Search Publications
Obscured AGNs in Bulgeless Hosts discovered by WISE: The Case Study of SDSS J1224+5555
Hickox, R. C.; Secrest, N. J.; Satyapal, S. +6 more
There is mounting evidence that supermassive black holes (SMBHs) form and grow in bulgeless galaxies. However, a robust determination of the fraction of active galactic nuclei (AGNs) in bulgeless galaxies, an important constraint to models of SMBH seed formation and merger-free models of AGN fueling, is unknown, since optical studies have been sho…
Undercover EUV Solar Jets Observed by the Interface Region Imaging Spectrograph
Innes, D. E.; Chen, N. -H.
It is well-known that extreme ultraviolet (EUV) emission emitted at the solar surface is absorbed by overlying cool plasma. Especially in active regions, dark lanes in EUV images suggest that much of the surface activity is obscured. Simultaneous observations from the Interface Region Imaging Spectrograph, consisting of UV spectra and slit-jaw ima…
Contemporaneous Broadband Observations of Three High-redshift BL LAC Objects
Troja, E.; Caraveo, P. A.; Mirabal, N. +101 more
We have collected broadband spectral energy distributions (SEDs) of three BL Lac objects 3FGL J0022.1-1855 (z = 0.689), 3FGL J0630.9-2406 (z\quad ≳ 1.239), and 3FGL J0811.2-7529 (z = 0.774), detected by Fermi with relatively flat gigaelectronvolt spectra. By observing simultaneously in the near-infrared to hard X-ray band, we can well characterize…
Exploring Damped Lyα System Host Galaxies Using Gamma-Ray Bursts
Cenko, S. Bradley; Rafelski, Marc; Veilleux, Sylvain +6 more
We present a sample of 45 Damped Lyα system (DLA; {N}{{H}{{I}}} ≥slant 2× {10}20 {{cm}}-2) counterparts (33 detections, 12 upper limits) which host gamma-ray bursts (GRB-DLAs) in order to investigate star formation and metallicity within galaxies hosting DLAs. Our sample spans z∼ 2{--}6 and is nearly three times la…
Spectroscopy of Luminous Compact Blue Galaxies in Distant Clusters. II. Physical Properties of dE Progenitor Candidates
Randriamampandry, S. M.; Wirth, Gregory D.; Bershady, M. A. +1 more
Luminous Compact Blue Galaxies (LCBGs) are an extreme star-bursting population of galaxies that were far more common at earlier epochs than today. Based on spectroscopic and photometric measurements of LCBGs in massive (M > 1015 M⊙), intermediate redshift (0.5 < z < 0.9) galaxy clusters, we present their rest-frame p…
Hard X-Ray Tail Discovered in the Clocked Burster GS 1826-238
Jourdain, E.; Roques, J. P.; Rodi, J.
The low-mass X-ray binary (LMXB) neutron star (NS) GS 1826-238 was discovered by Ginga in 1988 September. Due to the presence of quasi-periodicity in the type I X-ray burst rate, the source has been a frequent target of X-ray observations for almost 30 years. Though the bursts were too soft to be detected by INTEGRAL/SPI, the persistent emission f…
On More Sensitive Periodogram Statistics
Bélanger, G.
Period searches in event data have traditionally used the Rayleigh statistic, R 2. For X-ray pulsars, the standard has been the Z 2 statistic, which sums over more than one harmonic. For γ-rays, the H-test, which optimizes the number of harmonics to sum, is often used. These periodograms all suffer from the same problem, name…
Prediction of Forbidden Ultraviolet and Visible Emissions in Comet 67P/Churyumov-Gerasimenko
Galand, Marina; Bhardwaj, Anil; Raghuram, Susarla
Remote observation of spectroscopic emissions is a potential tool for the identification and quantification of various species in comets. The CO Cameron band (to trace CO2) and atomic oxygen emissions (to trace H2O and/or CO2, CO) have been used to probe neutral composition in the cometary coma. Using a coupled-che…
An Integrated Model for the Production of X-Ray Time Lags and Quiescent Spectra from Homogeneous and Inhomogeneous Black Hole Accretion Coronae
Becker, Peter A.; Kroon, John J.
Many accreting black holes manifest time lags during outbursts, in which the hard Fourier component typically lags behind the soft component. Despite decades of observations of this phenomenon, the underlying physical explanation for the time lags has remained elusive, although there are suggestions that Compton reverberation plays an important ro…
Evidence for Non-stellar Rest-frame Near-IR Emission Associated with Increased Star Formation in Galaxies at z ~ 1
van Dokkum, Pieter G.; Franx, Marijn; Brammer, Gabriel +5 more
We explore the presence of non-stellar rest-frame near-IR (2-5 µm) emission in galaxies at z ∼ 1. Previous studies identified this excess in relatively small samples and suggested that such non-stellar emission, which could be linked to the 3.3 µm polycyclic aromatic hydrocarbons feature or hot dust emission, is associated with an incr…