Search Publications
Multiwavelength monitoring of a very active dwarf nova AX J1549.8-5416 with an unusually high duty cycle
Gelfand, Joseph D.; Bernardini, Federico; Lewis, Fraser +5 more
We present the results of our analysis of new optical, ultraviolet (UV) and X-ray observations of a highly variable source - AX J1549.8-5416. Both the detection of several fast rise, exponential decay outbursts in the optical light curve and the lack of He II emission lines in the optical spectra suggest AX J1549.8-5416 is a cataclysmic variable o…
Cross-calibration of the Rosetta Navigation Camera based on images of the 67P comet nucleus
Statella, Thiago; Geiger, Bernhard
The Rosetta spacecraft carried a Navigation Camera (NavCam) for optical navigation in the vicinity of the comet. In order to facilitate the use of the data for quantitative scientific work, we performed a cross-calibration study based on images taken with the OSIRIS near-angle camera. For this purpose, we selected sets of images acquired roughly s…
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…