Search Publications
An active galactic nucleus recognition model based on deep neural network
Hashimoto, Tetsuya; Goto, Tomotsugu; Kim, Seong Jin +21 more
To understand the cosmic accretion history of supermassive black holes, separating the radiation from active galactic nuclei (AGNs) and star-forming galaxies (SFGs) is critical. However, a reliable solution on photometrically recognizing AGNs still remains unsolved. In this work, we present a novel AGN recognition method based on Deep Neural Netwo…
PS J1721+8842: a gravitationally lensed dual AGN system at redshift 2.37 with two radio components
Vegetti, S.; McKean, J. P.; Stacey, H. R. +4 more
Dual-Active Galactic Nuclei (AGN) are a natural consequence of the hierarchical structure formation scenario, and can provide an important test of various models for black hole growth. However, due to their rarity and difficulty to find at high redshift, very few confirmed dual-AGN are known at the epoch where galaxy formation peaks. Here we repor…
Discovery of soft and hard X-ray time lags in low-mass AGNs
Stalin, C. S.; De Marco, B.; Alston, W. N. +5 more
The scaling relations between the black hole (BH) mass and soft lag properties for both active galactic nuclei (AGNs) and BH X-ray binaries (BHXRBs) suggest the same underlying physical mechanism at work in accreting BH systems spanning a broad range of mass. However, the low-mass end of AGNs has never been explored in detail. In this work, we ext…
The origin of the soft X-ray excess in the narrow-line Seyfert 1 galaxy SBS 1353 + 564
Gu, Qiusheng; Guo, Xiaotong; Ding, Nan +2 more
We present for the first time the timing and spectral analyses for a narrow-line Seyfert 1 galaxy, SBS 1353 + 564, using XMM-Newton and Swift multiband observations from 2007 to 2019. Our main results are as follows: (1) The temporal variability of SBS 1353+564 is random, while the hardness ratio is relatively constant over a time span of 13 yr; (…
Magnetic chemically peculiar stars investigated by the Solar Mass Ejection Imager
Paunzen, E.; Prišegen, M.; Bernhard, K. +2 more
Since the discovery of the spectral peculiarities of their prototype α2 Canum Venaticorum in 1897, the so-called ACV variables, which are comprised of several groups of chemically peculiar stars of the upper main sequence, have been the target of numerous photometric and spectroscopic studies. Especially for the brighter ACV variables, …
Towards a robust estimation of orientation parameters between ICRF and Gaia celestial reference frames
Malkin, Zinovy
An analysis of the source position differences between very long baseline interferometry-based ICRF and Gaia-celestial reference frame catalogues is a key step in assessing their systematic errors and determining their mutual orientation. One of the main factors that limits the accuracy of determination of the orientation parameters between two fr…
Dense gas in local galaxies revealed by multiple tracers
Li, Juan; Gong, Yan; Li, Shanghuo +6 more
We present 3 mm and 2 mm band simultaneously spectroscopic observations of HCN 1-0, HCO+ 1-0, HNC 1-0, and CS 3-2 with the IRAM 30 m telescope, towards a sample of 70 sources as nearby galaxies with infrared luminosities ranging from several 10$^{5}\, \mathrm{L}_{\odot }$ to more than 10$^{12}\, \mathrm{L}_{\odot }$. After combining HCN…
Similar but different: the varied landscape of Onfp/Oef stars variability
Nazé, Yaël; Rauw, Gregor
The Oef category gathers rapidly rotating and evolved O-stars displaying a centrally reversed He II λ 4686 emission line. The origin of the variability of their photospheric and wind spectral lines is debated, with rotational modulation or pulsations as the main contenders. To shed new light on this question, we analysed high-quality and high-cade…
A deep search for faint Chandra X-ray sources, radio sources, and optical counterparts in NGC 6752
Anderson, Jay; Strader, Jay; Heinke, Craig O. +6 more
We report the results of a deep search for faint Chandra X-ray sources, radio sources, and optical counterparts in the nearby, core-collapsed globular cluster, NGC 6752. We combined new and archival Chandra imaging to detect 51 X-ray sources (12 of which are new) within the 1.9 arcmin half-light radius. Three radio sources in deep ATCA 5 and 9 GHz…
Double X/Peanut structures in barred galaxies - insights from an N-body simulation
Ciambur, Bogdan C.; Fragkoudi, Francesca; Khoperskov, Sergey +2 more
Boxy, peanut-, or X-shaped 'bulges' are observed in a large fraction of barred galaxies viewed in, or close to, edge-on projection, as well as in the Milky Way. They are the product of dynamical instabilities occurring in stellar bars, which cause the latter to buckle and thicken vertically. Recent studies have found nearby galaxies that harbour t…