Obscuring Torus Geometry from the NuSTAR Survey of Swift/BAT AGN

Transcription

1 Mislav Baloković (Caltech) with Fiona Harrison (Caltech) and the NuSTAR Extragalactic Survey Team Obscuring Torus Geometry from the NuSTAR Survey of Swift/BAT AGN Dartmouth, August 2016

2 1 HARD X-RAY SPECTROSCOPY MCG (Seyfert 1.9) - Compton hump reverberation Zoghbi et al. (2014) - reliable high-energy cut-of Baloković et al. (2015) NGC 1365 (Seyfert 1.9) - stable relativistic spin Walton et al. (2014) - variable line-of-sight absorption Rivers et al. (2014) NGC 1068 (Seyfert 2) - reprocessing on super-torus scale Bauer et al. (2015) - line-of-sight unveiling event Marinucci et al. (2016) Second-order spectral features carry signatures of AGN structure. Credits: R. Hurt / JPL / NASA 1 / 12

3 1 LARGE SAMPLE: SWIFT/BAT AGN Sample: 115 Seyfert 2 nuclei from the Swift/BAT 70-month catalog (½ of the total), observed with NuSTAR and Swift/XRT. c.f., Dadina 2008, Winter et al. 2009, Burlon et al. 2011, Ricci et al. 2011, Malizia et al. 2012, Rivers et al. 2013, Vasudevan et al / 12

4 2 QUESTION 1: PHENOMENOLOGY hardness ratio of known CT AGN CXB synthesis model from Gilli et al PHENOMENOLOGICAL TEMPLATES - local AGN spectra parametrized in simple terms - input for CXB models and high-z identification 3 / 12

5 2 PHENOMENOLOGICAL MODEL Aird et al. (2014) Disk reprocessing model pexrav (Magdziarz & Zdziarski 1995) is used almost ubiquitously in the literature to account for the torus signature (a.k.a. reflection). reflected (pexrav) transmitted 4 / 12

6 2 MAIN SPECTRAL PARAMETERS reflected (pexrav) Baloković et al. (2016a, in prep.) 5 / 12

7 3 QUESTION 2: AGN STRUCTURE The AGN torus is dead. Which parts of the complex structure can we simplify (and how) in order to better understand AGN? Murphy & Yaqoob (2009) 6 / 12

8 3 GEOMETRICAL TORUS MODELS Ikeda et al. (2009) Brightman & Nandra (2011) Liu & Li (2014) Furui et al. (2016) Baloković et al. (in prep.) NH in the line of sight does NOT have to be the same as the average torus NH two different values to measure! Variability can help... Paltani & Ricci (in prep.) observer 1 observer 2 7 / 12

9 KEY TORUS PARAMETERS ring-like: 10% covered torus covering factor sphere-like: 90% covered 3 Compton-thin: 23.5 Compton-thick: 24.5 log [ average NH of the torus / cm-2 ] 8 / 12

10 3 DIVERSITY OF AGN TORI torus covering factor individual AGN contours stacked 2σ regions for ~100 Seyfert 2s (type 2, RQ) (type 1, RL) log [ average NH of the torus / cm-2 ] Results challenge the idea that all AGN have a similar torus we find diversity! 9 / 12

11 4 NON-X-RAY CONSTRAINTS Reality is likely complicated... Baloković et al. (2016b, in prep.) Type 2 AGN have on average high dust covering factors (e.g., Ramos Almeida et al. 2013, Mateos et al. 2015). Tristram et al. (2007) Given the X-ray data quality, simple models may be sufficient for now. 10 / 12

12 4 MULTI-WAVELENGTH SYNERGY Farrah, Baloković et al. (2016) [ in press, arxiv: ] 11 / 12

13 5 SUMMARY observer large sample of local AGN shows considerable spectral diversity torus (i.e., distribution of gas) is shaping the spectra NuSTAR bandpass covers the key spectral signatures of the AGN torus independent approach, complimentary to existing multi-wavelength probes of AGN torus geometry 12 / 12