Optically Selected Type-2 AGN
This presentation is the property of its rightful owner.
Sponsored Links
1 / 16

Angela Bongiorno Max Planck Institut fuer E xtraterrestrische Physik (MPE) PowerPoint PPT Presentation


  • 75 Views
  • Uploaded on
  • Presentation posted in: General

Optically Selected Type-2 AGN from the 10k zCOSMOS sample. Angela Bongiorno Max Planck Institut fuer E xtraterrestrische Physik (MPE). AGN8 Torino 19-22 May. Collaborators: Marco Mignoli (INAF-Osservatorio Astronomico di Bologna)

Download Presentation

Angela Bongiorno Max Planck Institut fuer E xtraterrestrische Physik (MPE)

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Angela bongiorno max planck institut fuer e xtraterrestrische physik mpe

Optically Selected Type-2 AGN

from

the 10k zCOSMOS sample

Angela Bongiorno

Max Planck Institut fuer Extraterrestrische Physik

(MPE)

AGN8 Torino 19-22 May

Collaborators:

Marco Mignoli (INAF-Osservatorio Astronomico di Bologna)

Gianni Zamorani (INAF-Osservatorio Astronomico di Bologna)

and the COSMOS AGN working group


Angela bongiorno max planck institut fuer e xtraterrestrische physik mpe

PI N. Scoville


Angela bongiorno max planck institut fuer e xtraterrestrische physik mpe

The z-COSMOS project

VIMOS @VLT

spectra

  • Redshift survey of 40,000 galaxies in the HST-COSMOS field

  • 600 hrs of observation with VIMOS on VLT started April 2005

  • Spectra will be obtained for:

    • ~25,000 galaxies at 0.3 < z < 1.0 selected to have IAB<22.5

      (BRIGHT SAMPLE)

    • ~10,000 galaxies at 1.4 < z <2.5 with BAB<25 and chosen by

      color-selection criteria (DEEP SAMPLE)

    • Extra targets from XMM, GALEX and radio catalogue

  • Goals:

    • Redshift Survey to identify and characterize environment

    • Accurate census of galaxy populations

    • Targetted AGN & X-ray sources


Angela bongiorno max planck institut fuer e xtraterrestrische physik mpe

Spectra of Active Galactic Nuclei

According to the Unified Model, AGN can be classified into two categories depending on whether the central Black Hole and its associated continuum and broad emission line region are viewed directly (type-1) or are obscured by a dusty circumnuclear medium (type-2)

Type-1 AGN(BLAGN): permitted atomic transitions - “broad” ~ 10 4 Km s-1

forbidden atomic transitions - “narrow” ~300 Km s-1

continuum emission --> power law spectrum

easy to classify through the broad emission lines!!

Type-2 AGN (NLAGN) : permitted atomic transitions - “narrow” ~ 300 Km s-1

forbidden atomic transitions - “narrow” ~ 300 Km s-1

continuum emission dominated by the stellar emission of

their host galaxy

Similar to normal star forming galaxies!!

Difficult to classify just looking at the spectrum


Angela bongiorno max planck institut fuer e xtraterrestrische physik mpe

Optically selected Type-2 AGN

Type-2 AGN SELECTION:

  • Selection of all the emission line galaxies

  • Distinction between Star forming galaxy and type-2 AGN

To distinguish between type-2 AGN and SFG we used the Diagnostic Diagrams which use line ratios to determine the ionizing source responsible for the emission line spectrum.

  • At 0.15<z<0.45 (when we detect[NII], [SII], [OIII], H, H) we use the RED

    Diagnostic Diagrams (Kewley et al. (2001): [OIII]/H vs [SII]/H and [OIII]/H

    vs [NII]/H

  • At 0.5 <z<0.95(when we detect [OII], [OIII], H) we use the BLUEDiagnostic

    Diagram (Lamareille, F.; Contini, T.): [OIII]/H vs [OII]/H

  • Final quality flag on the basis of the quality of the spectra lines


Angela bongiorno max planck institut fuer e xtraterrestrische physik mpe

Red Diagnostic Diagrams

([NII], [SII], [OIII], Ha, Hb ): 0.15<z<0.45

Sey-2 region

Sey-2 region

LINERs region

LINERs region

Star forming galaxies region

Star forming galaxies region

The classification has been obtained using the position of each object in both diagrams.

Red circles correspond to objects classified as Sey-2, yellow circles correspond to the objects classified as LINER, while green circles are objects classified as SFG.


