STFC Summer School 2007 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 Active Galactic Nuclei IUE Swift

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

STFC Summer School 2007 History lesson – start (almost) at the beginning Leviathan, 1845, 1.8m telescope! Birr Castle, Parsonstown, Eire (wet) Owned by Lord Rosse (optimist) M51 – example of a “spiral nebula” PhD student goes here

STFC Summer School 2007 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!

STFC Summer School 2007 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]

STFC Summer School 2007 Example Seyfert spectra Wavelength (Å) HH HH Blue continuum Red continuum HH HH

STFC Summer School 2007 NGC 3783 See a large range in ionization species (too large for normal nebulae) Seyfert Type 1

STFC Summer School 2007 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) M87 optical M87 VLA 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.

STFC Summer School 2007 The Host Galaxy and the AGN galaxies at same redshift Disturbed morphology Interaction? Disturbed morphology Interaction?

STFC Summer School 2007 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” (  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…

STFC Summer School 2007 Size-scales Black-hole: Rs = 3x10 9 M 6 m Accretion disc: ~3 – 10 4 Rs Broad Line Region: ~1-100 light-days Molecular Torus: ~1-10 light-years AGN Type 1 and 2 Unification

STFC Summer School 2007 Type 1 AGN Type 2 AGN Radio loud AGN Obscuring stuff

STFC Summer School 2007 Black holes in every galaxy? M87 – ionized gas rotation curve. Large dark mass required (~10 9 M    Virial theorem: M  (r  V 2 /G) Magorrian et al. 1998

STFC Summer School 2007 M BH -  * relationship Reverberation Other methods Calibrate AGN method vs. stellar (Ferrarese). AGN follow same relation as in-active galaxies. “Bulge” mass correlates with mass of SMBH Peterson et al.

STFC Summer School 2007 PDS 456 – the most powerful object in the local Universe, but unknown until 1997… Torres et al. (1997); Yun et al. (2004) At z=0.184, 1'' = 3.1 kpc QSO Luminosity vs. redshift Nearby galaxies Interaction?

STFC Summer School 2007 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. ~ J s -1 (10% L bol ) (Reeves et al. 2003; O’Brien et al. 2005) X-ray and UV observations of PDS 456 CIV 1549  v km s -1   Ly  /NV Ly  BAL ( km s -1 ) PDS456 3C273 Massive absorption

STFC Summer School 2007 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 ~10 7 years X-ray outflows could deposit a total mechanical energy comparable to the binding energy of a Galactic bulge (~10 52 J). Feedback between outflows and star formation?? What could outflows mean – the concept of “feedback”

STFC Summer School 2007 Interaction in action…the Ultraluminous IR Galaxies IRAS revealed a large population of “Ultraluminous IR Galaxies”. Star-formation rate xGalactic. Most are interacting or highly disturbed. SMBHs (and galaxies?) grow through accretion, SF, outflows all driven by mergers, shocks, galactic bars etc.

STFC Summer School 2007 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

STFC Summer School 2007 Magdalena Ridge Observatory, NM – 10 x 1.4m optical/IR telescopes with baselines up to 340m. On schedule for 2008/2009 start. Observe from microns with spatial scale of mas. Creech-Eakman et al VLTI – 4x8.2m + 4x1.8m Baselines up to 200m, ~10mas Optical interferometry

STFC Summer School 2007 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!

STFC Summer School 2007 The end