Search Publications
A Narrow-Line Seyfert 1-Blazar Composite Nucleus in 2MASX J0324+3410
Yuan, Weimin; Zhou, Hongyan; Komossa, Stefanie +7 more
We report the identification of 2MASX J032441.19+341045.9 (hereafter 2MASX J0324+3410) with an appealing object that shows the dual properties of both a narrow-line Seyfert 1 galaxy (NLS1) and a blazar. Its optical spectrum, which has a Hβ line width of about 1600 km s-1 (FWHM), an [O III]-to-Hβ line ratio of ~=0.12, and strong Fe II em…
Quasi-periodic Variability in NGC 5408 X-1
Cropper, Mark; Soria, Roberto; Mushotzky, Richard F. +3 more
We report the discovery with XMM-Newton of quasi-periodic variability in the 0.2-10 keV X-ray flux from the ULX NGC 5408 X-1. The average power spectrum of all EPIC-pn data reveals a strong 20 mHz QPO with an average amplitude (rms) of 9% and a coherence Q≡ν0/σ~6. In a 33 ks time interval when the 20 mHz QPO is strongest we also find ev…
The Star Formation Epoch of the Most Massive Early-Type Galaxies
van Dokkum, Pieter G.; van der Marel, Roeland P.
We present new spatially resolved Keck spectroscopy of early-type galaxies in three galaxy clusters at z~0.5. We focus on the fundamental plane (FP) relation and combine the kinematics with structural parameters determined from HST images. The galaxies obey clear FP relations, which are offset from the FP of the nearby Coma Cluster due to passive …
Constraints on Dark Energy from Supernovae, Gamma-Ray Bursts, Acoustic Oscillations, Nucleosynthesis, Large-Scale Structure, and the Hubble Constant
Wright, E. L.
The luminosity distance versus redshift law is now measured using supernovae and γ-ray bursts, and the angular size distance is measured at the surface of last scattering by the CMB and at z=0.35 by baryon acoustic oscillations. In this paper, this data is fit to models for the equation of state with w=-1, w=constant, and w(z)=w0+w…
Identification of Absorption Features in an Extrasolar Planet Atmosphere
Barman, T.
Water absorption is identified in the atmosphere of HD 209458b by comparing models for the planet's transmitted spectrum to recent, multiwavelength, eclipse-depth measurements (from 0.3 to 1 µm) published by Knutson et al. A cloud-free model that includes solar abundances, rainout of condensates, and photoionization of sodium and potassium i…
Physical Properties, Baryon Content, and Evolution of the Lyα Forest: New Insights from High-Resolution Observations at z <~ 0.4
Savage, B. D.; Wakker, B. P.; Sembach, K. R. +3 more
We present a study of the Lyα forest at z<~0.4, from which we conclude that at least 20% of the total baryons in the universe are located in the highly ionized gas traced by broad Lyα absorbers. The cool photoionized low-z intergalactic medium (IGM) probed by narrow Lyα absorbers contains about 30% of the baryons. We further find that the ratio…
Further Indications of Jet Rotation in New Ultraviolet and Optical Hubble Space Telescope STIS Spectra
Bacciotti, Francesca; Coffey, Deirdre; Eislöffel, Jochen +2 more
We present survey results that suggest rotation signatures at the base of T Tauri jets. Observations were conducted with the Hubble Space Telescope Imaging Spectrograph at optical and near-ultraviolet (NUV) wavelengths. Results are presented for the approaching jet from DG Tau, CW Tau, HH 30, and the bipolar jet from TH 28. Systematic asymmetries …
Warm Gas in the Inner Disks around Young Intermediate-Mass Stars
Simon, Theodore; Najita, Joan R.; Rettig, Terrence W. +1 more
The characterization of gas in the inner disks around young stars is of particular interest because of its connection to planet formation. In order to study the gas in inner disks, we have obtained high-resolution K- and M-band spectroscopy of 14 intermediate-mass young stars. In sources that have optically thick inner disks, i.e., E(K-L)>1, ou…
The Prelude to and Aftermath of the Giant Flare of 2004 December 27: Persistent and Pulsed X-Ray Properties of SGR 1806-20 from 1993 to 2005
Hurley, Kevin; Kouveliotou, Chryssa; Göǧüş, Ersin +5 more
We report on the evolution of key spectral and temporal parameters of SGR 1806-20 prior to and following the highly energetic giant flare of 2004 December 27. Using RXTE, we track the pulse frequency of the SGR and find that the spin-down rate varied erratically in the months before and after the flare. Contrary to the giant flare in SGR 1900+14, …
Evolution of the Luminosity Function, Star Formation Rate, Morphology, and Size of Star-forming Galaxies Selected at Rest-Frame 1500 and 2800 Å
Dickinson, Mark; Ferguson, Henry C.; Giavalisco, Mauro +4 more
Using the multiwavelength photometric and spectroscopic data covering the Chandra Deep Field South obtained within the Great Observatories Origins Deep Survey, we investigate the rest-frame UV properties of galaxies to z~2.2, including the evolution of the luminosity function, the luminosity density, star formation rate (SFR), and galaxy morpholog…