Search Publications
Three-year Swift-BAT Survey of Active Galactic Nuclei: Reconciling Theory and Observations?
Greiner, J.; Merloni, A.; Comastri, A. +3 more
It is well accepted that unabsorbed as well as absorbed active galactic nuclei (AGNs) are needed to explain the nature and shape of the Cosmic X-ray background (CXB), even if the fraction of highly absorbed objects (dubbed Compton-thick sources) still substantially escapes detection. We derive and analyze the absorption distribution using a comple…
Probing the Intergalactic Medium/Galaxy Connection. V. On the Origin of Lyα and O VI Absorption at z < 0.2
Prochaska, J. Xavier; Mulchaey, J.; Weiner, B. +2 more
We analyze the association of galaxies with Lyα and O VI absorption, the most commonly detected transitions of the low-z intergalactic medium (IGM), in the fields of 14 quasars with z em = 0.06-0.57. Confirming previous studies, we observe a high covering fraction for Lyα absorption to impact parameter ρ = 300 h -1 72
A Model for the Sources of the Slow Solar Wind
Antiochos, S. K.; Linker, J. A.; Mikić, Z. +2 more
Models for the origin of the slow solar wind must account for two seemingly contradictory observations: the slow wind has the composition of the closed-field corona, implying that it originates from the continuous opening and closing of flux at the boundary between open and closed field. On the other hand, the slow wind also has large angular widt…
Constraints on the Assembly and Dynamics of Galaxies. II. Properties of Kiloparsec-scale Clumps in Rest-frame Optical Emission of z ~ 2 Star-forming Galaxies
Lutz, D.; Förster Schreiber, N. M.; Genzel, R. +11 more
We study the properties of luminous stellar "clumps" identified in deep, high-resolution Hubble Space Telescope NIC2/F160W imaging at 1.6 µm of six z ~ 2 star-forming galaxies with existing near-infrared integral field spectroscopy from SINFONI at the Very Large Telescope. Individual clumps contribute ~0.5%-15% of the galaxy-integrated rest-…
Extreme Feedback and the Epoch of Reionization: Clues in the Local Universe
Heckman, Timothy M.; Leitherer, Claus; Rich, R. Michael +8 more
The source responsible for reionizing the universe at z>6 remains uncertain. While an energetically adequate population of star-forming galaxies may be in place, it is unknown whether a large enough fraction of their ionizing radiation can escape into the intergalactic medium. Attempts to measure this escape fraction in intensely star-forming g…
Evolution of Galaxy Stellar Mass Functions, Mass Densities, and Mass-to-light Ratios from z ~ 7 to z ~ 4
Franx, Marijn; Labbé, Ivo; Kriek, Mariska +3 more
We derive stellar masses from spectral energy distribution fitting to rest-frame optical and UV fluxes for 401 star-forming galaxies at z ~ 4, 5, and 6 from Hubble-WFC3/IR camera observations of the Early Release Science field combined with the deep GOODS-S Spitzer/IRAC data (and include a previously published z ~ 7 sample). A mass-luminosity rela…
Observations of Arp 220 Using Herschel-SPIRE: An Unprecedented View of the Molecular Gas in an Extreme Star Formation Environment
Clements, D. L.; Wilson, Christine D.; Baes, Maarten +20 more
We present Herschel Spectral and Photometric Imaging Receiver Fourier Transform Spectrometer (Herschel SPIRE-FTS) observations of Arp 220, a nearby ultra-luminous infrared galaxy. The FTS provides continuous spectral coverage from 190 to 670 µm, a wavelength region that is either very difficult to observe or completely inaccessible from the …
Evidence for a Massive Neutron Star from a Radial-velocity Study of the Companion to the Black-widow Pulsar PSR B1957+20
Kulkarni, S. R.; van Kerkwijk, M. H.; Breton, R. P.
The most massive neutron stars constrain the behavior of ultra-dense matter, with larger masses possible only for increasingly stiff equations of state. Here, we present evidence that the black-widow pulsar, PSR B1957+20, has a high mass. We took spectra of its strongly irradiated companion and found an observed radial-velocity amplitude of K
Galaxy-wide Shocks in Late-merger Stage Luminous Infrared Galaxies
Kewley, L. J.; Dopita, M. A.; Rich, J. A.
We present an integral field spectroscopic study of two nearby luminous infrared galaxies (LIRGs), IC 1623 and NGC 3256, which exhibit evidence of widespread shock excitation induced by ongoing merger activity. We show the importance of carefully separating excitation due to shocks versus excitation by H II regions and the usefulness of integral f…
Dissecting Photometric Redshift for Active Galactic Nucleus Using XMM- and Chandra-COSMOS Samples
Kneib, J. -P.; Aussel, H.; Le Floc'h, E. +62 more
In this paper, we release accurate photometric redshifts for 1692 counterparts to Chandra sources in the central square degree of the Cosmic Evolution Survey (COSMOS) field. The availability of a large training set of spectroscopic redshifts that extends to faint magnitudes enabled photometric redshifts comparable to the highest quality results pr…