Search Publications
A Gaia DR2 search for dwarf galaxies towards Fermi-LAT sources: implications for annihilating dark matter
Calore, Francesca; Ciucǎ, Ioana; Kawata, Daisuke +3 more
We make the first attempt to find dwarf galaxies in eight Fermi-LAT extended, unassociated, source fields using Gaia DR2. After probing previously unexplored heliocentric distances of d < 20 kpc with an extreme-deconvolution (XD) technique, we find no sign of a dwarf galaxy in any of these fields despite Gaia's excellent astrometric accuracy. O…
Testing statistical isotropy in cosmic microwave background polarization maps
Rath, Pranati K.; Samal, Pramoda Kumar; Panda, Srikanta +2 more
We apply our symmetry based Power tensor technique to test conformity of PLANCK Polarization maps with statistical isotropy. On a wide range of angular scales (l = 40 - 150), our preliminary analysis detects many statistically anisotropic multipoles in foreground cleaned full sky PLANCK polarization maps viz., COMMANDER and NILC. We also study the…
The two ultraluminous X-ray sources in the galaxy NGC 925
Mereghetti, S.; Wolter, A.; Esposito, P. +7 more
NGC 925 ULX-1 and ULX-2 are two ultraluminous X-ray sources (ULXs) in the galaxy NGC 925, at a distance of 8.5 Mpc. For the first time, we analysed high quality, simultaneous XMM-Newton and NuSTAR data of both sources. Although at a first glance ULX-1 resembles an intermediate mass black hole candidate (IMBH) because of its high X-ray luminosity […
Unveiling the inner morphology and gas kinematics of NGC 5135 with ALMA
Cimatti, A.; Pozzi, F.; Massardi, M. +5 more
The local Seyfert 2 galaxy NGC 5135, thanks to its almost face-on appearance, a bulge overdensity of stars, the presence of a large-scale bar, an active galactic nucleus (AGN) and a supernova remnant, is an excellent target to investigate the dynamics of inflows, outflows, star formation, and AGN feedback. Here, we present a reconstruction of the …
A photometric analysis of Abell 1689: two-dimensional multistructure decomposition, morphological classification and the Fundamental Plane
Dalla Bontà, E.; Davies, R. L.; D'Eugenio, F. +2 more
We present a photometric analysis of 65 galaxies in the rich cluster Abell 1689 at z = 0.183, using the Hubble Space Telescope Advanced Camera for Surveys archive images in the rest-frame V band. We perform two-dimensional multicomponent photometric decomposition of each galaxy adopting different models of the surface-brightness distribution. We p…
LCO observations of a super-critical distorted pulsation in the roAp star J0855 (TYC 2488-1241-1)
Bowman, Dominic M.; Sefako, Ramotholo R.; Holdsworth, Daniel L. +1 more
We report the results of a 60-h photometric campaign of a rapidly oscillating Ap star, J0855 (TYC 2488-1241-1). We have utilized the multi-site Las Cumbres Observatory's (LCO) 0.4-m telescopes to obtain short cadence B-band observations of an roAp star previously lacking detailed study. Our observations confirm the rotation period presented in the…
Electron-impact excitation of diatomic hydride cations II: OH+ and SH+
Tennyson, Jonathan; Faure, Alexandre; Hamilton, James R.
R-matrix calculations combined with the adiabatic-nuclei-rotation and Coulomb-Born approximations are used to compute electron-impact rotational rate coefficients for two open-shell diatomic cations of astrophysical interest: the hydoxyl and sulphanyl ions, OH+ and SH+. Hyperfine resolved rate coefficients are deduced using t…
The gas and stellar mass of low-redshift damped Lyman-α absorbers
Prochaska, J. Xavier; Neeleman, Marcel; Kanekar, Nissim +1 more
We report Hubble Space Telescope Cosmic Origins Spectrograph far-ultraviolet and Arecibo Telescope H I 21 cm spectroscopy of six damped and sub-damped Lyman-α absorbers (DLAs and sub-DLAs, respectively) at z ≲ 0.1, which have yielded estimates of their H I column density, metallicity and atomic gas mass. This significantly increases the number of …
Broad-band high-energy emissions of the redback millisecond pulsar PSR J2129-0429
Kong, Albert K. H.; Zhao, J.; Hui, C. Y. +3 more
We present the first results from a joint XMM-Newton and NuSTAR observation of the gamma-ray emitting millisecond pulsar compact binary PSR J2129-0429. X-ray emission up to about 40 keV is detected and the joint spectrum can be modelled with a power-law plus a neutron star atmosphere model. At a distance of 1.4 kpc, the 0.3-79 keV luminosity is 3.…
Study of central light concentration in nearby galaxies
Ravikumar, C. D.; Aswathy, S.
We propose a novel technique to estimate the masses of supermassive black holes (SMBHs) residing at the centres of massive galaxies in the nearby Universe using simple photometry. Aperture photometry using SEXTRACTOR is employed to determine the central intensity ratio (CIR) at the optical centre of the galaxy image for a sample of 49 nearby galax…