Search Publications
LOFAR properties of SILVERRUSH Lyα emitter candidates in the ELAIS-N1 field
Bondi, M.; Prandoni, I.; Wang, L. +12 more
Lyman alpha emitters (LAEs) in the Epoch of Reionization (EoR) offer valuable probes of both early galaxy evolution and the process of reionization itself; however, the exact evolution of their abundance and the nature of their emission remain open questions. We combine samples of 229 and 349 LAE candidates at z = 5.7 and z = 6.6, respectively, fr…
Responses of the Indian Equatorial Ionization Anomaly to two CME-induced geomagnetic storms during the peak phase of solar cycle 24
Akala, A. O.; Oyedokun, O. J.; Simi, K. G. +4 more
This work analyzes the geo-effectiveness of Coronal Mass Ejection- (CME-) induced storms by investigating the responses of ionospheric Vertical Total Electron Content (VTEC) and the Equatorial Ionization Anomaly (EIA) over the Indian sector to two storms. One of the storms occurred on February 19, 2014 (SYM-H: -120 nT), while the other occurred on…
Improving the astrometric solution of the Hyper Suprime-Cam with anisotropic Gaussian processes
Rubin, D.; Astier, P.; Roodman, A. +5 more
Context. We study astrometric residuals from a simultaneous fit of Hyper Suprime-Cam images.
Aims: We aim to characterize these residuals and study the extent to which they are dominated by atmospheric contributions for bright sources.
Methods: We used Gaussian process interpolation with a correlation function (kernel) measured from the …
Gemini/Phoenix H-band analysis of the globular cluster AL 3
Minniti, D.; Zoccali, M.; Bica, E. +9 more
Context. The globular cluster AL 3 is old and located in the inner bulge. Three individual stars were observed with the Phoenix spectrograph at the Gemini South telescope. The wavelength region contains prominent lines of CN, OH, and CO, allowing the derivation of C, N, and O abundances of cool stars.
Aims: We aim to derive C, N, O abundances…
Principal Component Analysis for Estimating Parameters of the L1287 Dense Core by Fitting Model Spectral Maps into Observed Ones
Pirogov, L. E.; Zemlyanukha, P. M.
An algorithm has been developed for finding the global minimum of a multidimensional error function by fitting model spectral maps into observed ones. Principal component analysis is applied to reduce the dimensionality of the model and the coupling degree between the parameters, and to determine the region of the minimum. The k-nearest neighbors …
VEXAS: VISTA EXtension to Auxiliary Surveys. Data Release 2: Machine-learning based classification of sources in the Southern Hemisphere
Agnello, A.; Spiniello, C.; Khramtsov, V. +1 more
Context. We present the second public data release of the VISTA EXtension to Auxiliary Surveys (VEXAS), where we classify objects into stars, galaxies, and quasars based on an ensemble of machine learning algorithms.
Aims: The aim of VEXAS is to build the widest multi-wavelength catalogue, providing reference magnitudes, colours, and morpholo…
Around Which Stars Can TESS Detect Earth-like Planets? The Revised TESS Habitable Zone Catalog
Stassun, K.; Kaltenegger, L.; Pepper, J. +3 more
In the search for life in the cosmos, NASA's Transiting Exoplanet Survey Satellite (TESS) mission has already monitored about 74% of the sky for transiting extrasolar planets, including potentially habitable worlds. However, TESS only observed a fraction of the stars long enough to be able to find planets like Earth. We use the primary mission dat…
Nonthermal element abundances at astrophysical shocks
Eichmann, Björn; Rachen, Jörg P.
The nonthermal source abundances of elements play a crucial role in the understanding of cosmic ray phenomena from a few GeV up to several tens of EeV . We present a first systematic approach to describe the change of the abundances from the thermal to the nonthermal state via diffusive shock acceleration by a temporally evolving shock. We conside…
Fresh Insights on the Kinematics of M49's Globular Cluster System with MMT/Hectospec Spectroscopy
Zhang, Hongxin; Liu, Chengze; Zabludoff, Ann +10 more
We present the first results of an MMT/Hectospec campaign to measure the kinematics of globular clusters (GCs) around M49-the brightest galaxy in the Virgo galaxy cluster, which dominates the Virgo B subcluster. The data include kinematic tracers beyond 95 kpc (~5.2 effective radii) for M49 for the first time, enabling us to achieve three key insi…
Disappearance of the Fe K α emission line in ultracompact X-ray binaries 4U 1543-624 and Swift J1756.9-2508
Guillot, Sebastien; Vasilopoulos, Georgios; Webb, Natalie +1 more
We investigate the long-term variability of the iron K α line in the spectra of two ultracompact X-ray sources (UCXBs) with C/O-rich donors. We revisit archival observations from five different X-ray telescopes, over an ∼20-yr period. Adopting physically motivated models for the spectral continuum, we probe the long-term evolution of the source em…