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AGN Demographics

AGN Demographics. Christine Black 3/1/12. http://www.redorbit.com/news/space/1018193/satellites_unveil_new_type_of_active_galaxy/. 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 < z < 1

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AGN Demographics

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  1. AGN Demographics Christine Black 3/1/12 http://www.redorbit.com/news/space/1018193/satellites_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 < z < 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 > 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 < z < 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 • Koss 11 • BAT Ulta Hard Xray • 0.01 < z < 0.07 • Bluer hosts than normal galaxies of same mass • Massive Galaxies (log(M) > 10.5) are preferentially spirals • Ultra hard luminosity increases with stellar mess • BAT AGN found massive hosts with large bulge-disk ratios and SMBH

  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 < z < 1 • Haggard ‘10 • Chandra and SDSS • 100k+ galaxies to .7z • L >1042 ergs/s • Fraction evolves with z and correlates with mag • (1+z)3 and (1+z)4 • Larger fraction of bluer hosts • possibly dependent on z

  12. Other Theories • More in Blue/Green by factor of 2 • 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 Aird ‘12

  13. z ~ 1 • Nandra 07 • 0.6 < z < 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 < z < 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

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