DetecJng Faint Compton Thick AGN With NuSTAR and Swi) BAT Mike Koss ETH Zürich, Ambizione Fellow Craig Markwardt, Neil Gehrels, Wayne Baumgartner, Daniel Stern, Ezequiel Treister, Richard Mushotzky, Fiona Harrision, and NuSTAR Obscured AGN Team Swi$ BAT Hard X-‐ray All Sky Survey BAT wide FOV (1/10 of sky at 14-‐195 keV) 1100 Sources(824 are AGN) -‐ -‐ -‐ -‐ Average 8 Ms for whole sky Nearby, mean redshiZ is 0.026 Best studied AGN sample in X-‐rays in the local universe No decrease below Compton Thick levels (N_H<10^24) How can we go further in finding faint Compton Thick AGN! Cosmic X-‐ray Background Treister et al 2009 Local Compton Thick FracJon is 10% in SwiZ (Vasudevan et al 2013) 20-‐30% if we include SwiZ sensiJvity (Burlon et al 2011). Can we directly find the missing 10-‐20%? Difficulty Finding Compton Thick AGN SimulaJon for Compton thick AGN (8e44 erg/s L_bol, NGC 3393) 1. Find this source out to z=3-‐5 unobscured 2. Only z=0.3-‐0.5 if Compton thick 3. Determine intrinsic luminosity out to z<0.2. Deepest Chandra Surveys are biased against Compton-‐thick AGN. Bona fide samples of nearby Compton Thick AGN are 10-‐30 Total. Need to study more at low redshiH ObscuraJon ComplexiJes Yaqoob et al. 2010 ObscuraJon can be complicated… 1. Line of sight obscuraJon vs. global (Decoupled Model) 2. ObscuraJon is also Jme variable (RisaliJ et al. 2005) OpJmized WeighJng Scheme Compton Thick AGN excess at (20-‐50 keV) and decrement in others Good for NH of 10^23.8 to 10^24.5 WeighJng EquaJon= [14-‐20, 20-‐24, 24-‐35, 35-‐50 keV]*[-‐4.23, -‐0.79, 2.09, 3.48] Compton Curvature EquaJon Zero is unabsorbed power law source and value of 1 is 5e24 NH BAT EquaJon [14-‐20, 20-‐24, 24-‐35, 35-‐50 keV]*[-‐4.23, -‐0.79, 2.09, 3.48] NuSTAR [8-‐14, 14-‐20, 20-‐30 keV] *[-‐0.49, 0.66, 2.34] Project Overview Science Goal 1). Constraints on extreme reflecJon/nH in sample. 2). Direct measurement of CT AGN frequency ID Technique (3 Methods) 1. Use BAT spectra curvature to idenJfy CT AGN in catalog • 10 sources at 20 ks done) 3. Use a weighted algorithm to detect CT AGN rather than Crab (gamma=2.15). • 46 unique, 0.8 fake sources/run • 5 XMM/NuSTAR, 20 ks, 1 done, 2 planned 4. BAT sources with no XRT counterparts possibly CT AGN • 88 Unknown • 3 Planned NuSTAR What have we found so far? OpJcal Images of in Program 1 UGC 3157 NGC 7212 NGC 3588 Mrk 463 Mrk 9 CGCG 164-‐009 2MFGC 02280 NGC 1229 NGC 6232 Example: NGC 6232 3-‐10 keV Previous NuSTAR Program NGC 6232, Sey 2 No detecJon at 3-‐10 keV, 11 ks XRT SN 9.7 DetecJon NuSTAR vs. 5.1 BAT Because of Low 0.2-‐10 keV Lum, Invisible AGN 3-‐24 keV Results of Survey As Compared to Other NuSTAR/BAT BAT NuSTAR For z<0.03, NuSTAR BAT legacy survey sample. Results 1. Curvature >10 keV is highly effecJve at selecJng all known CT AGN 2. Not detecJng sources with extreme Compton Curvature (e.g. 10^25 NH) OIII excess? Many are not found by OIII excess methods >10 keV may be only way to find them Program 2 XMM-‐NuSTAR ObservaJon Selected by Gandhi et al for Suzaku observaJon using Palermo BAT catalog (Deeper Exposure) Arggghhh!!! Nature Is Complicated (Time variable obscuraJon) Program 3 SWIFT J0427.6-‐1201 Really Compton Thick? MCG -‐02-‐12-‐017 OpJcal Spectra No Hbeta-‐Xbong z=0.03 Summary What have we learned so far? 1. BAT detecJon for faint sources is robust (NuSTAR) 2. EffecJve for idenJfying unknown moderately CT AGN a. b. c. d. Development of Ultra hard X-‐ray hardness raJo. Only scratching surface source samples (NuSTAR BAT legacy survey) Method less effecJve at fainter fluxes (110 month vs. 70 month maps) Compton Thick FracJon, variability is an issue, probably a factor of 2x larger (20%) 3. Limits on the extreme nature of the ReflecJon/AbsorpJon a. b. Are high reflecJon/gamma/nH where are AGN excluded? Not detecJng sources with extreme Compton Curvature (e.g. 10^25 NH) Other SwiZ BAT Projects At ETH Zurich 1. BAT AGN Spectroscopic Survey (2 Masters) – Increase from 40 to 1000 spectroscopic and BH masses – Money from Swiss Government (300K for postdoc/conference) 2. Molecular Gas and the FIR – – – JCMT CO (45 BAT AGN, 30 Control Sample) SCUBA2 850 micron (75 AGN) ALMA Program, 4 Dual AGN 3. AGN and Mergers – Analysis of Chandra for hidden duals (Masters) – Merging below 2 kpc (AdapJve OpJcs, 7 nights Keck, Masters) Backup Molecular Gas Study In more X-‐ray luminous AGN (LBAT>43) 1. Larger CO Mass/Stellar Mass (0.04±0.01 vs. 0.01±0.01) 2. Larger CO 3-‐2/ CO 2-‐1 RaJo Control Sample (CO 2-‐1) • 2/15 matching normal galaxies detected • 6/20 opJcal AGN weak detecJon -‐-‐>Powerful Seyferts have larger amounts of molecular gas than Weak Seyferts and normal galaxies SwiZ BAT Sample Hidden Mergers AdapJve OpJcs Hidden Mergers in SwiZ BAT Sample Keck Pilot Study of BAT AGN Compared to InacJve Galaxies: • 6/110 vs. 1/250 (Malkan et al. 2004, HST). Hidden mergers at 1-‐2 kpc are rare, but consider merger Jmescale
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