Search Publications
Where the Blue Stragglers Roam: Searching for a Link between Formation and Environment
Sills, Alison; Knigge, Christian; Leigh, Nathan
The formation of blue stragglers is still not completely understood, particularly the relationship between formation environment and mechanism. We use a large, homogeneous sample of blue stragglers in the cores of 57 globular clusters to investigate the relationships between blue straggler populations and their environments. We use a consistent de…
The Stellar Population of Lyα-emitting Galaxies at z ~ 5.7
Cowie, Lennox L.; Huang, Jia-Sheng; Hu, Esther M. +3 more
We present a study of three Lyα-emitting galaxies (LAEs), selected via a narrowband survey in the GOODS northern field and spectroscopically confirmed to have redshifts of z~5.65. Using HST ACS and Spitzer IRAC data, we constrain the rest-frame UV-to-optical spectral energy distributions (SEDs) of the galaxies. Fitting stellar population synthesis…
A More Fundamental Plane
Treu, Tommaso; Koopmans, Léon V. E.; Bolton, Adam S. +2 more
We combine strong-lensing masses with SDSS stellar velocity dispersions and HST ACS effective (half-light) radii for 36 lens galaxies from the Sloan Lens ACS (SLACS) Survey to study the mass dependence of mass-dynamical structure in early-type galaxies. We find that over a 180-390 km s-1 range in velocity dispersion, structure is indepe…
Old and Young Bulges in Late-Type Disk Galaxies
Carollo, C. M.; Scarlata, C.; Stiavelli, M. +2 more
We use HST ACS and NICMOS imaging to study the inner B-I and I-H colors of nine late-type spiral galaxies, which we interpret on the basis of different star formation histories. The colors and scale lengths of the bulges of these late-type systems are correlated with those of the disks in which they are embedded. We find that in about half of the …
On the Formation of Filament Channels
Wang, Y. -M.; Muglach, K.
From the Hα archive of the Big Bear Solar Observatory (BBSO) we have selected three examples showing fibril structures that change their orientation, over 1 or 2 days, from nearly perpendicular to nearly parallel to the polarity inversion line (PIL). In one case, the filament channel forms within a single decaying bipole; in the other two cases, i…
The Black Hole Mass of NGC 4151: Comparison of Reverberation Mapping and Stellar Dynamical Measurements
Peterson, Bradley M.; Heckman, Timothy M.; Pogge, Richard W. +11 more
We present a stellar dynamical estimate of the black hole (BH) mass in the Seyfert 1 galaxy, NGC 4151. We analyze ground-based spectroscopy as well as imaging data from the ground and space, and we construct three-integral axisymmetric models in order to constrain the BH mass and mass-to-light ratio. The dynamical models depend on the assumed incl…
Structure and Dynamics of the Sun's Open Magnetic Field
Antiochos, S. K.; Mikić, Z.; DeVore, C. R. +1 more
The solar magnetic field is the primary agent that drives solar activity and couples the Sun to the heliosphere. Although the details of this coupling depend on the quantitative properties of the field, many important aspects of the corona-solar wind connection can be understood by considering only the general topological properties of those regio…
Resolving the Unresolved Cosmic X-Ray Background in the Chandra Deep Fields
Hickox, Ryan C.; Markevitch, Maxim
We present a measurement of the surface brightness of the cosmic X-ray background (CXB) in the Chandra Deep Fields, after excluding all detected X-ray, optical, and infrared sources. The work is motivated by a recent X-ray stacking analysis by Worsley and collaborators, which showed that galaxies detected by HST but not by Chandra may account for …
On the Putative Detection of z > 0 X-Ray Absorption Features in the Spectrum of Mrk 421
Rasmussen, Andrew P.; Kahn, Steven M.; Paerels, Frits +3 more
In a series of papers, Nicastro et al. have reported the detection of z>0 O VII absorption features in the spectrum of Mrk 421 obtained with the Chandra Low Energy Transmission Grating Spectrometer (LETGS). We evaluate this result in the context of a high-quality spectrum of the same source obtained with the Reflection Grating Spectrometer (RGS…
The Evolution of the Field and Cluster Morphology-Density Relation for Mass-Selected Samples of Galaxies
Kelson, D. D.; Wuyts, S.; Ford, H. C. +7 more
The Sloan Digital Sky Survey (SDSS) and photometric/spectroscopic surveys in the GOODS-South field (the Chandra Deep Field-South, CDF-S) are used to construct volume-limited, stellar-mass-selected samples of galaxies at redshifts 0<z<1. The CDF-S sample at 0.6<z<1.0 contains 207 galaxies complete down to M=4×1010 Msolar…