Search Publications
Star formation laws in the Andromeda galaxy: gas, stars, metals and the surface density of star formation
Barmby, P.; Lianou, S.; Rahmani, S.
We use hierarchical Bayesian regression analysis to investigate star formation laws in the Andromeda galaxy (M31) in both local (30, 155 and 750 pc) and global cases. We study and compare the well-known Kennicutt-Schmidt law, the extended Schmidt law and the metallicity/star formation correlation. Using a combination of Hα and 24 µm emission…
Testing light-traces-mass in Hubble Frontier Fields Cluster MACS-J0416.1-2403
Liesenborgs, Jori; Mohammed, Irshad; Saha, Prasenjit +2 more
We reconstruct the projected mass distribution of a massive merging Hubble Frontier Fields cluster MACSJ0416 using the genetic algorithm based free-form technique called Grale. The reconstructions are constrained by 149 lensed images identified by Jauzac et al. using HFF data. No information about cluster galaxies or light is used, which makes our…
Suzaku view of the Be/X-ray binary pulsar GX 304-1 during Type I X-ray outbursts
Naik, Sachindra; Jaisawal, Gaurava K.; Epili, Prahlad
We report the timing and spectral properties of the Be/X-ray binary pulsar GX 304-1 using two Suzaku observations during its 2010 August and 2012 January X-ray outbursts. Pulsations at ∼275 s were clearly detected in the light curves from both observations. Pulse profiles were found to be strongly energy-dependent. During the 2010 observation, the…
Statistical properties of dwarf novae-type cataclysmic variables: the outburst catalogue
Drake, Andrew J.; Coppejans, Deanne L.; Knigge, Christian +5 more
The outburst catalogue contains a wide variety of observational properties for 722 dwarf nova (DN)-type cataclysmic variables (CVs) and 309 CVs of other types from the Catalina Real-time Transient Survey. In particular, it includes the apparent outburst and quiescent V-band magnitudes, duty cycles, limits on the recurrence time, upper and lower li…
Revisiting the ultraluminous supersoft source in M 101: an optically thick outflow model
Soria, Roberto; Kong, Albert
The M 101 galaxy contains the best-known example of an ultraluminous supersoft source (ULS), dominated by a thermal component at kT ≈ 0.1 keV. The origin of the thermal component and the relation between ULSs and standard (broad-band spectrum) ultraluminous X-ray sources are still controversial. We re-examined the X-ray spectral and timing propert…
Super- and sub-Eddington accreting massive black holes: a comparison of slim and thin accretion discs through study of the spectral energy distribution
Netzer, H.; Castelló-Mor, N.; Kaspi, S.
We employ optical and ultraviolet (UV) observations to present spectral energy distributions (SEDs) for two reverberation-mapped samples of super-Eddington and sub-Eddington active galactic nuclei (AGN) with similar luminosity distributions. The samples are fitted with accretion disc (AD) models in order to look for SED differences that depend on …
Cosmic troublemakers: the Cold Spot, the Eridanus supervoid, and the Great Walls
García-Bellido, Juan; Kovács, András
The alignment of the CMB Cold Spot and the Eridanus supervoid suggests a physical connection between these two relatively rare objects. We use galaxy catalogues with photometric (2MPZ) and spectroscopic (6dF) redshift measurements, supplemented by low-redshift compilations of cosmic voids, in order to improve the 3D mapping of the matter density i…
The prevalence of star formation as a function of Galactocentric radius
Moore, T. J. T.; Elia, D.; Molinari, S. +3 more
We present large-scale trends in the distribution of star-forming objects revealed by the Hi-GAL survey. As a simple metric probing the prevalence of star formation in Hi-GAL sources, we define the fraction of the total number of Hi-GAL sources with a 70 µm counterpart as the `star-forming fraction' or SFF. The mean SFF in the inner galactic…
Correlated X-ray/ultraviolet/optical variability in NGC 6814
Horne, Keith; Goad, Michael R.; Cackett, Edward M. +4 more
We present results of a three-month combined X-ray/UV/optical monitoring campaign of the Seyfert 1 galaxy NGC 6814. The object was monitored by Swift from June through August 2012 in the X-ray and UV bands and by the Liverpool Telescope from May through July 2012 in B and V. The light curves are variable and significantly correlated between waveba…
The global surface composition of 67P/Churyumov-Gerasimenko nucleus by Rosetta/VIRTIS. II) Diurnal and seasonal variability
Mottola, S.; Barucci, M. A.; Ip, W. -H. +24 more
VIRTIS-M observations of the nucleus of comet 67P/Churyumov-Gerasimenko acquired from 2014 August to 2015 May have been analysed to investigate surface temporal variability at both seasonal and diurnal scales. The measured reflectance spectra are studied by means of comet spectral indicators (CSI) such as slopes in the visible and infrared ranges,…