Search Publications
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 …
Neutral Interstellar Helium Parameters Based on IBEX-Lo Observations and Test Particle Calculations
Bochsler, P.; McComas, D. J.; Fuselier, S. A. +10 more
Because of its high ionization potential and weak interaction with hydrogen, neutral interstellar helium (NISHe) is almost unaffected at the heliospheric interface with the interstellar medium and freely enters the solar system. This second most abundant species provides some of the best information on the characteristics of the interstellar gas i…
The Large Longitudinal Spread of Solar Energetic Particles During the 17 January 2010 Solar Event
Gómez-Herrero, R.; Dresing, N.; Heber, B. +3 more
We investigate multi-spacecraft observations of the 17 January 2010 solar energetic particle event. Energetic electrons and protons have been observed over a remarkable large longitudinal range at the two STEREO spacecraft and SOHO, suggesting a longitudinal spread of nearly 360 degrees at 1 AU. The flaring active region, which was on the backside…
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…
Pitch angle distribution of suprathermal electrons behind dipolarization fronts: A statistical overview
Daly, P. W.; André, M.; Vaivads, A. +5 more
We examine the pitch angle distribution (PAD) of suprathermal electrons (>40 keV) inside the flux pileup regions (FPRs) that are located behind the dipolarization fronts (DFs), in order to better understand the particle energization mechanisms operating therein. The 303 earthward-propagating DFs observed during 9 years (2001-2009) by Cluster 1 …
Herschel/PACS spectroscopy of NGC 4418 and Arp 220: H2O, H218O, OH, 18OH, O I, HCN, and NH3
Lutz, D.; Genzel, R.; Poglitsch, A. +14 more
Full range Herschel/PACS spectroscopy of the (ultra)luminous infrared galaxies NGC 4418 and Arp 220, observed as part of the SHINING key programme, reveals high excitation in H2O, OH, HCN, and NH3. In NGC 4418, absorption lines were detected with Elower > 800 K (H2O), 600 K (OH), 1075 K (HCN), and 600…
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…
Extreme AGN feedback in the MAssive Cluster Survey: a detailed study of X-ray cavities at z>0.3
Fabian, A. C.; Hlavacek-Larrondo, J.; Edge, A. C. +4 more
We present the first statistical study of X-ray cavities in distant clusters of galaxies (z > 0.3). With the aim of providing further insight into how active galactic nucleus (AGN) feedback operates at higher redshift, we have analysed the Chandra X-ray observations of the MAssive Cluster Survey (MACS) and searched for surface brightness depres…