Search Publications
Super-Eddington accretion on to a stellar mass ultraluminous X-ray source NGC 4190 ULX1
Ghosh, T.; Rana, V.
We present the results of high-quality XMM-NEWTON observations of a ultraluminous X-ray source (ULX) in the galaxy NGC 4190. The detection of spectral cutoff in NGC 4190 ULX1 spectra rules out the interpretation of the ULX to be in a standard low/hard canonical accretion state. We report that the high quality EPIC spectra can be better described b…
An XMM-Newton study of active-inactive galaxy pairs
Guainazzi, Matteo; Paragi, Zsolt; Bianchi, Stefano +8 more
While theory and simulations indicate that galaxy mergers play an important role in the cosmological evolution of accreting black holes and their host galaxies, samples of active galactic nuclei (AGNs) in galaxies at close separations are still small. In order to increase the sample of AGN pairs, we undertook an archival project to investigate the…
Using heritability of stellar chemistry to reveal the history of the Milky Way
Jofré, Paula; de Brito Silva, Danielle; Das, Payel +3 more
Since chemical abundances are inherited between generations of stars, we use them to trace the evolutionary history of our Galaxy. We present a robust methodology for creating a phylogenetic tree, a biological tool used for centuries to study heritability. Combining our phylogeny with information on stellar ages and dynamical properties, we recons…
An updated distance to the Cygnus Loop based on Gaia Early DR3
Blair, William P.; Raymond, John C.; Fesen, Robert A. +2 more
We present a revised distance to the Cygnus Loop supernova remnant of 725 ± 15 pc based on Gaia Early Data Release 3 parallax measurements (EDR3) for several stars previously found to be located either inside or behind the supernova based on the presence of high-velocity absorption lines in their spectra. This revised distance estimate and error m…
Bow shocks, nova shells, disc winds and tilted discs: the nova-like V341 Ara has it all
Altamirano, D.; Knigge, C.; James, D. J. +21 more
V341 Ara was recently recognized as one of the closest (d ≃ 150 pc) and brightest (V ≃ 10) nova-like cataclysmic variables. This unique system is surrounded by a bright emission nebula, likely to be the remnant of a recent nova eruption. Embedded within this nebula is a prominent bow shock, where the system's accretion disc wind runs into its own …
Linking globular cluster structural parameters and their evolution: multiple stellar populations
Mastrobuono-Battisti, Alessandra; Perets, Hagai B.
Globular clusters (GCs) are known to host multiple stellar populations showing chemical anomalies in the content of light elements. The origin of such anomalies observed in Galactic GCs is still debated. Here we analyse data compiled from the Hubble Space Telescope, ground-based surveys, and Gaia Data Release 2 (DR2) and explore relationships betw…
Is the eclipsing binary RR Dra dancing with a hidden tertiary black hole candidate?
Zhu, Li-Ying; Wang, Zhi-Hua
Analysis of timing variation of the eclipsing binary RR Dra implies the existence of an additional object with mass of no less than 3.5(±0.2) M⊙. This third object is orbiting around the central eclipsing pair once every 98(±1) yr, making the whole a hierarchical triple system. However, reliable photometric solutions based on light curv…
Remote sensing of cometary bow shocks: modelled asymmetric outgassing and pickup ion observations
Alho, Markku; Jarvinen, Riku; Simon Wedlund, Cyril +3 more
Despite the long escort by the ESA Rosetta mission, direct observations of a fully developed bow shock around 67P/Churyumov-Gerasimenko have not been reported. Expanding on our previous work on indirect observations of a shock, we model the large-scale features in cometary pickup ions, and compare the results with the ESA Rosetta Plasma Consortium…
The effect of phased recurrent units in the classification of multiple catalogues of astronomical light curves
Cabrera-Vives, G.; Protopapas, P.; Carrasco-Davis, R. +2 more
In the new era of very large telescopes, where data are crucial to expand scientific knowledge, we have witnessed many deep learning applications for the automatic classification of light curves. Recurrent neural networks (RNNs) are one of the models used for these applications, and the Long Short-Term Memory (LSTM) unit stands out for being an ex…
Detection of a high-temperature blackbody hump in black hole spectra - the strongly redshifted annihilation line
Titarchuk, Lev; Seifina, Elena
We detected a so-called high-temperature blackbody (HBB) component, found in the 15-40 keV range, in the broad-band X-ray energy spectra of black hole (BH) candidate sources. A detailed study of this spectral feature is presented using data from five of the Galactic BH binaries, Cyg X-1, GX 339-4, GRS 1915+105, SS 433, and V4641 Sgr in the low/har…