Search Publications
A Comparison of X-Ray Photon Indices among the Narrow- and Broad-line Seyfert 1 Galaxies
Rakshit, Suvendu; Dewangan, Gulab Chand; Ojha, Vineet +1 more
We present a detailed comparative systematic study using a sample of 221 narrow-line Seyfert 1 (NLSy1) galaxies in comparison to a redshift-matched sample of 154 broad-line Seyfert 1 (BLSy1) galaxies based on their observations using ROSAT and/or XMM-Newton in soft X-ray band (0.1-2.0 keV). A homogeneous analysis is carried out to estimate their s…
First Solar Energetic Particles Measured on the Lunar Far-side
Wang, Yuming; Xu, Zigong; Guo, Jingnan +7 more
On 2019 May 6 the Lunar Lander Neutron & Dosimetry (LND) Experiment on board the Chang'E-4 lander on the far-side of the Moon detected its first solar energetic particle (SEP) event with proton energies up to 21 MeV. Combined proton energy spectra are studied based on the LND, SOHO/EPHIN, and ACE/EPAM measurements, which show that LND could pr…
Far-infrared Photometric Redshifts: A New Approach to a Highly Uncertain Enterprise
Casey, Caitlin M.
This paper presents a new approach to deriving far-infrared (FIR) photometric redshifts for galaxies based on their reprocessed emission from dust at rest-frame FIR through millimeter wavelengths. FIR photometric redshifts ("FIR-z") have been used over the past decade to derive redshift constraints for highly obscured galaxies that lack photometry…
Accretion History of AGNs. II. Constraints on AGN Spectral Parameters Using the Cosmic X-Ray Background
Kirkpatrick, Allison; Marchesi, Stefano; Urry, C. Megan +5 more
We constrain X-ray spectral shapes for the ensemble of active galactic nuclei (AGNs) based on the shape of the cosmic X-ray background (CXB). Specifically, we rule out regions of X-ray spectral parameter space that do not reproduce the CXB in the energy range 1-100 keV. The key X-ray spectral parameters are the photon index, Γ; the cutoff energy, …
Is Superorbital Modulation in SMC X-1 Caused by Absorption in a Warped Precessing Accretion Disk?
Maitra, Chandreyee; Paul, Biswajit; Pradhan, Pragati
We present a broadband spectral-timing analysis of SMC X-1 at different intensity states of its superorbital variation using 10 Suzaku and 6 Nuclear Spectroscopic Telescope Array (NuSTAR) observations. The spectrum in all the states can be described by an absorbed power law with a high-energy cutoff and a blackbody component along with an iron emi…
The Flare-dominated Accretion Mode of a Radio-bright Candidate Transitional Millisecond Pulsar
Strader, Jay; Chomiuk, Laura; Heinke, Craig O. +2 more
We report new simultaneous X-ray and radio continuum observations of 3FGL J0427.9-6704, a candidate member of the enigmatic class of transitional millisecond pulsars. These XMM-Newton and Australia Telescope Compact Array observations of this nearly edge-on, eclipsing low-mass X-ray binary were taken in the sub-luminous disk state at an X-ray lumi…
Surveying the Giant H II Regions of the Milky Way with SOFIA. II. M17
Lim, Wanggi; De Buizer, James M.; Radomski, James T.
We present our second set of results from our mid-infrared imaging survey of Milky Way giant H II regions. We used the FORCAST instrument on the Stratospheric Observatory For Infrared Astronomy (SOFIA) to obtain 20 and 37 µm images of the central ∼10' × 10' area of M17. We investigate the small- and large-scale properties of M17 using our da…
Hubble Space Telescope Imaging of Antlia B: Star Formation History and a New Tip of the Red Giant Branch Distance
Carlin, J. L.; Dolphin, A. E.; Crnojević, D. +8 more
A census of the satellite population around dwarf galaxy primary hosts in environments outside the Local Group is essential to understanding Λ cold dark matter galaxy formation and evolution on the smallest scales. We present deep optical Hubble Space Telescope imaging of the gas-rich, faint dwarf galaxy Antlia B (M V = -9.4)—a likely…
Coronal Mini-jets in an Activated Solar Tornado-like Prominence
Zhang, Jun; De Pontieu, Bart; Kliem, Bernhard +3 more
High-resolution observations from the Interface Region Imaging Spectrometer reveal the existence of a particular type of small solar jet, which arose singly or in clusters from a tornado-like prominence suspended in the corona. In this study, we perform a detailed statistical analysis of 43 selected mini-jets in the tornado event. Our results show…
Dynamical Masses of Young Stars. II. Young Taurus Binaries Hubble 4, FF Tau, and HP Tau/G3
Rizzuto, Aaron C.; Dupuy, Trent J.; Ireland, Michael J. +1 more
One of the most effective ways to test stellar evolutionary models is to measure dynamical masses for binary systems at a range of temperatures. In this paper, we present orbits of three young K+M binary systems in Taurus (Hubble 4, FF Tau, and HP Tau/G3) with very long baseline interferometry parallaxes. We obtained precision astrometry with Keck…