Search Publications
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…
An extended XMM-Newton observation of the Seyfert galaxy NGC 4051 - III. Fe K emission and absorption
Vaughan, S.; Pounds, K. A.
An extended XMM-Newton observation of the Seyfert 1 galaxy NGC 4051 in 2009 detected a photoionized outflow with a complex absorption-line velocity structure and a broad correlation of velocity with ionization parameter, shown by Pounds & Vaughan to be consistent with a highly ionized, high-velocity wind running into the interstellar medium or…
Submillimetre source counts in the fields of high-redshift galaxy clusters
Gladders, M. D.; Ivison, R. J.; Hoekstra, H. +11 more
We present a submillimetre survey of seven high-redshift galaxy clusters (0.64 < z < 1.0) using the Submillimetre Common-User Bolometer Array (SCUBA) at 850 and 450 ?m. The targets, of similar richness and redshift, are selected from the Red-sequence Cluster Survey (RCS). We use this sample to investigate the apparent excess of submillimetre…
Gamma-ray burst observations by Fermi Large Area Telescope revisited: new candidates found
Pshirkov, M. S.; Rubtsov, G. I.; Tinyakov, P. G.
We search the Fermi Large Area Telescope (LAT) photon data base for an extended gamma-ray emission which could be associated with any of the 581 previously detected gamma-ray bursts (GRBs) visible to the Fermi-LAT. For this purpose, we compare the number of photons with energies E > 100 MeV and E > 1 GeV which arrived in the first 1500 s aft…
Optical and infrared imaging and spectroscopy of the multiple-shell planetary nebula NGC 6369
Guerrero, M. A.; Ramos-Larios, G.; Phillips, J. P. +1 more
NGC 6369 is a double-shell planetary nebula consisting of a bright annular inner shell with faint bipolar extensions and a filamentary envelope. We have used ground- and space-based narrow-band optical and near-infrared (near-IR) images, broad-band mid-IR images, optical long-slit echelle spectra and mid-IR spectra to investigate its physical stru…
A search for z= 7.3 Lyα emitters behind gravitationally lensing clusters
Richard, Johan; Shibuya, Takatoshi; Egami, Eiichi +3 more
We searched for z= 7.3 Lyα emitters (LAEs) behind two gravitationally lensing clusters, Abell 2390 and CL 0024, using the Subaru Telescope Suprime-Cam and a narrow-band filter NB1006 (λc∼ 1005 nm and full width at half-maximum of about 21 nm). The combination of the fully depleted CCDs of the Suprime-Cam, sensitive to z∼ 7 Lyα emission …