Search Publications
The probabilistic random forest applied to the selection of quasar candidates in the QUBRICS survey
Grazian, Andrea; Boutsia, Konstantina; Cupani, Guido +5 more
The number of known, bright (i < 18), high-redshift (z > 2.5) QSOs in the Southern hemisphere is considerably lower than the corresponding number in the Northern hemisphere due to the lack of multiwavelength surveys at δ < 0. Recent works, such as the QUBRICS survey, successfully identified new, high-redshift QSOs in the South by means of…
The dust mass in Cassiopeia A from infrared and optical line flux differences
De Looze, I.; Barlow, M. J.; Milisavljevic, D. +2 more
The large quantities of dust that have been found in a number of high-redshift galaxies have led to suggestions that core-collapse supernovae (CCSNe) are the main sources of their dust and have motivated the measurement of the dust masses formed by local CCSNe. For Cassiopeia A (Cas A), an oxygen-rich remnant of a Type IIb CCSN, a dust mass of 0.6…
The rapid transition from star formation to AGN-dominated rest-frame ultraviolet light at z ≃ 4
Häußler, B.; Bowler, R. A. A.; Jarvis, M. J. +1 more
With the advent of deep optical-to-near-infrared extragalactic imaging on the degree scale, samples of high-redshift sources are being selected that contain both bright star-forming (SF) galaxies and faint active galactic nuclei (AGN). In this study, we investigate the transition between SF- and AGN-dominated systems at z ≃ 4 in the rest-frame ult…
Fast infrared variability from the black hole candidate MAXI J1535-571 and tight constraints on the modelling
Vincentelli, F. M.; Casella, P.; Maccarone, T. +7 more
We present the results regarding the analysis of the fast X-ray/infrared (IR) variability of the black hole transient MAXI J1535-571. The data studied in this work consist of two strictly simultaneous observations performed with XMM-Newton (X-rays: 0.7-10 keV), VLT/HAWK-I (Ks band, 2.2 µm) and VLT/VISIR (M and PAH2_2 bands, 4.85 a…
UOCS - III. UVIT catalogue of open clusters with machine learning-based membership using Gaia EDR3 astrometry
Jadhav, Vikrant V.; Subramaniam, Annapurni; Pennock, Clara M. +2 more
We present a study of six open clusters (Berkeley 67, King 2, NGC 2420, NGC 2477, NGC 2682, and NGC 6940), using the Ultra Violet Imaging Telescope (UVIT) aboard ASTROSAT and Gaia EDR3. We used combinations of astrometric, photometric, and systematic parameters to train and supervise a machine-learning algorithm along with a Gaussian mixture model…
Consistency testing for invariance of the speed of light at different redshifts: the newest results from strong lensing and Type Ia supernovae observations
Liu, Yuting; Cao, Shuo; Biesiada, Marek +3 more
The invariance of the speed of light in the distant Universe has profound significance for fundamental physics. In this paper, we propose a new model-independent method to test the invariance of the speed of light c at different redshifts by combining the strong gravitational lensing (SGL) systems and the observations of Type Ia supernovae (SNe Ia…
Long-term stellar activity variations and their effect on radial-velocity measurements
Günther, Maximilian N.; Jenkins, James S.; Watson, Christopher A. +8 more
Long-term stellar activity variations can affect the detectability of long-period and Earth-analogue extrasolar planets. We have, for 54 stars, analysed the long-term trend of five activity indicators: log $R^{\prime }_\mathrm{{HK}}$, the cross-correlation function (CCF) bisector span, CCF full-width-at-half-maximum, CCF contrast, and the area of …
Characterizing dynamical states of Galactic open clusters with Gaia DR2
Corradi, W. J. B.; Ferreira, F. A.; Maia, F. F. S. +2 more
In this work, we investigate the dynamical properties of 38 Galactic open clusters: 34 of them are located at low Galactic latitudes (|b| < 10°) and are projected against dense stellar fields; the other four comparison objects present clearer contrasts with the field population. We determine structural and time-related parameters that are assoc…
Star formation in the nearby dwarf galaxy DDO 53: interplay between gas accretion and stellar feedback
Egorov, Oleg V.; Lozinskaya, Tatiana A.; Vasiliev, Konstantin I. +4 more
We present the results of a multiwavelength study of the nearby dwarf galaxy DDO 53 - a relatively isolated member of the M 81 group. We analyse the atomic and ionized gas kinematics (based on the observations with Fabry-Perot interferometer in H α line and archival data in H I 21 cm line), distribution, excitation, and oxygen abundance of the ion…
Three ultraluminous X-ray sources hosted by globular clusters in NGC 1316
Kundu, Arunav; Strader, Jay; Dage, Kristen C. +8 more
We have identified three ultraluminous X-ray sources (ULXs) hosted by globular clusters (GCs) within NGC 1316's stellar system. These discoveries bring the total number of known ULXs in GCs up to 20. We find that the X-ray spectra of the three new sources do not deviate from the established pattern of spectral behaviour of the other known GC ULXs.…