Search Publications
The X-ray evolution and geometry of the 2018 outburst of XTE J1810-197
Tiengo, A.; Götz, D.; Mereghetti, S. +17 more
After 15 yr, in late 2018, the magnetar XTE J1810-197 underwent a second recorded X-ray outburst event and reactivated as a radio pulsar. We initiated an X-ray monitoring campaign to follow the timing and spectral evolution of the magnetar as its flux decays using Swift, XMM-Newton, NuSTAR, and NICER observations. During the year-long campaign, th…
Aggregates of clusters in the Gaia data
Paunzen, E.; Piecka, M.
Context. The precision of the parallax measurements by Gaia is unprecedented. As of Gaia Data Release 2, the number of known nearby open clusters has increased. Some of the clusters appear to be relatively close to each other and form aggregates, which makes them interesting objects to study.
Aims: We study the aggregates of clusters which sh…
Measuring the Mass Function of Isolated Stellar Remnants with Gravitational Microlensing I. Revisiting the OGLE-III Dark Lens Candidates
Mróz, P.; Wyrzykowski, Ł.
Gravitational microlensing may detect dark stellar remnants - black holes or neutron stars - even if they are isolated. However, it is challenging to estimate masses of isolated dark stellar remnants using solely photometric data for microlensing events. A recent analysis of OGLE-III long-timescale microlensing events exhibiting the annual paralla…
Causes of Jets in the Quasi-Perpendicular Magnetosheath
Kajdič, Primož; Raptis, Savvas; Blanco-Cano, Xóchitl +1 more
Magnetosheath jets are currently an important topic in the field of magnetosheath physics. It is thought that 97% of the jets are produced by the shock rippling at quasi-parallel shocks. Recently, large statistical studies of magnetosheath jets have been performed, however, it is not clear whether rippling also produces jets found downstream of qu…
A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE). VIII. Modeling ram pressure stripping of diffuse gas in the Virgo cluster spiral galaxy NGC 4330
Boquien, M.; Soida, M.; Boselli, A. +7 more
NGC 4330 is one of the Virgo galaxies whose UV emission distributions show a tail structure. An associated tail structure is also observed in the HI and Hα emission distributions. Previous dynamical modeling has shown that the galaxy is approaching the cluster center and is therefore undergoing increasing ram pressure stripping. Recent stellar pop…
Detecting the Figure Rotation of Dark Matter Halos with Tidal Streams
Price-Whelan, Adrian M.; Valluri, Monica; Snyder, Sarah J.
The dark matter halos that surround Milky Way-like galaxies in cosmological simulations are, to first order, triaxial. Nearly 30 yr ago it was predicted that such triaxial dark matter halos should exhibit steady figure rotation or tumbling motions for durations of several gigayears. The angular frequency of figure rotation predicted by cosmologica…
Lucky spectroscopy, an equivalent technique to lucky imaging. II. Spatially resolved intermediate-resolution blue-violet spectroscopy of 19 close massive binaries using the William Herschel Telescope
Simón-Díaz, S.; Maíz Apellániz, J.; Negueruela, I. +5 more
Context. Many massive stars have nearby companions. These hamper a characterization of massive stars through spectroscopy.
Aims: We continue to obtain spatially resolved spectroscopy of close massive visual binaries to derive their spectral types.
Methods: We used the lucky spectroscopy technique to obtain a large number of short long-sl…
Comparison of Gaia and Hipparcos parallaxes of close visual binary stars and the impact on determinations of their masses
Hussein, Abdallah M.; Al-Wardat, Mashhoor Ahmad; Al-Naimiy, Hamid M. +1 more
Precise measurement of the fundamental parameters of stellar systems, including mass and radius, depends critically on how well the stellar distances are known. Astrometry from space provides parallax measurements of unprecented accuracy, from which distances can be derived, initially from the Hipparcos mission, with a further refinement of that a…
STARCNET: Machine Learning for Star Cluster Identification
Calzetti, Daniela; Adamo, Angela; Messa, Matteo +4 more
We present a machine learning (ML) pipeline to identify star clusters in the multicolor images of nearby galaxies, from observations obtained with the Hubble Space Telescope as part of the Treasury Project LEGUS (Legacy ExtraGalactic Ultraviolet Survey). STARCNET (STAR Cluster classification NETwork) is a multiscale convolutional neural network (C…
A deep learning approach to quasar continuum prediction
Liu, Bin; Bordoloi, Rongmon
We present a novel intelligent quasar continuum neural network (iQNet), predicting the intrinsic continuum of any quasar in the rest-frame wavelength range of $1020 \, {\mathring{\rm A}}\le \lambda _{\text{rest}} \le 1600 \, {\mathring{\rm A}}$ . We train this network using high-resolution Hubble Space Telescope/Cosmic Origin Spectrograph ultravio…