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ACTIVE GALACTIC NUCLEI Optical spectral classification and Luminosity Function Introduction and some caveats Sy1/QSO QSO/quasar NLRG/QSO2/Sy2 RL QSO/RQ QSO Point-like/extended

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Active galactic nuclei l.jpg

ACTIVE GALACTIC NUCLEI

Optical spectral classification and Luminosity Function


Introduction and some caveats l.jpg
Introduction and some caveats

  • Sy1/QSO

  • QSO/quasar

  • NLRG/QSO2/Sy2

  • RL QSO/RQ QSO

  • Point-like/extended

    ”Active galactic nuclei (AGN) are a class of galaxies where a significant fraction of the energy output, emerging from their centers, is not produced by the normal galaxy components : stars, dust and interstellar gas. This energy can be emitted across the whole electromagnetic spectrum, from radio waves to gamma rays”

Reducing the AGN zoo

as much as possible !

Marco Mignoli: AGN Optical Classification & Luminosity Function


The uv optical nir spectrum l.jpg
The UV/optical/NIR spectrum

  • Power-law: emitted by an highly compact non-thermal source (power law)

  • Big Blue Bump: this component possibly comes from the BH accretion disk (black body)

Marco Mignoli: AGN Optical Classification & Luminosity Function


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The UV/optical AGN spectrum

  • Power-law

  • Big Blue Bump

  • Small Blue Bump: FeII+Balmer Continuum

  • Broad emission lines: FWHM > 1500 Km/s

  • Narrow emission lines: FWHM < 900 Km/s

    The emission lines characterize the AGN spectra: they are produced in two separate regions, a subarcsec Broad Line Region (BLR) close to the central engine, and a more extended Narrow Line Region (NLR).

  • Galaxy Starlight: usually overwhelmed by the AGN non-thermal continuum and emerging in the red part of the spectrum

Marco Mignoli: AGN Optical Classification & Luminosity Function


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The UV/optical emission line spectrum

Marco Mignoli: AGN Optical Classification & Luminosity Function


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What we learn from theAGN UV/optical spectra

  • Redshift

  • Classification (optical): Type 1/Type 2

  • AGN Unification: evidences

  • Physical state of the emitting-line gas

  • AGN/StB separation: Diagnostic Diagrams

  • Unconventional AGNs

Marco Mignoli: AGN Optical Classification & Luminosity Function


Redshift l.jpg
Redshift

  • Discovery of the true nature of quasar

  • Cosmological Distance

  • Absolute physical quantities (L,M,size)

  • Only the optical spectrum (sometimes UV, near-IR) gives z

  • Easy way to measure z

Marco Mignoli: AGN Optical Classification & Luminosity Function


In 1963 schmidt identifies highly redshifted balmer lines in 3c273 s spectrum l.jpg
In 1963 Schmidt identifies highly redshifted Balmer lines in 3C273’s spectrum

z = 0.158 (vr = 47500 km/s)

Marco Mignoli: AGN Optical Classification & Luminosity Function


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Redshift 3C273’s spectrum

  • Discovery of the true nature of quasar

  • Cosmological Distance

  • Absolute physical quantities (L,M,size)

  • Only the optical spectrum (sometimes UV, near-IR) gives z

  • Easy way to measure z

Marco Mignoli: AGN Optical Classification & Luminosity Function


Agn emission line spectra l.jpg
AGN emission line spectra 3C273’s spectrum

  • Type 1 AGNare those with very broad optical/UV permitted emission lines, with FWHM~1500-15000 km/s, while the forbidden lines, like [OII]3727, [OIII]4959/5007, [NII]6548/6583, typically have FWHMs of order of 500-1000 km/s.

  • Type 2 AGN have permitted and forbidden lines with approximately the same FWHM, similar to the FWHMs of the forbidden lines in Type 1 objects.

    The forbidden lines, while narrower than the permitted ones, are usually broader than the emission lines in most starburst galaxies.

Optical Type 1

Optical Type 2

Marco Mignoli: AGN Optical Classification & Luminosity Function


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AGN Unification: the 3C273’s spectrum“standard model”

Components:

Accretion Disk: r ~ 10−3pcn ~ 1015cm−3v~ 0.3c

Broad Line Region: r ~ 0.01−0.1 pcn ~ 1010cm−3v ~ few x 103km s−1

Dusty Torus: r ~ 1−100 pcn ~ 103 −106 cm−3

Narrow Line Region: r ~ 100−1000 pcn ~ 102 −104cm−3v ~ few x 102km s−1

Marco Mignoli: AGN Optical Classification & Luminosity Function


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AGN Unification: the paradigm 3C273’s spectrum

“... Much of the variety in AGN types isjust the result of varying orientation relative to the line of sight. [...]

