The dust masses of powerful radio galaxies: clues to the triggering of their activity

We use deep Herschel Space Observatory observations of a 90% complete sample of 32 intermediate-redshift 2Jy radio galaxies (0.05 < z < 0.7) to estimate the dust masses of their host galaxies and thereby investigate the triggering mechanisms for their quasar-like AGN. The dust masses derived for the radio galaxies (7.2x10^5 < M_d < 2.6x10^8 M_sun) are intermediate between those of quiescent elliptical galaxies on the one hand, and ultra luminous infrared galaxies (ULIRGs) on the other. Consistent with simple models for the co-evolution of supermassive black holes and their host galaxies, these results suggest that most of the radio galaxies represent the late time re-triggering of AGN activity via mergers between the host giant elliptical galaxies and companion galaxies with relatively low gas masses. However, a minority of the radio galaxies in our sample (~20%) have high, ULIRG-like dust masses, along with evidence for prodigious star formation activity. The latter objects are more likely to have been triggered in major, gas-rich mergers that represent a rapid growth phase for both their host galaxies and their supermassive black holes.Comment: 5 pages, 2 figures, accepted for publication in MNRAS Letter

The soft X-ray and narrow-line emission of Mrk573 on kiloparcec scales

We present a study of the circumnuclear region of the nearby Seyfert galaxy Mrk573 using Chandra, XMM-Newton and HST data. The X-ray morphology shows a biconical region extending up to 12 arcsecs (4 kpc) in projection from the nucleus. A strong correlation between the X-rays and the highly ionized gas seen in the [O III] image is reported. Moreover, we have studied the line intensities detected with the RGS/XMM-Newton and used them to fit the low resolution EPIC/XMM-Newton and ACIS/Chandra spectra. The RGS spectrum is dominated by emission lines of C VI, O VII, O VIII, Fe XVII, and Ne IX, among others. A good fit is obtained using these emission lines found in the RGS spectrum as a template for Chandra spectra of the nucleus and extended emission. The photoionization model Cloudy provides a reasonable fit for both the nuclear region and the cone-like structures. For the nucleus the emission is modelled using two phases: a high ionization [log(U)=1.23] and a low ionization [log(U)=0.13]. For the high ionization phase the transmitted and reflected component are in a ratio 1:2, whereas for the low ionization the reflected component dominates. For the extended emission, we successfully reproduced the emission with two phases. The first phase shows a higher ionization parameter for the NW (log(U)=0.9) than for the SE cone (log(U)=0.3). The second phase shows a low ionization parameter (log(U)=-3) and is rather uniform for NW and SE cones. In addition, the nuclear optical/infrared SED has been modeled by a clumpy torus model. The torus bolometric luminosity agrees with the AGN luminosity inferred from the observed hard X-ray spectrum. The optical depth along the line of sight derived from the SED fit indicates a high neutral column density in agreement with the classification of the nucleus as a Compton-thick AGN.Comment: 15 pages, 14 figures, final version of the paper submitted to Ap

The optical morphologies of the 2Jy sample of radio galaxies: evidence for galaxy interactions

We present deep GMOS-S/Gemini optical broad-band images for a complete sample of 46 southern 2Jy radio galaxies at intermediate redshifts (0.05<z<0.7). Based on them, we discuss the role of galaxy interactions in the triggering of powerful radio galaxies (PRGs). The high-quality observations presented here show for the first time that the overall majority of PRGs at intermediate redshifts (78-85%) show peculiarities in their optical morphologies at relatively high levels of surface brightness(˜μV = 23.6 mag arcsec−2; μV ≃ [21, 26] mag arcsec−2). The observed morphological peculiarities include tails, fans, bridges, shells, dust lanes, irregular features, amorphous haloes, and multiple nuclei. While the results for many of the galaxies are consistent with them being observed at, or after, the time of coalescence of the nuclei in a galaxy merger, we find that more than one-third of the sample are observed in a pre-coalescence phase of the merger, or following a close encounter between galaxies that will not necessarily lead to a merger. By dividing the sample into Weak-Line Radio Galaxies (WLRGs; 11 objects) and Strong-Line Radio Galaxies (SLRGs; 35 objects) we find that only 27% of the former show clear evidence for interactions in their optical morphologies, in contrast to the SLRGs, of which at least 94% appear interacting. This is consistent with the idea that many WLRGs are fuelled/triggered by Bondi accretion of hot gas. However, the evidence for interactions and dust features in a fraction of them indicates that the accretion of cold gas cannot always be ruled out. Of the 28% of the sample that display evidence for significant starburst activity, we find that 92% present disturbed morphologies, following the same general trend as the total and SLRG samples. By comparing our PRGs with various samples of quiescent ellipticals from the literature, we conclude that the percentage of morphological disturbance that we find here exceeds that found for quiescent ellipticals when similar surface brightnesses are considered. Overall, our study indicates that galaxy interactions are likely to play a key role in the triggering of AGN/jet activity

Polarization of the changing-look quasar J1011+5442

If the disappearance of the broad emission lines observed in changing-look quasars were caused by the obscuration of the quasar core through moving dust clouds in the torus, high linear polarization typical of type 2 quasars would be expected. We measured the polarization of the changing-look quasar J1011+5442 in which the broad emission lines have disappeared between 2003 and 2015. We found a polarization degree compatible with null polarization. This measurement suggests that the observed change of look is not due to a change of obscuration hiding the continuum source and the broad line region, and that the quasar is seen close to the system axis. Our results thus support the idea that the vanishing of the broad emission lines in J1011+5442 is due to an intrinsic dimming of the ionizing continuum source that is most likely caused by a rapid decrease in the rate of accretion onto the supermassive black hole.Comment: Accepted for publication in Astronomy and Astrophysics Letter

Inmates’ empathy: relationship with childhood victimization

Poster presented at the 4th International Congress of CiiEM – “Health, Well-being and Ageing in the XXI Century.” 2-5 June 2019, Campus Egas Moniz, Monte de Caparica, PortugalN/

Polyvictimization among a juvenile Portuguese sample

Abstract in proceedings of the Fourth International Congress of CiiEM: Health, Well-Being and Ageing in the 21st Century, held at Egas Moniz’ University Campus in Monte de Caparica, Almada, from 3–5 June 2019.This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.info:eu-repo/semantics/publishedVersio

Polyvictimization among a juvenile Portuguese sample

Poster presented at the 4th International Congress of CiiEM – “Health, Well-being and Ageing in the XXI Century.” 2-5 June 2019, Campus Egas Moniz, Monte de Caparica, PortugalN/