Search Publications
Surveying Flux Density in Galaxies with Apparent Large Black Holes at Millimeter/Submillimeter Wavelengths
Matsushita, Satoki; Bower, Geoffrey C.; Nakamura, Masanori +5 more
We present millimeter and submillimeter continuum observations for 36 sources with potentially large black hole shadows at 230 and 345 GHz using the Submillimeter Array. The sources are selected based on the criterion of the large diameter of the black hole shadows. Our motivation is to explore the nature of the accretion flow of the potential can…
Numerical Simulation on the Leading Edge of Coronal Mass Ejection in the Near-Sun Region
Ye, Jing; Li, Yan; Mei, Zhixing +3 more
The coronal mass ejections (CMEs) observed by white-light coronagraphs, such as the Large Angle and Spectrometric Coronagraph (LASCO) C2/C3, commonly exhibit the three-part structure, with the bright leading edge as the outermost part. In this work, we extend previous work on the leading edge by performing a large-scale 3D magnetohydrodynamic nume…
Sudden Extreme Obscuration of a Sun-like Main-sequence Star: Evolution of the Circumstellar Dust around ASASSN-21qj
Kemper, Francisca; Ertel, Steve; Scicluna, Peter +6 more
ASASSN-21qj is a distant Sun-like star that recently began an episode of deep dimming events after no prior recorded variability. Here we examine archival and newly obtained optical and near-infrared data of this star. The deep aperiodic dimming and absence of previous infrared excess are reminiscent of KIC 8462852 ("Boyajian's Star"). The observe…
Structure of a Quasi-parallel Shock Front
Zhang, Tielong; Gedalin, Michael; Walker, Simon N. +2 more
The aim of this study is to compare observations of the magnetic field structure of observed quasi-parallel collisionless shock fronts with the results obtained analytically. A two-fluid analytic model of the shock front structure was derived under the assumptions that the shock is stationary and planar. The ion and electron kinetic pressures were…
Point-source Contribution to the Diffuse X-Ray Background below 1 keV and Its Effect on Our Understanding of the Circumgalactic Medium
Gupta, Anjali; Galeazzi, Massimiliano; Ursino, Eugenio +4 more
We studied the spectral signature of different components of the diffuse X-ray background (DXB), including Local Hot Bubble, solar wind charge exchange, galactic halo, and typically unresolved point sources (galaxies and active galactic nuclei), in the direction of the Chandra Deep Field South using the 4 Ms XMM-Newton survey and Chandra 4 Ms Sour…
Observations of Multiphase, High-velocity, Shocked Gas in the Vela Supernova Remnant
Ritchey, Adam M.
We present an analysis of high-resolution far-UV archival spectra obtained with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope of the star HD 75309, which probes high-velocity shocked gas in the Vela supernova remnant (SNR). We examine high-velocity features from intrinsically strong absorption lines of O I, Si II, Si II*, …
Population of X-Ray Sources in the Intermediate-age Cluster NGC 3532: a Test Bed for Machine-learning Classification
Kargaltsev, Oleg; Chen, Steven; Yang, Hui +4 more
Open clusters are thought to be the birthplace of most stars in the galaxy. Thus, they are excellent laboratories for investigating stellar evolution, and X-ray properties of various types of stars (including binary stars, evolved stars, and compact objects). In this work, we investigate the population of X-ray sources in the nearby 300 Myr old op…
The [O III] Profiles of Far-infrared Active and Inactive Optically Selected Green Valley Galaxies
Pović, Mirjana; Väisänen, Petri; Márquez, Isabel +8 more
We present a study of the [O III] λ5007 line profile in a subsample of eight active galactic nuclei (AGNs) and six non-AGNs in the optically selected green valley at z < 0.5 using long-slit spectroscopic observations obtained with the 11 m Southern African Large Telescope. Gaussian decomposition of the line profile was performed to study its di…
G 68-34: A Double-lined M-dwarf Eclipsing Binary in a Hierarchical Triple System
Charbonneau, David; Pass, Emily K.
Using high-resolution spectra from the Tillinghast Reflector Echelle Spectrograph and photometry from sector 56 of the Transiting Exoplanet Survey Satellite, we report that the nearby M dwarf G 68-34 is a double-lined eclipsing binary. The pair is spin-orbit synchronized with a period of 0.655 days. The light curve shows significant spot modulatio…
Nonthermal X-Rays from Pulsation-driven Shocks in Cepheids
Drake, Jeremy J.; Evans, Nancy Remage; Fraschetti, Federico +1 more
Rapid X-ray phase-dependent flux enhancement in the archetype classical Cepheid star δ Cep was observed by XMM-Newton and Chandra. We jointly analyze thermal and nonthermal components of the time-resolved X-ray spectra prior to, during, and after the enhancement. A comparison of the timescales of shock particle acceleration and energy losses is co…