Search Publications
Rapid Accretion State Transitions following the Tidal Disruption Event AT2018fyk
Wevers, T.; Uttley, P.; Miller-Jones, J. C. A. +7 more
Following a tidal disruption event (TDE), the accretion rate can evolve from quiescent to near-Eddington levels and back over timescales of months to years. This provides a unique opportunity to study the formation and evolution of the accretion flow around supermassive black holes (SMBHs). We present 2 yr of multiwavelength monitoring observation…
Rapid Variability of Sgr A* across the Electromagnetic Spectrum
Morris, Mark R.; Smith, Howard A.; Fazio, G. G. +17 more
Sagittarius A* (Sgr A*) is the variable radio, near-infrared (NIR), and X-ray source associated with accretion onto the Galactic center black hole. We have analyzed a comprehensive submillimeter (including new observations simultaneous with NIR monitoring), NIR, and 2-8 keV data set. Submillimeter variations tend to lag those in the NIR by ~30 min…
Bridging the Gap between Protoplanetary and Debris Disks: Separate Evolution of Millimeter and Micrometer-sized Dust
Matthews, Brenda C.; van der Marel, Nienke; Michel, Arnaud
The connection between the nature of a protoplanetary disk and that of a debris disk is not well understood. Dust evolution, planet formation, and disk dissipation likely play a role in the processes involved. We aim to reconcile both manifestations of dusty circumstellar disks through a study of optically thin Class III disks and how they correla…
Identification of a Local Sample of Gamma-Ray Bursts Consistent with a Magnetar Giant Flare Origin
Cenko, S. B.; Hurley, K.; Ridnaia, A. +23 more
Cosmological gamma-ray bursts (GRBs) are known to arise from distinct progenitor channels: short GRBs mostly from neutron star mergers and long GRBs from a rare type of core-collapse supernova (CCSN) called collapsars. Highly magnetized neutron stars called magnetars also generate energetic, short-duration gamma-ray transients called magnetar gian…
22Ne Phase Separation as a Solution to the Ultramassive White Dwarf Cooling Anomaly
Blouin, Simon; Saumon, Didier; Daligault, Jérôme
The precise astrometric measurements of the Gaia Data Release 2 have opened the door to detailed tests of the predictions of white dwarf cooling models. Significant discrepancies between theory and observations have been identified, the most striking affecting ultramassive white dwarfs. Cheng et al. found that a small fraction of white dwarfs on t…
3D Morphology of Open Clusters in the Solar Neighborhood with Gaia EDR 3: Its Relation to Cluster Dynamics
Tang, Shih-Yun; Pang, Xiaoying; Kroupa, Pavel +5 more
We analyze the 3D morphology and kinematics of 13 open clusters (OCs) located within 500 pc of the Sun, using Gaia EDR 3 and kinematic data from the literature. Members of OCs are identified using the unsupervised machine-learning method StarGO, using five parameters (X, Y, Z, ${\mu }_{\alpha }\cos \delta ,{\mu }_{\delta }$ ). The OC sample covers…
Luminosity Functions and Host-to-host Scatter of Dwarf Satellite Systems in the Local Volume
Greene, Jenny E.; Beaton, Rachael L.; Peter, Annika H. G. +2 more
Low-mass satellites around Milky Way (MW)-like galaxies are important probes of small-scale structure and galaxy formation. However, confirmation of satellite candidates with distance measurements remains a key barrier to fast progress in the Local Volume (LV). We measure the surface brightness fluctuation distances to recently cataloged candidate…
Turbulent Generation of Magnetic Switchbacks in the Alfvénic Solar Wind
Cranmer, Steven R.; Shoda, Munehito; Chandran, Benjamin D. G.
One of the most important early results from the Parker Solar Probe (PSP) is the ubiquitous presence of magnetic switchbacks, whose origin is under debate. Using a three-dimensional direct numerical simulation of the equations of compressible magnetohydrodynamics from the corona to 40 solar radii, we investigate whether magnetic switchbacks emerge…
UV/Optical Disk Thermal Reverberation in Active Galactic Nuclei: An In-depth Study with an Analytic Prescription for Time-lag Spectra
Papadakis, I. E.; Dovčiak, M.; Karas, V. +2 more
Several active galactic nuclei show correlated variations in the UV/optical range, with time delays increasing at longer wavelengths. Thermal reprocessing of the X-rays illuminating the accretion disk has been proposed as a viable explanation. In this scenario, the variable X-ray flux irradiating the accretion disk is partially reflected in X-rays…
Illuminating the Dark Side of Cosmic Star Formation Two Billion Years after the Big Bang
Le Fèvre, Olivier; Faisst, Andreas; Cimatti, Andrea +5 more
How and when did galaxies form and assemble their stars and stellar mass? The answer to these questions, so crucial to astrophysics and cosmology, requires the full reconstruction of the so-called cosmic star formation rate density (SFRD), i.e., the evolution of the average star formation rate per unit volume of the universe. While the SFRD has be…