X-RAY SPECTRAL PROPERTIES OF THE BAT AGN SAMPLE

By L. Winter, R. Mushotzky, C. Reynolds, J. Tueller. 2008

207 citations recorded by the source corpus.

The 9-month Swift Burst Alert Telescope (BAT) catalog provides the first unbiased (NH < 1024 cm−2) look at local (〈z〉 = 0.03) active galactic nuclei (AGNs). In this paper, we present the collected X-ray properties (0.3–12 keV) for the 153 AGNs detected. In addition, we examine the X-ray properties for a complete sample of nonbeamed sources, above the Galactic plane (b ⩾ 15°). Of these, 45% are best fit by simple power law models, while 55% require the more complex partial covering model. One of our goals was to determine the fraction of “hidden” AGNs, which we define as sources with scattering fractions less than or equal to 0.03 and ratios of soft to hard X-ray flux less than or equal to 0.04. We found that “hidden” AGNs constitute a high percentage of the sample (24%), proving that they are a very significant portion of local AGNs. Further, we find that the fraction of absorbed sources does increase at lower unabsorbed 2–10 keV luminosities, as well as accretion rates. This suggests that the unified model requires modification to include luminosity dependence, as suggested by models such as the “receding torus” model. Some of the most interesting results for the BAT AGN sample involve the host galaxy properties. We found that 33% are hosted in peculiar/irregular galaxies and only 5/74 are hosted in ellipticals. Further, 54% are hosted in interacting/merger galaxies. Finally, we present both the average X-ray spectrum (0.1–10 keV) and log N–log S in the 2–10 keV band. With our average spectrum, we have the remarkable result of reproducing the measured CXB X-ray power law slope of Γ ≈ 1.4. From the log N–log S relationship, we show that we are complete to log S ⩾ −11 in the 2–10 keV band. Below this value, we are missing as many as 3000 sources at log S = −12. Both the collected X-ray properties of our uniform sample and the log N–log S relationship will now provide valuable input to X-ray background models for z ≈ 0.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/471411317bbcaf999a53b7bd696a2c0997efad90

