Heavily-Obscured Super-Massive Black Holes at Low and High Redshift Ezequiel Treister (IfA, Hawaii Ezequiel Treister (IfA, Hawaii) Meg Urry, Priya Natarajan, Carie Cardamone, Kevin Schawinski (Yale), Eric Gawiser (Rutgers), Dave Sanders (IfA) and the MUSYC collaboration Credit: ESO/NASA, the AVO project and Paolo Padovani

Active Galactic Nuclei (AGN) Urry & Padovani, 1995

Black hole–galaxy connection All (massive) galaxies have black holes All (massive) galaxies have black holes Tight correlation of M BH with  Common BH/SFR Evolution AGN feedback important

All (Massive) Galaxies have super-massive black holes

Black hole–galaxy connection All (massive) galaxies have black holes All (massive) galaxies have black holes Tight correlation of M BH with  Tight correlation of M BH with  Common BH/SFR Evolution AGN feedback important

M BH -  Correlation Greene & Ho, 2006 Same relation for both active and non-active galaxies.

Black hole–galaxy connection All (massive) galaxies have black holes All (massive) galaxies have black holes Tight correlation of M BH with  Tight correlation of M BH with  Common BH/SFR Evolution Common BH/SFR Evolution AGN feedback important

Common BH/Star Formation Evolution Marconi et al. 2004

Black hole–galaxy connection All (massive) galaxies have black holes All (massive) galaxies have black holes Tight correlation of M BH with  Tight correlation of M BH with  Common BH/SFR Evolution AGN feedback important AGN feedback important

AGN Feedback Springel et al No AGNWith AGN Feedback

Supermassive Black Holes Credit: ESO/NASA, the AVO project and Paolo Padovani Many obscured by gas and dust How do we know that?  Local AGN Unification  Explain Extragalactic X-ray “Background”

Observed X-ray “Background” Frontera et al. (2006)

AGN in X-rays Increasing N H Photoelectric absorption affect mostly low energy emission making the observed spectrum look harder.

X-ray Background Gilli et al., 2007 XRB well explained using a combination of obscured and unobscured AGN. Setti & Woltjer 1989 Madau et al Comastri et al Gilli et al. 1999,2001 Treister & Urry 2005 Gilli et al And others…

Compton Thick AGN Defined as obscured sources with N H >10 24 cm -2. Very hard to find (even in X-rays). Observed locally and needed to explain the X-ray background. Number density highly uncertain. May contribute significantly to SMBH accretion. Multiwavelength observations are required to find them. Hard X-rays (E>10keV) very useful locally.

Swift INTEGRAL

ISDC Swift Sources Tueller et al. 2007

Significance Image, keV Deep INTEGRAL Survey (3 Msec)

Log N-Log S Treister et al. 2009

Log N-Log S Treister et al. 2009

Fraction of CT AGN Treister et al X-ray background does not constrain density of CT AGN

X-Ray Background Synthesis Treister et al. 2009

Contribution of CT AGN to the XRB Only 1% of the XRB comes from CT AGN at z≥2.  We can increase the # of CT AGN by ~10x and still fit the XRB. Only 1% of the XRB comes from CT AGN at z≥2.  We can increase the # of CT AGN by ~10x and still fit the XRB. Treister et al. 2009

CT AGN at High Redshift Treister et al. 2009

Energy Range5-600 keV Angular resolution~80” Field of View~half sky CoverageFull sky every 95’ Flux Limit5x (20-50keV) Launch Date???? ~2015 PIJosh Grindlay

NuSTAR Energy Range6-80 keV Angular resolution40” Field of View12’x12’ Flux Limit~2x in 1 Msec Launch DateAugust 2011 PIFiona Harrison

How to find high-z CT AGN NOW? X-rays Tozzi et al Trace rest-frame higher energies at higher redshifts  Less affected by obscuration Tozzi et al. claimed to have found 14 CT AGN (reflection dominated) candidates in the CDFS. Polletta et al. (2006) report 5 CT QSOs (transmission dominated) in the SWIRE survey.

Fiore et al How to find high-z CT AGN NOW? Mid-IR X-ray Stacking F 24 /F R >1000 F 24 /F R <200 4  detection in X-ray stack. Hard spectral shape, harder than X- ray detected sources.  Good CT AGN candidates. Similar results found by Daddi et al. (2007)

Extended Chandra Deep Field-South Area: Area: 0.3 deg 2 X-rays: X-rays: Chandra 250ks/pointing Optical: Optical: Broad band UBVRIz (V=26.5)+ 18 Medium band filters (to R=26) Near-IR: Near-IR: JHK to K=20 (Vega) Mid-IR: Mid-IR: IRAC microns + MIPS 24 microns to 35 µJy Spectroscopy: Spectroscopy: VLT/VIMOS, Magellan/IMACS (optical) VLT/SINFONI, Subaru/MOIRCS (near-IR)

