Search Publications
Predicting the black hole mass and correlations in X-ray reverberating AGNs using neural networks
Chainakun, P.; Young, A. J.; Hancock, S. +1 more
We develop neural network models to predict the black hole mass using 22 reverberating active galactic nucleus (AGN) samples in the XMM-Newton archive. The model features include the fractional excess variance (Fvar) in 2-10 keV band, Fe-K lag amplitude, 2-10 keV photon counts, and redshift. We find that the prediction accuracy of the n…
Non-LTE Inversion of Prominence Spectroscopic Observations in Hα and Mg II h&k lines
Heinzel, Petr; Schmieder, Brigitte; Jejčič, Sonja +4 more
We continued our investigation of the plasma characteristics of a quiescent prominence that occurred on 2017 March 30. The prominence was observed simultaneously by several instruments, including the Interface Region Imaging Spectrograph (IRIS) and the Multichannel Subtractive Double Pass (MSDP) spectrograph operating at the Meudon solar tower. We…
Solenoidal turbulent modes and star formation efficiency in Galactic plane molecular clouds
Rigby, Andrew J.; Eden, David J.; Rani, Raffaele +1 more
It is speculated that the high star formation efficiency observed in spiral-arm molecular clouds is linked to the prevalence of compressive (curl-free) turbulent modes, while the shear-driven solenoidal (divergence-free) modes appear to be the main cause of the low star formation efficiency that characterizes clouds in the Central Molecular Zone. …
Age-morphology dependence of the Milky Way boxy/peanut bulge seen in Mira variables
Schönrich, Ralph; Dehnen, Walter; Semczuk, Marcin +1 more
We analyse the distribution of Mira variable stars in the central region of the Milky Way. We find that with increasing period, i.e. decreasing age, the Miras shift towards negative Galactic longitudes ℓ. Comparing to a cosmological zoom simulation of a barred galaxy, we find that this shift with age can be explained by an age-morphology dependenc…
An X-Ray Study of Coronally Connected Active Eclipsing Binaries
Pandey, J. C.; Singh, Gurpreet
We present a detailed X-ray analysis and imaging of stellar coronae of five coronally connected eclipsing binaries, namely, 44 Boo, DV Psc, ER Vul, XY UMa, and TX Cnc. Both components of these binaries are found to be active. The X-ray light curves of detached and semidetached type systems show eclipsed-like features, whereas no evidence for coron…
Absolute calibration of the Colour and Stereo Surface Imaging System (CaSSIS)
Almeida, Miguel; Cremonese, Gabriele; Thomas, Nicolas +5 more
The Colour and Stereo Surface Imaging System (CaSSIS) onboard the ExoMars Trace Gas Orbiter (TGO) has observed several standard stars and Jupiter with the aim of deriving the absolute calibration factors that convert observed signal into reflectance ("I over F"). The targets were observed through all four colour filters and hence a relative calibr…
Multiwavelength study of the gravitationally lensed blazar QSO B0218+357 between 2016 and 2020
Maraschi, L.; Covino, S.; Antonelli, L. A. +207 more
We report multiwavelength observations of the gravitationally lensed blazar QSO B0218+357 in 2016-2020. Optical, X-ray, and GeV flares were detected. The contemporaneous MAGIC observations do not show significant very high energy (VHE; ≳100 GeV) gamma-ray emission. The lack of enhancement in radio emission measured by The Owens Valley Radio Observ…
Mass-ratio Distribution of Binaries from the LAMOST-MRS Survey
Wang, Luqian; Han, Zhanwen; Chen, Xuefei +7 more
Binary evolution leads to the formation of important objects that are crucial for the development of astrophysics, but the statistical properties of binary populations are still poorly understood. The LAMOST-MRS has provided a large sample of stars to study the properties of binary populations, especially for the mass-ratio distributions and binar…
Polar and mid-latitude vortices and zonal flows on Jupiter and Saturn
Yadav, Rakesh K.; Featherstone, Nicholas A.; Aurnou, Jonathan M. +1 more
Zonal flow on Jupiter and Saturn consists of equatorial super-rotation and alternating East-West jet streams at higher latitudes. Interacting with these zonal flows, numerous vortices occur with various sizes and lifetimes. The Juno mission and Cassini's grand finale have shown that the zonal jets of Jupiter and Saturn extend deeply into their mol…
Effects of Hydrogen versus Helium on Electromagnetic Black Hole Observables
Gammie, Charles F.; Wong, George N.
The centers of our Galaxy and the nearby Messier 87 are known to contain supermassive black holes, which support accretion flows that radiate across the electromagnetic spectrum. Although the composition of the accreting gas is unknown, it is likely a mix of ionized hydrogen and helium. We use a simple analytic model and a suite of numerical gener…