Search Publications
Test for Echo: X-Ray Reflection Variability in the Seyfert-2 Active Galactic Nucleus NGC 4388
Brandt, W. N.; Arzoumanian, Zaven; Gendreau, Keith +4 more
We report on a study of the narrow Fe Kα line and reflection spectrum in the well-known Seyfert-2 active galactic nucleus (AGN), NGC 4388. X-ray spectra summed from two extensive NICER monitoring campaigns, separated by years, show strong evidence of variation in the direct continuum and reflected emission, but only small variations in the obscuri…
X-ray Observations of the Intermediate Polar TX Col
Joshi, Arti; Rawat, Nikita; Rao, Srinivas M. +2 more
We present the timing analysis of the intermediate polar TX Col in the X-ray band using the observations made by Chandra, Swift, and Suzaku during the years 2000, 2007, and 2009, respectively. The spin, orbital, and beat periods derived from these data are consistent with the earlier findings. We found that the spin modulation was dominant during …
Se-ResNet+SVM Model: An Effective Method of Searching for Hot Subdwarfs from LAMOST
Wu, Tianmin; Yi, Zhenping; Lei, Zhenxin +7 more
This paper presents a robust neural network approach for identifying hot subdwarfs. Our method leveraged the Squeeze-and-Excitation Residual Network to extract abstract features, which were combined with experience features to create hybrid features. These hybrid features were then classified using a support vector machine. To enhance accuracy, we…
V0405 Dra: A New Deep and Low Mass Ratio Contact Binary with Extremely Fast Decrease in the Orbital Period
Zheng, Jie; Jiang, Lin-Qiao; Tian, Xiao-Man +5 more
V0405 Dra is a W UMa-type binary star. Based on the TESS data, we have conducted an orbital period study and performed a light curve analysis for the system. The orbital period study reveals that the O ‑ C curve for V0405 Dra exhibits secular decrease at an extremely high rate of dP/dt = ‑2.71 × 10‑6 day year‑1, along with pe…
Searching for new cataclysmic variables in different X-ray and optical catalogs
Galiullin, I. I.
Cataclysmic variables (CVs) are binary systems in which a white dwarf accretes matter from a Roche-lobe-filling companion star. Numerous CVs can be seen in optical light curves as periodic sources. Moreover, accretion can result in outbursts, which are visible in their optical light curves, especially in non-magnetic CVs. I review a modern multiwa…
MUSE-ALMA Haloes X: the stellar masses of gas-rich absorbing galaxies
Hayes, M.; Kacprzak, G. G.; Kuntschner, H. +13 more
The physical processes by which gas is accreted onto galaxies, transformed into stars, and then expelled from galaxies are of paramount importance to galaxy evolution studies. Observationally constraining each of these baryonic components in the same system, however, is challenging. Furthermore, simulations indicate that the stellar mass of galaxi…
Temperature anisotropy instabilities driven by intermittent velocity shears in the solar wind
Sorriso-Valvo, Luca; Verscharen, Daniel; Chen, Christopher H. K. +5 more
Where and under what conditions the transfer of energy between electromagnetic fields and particles takes place in the solar wind remains an open question. We investigate the conditions that promote the growth of kinetic instabilities predicted by linear theory to infer how turbulence and temperature-anisotropy-driven instabilities are interrelate…
Reconstructing the mid-infrared spectra of galaxies using ultraviolet to submillimeter photometry and Deep Generative Networks
Efstathiou, A.; Rissaki, Agapi; Pavlou, O. +2 more
The mid-infrared spectra of galaxies are rich in features such as the Polycyclic Aromatic Hydrocarbon (PAH) and silicate dust features which give valuable information about the physics of galaxies and their evolution. For example they can provide information about the relative contribution of star formation and accretion from a supermassive black …
A summary of instruments proposed for observing pulsating variables from the Mt. Abu Observatory
Ganesh, Shashikiran; Prajapati, Prachi; Mishra, Anwesh Kumar +3 more
Pulsating variables play a significant role in shaping modern astronomy. Presently it is an exciting era in observational study of variable stars owing to surveys like OGLE and TESS. The vast number of sources being discovered by these surveys is also creating opportunities for 1–2-m class telescopes to provide follow-up observations to characteri…
Variable circularly polarized radio emission from the young stellar object [BHB2007]-1: Another ingredient of a unique system
Viganò, Daniele; Cleeves, L. Ilsedore; Zurlo, Alice +7 more
The young stellar object [BHB2007]-1 has been extensively studied in the past at radio, millimeter, and infrared wavelengths. It has revealed a gap in the disk and previous observations have claimed possible emission from a sub-stellar object undergoing formation, in correspondence to the disk gap. In this work, we analyzed a set of eight Karl G. …