Angela bongiorno max planck institut fuer e xtraterrestrische physik mpe

BLUE Diagnostic DiagramS:

( [OII], [OIII], Hb) : 0.5<z<0.95

Red circles: Sey-2

Green circles: SFG.

Cyan circlescandidate Sey2Magenta circles: candidate SFG

Sey-2 region

Star forming galaxies region


Angela bongiorno max planck institut fuer e xtraterrestrische physik mpe

Comparison with X-RAY Selected Sample (XMM):

  • In the total sample of objects with emission lines only 52/3651 (=1.4%)

  • objects have an X-counterpart

    • 18 of them are optically classified as Sey-2, LINER or Sey-2 cand.

      They constitute the 7% (18/258) of the type-2 AGN sample.

      But they become the 21% (16/77) if we consider obj at I<21.0.

    • 34 of them are optically classified as SFG or SFG candidates.

      They constitute the 1% (34/3209) of the SFG sample.


Angela bongiorno max planck institut fuer e xtraterrestrische physik mpe

Position of X-ray sources in the Red Diagnostic Diagrams

IN the RED Diagnostic Diagrams, most of the X-ray sources (crosses) occupy the Sey-2 / LINER region or at least they lie close to the AGN/SF separation.


Angela bongiorno max planck institut fuer e xtraterrestrische physik mpe

Position of X-ray sources in the

blue Diagnostic Diagram

Emission line dominated by extremely powerful starburst galaxy (but Lx>1043 for most of them)

b)Composite Starburst - AGN

(Stasinska et al. 2007)

X-ray sources seem to lie in a different

region of the plane !!!

Red and blue lines: Increasing AGN contribution to the stellar locus. The difference between blue and red is in the ionization parameter.


Angela bongiorno max planck institut fuer e xtraterrestrische physik mpe

Composite spectra

SFG identified in the XMM catalog

SFG not identified in the XMM catalog

NeV (AGN)

Extinction?


Angela bongiorno max planck institut fuer e xtraterrestrische physik mpe

TYPE-2 AGN FINAL SAMPLE

Sey2 : 81

Sey2 cand: 55

LINER: 122

TOT= 258type-2 AGN @ 0.15 < z < 0.95


Angela bongiorno max planck institut fuer e xtraterrestrische physik mpe

B-band Luminosity Function: Comparison with other surveys

Weight

: Vmax estimator

M:

( mobs, for each object, is chosen in the band which is sampling the rest-wavelength closer to the B-band)

  • Local Samples (for comparison):

    Palomar Sey sample (45 -- type-1+type-2) @ z~0

    CfA Sey-2 sample (23) @ z~0

    SDSS best fit LF for Sey-2 @ z<0.13


Angela bongiorno max planck institut fuer e xtraterrestrische physik mpe

SED: AGN contribution to the continuum

(in the observed wavelength range)

PURE GALAXIES

AGN 52%, E(B-V)=0.53

AGN=16%, E(B-V)=0.04


Angela bongiorno max planck institut fuer e xtraterrestrische physik mpe

No dependence

on z and/or magnitude

4%

71%

25%

4%

Early type Disk Irregular

SED: AGN contribution to the continuum

(in the observed wavelength range)

AGN contribution to the SED

Statistic on galaxies that host AGN

Most AGN are hosted in disk galaxies


Angela bongiorno max planck institut fuer e xtraterrestrische physik mpe

Summary

  • 258 type-2 AGN optically selected from the 10k zCOSMOS sample through the emission lines ratio

    b) The comparison with the X-ray catalog shows that:

    • A significant fraction of optically selected type-2 AGN is missed from the XMM catalog because the line selection method allow us to go deeper (Chandra will add some sources).

    • A significant number of objects X-ray detected fall in the starforming region of the DD. A reasonable explanation is that they are composite objects (AGN/SB) and/or with a significant extinction on galaxy scale.

  • c) Determination of the luminosity function up to high redshift (z<0.95)

    d) The fraction of galaxy with active nuclei is ~5% in the whole redshift range

Work in progress and still To DO

1) Study of the Spectral Energy Distribution. Decomposition of AGN and host galaxy.

  • Derivation of the AGN contribution to the continuum in the observed wavelength.

  • Host galaxies type and comparison with the morphology derived from the ACS images.

    2) Study of the environment (bright excess of type-2 at z<0.45)

    3) OIII line luminosity function


  • Login