Search Publications
The enigmatic black hole candidate and X-ray transient IGR J17091-3624 in its quiescent state as seen with XMM-Newton
Altamirano, D.; Wijnands, R.; Yang, Y. J.
We report on two short XMM-Newton observations performed in 2006 August and 2007 February during the quiescence state of the enigmatic black hole candidate system IGR J17091-3624. During both observations the source was clearly detected. Although the errors on the estimated fluxes are large, the source appears to be brighter by several tens of per…
O/O 2 emissions in the Venus nightglow
Chanover, Nancy J.; Bida, Thomas A.; Slanger, Tom G. +1 more
The oxygen green line is one of the most characteristic features in the terrestrial visible nightglow; it can be seen in the Venus nightglow, but with much greater intensity variation than in the terrestrial case. Here we synthesize our current understanding of the green line in the Venus nightglow and discuss what might be expected observationall…
A Multi-wavelength Study of the Jet, Lobes, and Core of the Quasar PKS 2101-490
Birkinshaw, M.; Worrall, D. M.; Schwartz, D. A. +9 more
We present a detailed study of the x-ray, optical, and radio emission from the jet, lobes, and core of the quasar PKS 2101-490 as revealed by new Chandra, Hubble Space Telescope (HST), and ATCA images. We extract the radio to x-ray spectral energy distributions from seven regions of the 13'' jet, and model the jet x-ray emission in terms of Dopple…
Measuring the orbital inclination of Z Andromedae from Rayleigh scattering
Skopal, A.; Shagatova, N.
Context. The orbital inclination of the symbiotic prototype Z And has not been established yet. At present, two very different values are considered, i ~ 44° and i ≳ 73°. The correct value of i is a key parameter in, for example, modeling the highly-collimated jets of Z And.
Aims: To measure the orbital inclination of Z And.
Methods: Fir…
A model for the vertical sound speed and absorption profiles in Titan's atmosphere based on Cassini-Huygens data
Petculescu, Andi; Achi, Peter
Measurements of thermodynamic quantities in Titan's atmosphere during the descent of Huygens in 2005 are used to predict the vertical profiles for the speed and intrinsic attenuation (or absorption) of sound. The calculations are done using one author's previous model modified to accommodate non-ideal equations of state. The vertical temperature p…
Evolution of the luminosity function and obscuration of active galactic nuclei: comparison between X-ray and infrared
Han, Zhanwen; Zhang, Fenghui; Wang, Bo +2 more
We present a detailed comparison between the 2-10 keV hard X-ray and infrared (IR) luminosity functions (LFs) of active galactic nuclei (AGNs). The composite X-ray to IR spectral energy distributions (SEDs) of AGNs, which are used to compare the hard X-ray LF (HXLF) and the IRLF, are modelled with a simple, but well-tested torus model, based on th…
Suzaku study of the centrally brightened supernova remnant G272.2-3.2
Sezer, A.; Gök, F.
In this paper, we present the results from a Suzaku observation of the Galactic supernova remnant G272.2-3.2. The spectra of G272.2-3.2 are well fitted by a single-temperature variable abundance non-equilibrium ionization (VNEI) model with an electron temperature kTe∼ 0.77 keV, an ionization time-scale τ∼ 6.5 × 1010 cm-3…
Automated measurement of redshifts from mid-infrared low-resolution spectroscopy
Hernán Caballero, Antonio
Obtaining accurate redshifts from mid-infrared (MIR) low-resolution (R ∼ 100) spectroscopy is challenging because the wavelength resolution is too low to detect narrow lines in most cases. Yet, the number of degrees of freedom and diversity of spectral features are too high for regular spectral energy distribution (SED) fitting techniques to be co…
Suppression of X-rays during an optical outburst of the helium dwarf nova KL Dra
Barclay, Thomas; Ramsay, Gavin; Wheatley, Peter J. +2 more
KL Dra is a helium-accreting AM CVn binary system with an orbital period close to 25 min. Approximately every 60 d there is a 4-mag optical outburst lasting ∼10 d. We present the most sensitive X-ray observations made of an AM CVn system during an outburst cycle. A series of eight observations were made using XMM-Newton which started shortly after…
Radio detection of nebulae around four luminous blue variable stars in the Large Magellanic Cloud
Umana, G.; Agliozzo, C.; Noriega-Crespo, A. +5 more
The nebulae associated with four luminous blue variables (LBVs) in the Large Magellanic Cloud (LMC) have been observed at 5.5 and 9 GHz using the Australia Telescope Compact Array, and radio emission has been detected for first time in sources R127, R143, S61 and S119. The radio maps of the nebulae have an angular resolution of ∼1.5 arcsec and a s…