Search Publications
Inferring Compton-thick AGN candidates at z > 2 with Chandra using the >8 keV rest-frame spectral curvature
Treister, E.; Salvato, M.; Comastri, A. +10 more
To fully understand cosmic black hole growth, we need to constrain the population of heavily obscured active galactic nuclei (AGNs) at the peak of cosmic black hole growth (z ∼1-3). Sources with obscuring column densities higher than 1024 atoms cm-2, called Compton-thick (CT) AGNs, can be identified by excess X-ray emission a…
CARMA observations of massive Planck -discovered cluster candidates at z ≳ 0.5 associated with WISE overdensities: breaking the size-flux degeneracy
Shimwell, T.; Melin, J. -B.; Feroz, F. +4 more
We use a Bayesian software package to analyse CARMA-8 data towards 19 unconfirmed Planck Sunyaev-Zel'dovich-cluster candidates from Rodríguez-Gonzálvez et al. that are associated with significant overdensities in WISE. We use two cluster parameterizations, one based on a (fixed shape) generalized-NFW (gNFW) pressure profile and another on a β gas …
A jet-dominated model for a broad-band spectral energy distribution of the nearby low-luminosity active galactic nucleus in M94
Connors, Riley; McHardy, Ian; Markoff, Sera +4 more
We have compiled a new multiwavelength spectral energy distribution (SED) for the closest obscured low-ionization emission-line region active galactic nucleus (AGN), NGC 4736, also known as M94. The SED comprises mainly high-resolution (mostly sub-arcsecond, or, at the distance to M94, ≲23 pc from the nucleus) observations from the literature, arc…
Spectroscopic classification of X-ray sources in the Galactic Bulge Survey
Maccarone, T. J.; Udalski, A.; Kostrzewa-Rutkowska, Z. +14 more
We present the classification of 26 optical counterparts to X-ray sources discovered in the Galactic Bulge Survey. We use (time-resolved) photometric and spectroscopic observations to classify the X-ray sources based on their multiwavelength properties. We find a variety of source classes, spanning different phases of stellar/binary evolution. We …
An investigation of four chemically peculiar stars with photometric periods below 12 h
Paunzen, Ernst; Hambsch, Franz-Josef; Hümmerich, Stefan +3 more
We present an investigation of three chemically peculiar (CP) stars and one CP star candidate that exhibit photometric periods below 12 h. New spectroscopic observations have been acquired that confirm the peculiar nature of all objects. HD 77013 and HD 81076 are classical CP1 (Am) stars, HD 67983 is a marginal CP1 (Am:) star and HD 98000 is a CP2…
Supra-galactic colour patterns in globular cluster systems
Forte, Juan C.
An analysis of globular cluster systems associated with galaxies included in the Virgo and Fornax Hubble Space Telescope-Advanced Camera Surveys reveals distinct (g - z) colour modulation patterns. These features appear on composite samples of globular clusters and, most evidently, in galaxies with absolute magnitudes Mg in the range fr…
Kinematics of the ionized and molecular gas in nearby luminous infrared interacting galaxies
Borlaff, Alejandro; Rosado, Margarita; Zaragoza-Cardiel, Javier +3 more
We have observed three luminous infrared galaxy systems which are pairs of interacting galaxies, with the Galaxy Hα Fabry-Perot system mounted on the 4.2 m William Herschel Telescope at the Roque de los Muchachos Observatory, and combined the observations with the Atacama Large Millimeter Array observations of these systems in CO emission to compa…
The lack of X-ray pulsations in the extreme helium star BD+37°442 and its possible stellar wind X-ray emission
Mereghetti, Sandro; Esposito, Paolo; Tiengo, Andrea +1 more
We report the results of a new XMM-Newton observation of the helium-rich hot subdwarf BD+37°442 carried out in 2016 February. The possible periodicity at 19 s seen in a 2011 shorter observation is not confirmed, thus dismissing the evidence for a binary nature. This implies that the observed soft X-ray emission, with a luminosity of a few 103…
Covariance of lucky images: performance analysis
Ginski, C.; Mugrauer, M.; Seeliger, M. +5 more
The covariance of ground-based lucky images is a robust and easy-to-use algorithm that allows us to detect faint companions surrounding a host star. In this paper, we analyse the relevance of the number of processed frames, the frames' quality, the atmosphere conditions and the detection noise on the companion detectability. This analysis has been…
First hard X-ray detection and broad-band X-ray study of the unidentified transient AX J1949.8+2534
Masetti, N.; Sidoli, L.; Bird, A. J. +3 more
We present the results from INTEGRAL and Swift/XRT observations of the hitherto poorly studied unidentified X-ray transient AX J1949.8+2534, and on archival multiwavelength observations of field objects. Bright hard X-ray outbursts have been discovered above 20 keV for the first time, the measured duty cycle and dynamic range are of the order of ∼…