Active Galactic Nuclei

1. Active Galactic Nuclei IUE Swift Paul O’Brien X-ray & Observational Astronomy Group University of Leicester Previously at: University College London [PhD, UCL 1987: A study of the UV continuum of quasars] IUE Project, UCL/RAL University of Oxford University of Leicester XMM-Newton, Faulkes Telescopes & Swift

2. A little history • Taxonomy (split them up) • Unification (join them together again) • Mass, size and structure Active Galactic Nuclei Radio mm IR Opt./UV X-ray AGN: an object with nuclear, non-stellar energetic phenomena. Power-source: accretion disc feeding a massive black hole. But why, when, where, how…?

3. History lesson – start (almost) at the beginning PhD student goes here Leviathan, 1845, 1.8m telescope! Birr Castle, Parsonstown, Eire (wet) Owned by Lord Rosse (optimist) M51 – example of a “spiral nebula”

4. The first galaxy/AGN spectra • Photography improved (dry plates) by late 1800s so could be used in a spectrograph  stellar spectral classification (Pickering, Cannon etc.). • Sir William Huggins, 1864 – spectroscopy of M31 (Andromeda). Saw (faint) absorption lines but unsure if they were reflected Moon-light • Edward Fath, 1909 PhD – displayed nebulae spectra showing that galaxies look like stars – i.e. galaxies are made out of stars! • But, also found a galaxy (in 1908) that had: “bright lines in its spectrum, has also a strong continuous spectrum which contains absorption lines”. • Object: NGC1068 (M77) – the first AGN!

5. Seyfert Galaxies • Fath followed by Slipher (M31 velocity), and Hubble…(fame, fortune?, telescope) • Carl Seyfert (1943) – Postdoc at Mount Wilson • Isolated 6 spiral galaxies with blue nuclei which show “high-ionization emission lines much wider than absorption lines in normal galaxies”. • Two basic types: • Seyfert 1 - broad permitted lines + narrow forbidden lines • Seyfert 2 - narrow permitted and forbidden lines H [OIII]

6. Example Seyfert spectra H H Blue continuum Red continuum Wavelength (Å)

7. NGC 3783 Seyfert Type 1 See a large range in ionization species (too large for normal nebulae)

8. M87VLA • Radio Galaxies • Discovered after WWII (Ryle, Mills etc.) • Example:M87 (NGC4486). Identified by Bolton, Stanley & Slee (1949). [Optical jet found by Curtis in 1918] • Radio emission is non-thermal (Synchrotron. + Inverse Compton) • Quasars/QSOs • 3C273 (Mararten Schmidt 1963). • High redshift (0.158) implied huge luminosity. Also variable  small size • Most (~90%) are radio-quiet (QSOs). • Quasars found in elliptical galaxies. • QSOs found in either spirals or ellipticals. M87 optical

9. The Host Galaxy and the AGN galaxies at same redshift Disturbed morphology Interaction?

10. Need to explain the diverse properties of AGN • AGN can be very luminous (1000x bright galaxies) • The continuum varies on (fairly) short timescale small objects • Broad-band continuum + wide range in emission line ionisation • See both “broad” (10000 km s-1) and “narrow” (2000 km s-1) emission lines. The narrow lines are broader than normal galactic lines. • Solution: the accreting supermassive black hole (SMBH) model…

11. AGN Type 1 and 2 Unification Size-scales Black-hole: Rs = 3x109 M6 m Accretion disc: ~3 – 104Rs Broad Line Region: ~1-100 light-days Molecular Torus: ~1-10 light-years

12. Type 2 AGN Type 1 AGN Obscuring stuff Radio loud AGN

13. Black holes in every galaxy? M87 – ionized gas rotation curve. Large dark mass required (~109 M) Virial theorem: M(rV 2/G) Magorrian et al. 1998

14. Other methods Reverberation MBH-* relationship Peterson et al. Calibrate AGN method vs. stellar (Ferrarese). AGN follow same relation as in-active galaxies. “Bulge” mass correlates with mass of SMBH

15. PDS 456 – the most powerful object in the local Universe, but unknown until 1997… QSO Luminosity vs. redshift Nearby galaxies Interaction? At z=0.184, 1'' = 3.1 kpc Torres et al. (1997); Yun et al. (2004)

16. CIV 1549 v -5000 km s-1  Ly/NV Ly BAL (12-22000 km s-1) X-ray and UV observations of PDS 456 PDS456 3C273 Massive absorption X-ray spectrum requires a massive, highly-ionized outflow moving at ~0.15c . Also see fast outflow in the UV. Outflow mass-loss rate ~ 10 M yr-1 For 10% covering factor, outflow K.E. ~ 1039 J s-1 (10% Lbol) (Reeves et al. 2003; O’Brien et al. 2005)

17. What could outflows mean – the concept of “feedback” • Some outflows have a K.E. comparable to the radiation luminosity: are they common in the early Universe? • Most SMBH mass probably assembled by luminous accretion. So perhaps built when the accretion rate is high/spin low? • Over ~107 years X-ray outflows could deposit a total mechanical energy comparable to the binding energy of a Galactic bulge (~1052 J). • Feedback between outflows and star formation??

18. Interaction in action…the Ultraluminous IR Galaxies IRAS revealed a large population of “Ultraluminous IR Galaxies”. Star-formation rate 100-1000 xGalactic. Most are interacting or highly disturbed. SMBHs (and galaxies?) grow through accretion, SF, outflows all driven by mergers, shocks, galactic bars etc.

19. How do we see into the heart of an AGN ? Try radio interferometry e.g. M87 , only ~18Mpc away (1" ~ 300 light-years) But, we need to look in the optical/IR

20. Optical interferometry VLTI – 4x8.2m + 4x1.8m Baselines up to 200m, ~10mas Creech-Eakman et al. 2006 Magdalena Ridge Observatory, NM – 10 x 1.4m optical/IR telescopes with baselines up to 340m. On schedule for 2008/2009 start. Observe from 0.6-2.4 microns with spatial scale of 0.3-30 mas.

21. AGN – The Future • More data of all kinds + better models • Deep surveys in sub-mm, IR, X-ray, etc. to find all the AGN • High-resolution imaging in radio, optical, IR (e.g. SKA, VLTI, MRO) Time-dependent, 3-D, MHD disc(torus) simulation (Hawley et al.) UK astronomers have UKAFF – the UK Astrophysics Fluids Facility at Leicester – build your own disc, jet, black hole… Have fun!

22. The end