Search Publications
The radio-mid-infrared correlation and the contribution of 15-µm galaxies to the 1.4-GHz source counts
Pozzi, F.; Calabrese, E.; Gruppioni, C. +5 more
The radio counterparts to the 15-µm sources in the European Large Area ISO Survey southern fields are identified in 1.4-GHz maps down to ~80 µJy. The radio-mid-infrared correlation is investigated and derived for the first time at these flux densities for a sample of this size. Our results show that radio and mid-infrared (MIR) luminos…
A two-component ionized reflection model of MCG-6-30-15
Vaughan, S.; Fabian, A. C.; Ballantyne, D. R.
Ionized reflection has often been considered as the explanation for the unusual Fe Kα variability observed in MCG-6-30-15. In this paper, we test this model using a 325-ks observation of MCG-6-30-15 by XMM-Newton and BeppoSAX. The data are fitted between 2.5 and 80 keV with the constant-density models of Ross & Fabian. The best-fitting ionized…
Core radius evolution of star clusters
Mackey, A. D.; Wilkinson, M. I.; Tout, C. A. +2 more
We use N-body simulations of star clusters to investigate the possible dynamical origins of the observed spread in core radius among intermediate-age and old star clusters in the Large Magellanic Cloud (LMC). Two effects are considered, a time-varying external tidal field and variations in primordial hard binary fraction. Simulations of clusters o…
The X-ray spectrum of the North Polar Spur
Warwick, R. S.; Snowden, S. L.; Burrows, D. N. +2 more
An analysis is presented of the soft X-ray background spectrum measured by the EPIC-MOS cameras on XMM-Newton in three observations targeted on the North Polar Spur (NPS). Three distinct Galactic plasma components are identified: a cool local hot bubble (LHB) component, Tlo~ 0.1 keV; a cool Galactic halo component, at a similar temperat…
Far-infrared photometry of deeply embedded outflow sources
Smith, M. D.; Eislöffel, J.; Froebrich, D. +1 more
We present far-infrared maps and spectroscopy for a number of deeply embedded protostellar objects (CepE, HH211-MM, IC1396 W, L1157, L1211, and RNO 15FIR) from data that we acquired with the Infrared Space Observatory (ISO) photopolarimeter (PHOT) and Long Wavelength Spectrometer (LWS). Several previously undetected deeply embedded sources are fou…
Is there really a Lutz-Kelker bias? Reconsidering calibration with trigonometric parallaxes
Smith, Haywood
In the recent literature there are indications of some confusion regarding the Lutz-Kelker bias: whether or not it exists, and if so, what it is and when it should be corrected. Here we carefully reexamine Lutz & Kelker's original work to understand what they actually did, and then look at their later papers and some other works on the subject…
Anatomy of the Herbig-Haro object HH7 bow shock
Smith, Michael D.; Davis, Christopher J.; Khanzadyan, Tigran
We perform a detailed shock diagnosis of the Herbig-Haro object HH7, a well-defined bow shock from a protostellar outflow. We first present molecular hydrogen images in the 2-1 S(1) and 1-0 S(1) K-band emission lines. We then introduce revised models for magneto-hydrodynamic bow shocks that incorporate a limited C and O chemistry and account for t…
Temperature variations from Hubble Space Telescope spectroscopy of the Orion Nebula
Martin, P. G.; Blagrave, K. P. M.; Dufour, R. J. +5 more
We present Hubble Space Telescope (HST)/STIS long-slit spectroscopy of NGC 1976. Our goal is to measure the intrinsic line ratio [OIII] 4364/5008 and thereby evaluate the electron temperature (Te) and the fractional mean-square Te variation (t2A)across the nebula. We also measure the intrinsic line ratio…
Host galaxies and black hole masses of low- and high-luminosity radio-loud active nuclei
Treves, Aldo; Falomo, Renato; Carangelo, Nicoletta
We investigate the host galaxy luminosities of BL Lac objects (BLLs) and radio-loud quasars (RLQs) at z < 0.5, imaged with the Hubble Space Telescope (HST). From a homogeneous treatment of the data, we construct the host-galaxy luminosity functions (HGLFs) and find that RLQ hosts are ~0.5 mag brighter than those of BLLs: <MR>
The far-infrared signature of dust in high-latitude regions
del Burgo, C.; Ábrahám, P.; Laureijs, R. J. +1 more
We present ISOPHOT observations of eight interstellar regions in the 60-200 µm wavelength range. The regions belong to mostly quiescent high-latitude clouds and have optical extinction peaks from AV~1-6 mag. From the 150- and 200-µm emission, we derived colour temperatures for the classical big grain component which show a c…