Mid-IR Selection R-K (Vega) Log (f 24µm /f R ) sources with f 24  m /f R >1000 and R-K>4.5 - f 24  m >35  Jy - 18 X-ray detected Treister et al. ApJ in press

Redshift Distribution All Sources X-ray Detected X-ray Undetected - Photo-z for ~50% of the sources - X-ray sources brighter at all wavelengths - Spec-z for 3 X-ray sources and photo-z for 12 (83% complete). Treister et al. ApJ in press

Hardness Ratio  N H X-ray sources with redshift only - 2 unobscured - 11 obscured Compton-thin - 2 Compton Thick Assumed fixed  =1.9 Treister et al. ApJ in press

Stacking of non-Xrays Sources Soft (0.5-2 keV)Hard (2-8 keV) - ~4  detection in each band. - f soft =2.1x erg cm -2 s -1. F hard = 8x erg cm -2 s -1 - Sources can be detected individually in ~10 Msec. - Hardness ratio 0.13, N H =1.8x10 23 cm Alternatively, ~90% CT AGN and 10% star-forming galaxies. - Some evidence for a flux dependence. >95% CT AGN at the brightest bin, 80% at the lowest. Large error bars. Treister et al. ApJ in press

Rest-Frame Stacking Good fit with either NH  cm -2 or combination of CT AGN with star-forming galaxies. Consistent results with observed-frame stacking. Treister et al. ApJ in press

X-Ray to Mid-IR Ratio Both X-rays and 12µm good tracers of AGN activity. Observed ratios for X-ray sources consistent with local AGN (dashed line). Treister et al. ApJ in press

X-Ray to Mid-IR Ratio Effects of obscuration in X-ray band luminosity. Only important for Compton Thick sources. Treister et al. ApJ in press

X-Ray to Mid-IR Ratio ~100x lower ratio for X-ray undetected sources. Explained by N H ~5x10 24 to cm -2 Treister et al. ApJ in press

X-Ray to Mid-IR Ratio Ratio for sources with L 12µm >10 43 erg/s (~80% of the sources) ~2-3x higher than star-forming galaxies Treister et al. ApJ in press

X-Ray to Mid-IR Ratio Using Lx/L 12µm =0.007 to separate AGN and star-forming galaxies  ~80% AGN, consistent with HR value. In sources with L 12µm >10 44 erg/s outside selection region fraction of AGN ~10%. Treister et al. ApJ in press

Near to Mid-IR Colors - Distributions significantly different - X-ray detected sources much bluer - Average f 8 /f 24 =0.2 for X-ray sources and 0.04 for X-ray undetected sample BluerRedder Well explained by different viewing angle (30 o vs 90 o ) in the same torus model Can it be star-formation versus AGN? Treister et al. ApJ in press

Near to Mid-IR Colors Armus et al ULIRG, LINER ULIRG, Sey2

Morphologies Ground based: K,H,R HST/WFC3 J,H,Y GOODS-SUDF

Optical/Near-IR SED Fitting X-ray DetectedX-ray Undetected X-ray Detected X-ray Undetected - Median stellar mass for X-ray detected sources ~4.6x10 11 M sun. - For X-ray undetected source ~10 11 M sun. - Mild extinction values found in general. - Maximum Av~4 mags. - Median E(B-V)=0.6 for X-ray detected sources and 0.4 for undetected ones. Treister et al. ApJ in press Evidence for significant recent star formation in most sources

Heavily-Obscured AGN Space Density Systematic excess for L x >10 44 erg/s sources relative to extrapolation of Compton-thin LF Strong evolution in number of sources from z=1.5 to 2.5. Consistent with heavily- obscured phase after merger? Treister et al. ApJ in press

Obscured to Unobscured Quasar Ratio Treister et al. in prep.

The Merger-Quasar Connection Treister et al. in prep. Obscured quasars are the product of the merger of two massive gas-rich galaxies. After a time  t the quasar becomes unobscured.

The Merger-Quasar Connection Treister et al. in prep.  t=77  16 Myrs

Summary Number of mildly CT sources at z~0 lower than expected. Only ~1% of XRB comes from CT AGN at z~2. Multiwalength surveys critical to find high-z CT AGN. Mid-IR selection finds large number of CT AGN at z>1.5. Morphologies indicates interactions/mergers. Host galaxy masses ~10 11 M sun with young and obscured stellar populations. Strong evolution in numbers up to z~3. This could be evidence for a heavily obscured phase after quasar triggering. Number of mildly CT sources at z~0 lower than expected. Only ~1% of XRB comes from CT AGN at z~2. Multiwalength surveys critical to find high-z CT AGN. Mid-IR selection finds large number of CT AGN at z>1.5. Morphologies indicates interactions/mergers. Host galaxy masses ~10 11 M sun with young and obscured stellar populations. Strong evolution in numbers up to z~3. This could be evidence for a heavily obscured phase after quasar triggering.