We can define an extreme hypothesis in which there are only two basic AGN types: the radio quiet and radio loud.”

(Antonucci 1993)

XBONG

Marco Mignoli: AGN Optical Classification & Luminosity Function


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Spectral classification (em.lines) 3C273’s spectrum

  • Type 1

  • Type 2

  • Starforming galaxies

Marco Mignoli: AGN Optical Classification & Luminosity Function


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Spectral classification (em.lines) 3C273’s spectrum

  • Type 1

  • Type 2

  • Starforming galaxies

    How we can discriminate the narrow line objects?

Marco Mignoli: AGN Optical Classification & Luminosity Function


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Spectral classification (em.lines) 3C273’s spectrum

SDSS

DIAGNOSTIC DIAGRAM

  • Sy 1 galaxies

  • Sy 2 galaxies

  • Starforming galaxies

  • Composite galaxies

Marco Mignoli: AGN Optical Classification & Luminosity Function


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Diagnostic Diagrams 3C273’s spectrum

SDSS

  • Sy2/StB theoretical separation Kewley et al. (1991)

Marco Mignoli: AGN Optical Classification & Luminosity Function


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Diagnostic Diagrams 3C273’s spectrum

SDSS

  • Sy2/StB empirical separation Kauffmann et al. (1994).

Marco Mignoli: AGN Optical Classification & Luminosity Function


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Diagnostic Diagrams 3C273’s spectrum

The BPT diagrams (Balwin, Phillips & Terlevich 1981, Veilleux & Ostrebrock 1987),are usedin narrow-line emission systems, to distinguish between the origins of the photo-ionization, hard and soft radiation, which is usually ascribed to non-stellar and stellar activity, respectively.

The general criterium [O III] / Hβ > 3 could be wrong !

Shock-heated

Power-law

Sey2

Planetary nebulae

LINERs

H II gal

H II galaxies

(BPT 1981)(Peterson 1997)

Marco Mignoli: AGN Optical Classification & Luminosity Function


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Diagnostic Diagrams 3C273’s spectrum

DIAGNOSTIC DIAGRAMS

Em.lines in the red range

  • [NIII]6584/Hα vs. [OIII]5007/Hβ

  • [SII]6717-31/Hα vs. [OIII]5007/Hβ

  • [OI]6300/Hα vs. [OIII]5007/Hβ

    Em.lines in the blue range

  • [OII]3727/Hβ vs. [OIII]5007/Hβ

  • [OII]3727/Hβ vs. continuum index

    Other line ratios in UV, NIR andFIR spectral ranges

    NV1240/Lyα, NV1240/HeII1640, CIV /Lyα

    [Si VI] 1.962μm/Paα

    [NeV]14μm/[NeII]12.8μm,

    [OIV]26μm/[NeII]12.8μm,

    EW(PAH 7.7μm)

Marco Mignoli: AGN Optical Classification & Luminosity Function


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AGN taxonomy: LINERs 3C273’s spectrum

LINER= Low-Ionization Narrow-Line Region

They are characterized by [O II] λ3727Å / [O III] λ5007Å ≥ 1

[O I] λ6300Å / [O III] λ5007Å ≥ 1/3

Most of the nuclei of nearby galaxies are LINERs. A census of the brightest 250 galaxies in the nearby Universe shows that 50–75% of giant galaxies have some weak LINER activity(Phillips et al. 1986, Ho, Filippenko & Sargent 1993, …).

They are the weakest form of activity in the AGN zoo.

(Heckman 1980)

Marco Mignoli: AGN Optical Classification & Luminosity Function


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AGN taxonomy: BAL QSOs 3C273’s spectrum

BAL QSOs= Broad Absorption Line QSOs

Otherwise normal QSOs that show deep broad absorption lines, blueward of the corresponding emission resonance lines of CIV, SiIV, NV. The interpre-tation is that they are intrinsic and arise from clouds outflowing the nucleus.

They mainly are at z ≥ 1.5 because the phenomenon is observed in the rest-frame UV. At these redshifts, they are ~10% of the observed population.

