Search Publications
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,…
High-energy gamma-ray observations of the accreting black hole V404 Cygni during its 2015 June outburst
Rodriguez, J.; Fender, R.; Dubus, G. +7 more
We report on Fermi/Large Area Telescope observations of the accreting black hole low-mass X-ray binary V404 Cygni during its outburst in 2015 June-July. Detailed analyses reveal a possible excess of γ-ray emission on 2015 26 June, with a very soft spectrum above 100 MeV, at a position consistent with the direction of V404 Cyg (within the 95 per ce…
The JCMT and Herschel Gould Belt Surveys: a comparison of SCUBA-2 and Herschel data of dense cores in the Taurus dark cloud L1495
Hill, T.; Könyves, V.; Palmeirim, P. +27 more
We present a comparison of Submillimetre Common User Bolometer Array-2 (SCUBA-2) 850-µm and Herschel 70-500-µm observations of the L1495 filament in the Taurus Molecular Cloud with the goal of characterizing the SCUBA-2 Gould Belt Survey (GBS) data set. We identify and characterize starless cores in three data sets: SCUBA-2 850-µ…
Early science with the Large Millimetre Telescope: Deep LMT/AzTEC millimetre observations of ɛ Eridani and its surroundings
Dent, W. R. F.; Eiroa, C.; Marshall, J. P. +21 more
ɛ Eridani is a nearby, young Sun-like star that hosts a ring of cool debris analogous to the Solar system's Edgeworth-Kuiper belt. Early observations at (sub-)mm wavelengths gave tentative evidence of the presence of inhomogeneities in the ring, which have been ascribed to the effect of a putative low eccentricity planet, orbiting close to the rin…
Ancient eruptions of η Carinae: a tale written in proper motions
Smith, Nathan; Reiter, Megan; Kiminki, Megan M.
We analyse eight epochs of Hubble Space Telescope Hα+[N II] imaging of η Carinae's outer ejecta. Proper motions of nearly 800 knots reveal that the detected ejecta are divided into three apparent age groups, dating to around 1250 A.D., to around 1550 A.D., and to during or shortly before the Great Eruption of the 1840s. Ejecta from these groups re…