Search Publications
Detection of open cluster members inside and beyond tidal radius by machine learning methods based on Gaia DR3
Noormohammadi, M.; Khakian Ghomi, M.; Javadi, A.
In our previous work, we introduced a method that combines two unsupervised algorithms: Density-based spatial clustering of applications with noise (DBSCAN) and Gaussian mixture model (GMM). We applied this method to 12 open clusters based on Gaia Early Data Release 3 (EDR3) data, demonstrating its effectiveness in identifying reliable cluster mem…
WISDOM project - XVIII. Molecular gas distributions and kinematics of three megamaser galaxies
Greene, Jenny E.; Williams, Thomas G.; Cappellari, Michele +11 more
The co-evolution of galaxies and supermassive black holes (SMBHs) underpins our understanding of galaxy evolution, but different methods to measure SMBH masses have only infrequently been cross-checked. We attempt to identify targets to cross-check two of the most accurate methods, megamaser, and cold molecular gas dynamics. Three promising galaxi…
Optical spectroscopic and photometric classification of the X-ray transient EP240309a (EP J115415.8-501810) as an intermediate polar
Scaringi, S.; Monageng, I. M.; Buckley, David A. H. +13 more
We report on optical follow-up observations of an X-ray source initially detected by the Einstein Probe mission. Our investigations categorize the source as an intermediate polar, a class of magnetic cataclysmic variables, exhibiting an orbital period of 3.7614(4) h and a white dwarf spin period of 3.97 min. The orbital period was identified throu…
Cygnus A obscuring torus: ionized, atomic, or molecular?
Ogle, Patrick; Antonucci, Robert; Bagul, Atharva +2 more
The prototypical powerful FR II radio galaxy Cygnus A fits extremely well into the quasar/radio galaxy unified model: high polarization with an angle almost perpendicular to the radio jet and polarized flux showing broad permitted lines. It has been claimed that ionized gas in the torus reveals a very clear torus shape via Bremmstrahlung emission.…
Discovery of a new IW And-type dwarf nova with both tilted disc and tidal instability
Shi, Jianrong; Huang, Yang; Liu, Jifeng +6 more
IW And-type dwarf novae are anomalous Z Cam stars featured with outbursts happening during standstill states, which are not expected in the standard disc instability model. The physical mechanisms for these variations remain unclear. In this study, we report the discovery of a new candidate IW And-type dwarf nova J0652+2436, identified with its fr…
Rapid variability of Markarian 421 during extreme flaring as seen through the eyes of XMM-Newton
Nowak, M. A.; Walter, R.; Dauser, T. +31 more
By studying the variability of blazars across the electromagnetic spectrum, it is possible to resolve the underlying processes responsible for rapid flux increases, so-called flares. We report on an extremely bright X-ray flare in the high-peaked BL Lacertae object Markarian 421 (Mrk 421) that occurred simultaneously with enhanced γ-ray activity d…
H I content at cosmic noon - a millimetre-wavelength perspective
Messias, Hugo; Vioque, Miguel; Guerrero, Andrea +4 more
In order to understand galaxy growth evolution, it is critical to constrain the evolution of its building block: gas. Mostly comprised by Hydrogen in its neutral (H I) and molecular (H
Observational properties of active galactic nucleus obscuration during the peak of accretion growth
Sawicki, Marcin; Schramm, Malte; Gwyn, Stephen +11 more
We investigated the gas obscuration and host galaxy properties of active galactic nuclei (AGNs) during the peak of cosmic accretion growth of supermassive black holes at redshift 0.8-1.8 using X-ray-detected AGNs with mid-infrared and far-infrared detection. The sample was classified as type-1 and type-2 AGNs using optical spectral and morphologic…
On the similarity of rotational motion of dust particles in the inner atmosphere of comets
Fulle, M.; Moreno, F.; Rotundi, A. +6 more
In situ measurements of individual dust grain parameters in the immediate vicinity of a cometary nucleus are being carried by the Rosetta spacecraft at comet 67P/Churyumov-Gerasimenko. For interpretation of these observational data, a model of dust grain motion as realistic as possible is requested. In particular, the results of Stardust mission a…
A search for extragalactic fast optical transients in the Tomo-e Gozen high-cadence survey
Kobayashi, Naoto; Arimatsu, Ko; Tominaga, Nozomu +15 more
The population of optical transients evolving within a time-scale of a few hours or a day (so-called fast optical transients, FOTs) has recently been debated extensively. In particular, our understanding of extragalactic FOTs and their rates is limited. We present a search for extragalactic FOTs with the Tomo-e Gozen high-cadence survey. Using the…