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Citations in the corpus

• THREE-YEAR SWIFT–BAT SURVEY OF ACTIVE GALACTIC NUCLEI: RECONCILING THEORY AND OBSERVATIONS? (2010, methodology): “0+3035 355.500 30.600 1.08 ± 0.19 5.7 UGC 12741 Sy2 0.02 1.64+0.33−0.30 23.7 (2) Notes. a The optical classification comes mainly from Tueller et al. (2008), Winter et al. (2009a), Parisi et al. (2009), Cusumano et al. (2010), SIMBAD, and NED.”
• Determining Inclinations of Active Galactic Nuclei Via Their Narrow-Line Region Kinematics (2012, background): “The emission that remains is fit with an absorbed power law model to determine NH (Winter et al. 2009).”
• The incidence of obscuration in active galactic nuclei (2013, background): “These are known to be present in many local AGN (Winter et al. 2009), albeit at luminosities typically lower than those we are probing with our D ow nloaded from https://academ ic.oup.com /m nras/article-abstract/437/4/3550/1006867 by Biblioteca di Scienze, U niversità degli studi di Firenze user…”
• THE SPACE DENSITY OF COMPTON-THICK ACTIVE GALACTIC NUCLEUS AND THE X-RAY BACKGROUND (2009, background): “In any case, it is important to remark that according to a detailed study by Winter et al. (2009), while all these complexspectrum sources are highly obscured, only half a dozen have some evidence of Compton-thick column densities.”
• THE 22 MONTH SWIFT-BAT ALL-SKY HARD X-RAY SURVEY (2009, methodology): “Winter et al. (2009) provide X-ray spectral fits for these sources and provide measures of the luminosity, nH , etc. for the sources in the 9-month catalog.”
• X-RAY REFLECTED SPECTRA FROM ACCRETION DISK MODELS. III. A COMPLETE GRID OF IONIZED REFLECTION CALCULATIONS (2013, background): “The ubiquity of this feature has been established observationally for a large number of sources (e.g., Gottwald et al. 1995; Winter et al. 2009; Ng et al. 2010; Fukazawa et al. 2011) for the following two reasons.”
• THE SIMULTANEOUS OPTICAL-TO-X-RAY SPECTRAL ENERGY DISTRIBUTION OF SOFT X-RAY SELECTED ACTIVE GALACTIC NUCLEI OBSERVED BY SWIFT (2010, methodology): “…the bolometric corrections for 29 AGN with simultaneous optical/UV and X-ray observations from the XMM-Newton OM and EPIC pn and Vasudevan et al. (2009b) presented a sample of 26 AGN selected from the 9 months Swift BAT survey (Markwardt et al. 2005; Winter et al 2009) with Swift UVOT and XRT data.”
• BAT AGN Spectroscopic Survey. V. X-Ray Properties of the Swift/BAT 70-month AGN Catalog (2017, methodology): “A large number of works have already been carried out studying pointed X-ray observations (e.g., Winter et al. 2009b; Ricci et al. 2010; Tazaki et al. 2011, 2013; Kawamuro et al. 2016b; Tanimoto et al. 2016; Marchesi et al. 2017; Oda et al. 2017) and the multiwavelength properties of Swift/BAT AGN.”
• The nature of the Compton-thick X-ray reprocessor in NGC 4945 (2012, background): “However, above 10 keV, NGC 4945 is much brighter and highly variable, and it is one of the brightest AGNs in the 14–195 keV Swift BAT all-sky survey (e.g., see Winter et al. 2008, 2009; Tueller et al. 2009, 2010).”
• What drives the growth of black holes (2011, background): “Sensitive radio, mid-IR spectroscopy, and X-ray observations (particularly at > 10 keV; e.g., Sazonov et al. 2007; Winter et al. 2009; Burlon et al. 2011) further extend our understanding and census of nearby AGN activity, providing the identification of AGNs even in the presence of significant…”
• Intermediate mass black holes in AGN discs – I. Production and growth (2012, methodology): “The ultra-luminous X-ray sources (ULXs) observed outside galactic nuclei (e.g. Winter et al. 2009) may be powered by accretion onto IMBH (Miller & Colbert 2004).”
• GOODS-Herschel: the far-infrared view of star formation in active galactic nucleus host galaxies since z ≈ 3 (2011, methodology): “7 and 10 of Winter et al. 2009 where they plot theLX and NH of the Swift-BAT AGN sample).”
• THE CORES OF THE Fe Kα LINES IN ACTIVE GALACTIC NUCLEI: AN EXTENDED CHANDRA HIGH ENERGY GRATING SAMPLE (2010, background): “However, Winter et al. (2009) found that the X-ray Baldwin effect was only significant if the EW and Lx/LEDD values were binned, and the formal significance of the anti-correlation depended strongly on the details of the binning procedure.”
• CAIXA: a catalogue of AGN in the XMM-Newton archive - II. Multiwavelength correlations (2009, background): “In particular, in the literature there are claims of a correlation between Γh and the 2–10 keV luminosity (e.g. Dai et al. 2004; Saez et al. 2008), but there are also several studies that do not find such a correlation (e.g. Reeves & Turner 2000; George et al. 2000; Winter et al. 2009).”
• The subarcsecond mid-infrared view of local active galactic nuclei – II. The mid-infrared–X-ray correlation (2015, background): “…and column densities: 1: Massaro et al. (2012); 2: Mingo et al. (2014); 3: González-Martı́n et al. (2009b); 4: González-Martı́n et al. (2009a); 5: Winter et al. (2009a); 6: Evans et al. (2008a); 7: Maiolino et al. (2003); 8: Zezas, Ward & Murray (2003); 9: Ballo et al. (2004); 10: Ptak et…”
• Defining the intrinsic AGN infrared spectral energy distribution and measuring its contribution to the infrared output of composite galaxies (2011, methodology): “Of the 104Swift-BAT AGNs with measuredL2−10keV (see Winter et al. 2009), 36 have publicly available archival low resolution IRS spectra covering (observed frame)∼ 6− 35 µm.”