Search Publications
Detection of a Highly Ionized Outflow in the Quasiperiodically Erupting Source GSN 069
Pinto, C.; Miniutti, G.; Brenneman, L. +8 more
Quasiperiodic eruptions (QPEs) are high-amplitude, soft X-ray bursts recurring every few hours, associated with supermassive black holes. Many interpretations for QPEs were proposed since their recent discovery in 2019, including extreme mass ratio inspirals and accretion disk instabilities. But, as of today, their nature still remains debated. We…
The Size of Accretion Disks from Self-consistent X-Ray Spectra and UV/Optical/NIR Photometry Fitting: Applications to ASASSN–14li and HLX–1
Mummery, Andrew; Guolo, Muryel
We implement a standard thin disk model with the outer disk radius (Rout) as a free parameter, integrating it into a standard X-ray fitting package to enable self-consistent and simultaneous fitting of X-ray spectra and Ultraviolet (UV), Optical, and Near-infrared (NIR) photometry. We apply the model to the late-time data (Δt ≈ 350–1300…
Einstein Probe Discovery of EP J005245.1‑722843: A Rare Be–White Dwarf Binary in the Small Magellanic Cloud?
Liu, Y.; Haberl, F.; Ness, J. -U. +32 more
On 2024 May 27, the Wide-field X-ray Telescope on board the Space Sciences, University of Chinese Academy of Einstein Probe (EP) mission detected enhanced X-ray emission from a new transient source in the Small Magellanic Cloud during its commissioning phase. Prompt follow-up with the EP Follow-up X-ray Telescope, the Swift X-ray Telescope. and NI…
Episodic X-Ray Outflows from the Tidal Disruption Event ASASSN-14li
Steiner, James F.; Tombesi, Francesco; Pasham, Dheeraj R. +4 more
ASASSN-14li is a low-redshift (z = 0.0206) tidal disruption event (TDE) that has been studied extensively across the entire electromagnetic spectrum and has provided one of the most sensitive measurements of a TDE to date. Its X-ray spectrum is soft and thermal (kT ∼ 0.05 keV) and shows a residual broad absorption feature between 0.6 and 0.8 keV, …
Hydrogen Column Density Variability in a Sample of Local Compton-thin AGN II
Buchner, J.; Ajello, M.; Marchesi, S. +7 more
We present the multiepoch analysis of 13 variable, nearby (z ≲ 0.1), and Compton-thin (1022 < NH < 1.5 × 1024 cm‑2) active galactic nuclei (AGN) selected from the 105-month BAT catalog. Analyzing all available archival soft and hard X-ray observations, we investigate the line-of-sight hydrogen colu…
The NuSTAR Local AGN N H Distribution Survey (NuLANDS). I. Toward a Truly Representative Column Density Distribution in the Local Universe
Brandt, William N.; Gandhi, Poshak; Ueda, Yoshihiro +33 more
Hard X-ray-selected samples of active galactic nuclei (AGN) provide one of the cleanest views of supermassive black hole accretion but are biased against objects obscured by Compton-thick gas column densities of N H > 1024 cm‑2. To tackle this issue, we present the NuSTAR Local AGN N H Distribution Su…
Characterization of a Peculiar Einstein Probe Transient EP240408a: An Exotic Gamma-Ray Burst or an Abnormal Jetted Tidal Disruption Event?
Buckley, David; Cenko, S. Bradley; Klingler, Noel +30 more
We present the results of our multiwavelength (X-ray to radio) follow-up campaign of the Einstein Probe transient EP240408a. The initial 10 s trigger displayed bright soft X-ray (0.5–4 keV) radiation with peak luminosity LX ≳ 1049 (1050) erg s‑1 for an assumed redshift z ≳ 0.5 (2.0). The Neil Gehrels Swi…
Multiwavelength Constraints on the Local Black Hole Occupation Fraction
Geha, Marla; Baldassare, Vivienne F.; Natarajan, Priyamvada +1 more
The fraction of dwarf galaxies hosting central, intermediate-mass black holes (IMBHs) at low redshifts is an important observational probe of black hole seeding at high redshift. Detections of nuclear accretion signatures in dwarf galaxies provides strong evidence for the presence of these IMBHs. We develop a Bayesian model to infer the black hole…
Time-resolved Hubble Space Telescope UV Observations of an X-Ray Quasiperiodic Eruption Source
Wevers, T.; Arcodia, R.; Pasham, D. R. +3 more
X-ray quasiperiodic eruptions (QPEs) are a novel mode of variability in nearby galactic nuclei whose origin remains unknown. Their multiwavelength properties are poorly constrained, as studies have focused almost entirely on the X-ray band. Here, we report on time-resolved, coordinated Hubble Space Telescope far-ultraviolet (FUV) and XMM-Newton X-…
The Mega-MUSCLES Treasury Survey: X-Ray to Infrared Spectral Energy Distributions of a Representative Sample of M Dwarfs
Loyd, R. O. Parke; Redfield, Seth; Roberge, Aki +15 more
We present 5–1 × 107 Å spectral energy distributions (SEDs) for 12 M dwarf stars covering spectral types M0–M8. Our SEDs are provided for community use as a sequel to the Measurements of the Ultraviolet Spectral Characteristics of Low-mass Exoplanetary Systems (MUSCLES) survey. The 12 stars include eight known exoplanet hosts and four s…