Search Publications
Quasi-periodic oscillations and energy spectra from the two brightest Ultra-Luminous X-ray sources in M82
Belloni, T.; Zampieri, L.; Caballero-García, M. D.
Ultra-Luminous X-ray sources (ULXs) are thought to be accreting black holes (BHs) that might host intermediate-mass black holes (IMBH), proposed to exist by theoretical studies, even though a firm detection (as a class) is still missing. The brightest ULX in M82 (M82 X-1) is probably one of the best candidates to host an IMBH. In this work, we ana…
Deep hard X-ray survey of the Large Magellanic Cloud
Tsygankov, S. S.; Lutovinov, A. A.; Grebenev, S. A. +1 more
Results of the deep survey of the Large Magellanic Cloud (LMC) obtained with the INTEGRAL observatory are presented. The long exposure ( ∼ 7 Ms) allowed us to detect 21 sources in this sky region: ten belonging to the LMC itself (7 HMXBs, 2 PSRs, 1 LMXB), six of extragalactic origin and three belonging to other galaxies in the Local Group - the Mi…
The NGC 3341 minor merger: a panchromatic view of the active galactic nucleus in a dwarf companion
Fiore, Fabrizio; Mathur, Smita; Bianchi, Stefano +4 more
We present X-ray (Chandra), radio (Expanded Very Large Array and European VLBI Network) and archival optical data of the triple-merging system in NGC 3341. Our panchromatic analysis confirms the presence of a Seyfert 2 active galactic nucleus (AGN) in NGC 3341B, one of the secondary dwarf companions. On the other hand, the nucleus of the primary g…
Supernovae and radio transients in M82
Smartt, S. J.; Fraser, M.; Romero-Cañizales, C. +4 more
We present optical and near-infrared (NIR) photometry and NIR spectroscopy of SN 2004am, the only optically detected supernova (SN) in M82. These demonstrate that SN 2004am was a highly reddened Type II-P SN similar to the low-luminosity Type II-P events such as SNe 1997D and 2005cs. We show that SN 2004am was located coincident with the obscured …
Discovery of a 6.4 h black hole binary in NGC 4490
Sidoli, L.; Esposito, P.; Motta, S. E. +3 more
We report on the discovery with Chandra of a strong modulation (∼90 per cent pulsed fraction) at ∼6.4 h from the source CXOU J123030.3+413853 in the star-forming, low-metallicity spiral galaxy NGC 4490, which is interacting with the irregular companion NGC 4485. This modulation, confirmed also by XMM-Newton observations, is interpreted as the orbi…
The build-up of nuclear stellar cusps in extreme starburst galaxies and major mergers
Sanders, D. B.; Surace, J. A.; Inami, H. +15 more
Nuclear stellar cusps are defined as central excess light component in the stellar light profiles of galaxies and are suggested to be stellar relics of intense compact starbursts in the central ∼100-500 pc region of gas-rich major mergers. Here, we probe the build-up of nuclear cusps during the actual starburst phase for a complete sample of lumin…
A comprehensive near- and far-ultraviolet spectroscopic study of the hot DA white dwarf G191-B2B
Barstow, M. A.; Holberg, J. B.; Preval, S. P. +1 more
We present a detailed spectroscopic analysis of the hot DA white dwarf G191-B2B, using the best signal-to-noise ratio, high-resolution near- and far-UV spectrum obtained to date. This is constructed from co-added Hubble Space Telescope (HST) Space Telescope Imaging Spectrometer (STIS) E140H, E230H and FUSE observations, covering the spectral range…
Flexion measurement in simulations of Hubble Space Telescope data
Massey, Richard; Rhodes, Jason; Heymans, Catherine +5 more
We present a simulation analysis of weak gravitational lensing flexion and shear measurement using shapelet decomposition, and identify differences between flexion and shear measurement noise in deep survey data. Taking models of galaxies from the Hubble Space Telescope Ultra Deep Field (HUDF) and applying a correction for the HUDF point spread fu…
VLT/XSHOOTER and Subaru/MOIRCS spectroscopy of HUDF.YD3: no evidence for Lyman α emission at z = 8.55
Wilkins, Stephen M.; Bunker, Andrew J.; Caruana, Joseph +5 more
We present spectroscopic observations with VLT/XSHOOTER and Subaru/MOIRCS of a relatively bright Y-band drop-out galaxy in the Hubble Ultra Deep Field (HUDF), first selected by Bunker et al., McLure et al. and Bouwens et al. to be a likely z ≈ 8-9 galaxy on the basis of its colours in the Hubble Space Telescope (HST) Advanced Camera for Surveys an…
The Herschel-PEP survey: evidence for downsizing in the hosts of dusty star-forming systems
Berta, S.; Magnelli, B.; Nordon, R. +27 more
By making use of Herschel PACS Evolutionary Probe observations of the COSMOS and Extended Groth Strip fields, we have estimated the dependence of the clustering properties of FIR-selected sources on their 100 µm fluxes. Our analysis shows a tendency for the clustering strength to decrease with limiting fluxes. By assuming a power-law slope w…