Mean QSO spectrum PG 0946+301. Arav et al. (1999)

Marco Mignoli: AGN Optical Classification & Luminosity Function


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AGN taxonomy: BL Lac 3C273’s spectrums & Blazars

  • BL Lacertaeis the prototype of this class: an object, stellar in appearance, with very weak emission lines and variable, intense and highly polarized continuum. The weak lines often just appear in the most quiescent stages. BL Lacs, along with optically violent-variable (OVV) QSOs, constitute the class of Blazars: these are believed to be objects with a strong relativistically beamed jet in the line of sight.

Marco Mignoli: AGN Optical Classification & Luminosity Function


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AGN taxonomy: XBONGs 3C273’s spectrum

XBONGs= X-rayBrightOpticallyNormalGalaxies

This AGN class consists of luminous hard X-ray sources hosted by "normal" galaxies with optical spectra typical of early-type systems (Comastri et al. 2002). Why the relatively bright X-ray emission, typical of moderately luminous (1042-43 erg s-1) Active Galactic Nuclei , does not leave any optical signature of the presence of a nuclear source is still matter of debate.

Marco Mignoli: AGN Optical Classification & Luminosity Function


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AGN taxonomy: XBONGs 3C273’s spectrum

  • The upper limits on the optical emission lines ([OIII], Hα), expected from the nuclear activity, in some XBONGs are tight enough to place these sources outside the typical AGN properties.

  • Possible interpretations:

  • Dilution from the host galaxy light

  • Radiatively inefficient accretion flow

  • Heavy obscuration by Compton-thick nuclear gas

  • NLR obscured on galaxy scale (i.e., Kpc dust lanes, see Malkan et al. 1998, Rigby et al. 2006)

  • Extreme BL Lacs objects

Hellas2XMM

Marco Mignoli: AGN Optical Classification & Luminosity Function


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AGN taxonomy: 3C273’s spectrumthe type-2 QSOs

Definition:

“Quasar (high L) analogue of Sy2 galaxies”

OPTICAL:high bolometric luminosity (→ high z) objects with high ionization, narrow (FWHM<1500km/s) emission lines, no broad lines. (expected according to the Unification models of AGN)

X-RAYS: high-luminosity (Lx> 1044 erg/cm/s2) and obscured (NH>1022cm-2) AGN (required by XRB synthesis models).

Do obscured (type II) quasars exist? To date, only a small number of candidates have been found (but NLRG). First examples did not confirm their classification after follow-up observations (high S/N and/or redward).

Marco Mignoli: AGN Optical Classification & Luminosity Function


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AGN taxonomy: 3C273’s spectrumthe type-2 QSOs

Boyle et al. (1999)

Type2

Without the low order Balmer lines, a secure type2 classification is a moot point.

Halpern et al. (1999)

Type 1

Marco Mignoli: AGN Optical Classification & Luminosity Function


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AGN taxonomy: 3C273’s spectrumthe type-2 QSOs

The high-z type-2 QSOs do exist! Selected both in optical, X-rays and FIR. But they are demanding targets for optical spectroscopy. (but see SDSS…)

Stern et al. (2002)

Norman et al. (2002)

Martinez-Sansigre et al. (2005)

Marco Mignoli: AGN Optical Classification & Luminosity Function


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The “ 3C273’s spectrumredshift desert” for type-2 QSOs

Redhift desert (1.4<z<2)

High-z range

Low-z range

Marco Mignoli: AGN Optical Classification & Luminosity Function


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Optical spectra of different AGN types 3C273’s spectrum

Marco Mignoli: AGN Optical Classification & Luminosity Function


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Points to Take Away ( 3C273’s spectrum1)

  • The optical spectrum offers a wealth of information about BLR/NLR and the AGN structure, but it is mainly composed by “secondary” radiations.

  • The unification scheme is a clear and simple way to classify AGN, but don’t tell us all the truth.

    ty1/ty2 ↔ f(L),f(z),f(λ),f(env),f(host-type),f(t)

  • Multi-wavelength approach to AGN study

Marco Mignoli: AGN Optical Classification & Luminosity Function



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The Luminosity Function Function

  • To study galaxy/AGN evolution we need to compare extragalactic objects today with the same kind of objects in the past

  • To perform a fair comparison we need to compare the emitted power at the same wavelengths, hence K-corrections [k(z)]

  • We cannot observe the same galaxy at different times, so we must look at the statistical properties as populations, hence we study Luminosity Functions (LF)

Marco Mignoli: AGN Optical Classification & Luminosity Function


The luminosity function33 l.jpg
The Luminosity Function Function

  • The luminosity function characterises the number density of (active) galaxies as a function of the luminosity L

  • Luminosity function, usually written (L), is defined as the co-moving number density (number of objects per co-moving volume) in some luminosity range (usually logarithmic)

