AGN Black Hole Masses and Bolometric Luminosities

Black hole mass, along with mass accretion rate, is a fundamental property of active galactic nuclei. Black hole mass sets an approximate upper limit to AGN energetics via the Eddington limit. We collect and compare all AGN black hole mass estimates from the literature; these 177 masses are mostly based on the virial assumption for the broad emission lines, with the broad-line region size determined from either reverberation mapping or optical luminosity. We introduce 200 additional black hole mass estimates based on properties of the host galaxy bulges, using either the observed stellar velocity dispersion or using the fundamental plane relation to infer $\sigma$; these methods assume that AGN hosts are normal galaxies. We compare 36 cases for which black hole mass has been generated by different methods and find, for individual objects, a scatter as high as a couple of orders of magnitude. The less direct the method, the larger the discrepancy with other estimates, probably due to the large scatter in the underlying correlations assumed. Using published fluxes, we calculate bolometric luminosities for 234 AGNs and investigate the relation between black hole mass and luminosity. In contrast to other studies, we find no significant correlation of black hole mass with luminosity, other than those induced by circular reasoning in the estimation of black hole mass. The Eddington limit defines an approximate upper envelope to the distribution of luminosities, but the lower envelope depends entirely on the sample of AGN included. For any given black hole mass, there is a range in Eddington ratio of up to three orders of magnitude.Comment: 43 pages with 10 figures. Accepted for publication in Ap

INTEGRAL high energy monitoring of the X-ray burster KS 1741-293

KS 1741-293, discovered in 1989 by the X-ray camera TTM in the Kvant module of the Mir space station and identified as an X-ray burster, has not been detected in the hard X band until the advent of the INTEGRAL observatory. Moreover this source has been recently object of scientific discussion, being also associated to a nearby extended radio source that in principle could be the supernova remnant produced by the accretion induced collapse in the binary system. Our long term monitoring with INTEGRAL, covering the period from February 2003 to May 2005, confirms that KS 1741-293 is transient in soft and hard X band. When the source is active, from a simultaneous JEM-X and IBIS data analysis, we provide a wide band spectrum from 5 to 100 keV, that can be fit by a two component model, a multiple blackbody for the soft emission and a Comptonized or a cut-off power law model for the hard component. Finally, by the detection of two X-ray bursters with JEM-X, we confirm the bursting nature of KS 1741-293, including this source in the class of the hard tailed X-ray bursters.Comment: 7 pages, accepted for publication on MNRA

First INTEGRAL Observations of Eight Persistent Neutron Star Low Mass X-ray Binaries

Early results from the INTEGRAL Core Program, for a sample of eight persistently bright neutron star low mass X-ray binaries in the energy range from 5 keV to 200 keV are presented. It is shown that INTEGRAL efficiently detects sources and that spectra may be obtained up to several hundreds of keV by combining data from three of the four INTEGRAL instruments: JEM-X, IBIS and SPI. For the source GX 17+2 it is shown that the spectrum extends well above 100 keV with a flattening of the spectrum above 30 keV. This might suggest a non-thermal comptonisation emission, but uncertainties in the current data reduction and background determination do not allow firm conclusions to be drawn.Comment: 5 pages, 6 figures, accepted for publication in Astronomy & Astrophysic

INTEGRAL observations of the field of the BL Lacertae object S5~0716+714

We have performed observations of the blazar S5 0716+714 with INTEGRAL on 2-6 April 2004. In the first months of 2004, the source had increased steadily in optical brightness and had undergone two outbursts. During the latter, occurred in March, it reached the extreme level of R = 12.1 mag, which triggered our INTEGRAL program. The target has been detected with IBIS/ISGRI up to 60 keV, with a flux of ~3 x 10e-11 erg/s/cm2 in the 30-60 keV interval, a factor of ~2 higher than observed by the BeppoSAX PDS in October 2000. In the field of S5 0716+714 we have also detected the Flat Spectrum Radio Quasar S5 0836+710 and the two Seyfert galaxies Mkn 3 and Mkn 6. Their IBIS/ISGRI spectra are rather flat, albeit consistent with those measured by BeppoSAX. In the spectrum of Mkn 3 we find some evidence of a break between ~60 and ~100 keV, reminiscent of the high energy cut-offs observed in other Seyfert galaxies. This is the first report of INTEGRAL spectra of weak Active Galactic Nuclei.Comment: 5 pages, 5 figures, in press in A&

Investigating the EGRET-radio galaxies link with INTEGRAL: the case of 3EG J1621+8203 and NGC 6251

