Search Publications
New Physical Insights about Tidal Disruption Events from a Comprehensive Observational Inventory at X-Ray Wavelengths
Ramirez-Ruiz, Enrico; Auchettl, Katie; Guillochon, James
We perform a comprehensive study of the X-ray emission from 70 transient sources that have been classified as tidal disruption events (TDEs) in the literature. We explore the properties of these candidates, using nearly three decades of X-ray observations to quantify their properties and characteristics. We find that the emission from X-ray TDEs i…
Simultaneous X-Ray, Gamma-Ray, and Radio Observations of the Repeating Fast Radio Burst FRB 121102
Ransom, S. M.; Chatterjee, S.; Cordes, J. M. +19 more
We undertook coordinated campaigns with the Green Bank, Effelsberg, and Arecibo radio telescopes during Chandra X-ray Observatory and XMM-Newton observations of the repeating fast radio burst FRB 121102 to search for simultaneous radio and X-ray bursts. We find 12 radio bursts from FRB 121102 during 70 ks total of X-ray observations. We detect no …
X-Ray Brightening and UV Fading of Tidal Disruption Event ASASSN-15oi
Cenko, S. B.; Arcavi, I.; Gezari, S.
We present late-time observations by Swift and XMM-Newton of the tidal disruption event (TDE) ASASSN-15oi that reveal that the source brightened in the X-rays by a factor of ∼10 one year after its discovery, while it faded in the UV/optical by a factor of ∼100. The XMM-Newton observations measure a soft X-ray blackbody component with {{kT}}{b…
iPTF Discovery of the Rapid “Turn-on” of a Luminous Quasar
Cenko, S. B.; Kulkarni, S. R.; Nugent, P. E. +13 more
We present a radio-quiet quasar at z = 0.237 discovered “turning on” by the intermediate Palomar Transient Factory (iPTF). The transient, iPTF 16bco, was detected by iPTF in the nucleus of a galaxy with an archival Sloan Digital Sky Survey spectrum with weak narrow-line emission characteristic of a low-ionization nuclear emission-line region (LINE…
X-Ray Morphological Analysis of the Planck ESZ Clusters
Lovisari, Lorenzo; Andrade-Santos, Felipe; Jones, Christine +7 more
X-ray observations show that galaxy clusters have a very large range of morphologies. The most disturbed systems, which are good to study how clusters form and grow and to test physical models, may potentially complicate cosmological studies because the cluster mass determination becomes more challenging. Thus, we need to understand the cluster pr…
Pulsator-like Spectra from Ultraluminous X-Ray Sources and the Search for More Ultraluminous Pulsars
Mereghetti, S.; Stella, L.; Wolter, A. +3 more
Ultraluminous X-ray sources (ULXs) are a population of extragalactic objects whose luminosity exceeds the Eddington limit for a 10 M ⊙ black hole (BH). Their properties have been widely interpreted in terms of accreting stellar-mass or intermediate-mass BHs. However at least three neutron stars (NSs) have been recently identified in ULX…
Constraints on Axion-like Particles from X-Ray Observations of NGC1275
Berg, Marcus; Conlon, Joseph P.; Day, Francesca +4 more
Axion-like particles (ALPs) can induce localized oscillatory modulations in the spectra of photon sources passing through astrophysical magnetic fields. Ultra-deep Chandra observations of the Perseus cluster contain over 5× {10}5 counts from the active galactic nucleus (AGN) of the central cluster galaxy NGC1275 and represent a data set…
Spectral Changes in the Hyperluminous Pulsar in NGC 5907 as a Function of Super-orbital Phase
Harrison, F. A.; Stern, D.; Bachetti, M. +5 more
We present broadband, multi-epoch X-ray spectroscopy of the pulsating ultra-luminous X-ray source (ULX) in NGC 5907. Simultaneous XMM-Newton and NuSTAR data from 2014 are best described by a multicolor blackbody model with a temperature gradient as a function of accretion disk radius significantly flatter than expected for a standard thin accretio…
General Physical Properties of CGRaBS Blazars
Ajello, M.; Rao, A. R.; Hartmann, D. +4 more
We present the results of a multi-frequency, time-averaged analysis of blazars included in the Candidate Gamma-ray Blazar Survey catalog. Our sample consists of 324 γ-ray detected (γ-ray loud) and 191 γ-ray undetected (γ-ray quiet) blazars; we consider all the data up to 2016 April 1. We find that both the γ-ray loud and γ-ray quiet blazar populat…
X-Ray and Radio Observations of the Magnetar SGR J1935+2154 during Its 2014, 2015, and 2016 Outbursts
Göğüş, Ersin; Kouveliotou, Chryssa; Lin, Lin +10 more
We analyzed broadband X-ray and radio data of the magnetar SGR J1935+2154 taken in the aftermath of its 2014, 2015, and 2016 outbursts. The source soft X-ray spectrum <10 keV is well described with a blackbody+power-law (BB+PL) or 2BB model during all three outbursts. Nuclear Spectroscopic Telescope Array observations revealed a hard X-ray tail…