Examinando por Autor "Koss, M."

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    BAT AGN Spectroscopic Survey – XIX. Type 1 versus type 2 AGN dichotomy from the point of view of ionized outflows
    (Oxford University Press, 2019-11) Rojas, A.F; Sani, E.; Gavignaud, I.; Ricci, C.; Lamperti, I.; Koss, M.; Trakhtenbrot, B.; Schawinski, K.; K., Oh.; Bauer, F. E.; Bischetti, M.; Boissay-Malaquin, R.; Bongiorno, A.; Harrison, F.; Kakkad, A.D; Masetti, N.; Ricci, F.; Shimizu, T.; Stalevski, M.; Stern, D.; Vietri, G.
    We present a detailed study of ionized outflows in a large sample of ∼650 hard X-raydetected active galactic neuclei (AGNs). Using optical spectroscopy from the BAT AGN Spectroscopic Survey (BASS), we are able to reveal the faint wings of the [OIII] emission lines associated with outflows covering, for the first time, an unexplored range of low AGN bolometric luminosity at low redshift (z ∼0.05).We test if and how the incidence and velocity of ionized outflow is related to AGN physical parameters: black hole mass (MBH), gas column density (NH), Eddington ratio (λEdd), [O III], X-ray, and bolometric luminosities. We find a higher occurrence of ionized outflows in type 1.9 (55 per cent) and type 1 AGNs (46 per cent) with respect to type 2 AGNs (24 per cent). While outflows in type 2 AGNs are evenly balanced between blue and red velocity offsets with respect to the [OIII] narrow component, they are almost exclusively blueshifted in type 1 and type 1.9 AGNs. We observe a significant dependence between the outflow occurrence and accretion rate, which becomes relevant at high Eddington ratios [log(λEdd) −1.7]. We interpret such behaviour in the framework of covering factor-Eddington ratio dependence. We do not find strong trends of the outflow maximum velocity with AGN physical parameters, as an increase with bolometric luminosity can be only identified when including samples of AGNs at high luminosity and high redshift taken from literature.
  • Miniatura
    Ítem
    BAT AGN Spectroscopic Survey. I. Spectral Measurements, Derived Quantities, and AGN Demographics
    (Institute of Physics Publishing, 2017-11) Koss, M.; Trakhtenbrot, B.; Ricci, C.; Lamperti, I.; Oh, K.; Berney, S.; Schawinski, K.; Baloković, M.; Baronchelli, L.; Crenshaw, D.M.; Fischer, T.; Gehrels, N.; Harrison, F.; Hashimoto, Y.; Hogg, D.; Ichikawa, K.; Masetti, N.; Mushotzky, R.; Sartori, L.; Stern, D.; Treister, E.; Ueda, Y.; Veilleux, S.; Winter, L.
    We present the first catalog and data release of the Swift-BAT AGN Spectroscopic Survey. We analyze optical spectra of the majority of the detected AGNs (77%, 642/836)based on their 14-195 keV emission in the 70-month Swift-BAT all-sky catalog. This includes redshift determination, absorption and emission-line measurements, and black hole mass and accretion rate estimates for the majority of obscured and unobscured AGNs (74%, 473/642), with 340 measured for the first time. With ∼90% of sources at , the survey represents a significant advance in the census of hard X-ray-selected AGNs in the local universe. In this first catalog paper, we describe the spectroscopic observations and data sets, and our initial spectral analysis. The FWHMs of the emission lines show broad agreement with the X-ray obscuration (∼94%), such that Sy 1-1.8 have cm-2, and Seyfert 2 have cm-2. Seyfert 1.9, however, show a range of column densities. Compared to narrow-line AGNs in the SDSS, the X-ray-selected AGNs have a larger fraction of dusty host galaxies (), suggesting that these types of AGN are missed in optical surveys. Using the [O iii] λ5007/Hβ and [N ii] λ6583/Hα emission-line diagnostic, about half of the sources are classified as Seyferts; ∼15% reside in dusty galaxies that lack an Hβ detection, but for which the upper limits on line emission imply either a Seyfert or LINER, are in galaxies with weak or no emission lines despite high-quality spectra, and a few percent each are LINERS, composite galaxies, H ii regions, or in known beamed AGNs.