Transcript Jian Wu on "AGN in X

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 (1013Hz-1020Hz)
– 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

– Lb does not correlated well with Lgalaxy￫ cannot see low
luminosity AGN in massive galaxies (contamination)

Aftermath
– Omission (radio, IR, X-ray)
Optical Selection

Optical selection effect
– Luminosities
– Hard to evaluate

Alternatives
– Variability
– Absence of proper motion
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 XMMNewton
ACIS
(ergs-cm-2 sec-1 in 10 5 s)
4×10-15
HRC
(ergs-cm-2 sec -1 in 10 5 s )
EPIC MOS
(ergs-cm-2 sec-1 in 10 5 s)
~ 4×10-14
EPIC pn
(ergs-cm-2 sec -1 in 10 5 s )
4×10-15
~ 4×10-14
Advantages

Accurate positions from Chandra
– ~ 0.5 arcsec
Einstein
4
EXOSAT
18
ROSAT
4
BBXRT
/ASCA
75
Chandra
0.5
XMMNewton
20
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 (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 Surveys

Einstein (1978 11-1981 4) [0.2-20 keV]
 ROSAT (1990 1-1999 2) [0.1-2.5 keV]
Soft X-ray Surveys

Fruit
– Moderate correlation of optical and X-ray
Hard 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 Chandra and XMM-Newton
Surveys

Chandra (1999 7-present)
 XMM-Newton (1999 10-present)
Deep Chandra and XMM-Newton
Surveys

Fruit
– Numerous “optically dull” objects
– Greatly enlarge the AGN population
Deep Extragalactic X-ray Surveys
Deep Extragalactic X-ray Surveys
Deep Extragalactic X-ray Surveys
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
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
2000-3000 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) ~ 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
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
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 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
FB
HB
SB
SB1 SB2
0.5 1.0
2.0
HB1
HB2
4.0
8.0 keV
Point-source Detection

Key criterion
False positive probability
1×10-7
main CATAlog
1×10-5
supplementary optically bright
source CATAlog
Source Position Refinement
X –ray
2.5
1.4GHz Radio
503 sources
Position of sources in main
138 NEW!
Supplementary Optically
Bright Chandra Source CATA
X –ray
1.5
Optical R-band
79 sources
Primary analysis of S
X-ray Band ratio
Color-Color Diagram
SB2/SB1 vs. HB1/SB2
  1.8
Color-Color Diagram
HB1/SB2 vs. HB2/HB1
Background
Prospects

Doubling the exposure of a Chandra
observation leads to an increase in
sensitivity between 2 and 2 .
 The number of background counts is often
negligible.
 Negative K-correction of absorbed AGN
emission
Longer and longer