Search Publications
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…
IMACS: The Inamori-Magellan Areal Camera and Spectrograph on Magellan-Baade
Dressler, Alan; Kelson, Daniel; Shectman, Stephen +12 more
The Inamori-Magellan Areal Camera and Spectrograph (IMACS) is a wide-field, multipurpose imaging spectrograph on the Magellan-Baade telescope at Las Campanas Observatory. IMACS has two channels—f/2 and f/4, each with an 8K × 8K pixel mosaic of CCD detectors, that service the widest range of capabilities of any major spectrograph. These include wid…
The 511 keV emission from positron annihilation in the Galaxy
Moskalenko, I. V.; Marcowith, A.; Diehl, R. +9 more
The first γ-ray line originating from outside the Solar System that was ever detected is the 511 keV emission from positron annihilation in the Galaxy. Despite 30 years of intense theoretical and observational investigation, the main sources of positrons have not been identified up to now. Observations in the 1990s with OSSE/CGRO (Oriented Scintil…
Evolution of the solar irradiance during the Holocene
Solanki, S. K.; Usoskin, I.; Krivova, N. A. +1 more
Context. Long-term records of solar radiative output are vital for understanding solar variability and past climate change. Measurements of solar irradiance are available for only the last three decades, which calls for reconstructions of this quantity over longer time scales using suitable models.
Aims: We present a physically consistent rec…
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…
Creation of cosmic structure in the complex galaxy cluster merger Abell 2744
Okabe, N.; Zitrin, A.; Meneghetti, M. +15 more
We present a detailed strong-lensing, weak-lensing and X-ray analysis of Abell 2744 (z= 0.308), one of the most actively merging galaxy clusters known. It appears to have unleashed 'dark', 'ghost', 'bullet' and 'stripped' substructures, each ∼1014 M⊙. The phenomenology is complex and will present a challenge for numerical sim…
An actively accreting massive black hole in the dwarf starburst galaxy Henize2-10
Johnson, Kelsey E.; Reines, Amy E.; Sivakoff, Gregory R. +1 more
Supermassive black holes are now thought to lie at the heart of every giant galaxy with a spheroidal component, including our own Milky Way. The birth and growth of the first `seed' black holes in the earlier Universe, however, is observationally unconstrained and we are only beginning to piece together a scenario for their subsequent evolution. H…
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 …