic Restructuring in Solar Eruptions
Liu, Chang; Wang, Haimin
Most models of solar eruptions assume that coronal field lines are anchored in the dense photosphere and thus the photospheric magnetic fields would not have rapid, irreversible changes associated with eruptions resulted from the coronal magnetic reconnection. Motivated by the recent work of Hudson et al. on quantitatively evaluating the back reac…
Halo Gas and Galaxy Disk Kinematics Derived from Observations and ΛCDM Simulations of Mg II Absorption-selected Galaxies at Intermediate Redshift
Kacprzak, Glenn G.; Steidel, Charles C.; Churchill, Christopher W. +3 more
We obtained ESI/Keck rotation curves of 10 Mg II absorption-selected galaxies (0.3 <= z <= 1.0) for which we have WFPC-2/HST images and high-resolution HIRES/Keck and UVES/VLT quasar spectra of the Mg II absorption profiles. We perform a kinematic comparison of these galaxies and their associated halo Mg II absorption. For all 10 galaxies, t…
New Density Profile and Structural Parameters of the Complex Stellar System Terzan 5
Dalessandro, E.; Ransom, S. M.; Valenti, E. +9 more
Terzan 5 is a globular cluster-like stellar system in the Galactic bulge which has been recently found to harbor two stellar populations with different iron content and probably different ages. This discovery suggests that Terzan 5 may be the relic of a primordial building block that contributed to the formation of the Galactic bulge. Here we pres…
AMUSE-Virgo. II. Down-sizing in Black Hole Accretion
Treu, Tommaso; Marshall, Philip J.; Antonucci, Robert +3 more
We complete the census of nuclear X-ray activity in 100 early-type Virgo galaxies observed by the Chandra X-ray Telescope as part of the AMUSE-Virgo survey, down to a (3σ) limiting luminosity of 3.7 × 1038 erg s-1 over 0.5-7 keV. The stellar mass distribution of the targeted sample, which is mostly composed of formally "inact…
Cosmic Evolution of Black Holes and Spheroids. IV. The M BH-L sph Relation
Treu, Tommaso; Auger, Matthew W.; Malkan, Matthew A. +5 more
From high-resolution images of 23 Seyfert-1 galaxies at z = 0.36 and z = 0.57 obtained with the Near-Infrared Camera and Multi-Object Spectrometer on board the Hubble Space Telescope (HST), we determine host-galaxy morphology, nuclear luminosity, total host-galaxy luminosity, and spheroid luminosity. Keck spectroscopy is used to estimate black hol…