Search Publications
Missions
Journals
Publication Years
Precision Stellar Characterization of FGKM Stars using an Empirical Spectral Library
Petigura, Erik A.; von Braun, Kaspar; Yee, Samuel W.
Classification of stars, by comparing their optical spectra to a few dozen spectral standards, has been a workhorse of observational astronomy for more than a century. Here, we extend this technique by compiling a library of optical spectra of 404 touchstone stars observed with Keck/HIRES by the California Planet Search. The spectra have high reso…
The COS-Halos Survey: Metallicities in the Low-redshift Circumgalactic Medium
Tripp, Todd M.; Worseck, Gábor; Prochaska, J. Xavier +8 more
We analyze new far-ultraviolet spectra of 13 quasars from the z∼ 0.2 COS-Halos survey that cover the H I Lyman limit of 14 circumgalactic medium (CGM) systems. These data yield precise estimates or more constraining limits than previous COS-Halos measurements on the H I column densities {N}{{H}{{I}}}. We then apply a Monte-Carlo Markov …
CMB bounds on disk-accreting massive primordial black holes
Calore, Francesca; Kohri, Kazunori; Poulin, Vivian +2 more
Stellar-mass primordial black holes (PBH) have been recently reconsidered as a dark matter (DM) candidate after the aLIGO discovery of several binary black hole (BH) mergers with masses of tens of M⊙ . Matter accretion on such massive objects leads to the emission of high-energy photons, capable of altering the ionization and thermal hi…
Electromagnetic evidence that SSS17a is the result of a binary neutron star merger
Rest, A.; Foley, R. J.; Boutsia, K. +18 more
Eleven hours after the detection of gravitational wave source GW170817 by the Laser Interferometer Gravitational-Wave Observatory and Virgo Interferometers, an associated optical transient, SSS17a, was identified in the galaxy NGC 4993. Although the gravitational wave data indicate that GW170817 is consistent with the merger of two compact objects…
The close environments of accreting massive black holes are shaped by radiative feedback
Lamperti, Isabella; Ho, Luis C.; Fabian, Andrew C. +13 more
The majority of the accreting supermassive black holes in the Universe are obscured by large columns of gas and dust. The location and evolution of this obscuring material have been the subject of intense research in the past decades, and are still debated. A decrease in the covering factor of the circumnuclear material with increasing accretion r…
Target Selection for the SDSS-IV APOGEE-2 Survey
Poleski, R.; Mészáros, Sz.; Covey, K. +34 more
APOGEE-2 is a high-resolution, near-infrared spectroscopic survey observing ∼3 × 105 stars across the entire sky. It is the successor to APOGEE and is part of the Sloan Digital Sky Survey IV (SDSS-IV). APOGEE-2 is expanding on APOGEE's goals of addressing critical questions of stellar astrophysics, stellar populations, and Galactic chem…
Asteroseismology and Gaia: Testing Scaling Relations Using 2200 Kepler Stars with TGAS Parallaxes
Chaplin, William J.; Davies, Guy R.; Latham, David W. +17 more
We present a comparison of parallaxes and radii from asteroseismology and Gaia DR1 (TGAS) for 2200 Kepler stars spanning from the main sequence to the red-giant branch. We show that previously identified offsets between TGAS parallaxes and distances derived from asteroseismology and eclipsing binaries have likely been overestimated for parallaxes …
CFHTLenS revisited: assessing concordance with Planck including astrophysical systematics
Heymans, Catherine; van Waerbeke, Ludovic; Choi, Ami +9 more
We investigate the impact of astrophysical systematics on cosmic shear cosmological parameter constraints from the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS) and the concordance with cosmic microwave background measurements by Planck. We present updated CFHTLenS cosmic shear tomography measurements extended to degree scales using a c…
The Physical Processes of CME/ICME Evolution
Vršnak, Bojan; Lugaz, Noé; Liu, Ying D. +4 more
As observed in Thomson-scattered white light, coronal mass ejections (CMEs) are manifest as large-scale expulsions of plasma magnetically driven from the corona in the most energetic eruptions from the Sun. It remains a tantalizing mystery as to how these erupting magnetic fields evolve to form the complex structures we observe in the solar wind a…
General constraints on dark matter decay from the cosmic microwave background
Slatyer, Tracy R.; Wu, Chih-Liang
Precise measurements of the temperature and polarization anisotropies of the cosmic microwave background can be used to constrain the annihilation and decay of dark matter. In this work, we demonstrate via principal component analysis that the imprint of dark matter decay on the cosmic microwave background can be approximately parametrized by a si…