A self-consistent NLTE-spectra synthesis model of FeLoBAL QSOs

The Astrophysical Journal (Impact Factor: 5.99). 04/2008; 676(2). DOI: 10.1086/528671
Source: arXiv


We present detailed radiative transfer spectral synthesis models for the Iron Low Ionization Broad Absorption Line (FeLoBAL) active galactic nuclei (AGN) FIRST J121442.3+280329 and ISO J005645.1-273816. Detailed NLTE spectral synthesis with a spherically symmetric outflow reproduces the observed spectra very well across a large wavelength range. While exact spherical symmetry is probably not required, our model fits are of high quality and thus very large covering fractions are strongly implied by our results. We constrain the kinetic energy and mass in the ejecta and discuss their implications on the accretion rate. Our results support the idea that FeLoBALs may be an evolutionary stage in the development of more ``ordinary'' QSOs. Comment: Accepted for publication in ApJ/removed misleading remarks about CLOUDY in section 2

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We present results on a survey to find extremely dust-reddened Type 1 quasars. Combining the FIRST radio survey, the 2MASS Infrared Survey and the Sloan Digital Sky Survey, we have selected a candidate list of 122 potential red quasars. With more than 80% spectroscopically identified objects, well over 50% are classified as dust-reddened Type 1 quasars, whose reddenings (E(B - V)) range from approximately 0.1 to 1.5 mag. They lie well off the color selection windows usually used to detect quasars and many fall within the stellar locus, which would have made it impossible to find these objects with traditional color selection techniques. The reddenings found are much more consistent with obscuration happening in the host galaxy rather than stemming from the dust torus. We find an unusually high fraction of broad absorption line (BAL) quasars at high redshift, all but one of them belonging to the low-ionization BAL (LoBAL) class and many also showing absorption in the metastable Fe II line (FeLoBAL). The discovery of further examples of dust-reddened LoBAL quasars provides more support for the hypothesis that BAL quasars (at least LoBAL quasars) represent an early stage in the lifetime of the quasar. The fact that we see such a high fraction of BALs could indicate that the quasar is in a young phase in which quasar feedback from the BAL winds is suppressing star formation in the host galaxy. Based on observations obtained with the W. M. Keck Observatory, which is jointly operated by the California Institute of Technology and the University of California.
    Full-text · Article · Jun 2009 · The Astrophysical Journal
  • [Show abstract] [Hide abstract]
    ABSTRACT: The review of activities on the project 146001 "Influence of collisional processes on the astrophysical plasma spectra", supported by the Ministry of Science and Technological development of Serbia, from 1st of January 2008 up to 31st of December 2009 is given, together with the bibliography of published works.
    No preview · Article · Jan 2010
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Low-ionization (MgII, FeII, FeIII) broad absorption line quasars (LoBALs) probe a relatively obscured quasar population, and could be at an early evolutionary stage for quasars. We study the intrinsic fractions of LoBALs using the SDSS, 2MASS, and FIRST surveys. We find that the LoBAL fractions of the near infra-red (NIR) and radio samples are approximately 5--7 times higher than those measured in the optical sample. This suggests that the fractions measured in the NIR and radio bands are closer to the intrinsic fractions of the populations, and that the optical fractions are significantly biased due to obscuration effects, similar to high-ionization broad absorption line quasars (HiBALs). We also find that the LoBAL fractions decrease with increasing radio luminosities, again, similar to HiBALs. In addition, we find tentative evidence for high fractions of LoBALs at high NIR luminosities, especially for FeLoBALs with a fraction of ~18 per cent at M_K_s < -31 mag. This population of NIR luminous LoBALs may be at an early evolutionary stage of quasar evolution. We use a two-component model of LoBALs including a pure geometric component and a luminosity dependent component at high NIR luminosities, and obtain better fits than those from a pure geometric model. Therefore, the LoBAL population can be modelled as a hybrid of both the geometric and evolutionary models, where the geometric component constitutes 3.4\pm0.3, 5.8\pm0.4, and 1.5\pm0.3 per cent of the quasar population for BI-LoBALs, AI-LoBALs, and FeLoBALs, respectively. Considering a population of obscured quasars that do not enter the SDSS survey, which could have a much higher LoBAL fraction, we expect that intrinsic fraction of LoBALs could be even higher.
    Full-text · Article · Apr 2010 · The Astrophysical Journal
Show more