AGN Demographics

1
AGN Demographics

• Christine Black
• 3/1/12

http//www.redorbit.com/news/space/1018193/satelli
tes_unveil_new_type_of_active_galaxy/
2
Major Points

• What is a demographical study?
• Very brief overview of AGNs
• Galaxy evolution roadmap
• Studies of AGN in the local universe
• Studies from 0 lt z lt 1
• Studies around z 1

3
What is a Demographical Study?

• Compare fraction of AGN to normal galaxies in
  collection
• How are AGN fueled
• Galaxy morphology
• Must be able to see host galaxy, that way can
  study stellar pop., structure, mass, etc

4
AGN vs normal galaxy

• Actively accreting SMBH at center of host
• Seen in several wavelengths
• Radio, optical, Hard/Soft Xray
• Luminosities of L gt 1042 ergs/s
• This helps in seeing them at higher z (1)

5
Galaxy Evolution

• Move through clouds
• Blue cloud
• Green Valley (Transition Zone)
• Red Cloud/Sequence

Georgakakis 08
6
Local Studies

• Kauffmann 03
• Looked at 123,000 galaxies from SDSS
• 22,623 host AGN
• From 0.02 lt z lt 0.3
• Use OIII emission line
• Strong for AGN
• Weak for metal-rich, star forming galaxies

7
Local

• Type 2 AGN found in more massive hosts
• 3x1010-1011 M?
• AGN fraction of massive galaxies is dependent on
  z
• Hosts are similar in size and mass to early
  type galaxies

8
Local

• Stars in Type 2 AGN are the same as those found
  in QSO with the same redshift and OIII luminosity
• Strong correlation btwn age and OIII luminosity
• Low-luminosity have older stars
• High-luminosity are like late-type galaxies
• Large number type 2 AGN had burst of SF 1-2 GY
  ago

9
Local

• Bluer hosts than normal galaxies of same mass
• Massive Galaxies (log(M) gt 10.5) are
  preferentially spirals
• Ultra hard luminosity increases with stellar mess
• BAT AGN found massive hosts with large bulge-disk
  ratios and SMBH

Koss 11 BAT Ulta Hard Xray 0.01 lt z lt 0.07
10
Local

• Best 05
• Radio luminosity is independent of BH mass
• More massive BHs host a larger fraction of
  radio-loud AGN
• Ho 08
• 2/3 E-Sb galaxies have activity in nuclei
• Most are AGNs fueled by accretion
• Detect AGNs in bulge-less galaxies

11
0 lt z lt 1

• Haggard 10
• Chandra and SDSS
• 100k galaxies to .7z
• L gt1042 ergs/s
• Fraction evolves with z and correlates with mag
• (1z)3 and (1z)4

• Larger fraction of bluer hosts
• possibly dependent on z

12
Other Theories

• Probability of a host with AGN defined by a
  universal Eddington Ratio is independent of
  stellar mass
• AGN not related to quenching or color change

• More in Blue/Green by factor of 2

Aird 12
13
z 1

• Nandra 07
• 0.6 lt z lt 1.4
• See low-level AGN in dense environments
• Majority of AGN in red sequence
• Supports quenching
• AGN activity is linked to host evolution in the
  late stages

14
z 1

• Gerogakakis 08
• Chandra All Wavelength
• 0.4 lt z lt 0.9
• Find AGN in the valley
• Some are obscured gas/dust must reform
• Based on morphology - not major mergers
• Accretion last longer than SF
• Find post-starburst at z 0.8

15
Conclusions

• Red vs Green vs Blue?
• Depends on z
• Star formation is not only fuel for AGN
• Morphology
• Soft-Hard Xray may not need bulges
• Ultra hard Xray found in Spirals
• Mergers
• Yes and No