The last Gift of BeppoSAX: PDS Observations of the two Blazars 1ES 0507-040 and PKS 1229-021

Towards the end of the BeppoSAX mission, the only operated Narrow Field Instrument was the PDS, which covers the energy range 13-300 keV. Two blazars, 1ES 0507-040 (z=0.304) and PKS 1229-021 (z= 1.045), suitably located in the sky for BeppoSAX pointing, were observed for about 2 days each in Spring 2002 with the PDS and detected up to 50 keV. 1ES0507-040 had been already observed by the BeppoSAX NFIs at an earlier epoch for a much shorter time. We have re-analysed those data as well, and identified a possible contamination problem in the PDS spectrum. We present our recent PDS data on both sources, combined with the previous BeppoSAX data and with non-simultaneous observations at other frequencies. The derived Spectral Energy Distributions allow us to discuss the origin of the high energy component.Comment: 4 pages, 6 figures, poster presented at the symposium: The Restless High-Energy Universe, Amsterdam, May 200

Rapid X-ray Variability of the BL Lacertae Object PKS 2155-304

(Abridged) We present a detailed power density spectrum and cross-correlation analysis of the X-ray light curves of the BL Lac object PKS 2155-304, observed with BeppoSAX in 1997 and 1996, aimed at exploring the rapid variability properties and the inter-band cross correlations in the X-rays. We also perform the same analysis on the (archival) X-ray light curve obtained with ASCA in 1994.Comment: 47 pages, 11 figures, AAS Latex macros V4.0, accepted for publication in the Astrophysical Journa

Individual Differences in Amygdala and Ventromedial Prefrontal Cortex Activity are Associated with Evaluation Speed and Psychological Well-being

Using functional magnetic resonance imaging, we examined whether individual differences in amygdala activation in response to negative relative to neutral information are related to differences in the speed with which such information is evaluated, the extent to which such differences are associated with medial prefrontal cortex function, and their relationship with measures of trait anxiety and psychological well-being (PWB). Results indicated that faster judgments of negative relative to neutral information were associated with increased left and right amygdala activation. In the prefrontal cortex, faster judgment time was associated with relative decreased activation in a cluster in the ventral anterior cingulate cortex (ACC, BA 24). Furthermore, people who were slower to evaluate negative versus neutral information reported higher PWB. Importantly, higher PWB was strongly associated with increased activation in the ventral ACC for negative relative to neutral information. Individual differences in trait anxiety did not predict variation in judgment time or in amygdala or ventral ACC activity. These findings suggest that people high in PWB effectively recruit the ventral ACC when confronted with potentially aversive stimuli, manifest reduced activity in subcortical regions such as the amygdala, and appraise such information as less salient as reflected in slower evaluative speed

BeppoSAX Observations of the Radio Galaxy Centaurus A

We present preliminary results from two observations of the radio galaxy Centaurus A performed by the BeppoSAX satellite. We did not detect any spectral variation of the nuclear continuum in spite of the long-term flux change (by a factor 1.3) between the two observations. At both epochs, the nuclear point-like emission was well fitted with a strongly absorbed power law with an exponential cutoff at high energies (E_cutoff>200 keV). We also observed a significant flux variation of the iron line between the two observations. The flux of the line and of the continuum changed in the opposite sense. The line is more intense at the first epoch, when the nuclear source was at the lower intensity level. The implied delay between the continuum and line variations strongly suggests that the cold material responsible for the iron line production is not located very near to the primary X-ray source. There is also evidence that the line profile changed between the two epochs, being broader and slightly blueshifted when the source was fainter. It is possible that the emission feature is a blend of cold and ionized iron lines produced in separate regions surrounding the nuclear source.Comment: 4 pages, 4 figures, accepted for publication in Advances in Space Research, proceedings of 32nd COSPAR Symposium (1998

Amygdala and ventromedial prefrontal cortex are inversely coupled during regulation of negative affect and predict the diurnal pattern of cortisol secretion among older adults

Among younger adults, the ability to willfully regulate negative affect, enabling effective responses to stressful experiences, engages regions of prefrontal cortex (PFC) and the amygdala. Because regions of PFC and the amygdala are known to influence the hypothalamic-pituitary-adrenal axis, here we test whether PFC and amygdala responses during emotion regulation predict the diurnal pattern of salivary cortisol secretion. We also test whether PFC and amygdala regions are engaged during emotion regulation in older (62- to 64-year-old) rather than younger individuals. We measured brain activity using functional magnetic resonance imaging as participants regulated (increased or decreased) their affective responses or attended to negative picture stimuli. We also collected saliva samples for 1 week at home for cortisol assay. Consistent with previous work in younger samples, increasing negative affect resulted in ventral lateral, dorsolateral, and dorsomedial regions of PFC and amygdala activation. In contrast to previous work, decreasing negative affect did not produce the predicted robust pattern of higher PFC and lower amygdala activation. Individuals demonstrating the predicted effect (decrease s attend in the amygdala), however, exhibited higher signal in ventromedial prefrontal cortex (VMPFC) for the same contrast. Furthermore, participants displaying higher VMPFC and lower amygdala signal when decreasing compared with the attention control condition evidenced steeper, more normative declines in cortisol over the course of the day. Individual differences yielded the predicted link between brain function while reducing negative affect in the laboratory and diurnal regulation of endocrine activity in the home environment

Radio Properties of FIRST Radio Sources at 1 mJy

This paper presents a detailed analysis of the radio properties for the sample of faint radio sources introduced in Magliocchetti et al. (2000). The sample comprises mainly intrinsically low-power sources whose majority (\simgt 70 per cent) is made of FR I radio galaxies. These objects show some degree (at 1$\sigma$ confidence level) of luminosity evolution, which is also needed to correctly reproduce the total number and shape of the counts distribution at 1.4 GHz. Analysis of the de-evolved local radio luminosity function shows a good agreement between data and model predictions for this class of sources. Particular care has been devoted to the issue of 'lined' galaxies (i.e. objects presenting in their spectra a continuum typical of early-type galaxies plus emission lines of different nature), which appear as an intermediate class of sources between AGN-dominated and starburst galaxies. Different evolutionary behaviours are seen between the two sub-populations of lined and non-lined low-power radio galaxies, the first class indicating a tendency for the radio luminosity to decrease with look-back time, the second one showing positive evolution. We note that different evolutionary properties also seem to characterize BL Lacs selected in different bands, so that one might envisage an association between lined FR I and the sub-class of BL Lacs selected in the X-ray band.Comment: 9 pages, 6 figures, to appear in MNRA

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

Chandra and HST observations of gamma-ray blazars: comparing jet emission at small and large scales

We present new Chandra and HST data for four gamma-ray blazars selected on the basis of radio morphology with the aim of revealing X-ray and optical emission from their jets at large scales. All the sources have been detected. Spectral Energy Distributions of the large scale jets are obtained as well as new X-ray spectra for the blazar cores. Modeling for each object the core (sub-pc scale) and large-scale (>100 kpc) jet SEDs, we derive the properties of the same jet at the two scales. The comparison of speeds and powers at different scales supports a simple scenario for the dynamics and propagation of high power relativistic jets.Comment: Accepted for publication in Ap