Search Publications
Constraints on the Ubiquity of Coronal X-Ray Cycles
Wright, Nicholas J.; Hoffman, John; Günther, Hans M.
Stellar activity cycles are known to be a widespread phenomenon amongst moderately active solar- and late-type stars from long-term periodic variations in chromospheric Ca II H and K emission lines, yet to date, only a handful of coronal X-ray cycles are known. We have surveyed serendipitously observed stellar sources in fields observed multiple t…
The X-Ray Transient 2XMMi J003833.3+402133: A Candidate Magnetar at High Galactic Latitude
Callingham, J. R.; Farrell, S. A.; Gaensler, B. M. +2 more
We present detailed analysis of the transient X-ray source 2XMMi J003833.3+402133 detected by XMM-Newton in 2008 January during a survey of M31. The X-ray spectrum is well fitted by either a steep power law plus a blackbody model or a double blackbody model. Prior observations with XMM-Newton, Chandra, Swift, and ROSAT spanning 1991-2007, as well …
Erratum: "Suzaku Observations of the Non-thermal Supernova Remnant HESS J1731-347" (2012, ApJ, 756, 149)
Acero, Fabio; Klochkov, Dmitry; Bamba, Aya +7 more
Foreground Predictions for the Cosmic Microwave Background Power Spectrum from Measurements of Faint Inverted Radio Sources at 5 GHz
White, Richard L.; Becker, Robert H.; Schneider, Michael D. +1 more
We present measurements of a population of matched radio sources at 1.4 and 5 GHz down to a flux limit of 1.5 mJy in 7 deg2 of the NOAO Deep Field South. We find a significant fraction of sources with inverted spectral indices that all have 1.4 GHz fluxes less than 10 mJy and are therefore too faint to have been detected and included in…
Are Pulsing Solitary Waves Running inside the Sun?
Wolff, Charles L.
A precise sequence of frequencies—detected four independent ways—is interpreted as a system of solitary waves below the Sun's convective envelope. Six future observational or theoretical tests of this idea are suggested. Wave properties (rotation rates, radial energy distribution, nuclear excitation strength) follow from conventional dynamics of g…
A 3% Solution: Determination of the Hubble Constant with the Hubble Space Telescope and Wide Field Camera 3
Ferguson, Henry C.; Casertano, Stefano; Filippenko, Alexei V. +6 more
We use the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) to determine the Hubble constant from optical and infrared observations of over 600 Cepheid variables in the host galaxies of eight recent Type Ia supernovae (SNe Ia), providing the calibration for a magnitude-redshift relation based on 253 SNe Ia. Increased precision over p…
The Lesser Role of Starbursts in Star Formation at z = 2
Berta, S.; Magnelli, B.; Nordon, R. +31 more
Two main modes of star formation are know to control the growth of galaxies: a relatively steady one in disk-like galaxies, defining a tight star formation rate (SFR)-stellar mass sequence, and a starburst mode in outliers to such a sequence which is generally interpreted as driven by merging. Such starburst galaxies are rare but have much higher …
Calibrating Extinction-free Star Formation Rate Diagnostics with 33 GHz Free-free Emission in NGC 6946
Helou, G.; Roussel, H.; Murphy, E. J. +20 more
Using free-free emission measured in the Ka band (26-40 GHz) for 10 star-forming regions in the nearby galaxy NGC 6946, including its starbursting nucleus, we compare a number of star formation rate (SFR) diagnostics that are typically considered to be unaffected by interstellar extinction. These diagnostics include non-thermal radio (i.e., 1.4 GH…
Galaxy Structure and Mode of Star Formation in the SFR-Mass Plane from z ~ 2.5 to z ~ 0.1
Barro, Guillermo; Hathi, Nimish P.; Kocevski, Dale D. +23 more
We analyze the dependence of galaxy structure (size and Sérsic index) and mode of star formation (ΣSFR and SFRIR/SFRUV) on the position of galaxies in the star formation rate (SFR) versus mass diagram. Our sample comprises roughly 640,000 galaxies at z ~ 0.1, 130,000 galaxies at z ~ 1, and 36,000 galaxies at z ~ 2.…
The Second Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope
Ozaki, M.; Troja, E.; Caraveo, P. A. +174 more
The second catalog of active galactic nuclei (AGNs) detected by the Fermi Large Area Telescope (LAT) in two years of scientific operation is presented. The second LAT AGN catalog (2LAC) includes 1017 γ-ray sources located at high Galactic latitudes (|b| > 10°) that are detected with a test statistic (TS) greater than 25 and associated statistic…