Search Publications
A Population of Bona Fide Intermediate-mass Black Holes Identified as Low-luminosity Active Galactic Nuclei
Boutsia, Konstantina; Chilingarian, Igor V.; Zolotukhin, Ivan Yu. +4 more
Nearly every massive galaxy harbors a supermassive black hole (SMBH) in its nucleus. SMBH masses are millions to billions of solar mass, and they correlate with properties of spheroids of their host galaxies. While the SMBH growth channels, mergers, and gas accretion are well established, their origin remains uncertain: they could have emerged eit…
Evidence for Pulsar-like Emission Components in the Broadband ULX Sample
Harrison, F. A.; Stern, D.; Fabian, A. C. +7 more
We present broadband X-ray analyses of a sample of bright ultraluminous X-ray sources (ULX) with the goal of investigating the spectral similarity of this population to the known ULX pulsars, M82 X-2, NGC 7793 P13, and NGC 5907 ULX. We perform a phase-resolved analysis of the broadband XMM-Newton+NuSTAR data set of NGC 5907 ULX, finding that the p…
Revival of the Magnetar PSR J1622-4950: Observations with MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR
Tasse, C.; Camilo, F.; Stappers, B. +205 more
New radio (MeerKAT and Parkes) and X-ray (XMM-Newton, Swift, Chandra, and NuSTAR) observations of PSR J1622-4950 indicate that the magnetar, in a quiescent state since at least early 2015, reactivated between 2017 March 19 and April 5. The radio flux density, while variable, is approximately 100× larger than during its dormant state. The X-ray flu…
The Extended Distribution of Baryons around Galaxies
Bregman, Joel N.; Anderson, Michael E.; Qu, Zhijie +5 more
We summarize and reanalyze observations bearing on missing galactic baryons, where we propose a consistent picture for halo gas in L ≳ L* galaxies. The hot X-ray-emitting halos are detected to 50-70 kpc, where typically M hot(<50 kpc) ∼ 5 × 109 M ⊙, and with density n ∝ r -3/2. When extrapolated to R …
The MUSCLES Treasury Survey. V. FUV Flares on Active and Inactive M Dwarfs
Loyd, R. O. Parke; Redfield, Seth; Brown, Alexander +10 more
M dwarf stars are known for their vigorous flaring. This flaring could impact the climate of orbiting planets, making it important to characterize M dwarf flares at the short wavelengths that drive atmospheric chemistry and escape. We conducted a far-ultraviolet flare survey of six M dwarfs from the recent MUSCLES (Measurements of the Ultraviolet …
The Kepler Light Curves of AGN: A Detailed Analysis
Howell, Steve B.; Gelino, Dawn M.; Boyd, Patricia T. +3 more
We present a comprehensive analysis of 21 light curves of Type 1 active galactic nuclei (AGN) from the Kepler spacecraft. First, we describe the necessity and development of a customized pipeline for treating Kepler data of stochastically variable sources like AGN. We then present the light curves, power spectral density functions (PSDs), and flux…
A Potential Cyclotron Resonant Scattering Feature in the Ultraluminous X-Ray Source Pulsar NGC 300 ULX1 Seen by NuSTAR and XMM-Newton
Harrison, F. A.; Fabian, A. C.; Pinto, C. +14 more
Based on phase-resolved broadband spectroscopy using XMM-Newton and NuSTAR, we report on a potential cyclotron resonant scattering feature (CRSF) at E ∼ 13 keV in the pulsed spectrum of the recently discovered ultraluminous X-ray source (ULX) pulsar NGC 300 ULX1. If this interpretation is correct, the implied magnetic field of the central neutron …
Compton-thick AGNs in the NuSTAR Era
Vignali, C.; Comastri, A.; Ajello, M. +3 more
We present the 2-100 keV spectral analysis of 30 candidate Compton-thick-(CT-)active galactic nuclei (AGNs) selected in the Swift-Burst Alert Telescope (BAT) 100 month survey. The average redshift of these objects is < z> ∼ 0.03, and they all lie within ∼500 Mpc. We used the MyTorus model to perform X-ray spectral fittings both without and w…
Intermediate-mass Elements in Young Supernova Remnants Reveal Neutron Star Kicks by Asymmetric Explosions
Katsuda, Satoru; Janka, Hans-Thomas; Tominaga, Nozomu +9 more
The birth properties of neutron stars (NSs) yield important information about the still-debated physical processes that trigger the explosion as well as on intrinsic neutron-star physics. These properties include the high space velocities of young neutron stars with average values of several 100 km s-1, with an underlying “kick” mechani…
Exploring the Effects of Disk Thickness on the Black Hole Reflection Spectrum
Reynolds, Christopher S.; Taylor, Corbin
The relativistically broadened reflection spectrum, observed in both AGN and X-ray binaries, has proven to be a powerful probe of the properties of black holes and the environments in which they reside. Emitted from the innermost regions of the accretion disk, this X-ray spectral component carries with it information not only about the plasma that…