Wisconsin Forward Forever

https://digitalcommons.library.umaine.edu/mmb-vp/5095/thumbnail.jp

Parent population of flat-spectrum radio-loud narrow-line Seyfert 1 galaxies

Flat-spectrum radio-loud Narrow-Line Seyfert 1 galaxies (NLS1s) are a recently discovered class of $\gamma$-ray emitting Active Galactic Nuclei (AGN), that exhibit some blazar-like properties which are explained with the presence of a relativistic jet viewed at small angles. When blazars are observed at larger angles they appear as radio-galaxies, and we expect to observe an analogue parent population for beamed NLS1s. However, the number of known NLS1s with the jet viewed at large angles is not enough. Therefore, we tried to understand the origin of this deficit. Current hypotheses about the nature of parent sources are steep-spectrum radio-loud NLS1s, radio-quiet NLS1s and disk-hosted radio-galaxies. To test these hypotheses we built three samples of candidate sources plus a control sample, and calculated their black hole mass and Eddington ratio using their optical spectra. We then performed a Kolmogorov-Smirnov statistical test to investigate the compatibility of our different samples with a beamed population. Our results indicate that, when the inclination angle increases, a beamed source appears as a steep-spectrum radio-loud NLS1, or possibly even as a disk-hosted radio-galaxy with low black hole mass and high Eddington ratio. Further investigations, involving larger complete samples and observations at radio frequency, are needed to understand the incidence of disk-hosted radio-galaxies in the parent population, and to assess whether radio-quiet NLS1s can play a role, as well.Comment: 12 pages, 6 figures, accepted for publication by Astronomy and Astrophysic

Compact steep-spectrum sources as the parent population of flat-spectrum radio-loud NLS1s

Narrow-line Seyfert 1 galaxies (NLS1s) are an interesting subclass of active galactic nuclei (AGN), which tipically does not exhibit any strong radio emission. Seven percent of them, though, are radio-loud and often show a flat radio-spectrum (F-NLS1s). This, along to the detection of $\gamma$-ray emission coming from them, is usually interpreted as a sign of a relativistic beamed jet oriented along the line of sight. An important aspect of these AGN that must be understood is the nature of their parent population, in other words how do they appear when observed under different angles. In the recent literature it has been proposed that a specific class of radio-galaxies, compact-steep sources (CSS) classified as high excitation radio galaxies (HERG), can represent the parent population of F-NLS1s. To test this hypothesis in a quantitative way,in this paper we analyzed the only two statistically complete samples of CSS/HERGs and F-NLS1s available in the literature. We derived the black hole mass and Eddington ratio distributions, and we built for the first time the radio luminosity function of F-NLS1s. Finally, we applied a relativistic beaming model to the luminosity function of CSS/HERGs, and compared the result with the observed function of F-NLS1s. We found that compact steep-spectrum sources are valid parent candidates and that F-NLS1s, when observed with a different inclination, might actually appear as CSS/HERGs.Comment: 9 pages, 5 figures, 4 tables. Accepted for publication in Astronomy & Astrophysic

Exploring the parent population of beamed NLS1s: from the black hole to the jet

The aim of this work is to understand the nature of the parent population of beamed narrow-line Seyfert 1 galaxies (NLS1s), by studying the physical properties of three parent candidates samples: steepspectrum radio-loud NLS1s, radio-quiet NLS1s and disk-hosted radiogalaxies. In particular, we focused on the black hole mass and Eddington ratio distribution and on the interactions between the jet and the narrowline region.Facultad de Ciencias Astronómicas y Geofísica

Western blot analysis of ERK1/2 expression and phosphorylation in infected macrophages.

<p>Macrophages were infected with (A) wild-type or (B) Δ<i>choD</i> strains for 2 hours, washed with HBSS, and cultured for 24 hours. Cells were then treated with PMA for 2 hours. Representative immunoblots of ERK1/2 protein level and phosphorylation status are presented. Bands were quantified by densitometric analysis. Data are presented as optical density intensity of the area under each phosphoERK1/2 band’s peak (ODI) ± SEM (*p≤0.04, PMA vs. wild-type+PMA; Mann-Whitney <i>U</i> test). Data are presented from five independent experiments.</p