Marco Mignoli: AGN Optical Classification & Luminosity Function


The luminosity function34 l.jpg
The Luminosity Function Function

  • In order to allow easy comparison between different determinations and different types of LF it is usual to use simple parameterisations

  • Schecter  common for galaxies

  • Two-Power-Law  common for AGN

  • Power-Law with exponential cut-off  infrared galaxies

Marco Mignoli: AGN Optical Classification & Luminosity Function


Lf schecter function for galaxies l.jpg

Power-Law slope Function a

*

Log((L))

L*

Log (Luminosity)

LF: Schecter Function (for galaxies)

Exponential Cut-off

Marco Mignoli: AGN Optical Classification & Luminosity Function


Parametric evolution of luminosity functions l.jpg

Function *

Log((L))

L*

Log (Luminosity)

Parametric Evolution of Luminosity Functions

Pure density evolution

Density

Evolution

Pure Luminosity evolution

Luminosity

Evolution

Marco Mignoli: AGN Optical Classification & Luminosity Function


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Density Function

Evolution

*

Log((L))

Luminosity

Evolution

L*

Log (Luminosity)

Parametric Evolution of Luminosity Functions

Marco Mignoli: AGN Optical Classification & Luminosity Function


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Luminosity Function: methods of calculation Function

LF is just the number density of galaxies…

… so just have to count the number of galaxies...

… and divide by the observable volume of each one.

… simple but ....

Only complication is the magnitude limits of the survey

  • 1/Vmax (move the galaxy)

    Move the galaxy forwards and backwards in redshift, to find the maximum volume it could have inhabited and still been observed.

  • Maximum likelihood (change its brightness)

    At a fixed redshift, what is the range of luminosities that a galaxy could have - and still be observed… need to assume a form for the LF.

Marco Mignoli: AGN Optical Classification & Luminosity Function


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The QSO LF: goals Function

  • The optical luminosity functions of quasars (OLF), as well as different types of AGN, hold important clues about the demographics of the AGN population, providing strong constraints on physical models and evolutionary theories of AGN.

  • The QSO OLF at high redshifts provides important constraints on the ionizing UV radiation field of the early universe.

    • The faint end of the QSO LF has not been measured at high redshift until now. Instead, low-z measurements of the faint end were combined with high-z measurements of the bright end to estimate the entire LF at high z.

  • The luminosity function of quasars is one of the principal constraints on the accretion history of the most massive black holes

Marco Mignoli: AGN Optical Classification & Luminosity Function


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The QSO LF: goals Function

  • Derive the density of AGNs as function of bolometric luminosity, redshift

    (Lbol | z |type)

  • Relates to:

    • Characterizing accretion history:

      • Distribution functions of black hole activity as function of MBH, accrection rate and radiative efficiency and redshift

    • Probing galaxy/BH coevolution

    • Test unification model

Marco Mignoli: AGN Optical Classification & Luminosity Function


The qso lf basic issues l.jpg
The QSO LF: basic issues Function

Instead of (Lbol| z | type), we observe:

  • N(f, z, AGN type, selection criteria)

  • Selection effect

    • Incompleteness due to selection criteria (correctable)

    • Selection bias (e.g., optical survey missing obscured sources)

  • Bolometric correction

  • Redshift effect

    • Flux-limited vs. volume limited, truncated data set

    • Limited luminosity range at any given redshift

    • K-correction

Marco Mignoli: AGN Optical Classification & Luminosity Function


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Accretion history of AGNs Function

Quasar space density as a function of redshift.

Marco Mignoli: AGN Optical Classification & Luminosity Function


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Luminosity function describes the space number density of AGNs with luminosity L at redshift z.

The black hole mass density accreted in bright AGN phases is

where is the AGN luminosity function,

is radiation efficiency.

Accretion history and luminosity function of AGNs

Marco Mignoli: AGN Optical Classification & Luminosity Function


Slide44 l.jpg

The local black hole mass density can be estimated from the optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

Black hole mass density and the OLF of AGNs

Local black hole mass density mainly comes from the accretion during bright AGN phases.

Marco Mignoli: AGN Optical Classification & Luminosity Function


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Formation history of the optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):SMBHs: mass density

  • Total accreted mass (hence BH mass density) can be estimated by LF assuming the mass-to-energy conversion factorε(Soltan 1982).

  • Compare with a local BH mass density estimated from the relation between BH mass and velocity dispersion to constrain ε.

