# Presentation: 198803

## Large-scale X-ray AGN Surveys

*Xavier Barcons*
*Instituto de Física de Cantabria*
*(CSIC-UC)*
*Santander (Spain)*

## Why Large-Scale AGN surveys?
Previous work on AGN clustering and the bias parameter bX
Understanding bX :
Bulge to BH mass relation
What determines X-ray emission in AGN?
Redshift distortions in the power-spectrum
Optical identifications
Outlook

- Previous work on AGN clustering and the bias parameter bX
- Understanding bX :
- Bulge to BH mass relation
- What determines X-ray emission in AGN?
- Redshift distortions in the power-spectrum
- Optical identifications
- Outlook

## Why X-ray AGN?

- Most numerous sources in high Galactic latitude X-ray sky (“noise” for cluster searches, at least)
- Dominate the energy output in the Universe (although most of it likely obscured)
- Potentially able to trace the formation and evolution of super-massive Black Holes in the Universe
- Most interesting redshift range in the evolution of the Universe: might complement other cosmological studies.

## Why Large-Scale X-ray surveys

- Planned surveys (DUO, ROSITA)
- Best statistics, so can determine dependence of properties on many parameters (redshift, luminosity, etc.)
- Distribution on the largest scales and link to Cosmology

## The dipole in the source distribution

*Miyaji & Boldt 1990*

-  Saturates at ~ 50-100 h-1 Mpc
-  Roughly aligned with CMB dipole
-  Large bX

**AGN**

**Clusters**

-  Saturates at ~ 160 h-1 Mpc
-  Roughly aligned with CMB dipole

*Plionis & Kolokotronis 1998*

- AGN clustering and bX

## The X-ray Background dipole

-   Roughly aligned with
-    CMB direction at all bands
-  LSS dipole detected
-    over Compton-Getting
-  Amplitude strongly dependent
-    on energy band, from
-    >1% @ 0.9-2 keV to
-    ~0.2-0.8% @ 2-10 keV
-  Residual galactic contribution?

*Plionis & Georgantopoulos 1999*

- Soft XRB dipole

- AGN clustering and bX

## The XRB multipoles

*Lahav, Piran & Treyer 1997*

-  Cosmic signal a*lm** l*-0.4
-   Sources not removed produce
-    noise a*lm** S**cut**1/2*

- AGN clustering and bX

*Scharf et al 2000*

*Treyer et al 1998*

## Summary of dipole results

- AGN clustering and bX

## Cross correlations of the XRB with galaxy catalogues

- It measures the volume emissivity of the
- Catalogued sources or sources clustered
- with the catalogued ones on scales of the
- XRB beam.
**Indirect constraint on X-ray**
**AGN clustering amplitude.**

- AGN clustering and bX

- Optical

- 12

-  Local X-ray volume emissivity
-   ~ 1039 h erg s-1 Mpc-3
-  Mostly contributed by AGNs
-  Consistent with moderate clustering
-   amplitude, **b****X****~1**

## Clustering of X-ray selected AGN

-  ROSAT soft X-ray selected
-    samples (RIXOS and RDS)
-  Clustering detected at ~ 2
-    in the low redshift sample
-  No clustering in the high z
-   sample

*Carrera et al 1998*

- RIXOS

- RDS

- (rc,z)=(rc/r0)- (1+z)p

- AGN clustering and bX

## AGN clustering and evolution(optical)

**2QZ** (Croom et al 2003)

- AGN clustering and bX

## The Auto-Correlation Function of the  soft XRB 

- Soltan et al (1999)

- The ACF of the soft XRB on small scales suggests clustering is stronger than in “normal” galaxies.

**b****X****>1**

- Careful elimination
- of cluster
- contribution

- AGN clustering and bX

## The ACF of the XRB at 2-10 keV

- Boughn et al 2002

- The amplitude of the ACF can be obtained from the cosmic distribution of matter, assuming a bias factor.

