Search Publications
XMM-Newton and NuSTAR Observations of the Compact Millisecond Pulsar Binary PSR J1653-0158
Wu, Kinwah; Kong, Albert K. H.; Takata, Jumpei +4 more
We have presented the first joint XMM-Newton and NuSTAR analysis of the millisecond pulsar (MSP) binary PSR J1653-0158. The 75 minute orbital period inferred from optical and gamma-ray observations together with the 1.97 ms pulsation in the gamma-rays indicate that this system is the most compact Black Widow MSP system known to date. The orbital p…
Solar Polar Flux Redistribution Based on Observed Coronal Holes
Jones, Shaela I.; Arge, Charles N.; Henney, Carl J. +1 more
We explore the use of observed polar coronal holes (CHs) to constrain the flux distribution within the polar regions of global solar magnetic field maps in the absence of reliable quality polar field observations. Global magnetic maps, generated by the Air Force Data Assimilative Photospheric flux Transport (ADAPT) model, are modified to enforce f…
Estimating the Spin of the Black Hole Candidate MAXI J1659-152 with the X-Ray Continuum-fitting Method
Steiner, James F.; Gou, Lijun; Wu, Jianfeng +6 more
As a transient X-ray binary, MAXI J1659-152 contains a black hole candidate as its compact star. MAXI J1659-152 was discovered on 2010 September 25 during its only known outburst. Previously published studies of this outburst indicate that MAXI J1659-152 may have an extreme retrograde spin, which, if confirmed, would provide an important clue as t…
Searching for Cataclysmic Variable Stars in Unidentified X-Ray Sources
Takata, J.; Kong, A. K. H.; Hui, C. Y. +6 more
We carry out a photometric search for new cataclysmic variable stars (CVs), with the goal of identification for candidates of AR Scorpii-type binary systems. We select GAIA sources that are likely associated with unidentified X-ray sources, and analyze the light curves taken by the Zwicky Transient Facility, Transiting Exoplanet Survey Satellite, …
X-Ray and GeV-γ-Ray Emission Property of TeV Compact Symmetric Object PKS 1413+135 and Implication for Episodic Jet Activity
Liang, En-Wei; Yao, Su; Zhang, Hai-Ming +3 more
PKS 1413+135, a compact symmetric object (CSO) with a two-sided parsec-scale structure in its miniature radio morphology, is spatially associated with 4FGL J1416.1+1320 and recently detected with MAGIC telescopes. We comprehensively analyze its X-ray and gigaelectronvolt γ-ray observation data to reveal its high-energy radiation physics. It is fou…
A Magnetic Valve at L1 Revealed in TESS Photometry of the Asynchronous Polar BY Cam
Ramsay, Gavin; Garnavich, Peter; Littlefield, Colin +7 more
We present TESS photometry of the asynchronous polar BY Cam, which undergoes a beat cycle between the 199.384 min white dwarf (WD) spin period and the 201.244 min orbital period. This results in changes in the flow of matter onto the WD. The TESS light curve covers 92% of the beat cycle once and 71% of the beat cycle twice. The strongest photometr…
Swift J0503.7-2819: a Short-period Asynchronous Polar or Stream-fed Intermediate Polar
Halpern, J. P.
We analyze a 7.4 hr XMM-Newton light curve of the cataclysmic variable Swift J0503.7-2819, previously classified using optical periods as an intermediate polar (IP) with an orbital period of 0.0567 days. A photometric signal at 975 s, previously suggested to be the spin period, is not present in X-rays and is readily understood as a quasiperiodic …
The Internal Line-of-Sight Kinematics of NGC 346: The Rotation of the Core Region
Sabbi, Elena; Nota, Antonella; Zeidler, Peter
We present the stellar radial velocity analysis of the central $1^{\prime} \times 1^{\prime} $ of the young massive Small Magellanic Cloud star cluster NGC 346. Using VLT/MUSE integral field spectroscopy in combination with Hubble Space Telescope photometry, we extract 103 spectra of cluster member stars suited to measure accurate line-of-sight ki…
Effect of Differential Rotation on the Magnetic Braking of Low-mass and Solar-like Stars: A Proof-of-concept Study
Finley, Adam J.; Matt, Sean P.; Ireland, Lewis G. +4 more
On the main sequence, low-mass and solar-like stars are observed to spin down over time, and magnetized stellar winds are thought to be predominantly responsible for this significant angular momentum loss. Previous studies have demonstrated that the wind torque can be predicted via formulations dependent on stellar properties, such as magnetic fie…
AstroSat View of Spectral Transition in the Changing-look Active Galaxy NGC 1566 during the Declining Phase of the 2018 Outburst
Dewangan, Gulab C.; Tripathi, Prakash
NGC 1566 is a changing-look active galaxy that exhibited an outburst during 2017-2018 with a peak in 2018 June. We triggered AstroSat observations of NGC 1566 twice in 2018 August and October during its declining phase. Using the AstroSat observations, along with two XMM-Newton observations in 2015 (pre-outburst) and 2018 June (peak outburst), we …