  • Previous studies:

    • Fabian and Iwasawa (1999) , Elvis et al (2002):

      use the XRB intensity assuming z=2 for all the XRB source

    • Yu and Tremaine (2002)

      use the QSO optical LF from 2dF survey

    • Marconi et al. (2004)

      use both the XRB and SDDS data (galaxies & quasars)

Marco Mignoli: AGN Optical Classification & Luminosity Function


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1. Birth of AGNs optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

Major mergers between galaxies trigger nuclear gas flows to feed the BH, and trigger nuclear starbursts. The nucleus is obscured by dense gas.

2. Bright AGN phase

Accreting at around or slightly less than the Eddington rate. The gas

becomes transparent and the nucleus can be seen.

3. Death of bright AGNs

Radiation of AGNs expels gases to quench both BH accretion and star formation.

4. Faint AGN phases

Accreting at very low rates

The scenario for AGN formation and evolution

Marco Mignoli: AGN Optical Classification & Luminosity Function


The qso lf parameterization l.jpg
The QSO LF: Parameterization optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

  • Quasar LF: double power-law

  • Luminosity-dependent density evolution (Schmidt and Green 1983):

    (L,z) = (L,z) (L,z=0)

    Overall density evolves;

    Shape (bright and faint end slopes) evolves as well

Marco Mignoli: AGN Optical Classification & Luminosity Function


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2QZ optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

QSO Luminosity Function from 2dF Quasar Survey

www.2dfquasar.org

Marco Mignoli: AGN Optical Classification & Luminosity Function


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3 Lya optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

2 CIV

CIII

MgII

1

OIII

0 4000 Åobserved wavelength8000 Å

redshift


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Properties of the 2dF Quasar Survey optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

  • Quasars selected from pointlike sources using U-B:B-R colours (UVX)

  • 0.3<z<2.5

  • ~25000 B<21 QSOs in final catalogue

  • Volume probed ~4 x109h-3Mpc3

    www.2dfquasar.org

Croom et al. 2002, MNRAS, 322, L29

Croom et al. 2004, MNRAS, 349, 1397

Marco Mignoli: AGN Optical Classification & Luminosity Function


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Optical Counts from 2dF Quasar Survey optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

Marco Mignoli: AGN Optical Classification & Luminosity Function


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Optical Luminosity Function from 2dF Quasar Survey optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

Boyle et al. 2001

Marco Mignoli: AGN Optical Classification & Luminosity Function


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Optical Luminosity Function from 2dF Quasar Survey optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

Best fit model: pure luminosity evolution (PLE):

 = cosmic look-back time;  ~ 6;  ~ -3.3;  ~ -1.0

  • M* constant apparent mag - Selection effect??

  • Faint end slope poorly determined

Marco Mignoli: AGN Optical Classification & Luminosity Function


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PLE optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

PDE

Marco Mignoli: AGN Optical Classification & Luminosity Function


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SDSS Quasar Survey optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

QSOs selected from imaging in 5 wavebands – u g r i z

Multi-colour selection  Sensitive to QSOs at high redshift (z<6.5)

Currently ~50000 QSOs in DR3

i<19 (main sample) i<20 (high-z sample)

NGP SGP

Schneider et al. 2003, AJ, 126, 2579

www.sdss.org

Marco Mignoli: AGN Optical Classification & Luminosity Function


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46,420 Quasars from the SDSS Data Release Three optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

5

Ly forest

3

Ly

2

CIV

redshift

CIII

MgII

FeII

1

FeII

H

OIII

0

Marco Mignoli: AGN Optical Classification & Luminosity Function

wavelength

4000 A

9000 A


Hubble diagram for sdss l.jpg
Hubble diagram for SDSS optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

Marco Mignoli: AGN Optical Classification & Luminosity Function


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Richards et al. 2006 optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

SDSS quasar OLF

Marco Mignoli: AGN Optical Classification & Luminosity Function


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< 2QZ range > optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

SDSS quasar OLF: evolution at high redshift ?

  • The SDSS counts and LF agree with the results of the 2QZ at redshifts and luminosities at which the two samples overlap, but the SDSS data probe to much higher redshifts than does the 2QZ sample.

  • Strong evolution in bright end slope at z>3 (can’t be PLE all the way); the slope flattens with redshift.

  • But SDSS doesn’t go faint enough at low-z to differentiate PLE from PDE or else.....

Marco Mignoli: AGN Optical Classification & Luminosity Function


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COMBO-17 optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

Due to the relatively bright magnitude limits of the SDSS and 2QZ surveys, the LF analysis is restricted to relatively bright QSOs – especially at high redshift.

