Search Publications
A Clear Age-Velocity Dispersion Correlation in Andromeda’s Stellar Disk
Bell, Eric F.; Skillman, Evan D.; Williams, Benjamin F. +9 more
The stellar kinematics of galactic disks are key to constraining disk formation and evolution processes. In this paper, for the first time, we measure the stellar age-velocity dispersion correlation in the inner 20 kpc (∼3.5 disk scale lengths) of M31 and show that it is dramatically different from that in the Milky Way (MW). We use optical Hubble…
Magellan Adaptive Optics First-light Observations of the Exoplanet β Pic b. II. 3-5 µm Direct Imaging with MagAO+Clio, and the Empirical Bolometric Luminosity of a Self-luminous Giant Planet
Weinberger, Alycia J.; Bailey, Vanessa P.; Close, Laird M. +14 more
Young giant exoplanets are a unique laboratory for understanding cool, low-gravity atmospheres. A quintessential example is the massive extrasolar planet β Pic b, which is 9 AU from and embedded in the debris disk of the young nearby A6V star β Pictoris. We observed the system with first light of the Magellan Adaptive Optics (MagAO) system. In Pap…
Magnetically Driven Accretion Disk Winds and Ultra-fast Outflows in PG 1211+143
Behar, Ehud; Tombesi, Francesco; Shrader, Chris +3 more
We present a study of X-ray ionization of MHD accretion-disk winds in an effort to constrain the physics underlying the highly ionized ultra-fast outflows (UFOs) inferred by X-ray absorbers often detected in various sub classes of Seyfert active galactic nuclei (AGNs). Our primary focus is to show that magnetically driven outflows are indeed physi…
Evidence of Lensing of the Cosmic Microwave Background by Dark Matter Halos
Hilton, Matt; Hasselfield, Matthew; Bond, J. Richard +41 more
We present evidence of the gravitational lensing of the cosmic microwave background by 1013 solar mass dark matter halos. Lensing convergence maps from the Atacama Cosmology Telescope Polarimeter (ACTPol) are stacked at the positions of around 12 000 optically selected CMASS galaxies from the SDSS-III/BOSS survey. The mean lensing signa…
Nearby Galaxy Filaments and the Ly-alpha Forest: Confronting Simulations and the UV Background with Observations
Savage, Blair D.; Wakker, Bart P.; Oppenheimer, Benjamin D. +3 more
Simulations of the formation of large-scale structures predict that dark matter, low density highly ionized gas, and galaxies form 10 to 40 Mpc scale filaments. These structures are easily recognized in the distribution of galaxies. Here we use Lyα absorption lines to study the gas in 30 × 6 Mpc filament at cz ∼ 3500 km s-1, defined usi…
Correcting the z ∼ 8 Galaxy Luminosity Function for Gravitational Lensing Magnification Bias
Stiavelli, Massimo; Schmidt, Kasper B.; Treu, Tommaso +7 more
We present a Bayesian framework to account for the magnification bias from both strong and weak gravitational lensing in estimates of high-redshift galaxy luminosity functions (LFs). We illustrate our method by estimating the z ∼ 8 UV LF using a sample of 97 Y-band dropouts (Lyman break galaxies) found in the Brightest of Reionizing Galaxies (BoRG…
Dust variations in the diffuse interstellar medium: constraints on Milky Way dust from Planck-HFI observations
Miville-Deschênes, M. -A.; Abergel, A.; Ysard, N. +3 more
Context. The Planck-HFI all-sky survey from 353 to 857 GHz combined with the IRAS data at 100 µm (3000 GHz, IRIS version of the data) show that the dust properties vary from line of sight to line of sight in the diffuse interstellar medium (ISM) at high Galactic latitude (1019 ≤ NH ≤ 2.5 × 1020 H/cm2
The Sizes of Candidate z∼9-10 Galaxies: Confirmation of the Bright CANDELS Sample and Relation with Luminosity and Mass.
Holwerda, B. W.; Bouwens, R.; Oesch, P. +3 more
Recently, a small sample of six z ∼ 9-10 candidates was discovered in CANDELS that are ∼ 10-20× more luminous than any of the previous z ∼ 9-10 galaxies identified over the HUDF/XDF and CLASH fields. We measure the sizes of these candidates to map out the size evolution of galaxies from the earliest observable times. Their sizes are also used to p…
Review on Current Sheets in CME Development: Theories and Observations
Reeves, Katharine K.; Lin, Jun; Raymond, John C. +5 more
We introduce how the catastrophe model for solar eruptions predicted the formation and development of the long current sheet (CS) and how the observations were used to recognize the CS at the place where the CS is presumably located. Then, we discuss the direct measurement of the CS region thickness by studying the brightness distribution of the C…
The Physical Conditions in a Pre-super Star Cluster Molecular Cloud in the Antennae Galaxies
Indebetouw, R.; Leroy, A. K.; Whitmore, B. C. +5 more
We present an analysis of the physical conditions in an extreme molecular cloud in the Antennae merging galaxies. This cloud has properties consistant with those required to form a globular cluster. We have obtained ALMA CO and 870 µm observations of the Antennae galaxy system with ∼0.″5 resolution. This cloud stands out in the data with a r…