**b****X****=2.3**

- AGN clustering and bX

## The bias of X-ray sources

- AGN clustering and bX

## Understanding the “bias” parameter of X-ray AGN

- From the underlying matter+energy distribution to X-ray luminosity:
- a) Dark matter  bulge mass
- b) Bulge mass   Black Hole mass
- c) Black Hole mass  Accretion power
- d) Accretion power  X-ray luminosity

- Understanding bX

## a) Dark matter Bulge mass 

- Depends on Cosmological parameters
- Bias likely to be redshift dependent (Fry 1996, Tegmark & Peebles 1998)
- ... but standard galaxy formation study

- Understanding bX

## b) Bulge mass  Black Hole mass

- MBH/Mbulge mass dependent?

- Understanding bX

## Self-regulated BH growth: stop when gas becomes unbound. MBH growth and star formation efficiency scale differently with halo mass (Wyithe & Loeb 2003)
Decrease of merger rate at lower z (Kauffmann & Haehnelt 2000)
Growth by accretion only or mergers play a role too? (Marconi et al 2004)

- Decrease of merger rate at lower z (Kauffmann & Haehnelt 2000)
- Growth by accretion only or mergers play a role too? (Marconi et al 2004)

- b) Bulge mass  Black Hole mass

- MBH/Mbulge is redshift dependent

- Understanding bX

## c) Black Hole mass  Accretion power

- What determines the accretion rate?
- When do BH go through accretion phases (once only, episodic, merger-driven, etc.)?
- Self-regulation? (Whyithe & Loeb 2002)
- Do BHs grow solely from accretion, or mergers play a role? (Marconi et al 2004)

- McLure & Dunlop 2002

- Understanding bX

## d) Accretion  X-ray emission

- Accretion mode, disk structure, etc only a function of MBH and Ṁ?
- What determines how much absorbing gas surrounds the central engine?
- Is absorption related to the formation of the bulge and the BH itself (Fabian et al 1998, Fabian 1999)
- Are absorbed and unabsorbed AGN distinct source populations (Franceschini et al 2002)?
- Are X-ray selected AGN a “fair sample” of the true AGN population?

- Understanding bX

## Understanding the “bias” parameter of X-ray AGN

- a) Dark matter  bulge mass
- b) Bulge mass   Black Hole mass
- c) Black Hole mass  Accretion power
- d) Accretion power  X-ray luminosity

- Understanding bX

- Standard Cosmology

- Modeling

- Modeling & more data

- More X-ray data

## Cosmological parameters from distortions in AGN clustering

- Assuming isotropic clustering, the power spectrum of distant AGN must be equal in transverse and parallel wavevectors. That fixes the cosmological parameters (Alcock & Pacynski 1979)
- Needs _large_ numbers of _high-z_ sources, so Cosmological effects come into play
- Could probe  if a variety of z’s are available (but independent of H0)

- Redshift distortions

## Redshift distortion test in the 2QZ

- 2dF QSO survey final catalogue (22600 objects)

- Croom et al 2003

- Redshift distortions

## The potential of ROSITA & DUO

- ROSITA:
- Determine bX (z=0) from low-z AGN clustering
- Local large-scale distribution (multipoles)
- Rare objects, fraction of absorbed/unabsorbed AGN
- DUO:
- >125,000 AGN  (Wide Survey), and >30,000 AGN (Deep Survey)
- AGN clustering at moderate and high z: bX(z)
- Power spectrum distortion test at various redshifts: consistency check

- But identifications (redshifts) needed!

- Optical identifications

## The optical identifications

- XMM SSC Medium Survey

- FX/Fopt=1

- FX/Fopt=10

- Optical identifications

## The optical colours of X-ray selected AGN

- Barcons et al 2002

- Optical identifications

- QSO-like:
- Spectro-z

- Galaxy-like
- Photo-z

## Outlook

- Enormous potential of large-scale X-ray AGN surveys (DUO, ROSITA, ...)
- Surveys at various depths/solid angles needed to track evolution and thence Cosmology
- Measure bX and cosmological parameters
- Measure z-dependent correlation function/power spectrum
-  Check scale-invariance of bX
- Joint constraints on bX (z) and cosmological parameters from power spectrum evolution
- Independent measure cosmological parameters via redshift distortions in power-spectrum