What about fainter QSOs?

The COMBO-17 survey, using multi-band photometry in 17 filters within 350 nm < obs < 930 nm, simultaneously determine photometric redshifts with an accuracy of Δz < 0,03 and obtain spectral energy distributions.

Photometric selection of 192 1.2<z<4.8 QSOs, reaching R~24

Marco Mignoli: AGN Optical Classification & Luminosity Function

Wolf et al. (2003)


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COMBO-17: OLF at optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):z>1

The evolving LF can be adequately described by either PLE (red dashed line) or PDE (black solid line) – largely due to the absence of an obvious break.

Marco Mignoli: AGN Optical Classification & Luminosity Function


Faint end of the quasar lf fainter qso surveys l.jpg

SDSS photometry & 2dF spectroscopy optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

1m deeper than 2QZ

Multicolor selection

5645 qso in 100+deg2

2SLAQ counts and LF are steeper in the faint end (34% more faint quasars)

LF: PLE evolution of a double power-law but no well-defined break (PDE not rejected)

Broad Line objects in the pure magnitude selected VVDS

130 AGN down to I = 24

Bongiorno et al. (2007) merge VVDS & SDSS samples to find Luminosity Dependent Density Evolution (LDDE ) model for the OLF of broad line AGN.

The peak of AGN space density shifts to lower redshifts for the lower luminosity objects (AGN cosmic downsizing) see X-rays !!

Faint end of the quasar LF  fainter qso surveys

2dF-SDSS QSO survey (2SLAQ)

VVDS type-1 AGN sample

Marco Mignoli: AGN Optical Classification & Luminosity Function


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Unaccounted AGNs optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

  • Significant obscured population:

    e.g. Seyfert 2s, Narrow line radio galaxies. How many type 2 QSOs?

  • Low luminosity AGNs

    e.g. Seyfert 1s, LINERs.

    host dilution, lack of all emission lines for diagnostic tests (z > 0.5)

Cosmic X-ray Background

NH ~ 1020 cm-2NH ~ 1024 cm-2

Gilli, Comastri & Hasinger 2006

Do they contribute significantly to the cumulative emissivity of AGNs?

Yu and Tremaine (2002) match local BH mass density using the OLF of QSOs.

Marco Mignoli: AGN Optical Classification & Luminosity Function


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AGN X-ray LF optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):: motivation

  • X-rays AGN Luminosity Function:

    a goal of X-ray surveys

    the most fundamental measure to understand the cosmological evolution of AGNs

  • How many AGNs in the universe (as a function of time)?

  • How supermassive black holes form?

see Roberto Gilli Lesson

Marco Mignoli: AGN Optical Classification & Luminosity Function


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AGN X-ray LF optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

  • Quasar density peaks at z~2-3

  • Low-L AGN density peaks at z~0.5 - 1

  • Paradox 1:

    • Most of BH accretion happens in quasars at high-z

    • Most of X-ray background in Seyfert 2s at low-z

Marco Mignoli: AGN Optical Classification & Luminosity Function


Agn x ray lf l.jpg
AGN X-ray LF optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

PLE doesn’t work; need luminosity-dependent density evolution (LDDE) to characterize evolution of the XLF

Miyaji et al. 2006

Marco Mignoli: AGN Optical Classification & Luminosity Function


Agn x ray lf67 l.jpg
AGN X-ray LF optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

  • Type 2 fraction a strong function of luminosity

  • Paradox 2:

  • At high (quasar) luminosity: type 2 <20%; optical color selection is highly complete since almost all are type 1s, and includes most of luminosity AGN population emitted in the Universe.

  • At low (Seyfert) luminosity: type 2 ~80%; optical color selection miss most of the AGNs in the Universe in terms of number .


What do the optical surveys tell us about quasar lf l.jpg
What do the optical surveys tell us about quasar LF ? optical data by using relation (Yu & Tremaine 2002, Marconi et al. 2004):

  • The LF is a powerful tool for the study of AGN population (demography and structure)

  • LF determination: bright end/high-z needs large survey area (rare objects) – faint end /high-z needs deep surveys (faint objects). Requisite to populate the bins  large N surveys. NO single survey

  • Survey ε= f (band| z |AGN type |selection criteria )  Multiwavelength approach to AGN study (again)

  • For some applications (e.g. BH mass density) the OLF of bright quasar is adequate.

Marco Mignoli: AGN Optical Classification & Luminosity Function