Search Publications
HSC-XD 52: An X-Ray Detected AGN in a Low-mass Galaxy at z ∼ 0.56
Johnson, Sean D.; Sawicki, Marcin; Gwyn, Stephen +8 more
The properties of low-mass galaxies hosting central black holes provide clues about the formation and evolution of the progenitors of supermassive black holes. In this Letter, we present HSC-XD 52, a spectroscopically confirmed low-mass active galactic nucleus (AGN) at an intermediate redshift of z ∼ 0.56. We detect this object as a very luminous …
The Nature of the Broadband X-Ray Variability in the Dwarf Seyfert Galaxy NGC 4395
Kaastra, J. S.; Stern, D.; Brandt, W. N. +14 more
We present a flux-resolved X-ray analysis of the dwarf Seyfert 1.8 galaxy NGC 4395, based on three archival XMM-Newton and one archival NuSTAR observations. The source is known to harbor a low-mass black hole (∼ {10}4{--}{{a}} {few} × {10}5 {M}⊙ ) and shows strong variability in the full X-ray range during these ob…
Probing Clumpy Wind Accretion in IGR J18027-2016 with XMM-Newton
Paul, Biswajit; Ferrigno, Carlo; Pradhan, Pragati +2 more
Supergiant X-ray binaries usually comprise a neutron star accreting from the wind of an OB supergiant companion. They are classified as classical systems and supergiant fast X-ray transients (SFXTs). The different behavior of these subclasses of sources in X-rays, with SFXTs displaying much more pronounced variability, is usually (at least) partly…
Dynamical Masses for the Hyades Binary 80 Tauri
Torres, Guillermo
The empirical mass-luminosity relation in the Hyades cluster rests on dynamical mass determinations for five binary systems, of which one is eclipsing and the other four are visual or interferometric binaries. The last one was identified and first measured more than 20 yr ago. Here we present dynamical mass measurements for a new binary system in …
Active Galactic Nuclei in Dusty Starbursts at z = 2: Feedback Still to Kick in
Daddi, E.; Rodighiero, G.; Rujopakarn, W. +18 more
We investigate a sample of 152 dusty sources at 1.5 < z < 2.5 to understand the connection of enhanced star formation rate (SFR) and black hole accretion rate. The sources are Herschel-selected, having stellar masses M * > 1010 M ⊙ and SFR (∼100-1000 M ⊙ yr-1) elevated (>4×) above …
Stellar Pulsation and the Production of Dust and Molecules in Galactic Carbon Stars
McDonald, Iain; Sloan, G. C.; Groenewegen, Martin A. T. +3 more
New infrared spectra of 33 Galactic carbon stars from FORCAST on SOFIA reveal strong connections between stellar pulsations and the dust and molecular chemistry in their circumstellar shells. A sharp boundary in overall dust content, which predominantly measures the amount of amorphous carbon, separates the semiregular and Mira variables, with the…
The Time-domain Spectroscopic Survey: Radial Velocity Variability in Dwarf Carbon Stars
Roulston, Benjamin R.; Green, Paul J.; Anderson, Scott F. +6 more
Dwarf carbon (dC) stars (main-sequence stars showing carbon molecular bands) were initially thought to be an oxymoron because only asymptotic giant branch (AGB) stars dredge carbon into their atmospheres. Mass transfer from a former AGB companion that has since faded to a white dwarf seems the most likely explanation. Indeed, a few types of giants…
On the Relation between Flare and CME during GLE-SEP and Non-GLE-SEP Events
Gan, W. Q.; Moon, Y. -J.; Rodríguez-Pacheco, J. +2 more
Association of solar flares and coronal mass ejections (CMEs) with ground-level enhancement (GLE) is a recognized fact, but questions arise when a similar association is observed for non-GLEs. In this respect, we carry out a detailed study of the relation between flare fluences (ϕ J m-2) and CME speeds (V cme km s-1
FUSE Spectroscopic Analysis of the Slowest Symbiotic Nova AG Peg During Quiescence
Sion, Edward M.; Godon, Patrick; Mikolajewska, Joanna +1 more
We present a far-UV (FUV) spectroscopic analysis of the slowest known symbiotic nova AG Peg that underwent a nova explosion in 1850 followed by a very slow decline that did not end until ∼1996, marking the beginning of quiescence. In 2015 June, when AG Peg exhibited a Z And-type outburst with an optical amplitude of ∼1.5 mag. We used accretion dis…
The Period Change of Cyg X-3
Antokhin, Igor I.; Cherepashchuk, Anatol M.
By using available archival X-ray data, we significantly extended the list of times of X-ray minima. The new list includes 65 data points obtained by critically reanalyzing RXTE ASM data, 88 data points based on observations by MAXI, and 2 data points based on observations by SUZAKU and AstroSat. Analyzing the data along with times of X-ray minima…