Search Publications
A Search for an Optical Counterpart to the Gravitational-wave Event GW151226
Della Valle, M.; Sollerman, J.; Gal-Yam, A. +37 more
We present a search for an electromagnetic counterpart of the gravitational-wave source GW151226. Using the Pan-STARRS1 telescope we mapped out 290 square degrees in the optical I P1 filter, starting 11.5 hr after the LIGO information release and lasting for an additional 28 days. The first observations started 49.5 hr after the time of…
Lighting the Dark Molecular Gas: H2 as a Direct Tracer
Togi, Aditya; Smith, J. D. T.
Robust knowledge of molecular gas mass is critical for understanding star formation in galaxies. The {{{H}}}2 molecule does not emit efficiently in the cold interstellar medium, hence the molecular gas content of galaxies is typically inferred using indirect tracers. At low metallicity and in other extreme environments, these tracers ca…
DDO 68: A Flea with Smaller Fleas that on Him Prey
Aloisi, Alessandra; Cignoni, Michele; Sacchi, Elena +7 more
We present new photometry of the dwarf irregular galaxy DDO 68, one of the most metal-poor and least massive dwarfs, located in the Lynx-Cancer Void. The images were acquired with the Large Binocular Telescope in the g and r passbands and show unequivocally that DDO 68 has previously unknown stellar streams related to the accretion of at least two…
Characterizing X-Ray and Radio Emission in the Black Hole X-Ray Binary V404 Cygni during Quiescence
Gandhi, Poshak; Chakrabarty, Deepto; Walton, Dominic J. +17 more
We present results from multi-wavelength simultaneous X-ray and radio observations of the black hole X-ray binary V404 Cyg in quiescence. Our coverage with NuSTAR provides the very first opportunity to study the X-ray spectrum of V404 Cyg at energies above 10 keV. The unabsorbed broadband (0.3-30 keV) quiescent luminosity of the source is 8.9 × 10…
Herschel-resolved Outer Belts of Two-belt Debris Disks—Evidence of Icy Grains
Bryden, G.; Stapelfeldt, K. R.; Werner, M. W. +1 more
We present dual-band Herschel/PACS imaging for 59 main-sequence stars with known warm dust (T warm ∼ 200 K), characterized by Spitzer. Of 57 debris disks detected at Herschel wavelengths (70 and/or 100 and 160 µm), about half have spectral energy distributions (SEDs) that suggest two-ring disk architectures mirroring that of the a…
The He II Proximity Effect and The Lifetime of Quasars
Worseck, G.; Hennawi, J. F.; McQuinn, M. +1 more
The lifetime of quasars is fundamental for understanding the growth of supermassive black holes, and is an important ingredient in models of the reionization of the intergalactic medium (IGM). However, despite various attempts to determine quasar lifetimes, current estimates from a variety of methods are uncertain by orders of magnitude. This work…
Discovery of an Extremely Wide-angle Bipolar Outflow in AFGL 5142
Kim, Kee-Tae; Lee, Jeong-Eun; Li, Di +12 more
Most bipolar outflows are associated with individual young stellar objects and have small opening angles. Here we report the discovery of an extremely wide-angle (∼180°) bipolar outflow (“EWBO”) in a cluster forming region AFGL 5142 from low-velocity emission of the HCN (3-2) and HCO+ (3-2) lines. This bipolar outflow is along a north-w…
Study of Swift/Bat Selected Low-luminosity Active Galactic Nuclei Observed with Suzaku
Ueda, Yoshihiro; Kawamuro, Taiki; Terashima, Yuichi +2 more
We systematically analyze the broadband (0.5-200 keV) X-ray spectra of hard X-ray (>10 keV) selected local low-luminosity active galactic nuclei (LLAGNs) observed with Suzaku and Swift/BAT. The sample consists of 10 LLAGNs detected with Swift/BAT with intrinsic 14-195 keV luminosities smaller than 1042 erg s-1 available in…
Light-curve Analysis of Neon Novae
Kato, Mariko; Hachisu, Izumi
We analyzed light curves of five neon novae, QU Vul, V351 Pup, V382 Vel, V693 CrA, and V1974 Cyg, and determined their white dwarf (WD) masses and distance moduli on the basis of theoretical light curves composed of free-free and photospheric emission. For QU Vul, we obtained a distance of d ∼ 2.4 kpc, reddening of E(B - V) ∼ 0.55, and WD mass of …
The Magnetic Classification of Solar Active Regions 1992-2015
Jaeggli, S. A.; Norton, A. A.
The purpose of this Letter is to address a blindspot in our knowledge of solar active region (AR) statistics. To the best of our knowledge, there are no published results showing the variation of the Mount Wilson magnetic classifications as a function of solar cycle based on modern observations. We show statistics for all ARs reported in the daily…