AGN in X-Ray Surveys For Astro597 Jian Wu November 10, 2004

OUTLINE Part I AGN Surveys in Different Bands Part II AGN X-ray Surveys

Part I AGN Surveys in Different Bands AGN Surveys in different bands – Retrospect – Optical selection and implications – Radio selection – Infrared selection – High-Energy selection Selection Effects

Part II AGN X-ray Surveys Soft X-rays Surveys Hard X-ray Surveys – Pre-Chandra and XMM-Newton – Deep Chandra and XMM-Newton Surveys Deep Extragalactic X-ray Surveys 2Ms Chandra Point-Source CATA

Part I AGN Surveys in Different Bands

Retrospect Lamppost Effect – find something in where we can find it Three types of surveys – Find object – Find object consistently – Find with well-defined selection criteria

Retrospect First indication (optical) – NGC1068-broad emission lines (Fath, 1913) – M87-jet (Curtis 1917) – Extragalactic radio sources – The origin of name for quasar (Schmidt et.al., 1964)

Retrospect Early AGN Surveys – Cambridge xC Surveys – Markarian Survey – Zwichky Survey Recent Large Surveys – 2dF – SDSS How to find AGN-SED – Power law (10 13 Hz Hz) – Highly ionized Emission lines-C N O – Low-ionization emission lines-Fe

Optical Selection Principle (Sandage 1971) – Systematic optical color deviation from starlight Bonus – Photometric red-shift estimation Declaration of “complete samples” Fatal bug – L b does not correlated well with L galaxy ￫ cannot see low luminosity AGN in massive galaxies (contamination) Aftermath – Omission (radio, IR, X-ray)

Optical selection effect – Luminosities – Hard to evaluate Alternatives – Variability – Absence of proper motion Optical Selection

Radio Selection Principles – Flat-spectrum, compact radio source – Object with low IR/radio – morphology Advantages – Efficient – Sensitive – Accurate – Find objects omitted by optical techniques Disadvantages – Incomplete (selection effect) – Star-forming region

Infrared Selection Disadvantages – Color difference is subtle – Equivalent width insufficient – An Island Potential advantages – mid-IR to be a “pivot point” in SED – PAH and high ionization IR lines Prospect – SIRTF

High-Energy Selection X-ray and γ-ray Disadvantages – Soft X-ray suffer from larger extinction – Red-shift distribution – γ-ray position – Soft X-ray bias

Selection Effect Dilution of the optical/IR brightness and color by the starlight. Obscuration Another selection effect

Part II AGN X-ray Surveys

Advantages High contrast between AGN and stellar light

Advantages Penetrating power of X-rays.

Advantages Great sensitivity of Chandra and XMM- Newton ACIS (ergs-cm -2 sec -1 in 10 5 s) HRC (ergs-cm -2 sec -1 in 10 5 s ) 4× EPIC MOS (ergs-cm -2 sec -1 in 10 5 s) EPIC pn (ergs-cm -2 sec -1 in 10 5 s ) ~ 4×10 -14

Advantages Accurate positions from Chandra – ~ 0.5 arcsec EinsteinEXOSATROSATBBXRT /ASCA ChandraXMM- Newton

Advantages A relatively large fraction of the bolometric energy (3-20%) is radiated in the classical X-ray bands. High area density (400 deg -2 ) Large amplitude and frequency of variability in the X-ray band. Little Contamination from other objects High red-shift quasars are easy to detect Close to the black hole

Early X-ray Surveys Uhuru ( ) [2-20 keV] Ariel-V ( ) [ keV] HEAO-1 ( ) [0.2keV-10MeV]

Soft X-ray Surveys Einstein ( ) [ keV] ROSAT ( ) [ keV]

Soft X-ray Surveys Fruit – Moderate correlation of optical and X-ray

Hard X-ray surveys ASCA ( ) [ keV] BeppoSAX ( ) [ keV] Fruit – ~ 500 serendipitous sources over ~ 100 deg 2

Deep Chandra and XMM-Newton Surveys Chandra ( present) XMM-Newton ( present)

Deep Chandra and XMM-Newton Surveys Fruit – Numerous “optically dull” objects – Greatly enlarge the AGN population

Deep Extragalactic X-ray Surveys

Source classification difficulties – Too faint to be identified by optical spectrum – Many of the X-ray sources have modest optical luminosities, often due to obscuration – “schism” between optical (type1 and type2) and X-ray (unobscured and obscured )

Deep Extragalactic X-ray Surveys

Basic AGN Types – Unobscured AGN – Obscured AGN with clear optical/UV AGN signatures. – Optically faint X-ray sources – XBONGs (X-ray Bright Optically Normal Galaxies)

AGN Red-shift Distribution Most AGN in deep X-ray surveys have z =0~2 Redshift distribution show “spikes” in z=0.5~2.5 [Bargar et al. 2002] [Bargar et al. 2003]

Luminosity-redshift Plot

AGN Selection Completeness Reasons of incompleteness – Compton thick AGN – Luminous at non-X-ray, but X-ray weak How many we haven’t seen deg -2

Key results from DEXS Large optically selected luminous quasars – PLE (Pure luminosity Evolution) Moderate-luminosity AGN – LDDE (luminosity-dependent density evolution)

Comoving space density

X-ray constraints Sky density – Bottom line (z > 4) ~ deg -2 – AGN contribution to reionization at z ~ 6 is small Accretion[z>4] ~ Accretion[local] Infrared and sub-millimeter – star-forming processes AGN/sub-mm galaxies >=40%. X-ray survey should remain an effective way to find AGN at the highest redshift

Future prospects Detailed cosmic history of SMBH accretion The nature of AGN activity in young, forming galaxies X-ray measurements of clustering and large-scale structure The X-ray properties of cosmologically distant starburst and normal galaxies

The 2Ms CDF-N Main CATAlog – High significant Chandra sources Supplementary CATAlog – Lower significance Chandra sources 20 observations arcmin 2 Flux limit=2.5× erg cm -2 s -1 ( keV) Flux limit=1.4 × erg cm -2 s -1 ( keV)

Data reduction CIAO – Chandra Interactive Analysis of Observations Radiation damage Quantum Efficiency Losses Bad column Bad pixel Cosmic ray afterglow Standard pixel randomization Potential background events

Production of CATAlogs Technique feature – Matched filter Accuracy of the X-ray source position Correlation of optically bright sources with lower significance Chandra sources

Image and Exposure Map Creation

Standard Bands keV FB SB SB1SB2HB1HB2 HB

Point-source Detection Key criterion 1×10 -5 supplementary optically bright source CATAlog False positive probability 1×10 -7 main CATAlog

Source Position Refinement X –ray1.4GHz Radio 503 sources

Position of sources in main 138 NEW!

Supplementary Optically Bright Chandra Source CATA X –rayOptical R-band 79 sources

Primary analysis of S

X-ray Band ratio

Color-Color Diagram SB2/SB1 vs. HB1/SB2

Color-Color Diagram HB1/SB2 vs. HB2/HB1

Background

Prospects Doubling the exposure of a Chandra observation leads to an increase in sensitivity between and. The number of background counts is often negligible. Negative K-correction of absorbed AGN emission Longer and longer