Search Publications
Automated algorithms to build active galactic nucleus classifiers
Larsson, J.; Falocco, S.; Carrera, F. J.
We present a machine learning model to classify active galactic nuclei (AGNs) and galaxies (AGN-galaxy classifier) and a model to identify type 1 (optically unabsorbed) and type 2 (optically absorbed) AGN (type 1/2 classifier). We test tree-based algorithms, using training samples built from the X-ray Multi-Mirror Mission-Newton (XMM-Newton) catal…
SDSS-IV MaStar: [α/Fe] for the MaNGA Stellar Library from synthetic model spectra
Bizyaev, Dmitry; Law, David R.; Stassun, Keivan G. +11 more
We calculate the α-enhancement ratio [α/Fe] for the Mapping Nearby Galaxies at APO (MaNGA) Stellar Library (MaStar) while also fitting for the fundamental atmospheric parameters effective temperature, surface gravity, and metallicity - Teff, log g, [Fe/H]. This approach builds upon a previous catalogue of stellar parameters, whereby onl…
Active longitudes and starspot evolution of the young rapidly rotating star USNO-B1.0 1388-0463685 discovered in the Yunnan-Hong Kong survey
Bai, Jinming; Wang, Xiaobin; Xiang, Yue +12 more
We have discovered a young, rapidly rotating active star USNO-B1.0 1388-0463685 with a rotational period of 0.508750 ± 0.000153 d in the Yunnan-Hong Kong wide-field photometric survey. Based on the chromospheric activity identified in the dedicated spectroscopic observations, the brightness variation of this star is attributed to cool spots on its…
CHANG-ES - XXVII. A radio/X-ray catalogue of compact sources in and around edge-on galaxies
Wang, Q. Daniel; Irwin, Judith; Wiegert, Theresa +5 more
We present catalogues of discrete, compact radio sources in and around the discs of 35 edge-on galaxies in the Continuum Halos in Nearby Galaxies - an EVLA Survey. The sources were extracted using the PYBDSF program at both 1.6 GHz (L band) and 6.0 GHz (C band) from matching resolution (≈3 arcsec) data. We also present catalogues of X-ray sources …
Close substellar-mass companions in stellar wide binaries: discovery and characterization with APOGEE and Gaia DR2
Bizyaev, Dmitry; Pan, Kaike; Majewski, Steven R. +12 more
We present a search for close, unresolved companions in a subset of spatially resolved Gaia wide binaries containing main-sequence stars within 200 pc of the Sun, utilizing the APOGEE-Gaia Wide Binary Catalog. A catalogue of 37 wide binaries was created by selecting pairs of stars with nearly identical Gaia positions, parallaxes, and proper motion…
The unusually high dark matter concentration of the galaxy group NGC 1600
Walker, S. A.; Mirakhor, M. S.; Runge, J.
We investigate the properties of the dark matter (DM) halo surrounding the nearby galaxy group NGC 1600. Through the use of deep (252 ks) Chandra observations and 64.3 ks of XMM-Newton observations, we construct surface brightness profiles in multiple energy bands in order to perform hydrostatic equilibrium analysis of the hot plasma within NGC 16…
Unveiling the main sequence to starburst transition region with a sample of intermediate redshift luminous infrared galaxies
Magdis, G. E.; Rigopoulou, D.; Combes, F. +8 more
We present a CO(3-2) study of four systems composed of six (ultra) luminous infrared galaxies (U/LIRGs), located at 0.28 <z < 0.44, that straddle the transition region between regular star-forming galaxies and starbursts. These galaxies benefit from previous multiwavelength analysis allowing in depth exploration of an understudied population…
Correlated variability of the reflection fraction with the X-ray flux and spectral index for Mrk 478
Jithesh, V.; Medhi, Biman J.; Misra, Ranjeev +2 more
The X-ray spectrum of Mrk 478 is known to be dominated by a strong soft excess that can be described using relativistic blurred reflection. Using observations from XMM-Newton, AstroSat, and Swift, we show that for the long-term (~years) and intermediate-term (days to months) variability, the reflection fraction is anticorrelated with the flux and …
Ionized filaments and ongoing physical processes in massive-star-forming sites around l = 345.°5
Dewangan, L. K.; Pirogov, L. E.; Bhadari, N. K. +1 more
Numerous research studies on dust and molecular filaments in star-forming sites have been conducted, but only a limited number have focused on ionized filaments. To observationally study this aspect, we present an analysis of multiwavelength data from an area of ~74.6 arcmin × 55 arcmin around l = 345${_{.}^{\circ}}$5. Using the 843-MHz continuum …
Dissipation of hydromagnetic waves in the viscous polytropic zone of the solar wind including FLR corrections, ohmic diffusion, and the Hall effect
Fok, Mei-Ching; Desta, Ephrem Tesfaye; Prajapati, Ram Prasad +1 more
In the polytropic zone of the solar wind, we have used the generalized polytrope pressure laws to investigate the dissipation of hydromagnetic waves and pressure-anisotropy-driven fluid instabilities in magnetized viscous plasmas, including finite Larmor radius (FLR) corrections and non-ideal magnetohydrodynamic (MHD) effects. The modified dispers…