VLBI detection of an AGN pair in the binary black hole candidate SDSS J1536+0441

We present first pc-scale radio imaging of the radio-quiet candidate binary black hole system SDSS J1536+0441. The observations were carried out by the European VLBI Network at the frequency of 5 GHz and allowed to image SDSS J1536+0441 with a resolution of about 10 mas (50 pc). Two compact radio cores are detected at the position of the kpc-scale components VLA-A and VLA-B, proving the presence of two compact active nuclei with radio luminosity about 10^{40} erg/s, thus ruling out the possibility that the two radio sources are both powered by one 0.1 pc binary black hole. From a comparison with published 8.5 GHz flux densities we derived an estimate of the radio spectral index of the two pc-scale cores. Both cores have flat or inverted spectral index and, at least for the case of VLA-A, we can rule out the possibility that synchrotron self-absorption is responsible for the inverted radio spectrum. We suggest that thermal free-free emission from an X-ray heated disk wind may be powering the radio emission in VLA-A.Comment: Accepted for publication in ApJ Letters

Massive black hole binaries: dynamical evolution and observational signatures

The study of the dynamical evolution of massive black hole pairs in mergers is crucial in the context of a hierarchical galaxy formation scenario. The timescales for the formation and the coalescence of black hole binaries are still poorly constrained, resulting in large uncertainties in the expected rate of massive black hole binaries detectable in the electromagnetic and gravitational wave spectra. Here we review the current theoretical understanding of the black hole pairing in galaxy mergers, with a particular attention to recent developments and open issues. We conclude with a review of the expected observational signatures of massive binaries, and of the candidates discussed in literature to date.Comment: 4 Figures. Accepted for publication in Advances in Astronom

A Bayesian blind survey for cold molecular gas in the Universe

A new Bayesian method for performing an image domain search for line-emitting galaxies is presented. The method uses both spatial and spectral information to robustly determine the source properties, employing either simple Gaussian, or other physically motivated models whilst using the evidence to determine the probability that the source is real. In this paper, we describe the method, and its application to both a simulated data set, and a blind survey for cold molecular gas using observations of the Hubble Deep Field North taken with the Plateau de Bure Interferometer. We make a total of 6 robust detections in the survey, 5 of which have counterparts in other observing bands. We identify the most secure detections found in a previous investigation, while finding one new probable line source with an optical ID not seen in the previous analysis. This study acts as a pilot application of Bayesian statistics to future searches to be carried out both for low-$J$ CO transitions of high redshift galaxies using the JVLA, and at millimeter wavelengths with ALMA, enabling the inference of robust scientific conclusions about the history of the molecular gas properties of star-forming galaxies in the Universe through cosmic time.Comment: 12 pages, 4 Figures, 5 Table

The optical spectrum of PKS 1222+216 and its black hole mass

We investigate the optical spectral properties of the blazar PKS 1222+216 during a period of 3 years. While the continuum is highly variable the broad line emission is practically constant. This supports a scenario in which the broad line region is not affected by jet continuum variations. We thus infer the thermal component of the continuum from the line luminosity and we show that it is comparable with the continuum level observed during the phases of minimum optical activity. The mass of the black hole is estimated through the virial method from the FWHM of MgII, Hbeta, and Halpha broad lines and from the thermal continuum luminosity. This yields a consistent black hole mass value of 6x10^8 solar masses.Comment: 7 pages, 4 figures, accepted for publication in MNRA

The black hole - host galaxy relation for very low-mass quasars

Recently, the relation between the masses of the black hole ($M_{BH}$) and the host galaxy ($M_{host}$) in quasars has been probed down to the parameter space of $M_{BH}\sim10^8 M_\odot$ and $M_{host}\sim10^{11} M_\odot$ at z $<$ 0.5. In this study, we have investigated the $M_{BH}$ - $M_{host}$ log-linear relation for a sample of 37 quasars with low black hole masses ($10^7 M_\odot < M_{BH} < 10^{8.3} M_\odot$) at 0.5 $<$ z $<$ 1.0. The black hole masses were derived using virial mass estimates from SDSS optical spectra. For 25 quasars, we detected the presence of the host galaxy from deep near-infrared H-band imaging, whereas upper limits for the host galaxy luminosity (mass) were estimated for the 12 unresolved quasars. We combined our previous studies with the results from this work to create a sample of 89 quasars at z $<$ 1.0 having a large range of black hole masses ($10^7 M_\odot < M_{BH} < 10^{10} M_\odot$) and host galaxy masses ($10^{10} M_\odot < M_{host} < 10^{13} M_\odot$). Most of the quasars at the low mass end lie below the extrapolation of the local relation. This apparent break in the linearity of the entire sample is due to increasing fraction of disc-dominated host galaxies in the low-mass quasars. After correcting for the disc component, and considering only the bulge component, the bilinear regression for the entire quasar sample holds over 3.5 dex in both the black hole mass and the bulge mass, and is in very good agreement with the local relation. We advocate secular evolution of discs of galaxies being responsible for the relatively strong disc domination.Comment: Accepted for publication by MNRAS. 9 pages, 4 figure

Modal strain-based post-earthquake damage characterization of r/c frame buildings

This paper contributes a novel numerical study to assess the potential of the two most widely used modalstrain based damage indices for damage detection in structural components under flexure for post-earthquake damage characterization of reinforced concrete multi-storey planar frame buildings. To this aim, buildings are treated as transversely vibrating beam-like structures and modal strains (i.e., second derivatives of mode shapes) are computed from lateral translational mode shape ordinates known at each floor/slab level along the height of buildings before (healthy state) and after (damaged state) a damaging seismic event. In this setting, the change of modal curvature (MC) along the height of the building as well as the change of modal strain energy (MSE) are adopted as damage sensitive indices and their effectiveness to localize damage to column or to beam elements at different floors and to characterize damage severity is gauged vis-à-vis. This is accomplished by considering computer-generated mode shape data obtained from linear modal analyses applied to finite element models of two different 10-storey r/c planar frames, a single-bay one and a two-bay one, under healthy and several different relatively light damaged states of varying severity. The furnished numerical results demonstrate that both the MC index evaluated based on first mode shape data and the MSE index determined from the first three mode shape data are equally able for both damage localization and severity characterization for most of the damaged case scenarios considered. Further research is warranted to account for the influence of noisy field-recorded mode shape data as well as for sparse instrumentation in which acceleration sensors are not deployed on every building floor

Configuração do projeto do Pibid de letras-língua portuguesa da unioeste, Câmpus de Marechal Cândido Rondon

Anais do II Seminário Seminário Estadual PIBID do Paraná: tecendo saberes / organizado por Dulcyene Maria Ribeiro e Catarina Costa Fernandes — Foz do Iguaçu: Unioeste; Unila, 2014No trabalho, será apresentada a configuração do subprojeto do PIBID-Letras/Língua Portuguesa da Unioeste, câmpus de Marechal Cândido Rondon, que se iniciou em março/2014, com 7 graduandos bolsistas e uma escola envolvida, o Colégio Estadual Eron Domingues, localizado na sede do município. A professora supervisora é Vera Beatriz Hoff Pagnussatti, docente de seis turmas de alunos, sendo quatro delas de 8o/9o anos e duas de Ensino Médio, todas envolvidas em atividades do PIBID. No subprojeto, estão previstas várias ações, as quais são apresentadas e comentadas. Elas objetivam a formação dos graduandos em diferentes aspectos e momentos de sua formação e resumem as principais atividades do PIBID para o período 2014-201