The analysis of an INTEGRAL AO2 observation of the error contours of the EGRET source 3EG J1621+8203 is presented. The only source found inside the error contours for energies between 20 and 30 keV at 5 sigma detection significance is the FR I radio galaxy NGC 6251. This supports the identification of NGC 6251 with 3EG J1621+8203. The observed flux is higher and softer than observed in the past, but consistent with a variable blazar-like spectral energy distribution.Comment: 5 pages, 2 figures. Accepted for publication on A&A Main Journa

The characterization of the distant blazar GB6 J1239+0443 from flaring and low activity periods

In 2008 AGILE and Fermi detected gamma-ray flaring activity from the unidentified EGRET source 3EG J1236+0457, recently associated with a flat spectrum radio quasar GB6 J1239+0443 at z=1.762. The optical counterpart of the gamma-ray source underwent a flux enhancement of a factor 15-30 in 6 years, and of ~10 in six months. We interpret this flare-up in terms of a transition from an accretion-disk dominated emission to a synchrotron-jet dominated one. We analysed a Sloan Digital Sky Survey (SDSS) archival optical spectrum taken during a period of low radio and optical activity of the source. We estimated the mass of the central black hole using the width of the CIV emission line. In our work, we have also investigated SDSS archival optical photometric data and UV GALEX observations to estimate the thermal-disk emission contribution of GB6 J1239+0443. Our analysis of the gamma-ray data taken during the flaring episodes indicates a flat gamma-ray spectrum, with an extension of up to 15 GeV, with no statistically-relevant sign of absorption from the broad line region, suggesting that the blazar-zone is located beyond the broad line region. This result is confirmed by the modeling of the broad-band spectral energy distribution (well constrained by the available multiwavelength data) of the flaring activity periods and by the accretion disk luminosity and black hole mass estimated by us using archival data.Comment: 30 pages, 7 figures, 4 tables MNRAS Accepted on 2012 June 1

Behavioural syndrome in a solitary predator is independent of body size and growth rate.

Models explaining behavioural syndromes often focus on state-dependency, linking behavioural variation to individual differences in other phenotypic features. Empirical studies are, however, rare. Here, we tested for a size and growth-dependent stable behavioural syndrome in the juvenile-stages of a solitary apex predator (pike, Esox lucius), shown as repeatable foraging behaviour across risk. Pike swimming activity, latency to prey attack, number of successful and unsuccessful prey attacks was measured during the presence/absence of visual contact with a competitor or predator. Foraging behaviour across risks was considered an appropriate indicator of boldness in this solitary predator where a trade-off between foraging behaviour and threat avoidance has been reported. Support was found for a behavioural syndrome, where the rank order differences in the foraging behaviour between individuals were maintained across time and risk situation. However, individual behaviour was independent of body size and growth in conditions of high food availability, showing no evidence to support the state-dependent personality hypothesis. The importance of a combination of spatial and temporal environmental variation for generating growth differences is highlighted

A Short Hard X-ray Flare from the Blazar NRAO 530 Observed by INTEGRAL

We report about a short flare from the blazar NRAO 530 occurred on 17 February 2004 and detected serendipitously by the IBIS/ISGRI detector on board INTEGRAL. In the 20-40 keV energy range, the source, that is otherwise below the detection limit, is detected at a level of ~2 x 10^-10 erg cm^-2 s^-1 during a time interval of less than 2000 s, which is about a factor 2 above the detection threshold. At other wavelengths, only nearly-simultaneous radio data are available (1 observation at 2 cm on 11 February 2004), indicating a moderate increase of the polarization. This appears to be the shortest time variability episode ever detected in a high luminosity blazar at hard X-rays, unless the blazar is contaminated by the presence of an unknown unresolved rapidly varying source.Comment: 5 pages, 4 figures. Accepted for publication on A&A Main Journal. Note added in proo

Charge separation relative to the reaction plane in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}= 2.76 TeV

Measurements of charge dependent azimuthal correlations with the ALICE detector at the LHC are reported for Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV. Two- and three-particle charge-dependent azimuthal correlations in the pseudo-rapidity range $|\eta| < 0.8$ are presented as a function of the collision centrality, particle separation in pseudo-rapidity, and transverse momentum. A clear signal compatible with a charge-dependent separation relative to the reaction plane is observed, which shows little or no collision energy dependence when compared to measurements at RHIC energies. This provides a new insight for understanding the nature of the charge dependent azimuthal correlations observed at RHIC and LHC energies.Comment: 12 pages, 3 captioned figures, authors from page 2 to 6, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/286