AGN in X-Ray SurveysAGN in X-Ray Surveys

For Astro597

Jian Wu

November 10, 2004

OUTLINEOUTLINE

Part IAGN Surveys in Different Bands

Part IIAGN X-ray Surveys

Part IPart IAGN Surveys in Different Bands 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 IIPart IIAGN X-ray SurveysAGN X-ray Surveys

Soft X-rays SurveysHard X-ray Surveys

– Pre-Chandra and XMM-Newton– Deep Chandra and XMM-Newton Surveys

Deep Extragalactic X-ray Surveys2Ms Chandra Point-Source CATA

Part IPart I

AGN Surveys in Different Bands

RetrospectRetrospect

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

RetrospectRetrospectFirst indication (optical)

– NGC1068-broad emission lines (Fath, 1913)– M87-jet (Curtis 1917)– Extragalactic radio sources– The origin of name for quasar (Schmidt et.al., 1

964)

Retrospect Retrospect Early AGN Surveys

– Cambridge xC Surveys– Markarian Survey– Zwichky Survey

Recent Large Surveys– 2dF– SDSS

How to find AGN-SED– Power law (1013Hz-1020Hz)– Highly ionized Emission lines-C N O– Low-ionization emission lines-Fe

Optical SelectionOptical Selection

Principle (Sandage 1971)– Systematic optical color deviation from starlight

Bonus– Photometric red-shift estimation

Declaration of “complete samples” Fatal bug

– Lb does not correlated well with Lgalaxy ￫ 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 SelectionOptical Selection

Radio SelectionRadio 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 SelectionInfrared 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 SelectionHigh-Energy Selection

X-ray and γ-rayDisadvantages

– Soft X-ray suffer from larger extinction– Red-shift distribution– γ-ray position– Soft X-ray bias

Selection EffectSelection Effect

Dilution of the optical/IR brightness and color by the starlight.

ObscurationAnother selection effect

Part IIPart II

AGN X-ray Surveys

AdvantagesAdvantages

High contrast between AGN and stellar light

Advantages Advantages Penetrating power of X-rays.

Advantages 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 )

4×10-15 4×10-15

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 ~ 4×10-14

Advantages Advantages

Accurate positions from Chandra– ~ 0.5 arcsec

Einstein EXOSAT ROSAT BBXRT/ASCA

Chandra XMM-Newton

4 18 4 75 0.5 20

Advantages 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 SurveysEarly X-ray Surveys

Uhuru (1970 10-1973 3) [2-20 keV]Ariel-V (1973 10-1980 3) [0.3-40 keV]HEAO-1 (1977 8-1979 1) [0.2keV-10MeV]

Soft X-ray SurveysSoft X-ray Surveys

Einstein (1978 11-1981 4) [0.2-20 keV]ROSAT (1990 1-1999 2) [0.1-2.5 keV]

Soft X-ray SurveysSoft X-ray SurveysFruit

– Moderate correlation of optical and X-ray

Hard X-ray surveysHard X-ray surveys

ASCA (1993 2-2001 3) [0.4-10 keV]BeppoSAX (1996 4-2002 4) [0.1-300 keV]Fruit

– ~ 500 serendipitous sources over ~ 100 deg2

Deep Deep ChandraChandra and and XMMXMM--NewtonNewton SurveysSurveys

Chandra (1999 7-present)XMM-Newton (1999 10-present)

Deep Deep ChandraChandra and and XMMXMM--NewtonNewton SurveysSurveys

Fruit– Numerous “optically dull” objects– Greatly enlarge the AGN population

Deep Extragalactic X-ray SurveysDeep Extragalactic X-ray Surveys

Deep Extragalactic X-ray SurveysDeep Extragalactic X-ray Surveys

Deep Extragalactic X-ray SurveysDeep Extragalactic X-ray Surveys

Deep Extragalactic X-ray SurveysDeep 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 SurveysDeep Extragalactic X-ray Surveys

Deep Extragalactic X-ray SurveysDeep Extragalactic X-ray Surveys

Basic AGN Types– Unobscured AGN– Obscured AGN with clear optical/UV AGN sig

natures.– Optically faint X-ray sources– XBONGs

(X-ray Bright Optically Normal Galaxies)

AGN Red-shift DistributionAGN 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 PlotLuminosity-redshift Plot

AGN Selection CompletenessAGN Selection Completeness

Reasons of incompleteness– Compton thick AGN– Luminous at non-X-ray, but X-ray weak

How many we haven’t seen

2000-3000 deg-2

Key results from DEXSKey results from DEXS

Large optically selected luminous quasars– PLE (Pure luminosity Evolution)

Moderate-luminosity AGN– LDDE (luminosity-dependent density

evolution)

Comoving space densityComoving space density

X-ray constraintsX-ray constraints

Sky density– Bottom line (z > 4) ~ 30-150 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 fi

nd AGN at the highest redshift

Future prospectsFuture prospects

Detailed cosmic history of SMBH accretionThe nature of AGN activity in young,

forming galaxiesX-ray measurements of clustering and

large-scale structureThe X-ray properties of cosmologically

distant starburst and normal galaxies

The 2Ms CDF-NThe 2Ms CDF-N

Main CATAlog– High significant Chand

ra sources

Supplementary CATAlog

– Lower significance Chandra sources

20 observations

447.8 arcmin2

Flux limit=2.5×10-17 erg cm-2 s-1 (0.5-2.0 keV)

Flux limit=1.4 ×10-16 erg cm-2 s-1 (2.0-8.0 keV)

Data reductionData 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 CATAlogsProduction 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 CreationImage and Exposure Map Creation

Standard BandsStandard Bands

5.0 keV0.1 0.2 0.4 0.8

FB

SB

SB1 SB2 HB1 HB2

HB

Point-source DetectionPoint-source Detection

Key criterion

1×10-5

supplementary optically bright source CATAlog

False positive probability 1×10-7

main CATAlog

Source Position RefinementSource Position Refinement

X –ray 1.4GHz Radio 5.2

503 sources

Position of sources in mainPosition of sources in main138 NEW!138 NEW!

Supplementary Optically Supplementary Optically Bright Chandra Source CATABright Chandra Source CATA

X –ray Optical R-band 5.1

79 sources

Primary analysis of SPrimary analysis of S

X-ray Band ratioX-ray Band ratio

Color-Color DiagramColor-Color DiagramSB2/SB1 vs. HB1/SB2SB2/SB1 vs. HB1/SB2

8.1

Color-Color DiagramColor-Color DiagramHB1/SB2 vs. HB2/HB1HB1/SB2 vs. HB2/HB1

BackgroundBackground

ProspectsProspects

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

2 2

Longer and longer