Search Publications
No Clear Submillimeter Signature of Suppressed Star Formation among X-Ray Luminous Active Galactic Nuclei
Magnelli, B.; Altieri, B.; Daddi, E. +18 more
Many theoretical models require powerful active galactic nuclei (AGNs) to suppress star formation in distant galaxies and reproduce the observed properties of today's massive galaxies. A recent study based on Herschel-SPIRE submillimeter observations claimed to provide direct support for this picture, reporting a significant decrease in the mean s…
Quantifying Spicules
De Pontieu, Bart; Carlsson, Mats; Pereira, Tiago M. D.
Understanding the dynamic solar chromosphere is fundamental in solar physics. Spicules are an important feature of the chromosphere, connecting the photosphere to the corona, potentially mediating the transfer of energy and mass. The aim of this work is to study the properties of spicules over different regions of the Sun. Our goal is to investiga…
Disentangling Baryons and Dark Matter in the Spiral Gravitational Lens B1933+503
McKean, J. P.; Treu, T.; Auger, M. W. +10 more
Measuring the relative mass contributions of luminous and dark matter in spiral galaxies is important for understanding their formation and evolution. The combination of a galaxy rotation curve and strong lensing is a powerful way to break the disk-halo degeneracy that is inherent in each of the methods individually. We present an analysis of the …
Dwarfs Gobbling Dwarfs: A Stellar Tidal Stream around NGC 4449 and Hierarchical Galaxy Formation on Small Scales
Carballo-Bello, Julio A.; Romanowsky, Aaron J.; Brodie, Jean P. +13 more
A candidate diffuse stellar substructure was previously reported in the halo of the nearby dwarf starburst galaxy NGC 4449 by Karachentsev et al. We map and analyze this feature using a unique combination of deep integrated-light images from the BlackBird 0.5 m telescope, and high-resolution wide-field images from the 8 m Subaru Telescope, which r…
Hubble Space Telescope Reveals Multiple Sub-giant Branch in Eight Globular Clusters
Anderson, J.; Milone, A. P.; Marino, A. F. +6 more
In the last few years many globular clusters (GCs) have revealed complex color-magnitude diagrams, with the presence of multiple main sequences (MSs), broad or multiple sub-giant branches (SGBs) and MS turnoffs, and broad or split red giant branches (RGBs). After a careful correction for differential reddening, high-accuracy photometry with the Hu…
The Herschel Exploitation of Local Galaxy Andromeda (HELGA). II. Dust and Gas in Andromeda
Blommaert, J. A. D. L.; Clements, D. L.; Boquien, M. +27 more
We present an analysis of the dust and gas in Andromeda, using Herschel images sampling the entire far-infrared peak. We fit a modified-blackbody model to ~4000 quasi-independent pixels with spatial resolution of ~140 pc and find that a variable dust-emissivity index (β) is required to fit the data. We find no significant long-wavelength excess ab…
Cosmic Microwave Background Constraints on the Duration and Timing of Reionization from the South Pole Telescope
Doré, O.; Bleem, L. E.; Stark, A. A. +48 more
The epoch of reionization is a milestone of cosmological structure formation, marking the birth of the first objects massive enough to yield large numbers of ionizing photons. However, the mechanism and timescale of reionization remain largely unknown. Measurements of the cosmic microwave background (CMB) Doppler effect from ionizing bubbles embed…
The CFHTLS-Strong Lensing Legacy Survey (SL2S): Investigating the Group-scale Lenses with the SARCS Sample
Kneib, J. -P.; Alard, C.; Gavazzi, R. +5 more
We present the Strong Lensing Legacy Survey-ARCS (SARCS) sample compiled from the final T0006 data release of the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) covering a total non-overlapping area of 159 deg2. We adopt a semi-automatic method to find gravitational arcs in the survey that makes use of an arc-finding algorithm. T…
The Star Formation Rate Function for Redshift z ~ 4-7 Galaxies: Evidence for a Uniform Buildup of Star-forming Galaxies during the First 3 Gyr of Cosmic Time
van Dokkum, Pieter G.; Franx, Marijn; Illingworth, Garth D. +4 more
We combine recent estimates of dust extinction at z ~ 4-7 with UV luminosity function (LF) determinations to derive star formation rate (SFR) functions at z ~ 4-7. SFR functions provide a more physical description of galaxy buildup at high redshift and allow for direct comparisons to SFRs at lower redshifts determined by a variety of techniques. O…
HST-COS Observations of AGNs. I. Ultraviolet Composite Spectra of the Ionizing Continuum and Emission Lines
Shull, J. Michael; Danforth, Charles W.; Stevans, Matthew
The ionizing fluxes from quasars and other active galactic nuclei (AGNs) are critical for interpreting the emission-line spectra of AGNs and for photoionization and heating of the intergalactic medium. Using ultraviolet spectra from the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST), we have directly measured the rest-frame …