Search Publications
A Library of Synthetic X-Ray Spectra for Fitting Tidal Disruption Events
Wen, Sixiang; Jonker, Peter G.; Stone, Nicholas C. +2 more
We present a tabulated version of our slim-disk model for fitting tidal disruption events (TDEs). We create a synthetic X-ray spectral library by ray-tracing stationary general relativistic slim disks and including gravitational redshift, Doppler, and lensing effects self-consistently. We introduce the library to reduce computational expense and i…
Bayesian Solar Wind Modeling with Pulsar Timing Arrays
Ransom, Scott M.; Zhu, Weiwei; Ray, Paul S. +29 more
Using Bayesian analyses we study the solar electron density with the NANOGrav 11 yr pulsar timing array (PTA) data set. Our model of the solar wind is incorporated into a global fit starting from pulse times of arrival. We introduce new tools developed for this global fit, including analytic expressions for solar electron column densities and open…
Anomalous Cosmic-Ray Oxygen Observations into 0.1 au
McComas, D. J.; Christian, E. R.; Leske, R. A. +10 more
The Integrated Science Investigation of the Sun instrument suite onboard NASA's Parker Solar Probe mission continues to measure solar energetic particles and cosmic rays closer to the Sun than ever before. Here, we present the first observations of cosmic rays into 0.1 au (21.5 solar radii), focusing specifically on oxygen from ~2018.7 to ~2021.2.…
Spectroastrometry and Reverberation Mapping: The Mass and Geometric Distance of the Supermassive Black Hole in the Quasar 3C 273
Zhang, Zhi-Xiang; Du, Pu; Hu, Chen +4 more
The quasar 3C 273 has been observed with infrared spectroastrometry (SA) of the broad Paα line and optical reverberation mapping (RM) of the broad Hβ line. SA delivers information about the angular size and structure of the Paα broad-line region (BLR), while RM delivers information about the physical size and structure of the Hβ BLR. Based on the …
The Unusually Weak and Exceptionally Steep Radio Relic in A2108
Lovisari, Lorenzo; Raychaudhury, Somak; Giacintucci, Simona +9 more
Mergers between galaxy clusters often drive shocks into the intracluster medium, the effects of which are sometimes visible via temperature and density jumps in the X-ray and via radio emission from relativistic particles energized by the shock's passage. A2108 was selected as a likely merger system through comparing the X-ray luminosity to the Pl…
Extremely Low-mass White Dwarf Stars Observed in Gaia DR2 and LAMOST DR8
Luo, Yangping; Németh, Péter; Wang, Kun +3 more
We present the first results from our ongoing project to study extremely low-mass (ELM) white dwarfs (WDs) (M ≤ 0.3M ⊙) with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectra. Based on the LAMOST DR8 spectral database, we analyzed 136 ELM WD candidates selected from Gaia DR2 data and 12 known objects previou…
NICER Monitoring of Supersoft X-Ray Sources
Luna, G. J. M.; Behar, E.; Orio, M. +9 more
We monitored four supersoft sources-two persistent ones, CAL 83 and MR Vel, and the recent novae YZ Ret (Nova Ret 2020), and V1674 Her (Nova Her 2021)-with NICER. The two persistent supersoft X-ray sources (SSS) were observed with unvaried X-ray flux level and spectrum, respectively, 13 and 20 yr after the last observations. Short-period modulatio…
A Multi-epoch, Multiwavelength Study of the Classical FUor V1515 Cyg Approaching Quiescence
Ogłoza, Waldemar; Cseh, B.; Kriskovics, L. +29 more
Historically, FU Orionis-type stars are low-mass, pre-main-sequence stars. The members of this class experience powerful accretion outbursts and remain in an enhanced accretion state for decades or centuries. V1515 Cyg, a classical FUor, started brightening in the 1940s and reached its peak brightness in the late 1970s. Following a sudden decrease…
Recurrent Strong Outbursts of an EXor-like Young Eruptive Star Gaia20eae
Ogłoza, Waldemar; Ábrahám, Péter; Kóspál, Ágnes +21 more
We present follow-up photometric and spectroscopic observations, and subsequent analysis of Gaia20eae. This source triggered photometric alerts during 2020 after showing a ~3 mag increase in its brightness. Its Gaia Alert light curve showed the shape of a typical eruptive young star. We carried out observations to confirm Gaia20eae as an eruptive …
Antaeus: A Retrograde Group of Tidal Debris in the Milky Way's Disk Plane
Martin, Nicolas; Famaey, Benoit; Viswanathan, Akshara +5 more
We present the discovery of a wide retrograde moving group in the disk plane of the Milky Way using action-angle coordinates derived from the Gaia DR3 catalog. The structure is identified from a sample of its members that are currently almost at the pericenter of their orbit and are passing through the solar neighborhood. The motions of the stars …