Black Holes and Black Holes Normal and Super-massive The Schwartzchild Radius () Normal and Super Massive Black Holes (SMBHs) The Galacc Centre (GC) The in Andromeda Acve Galacc Nuclei (AGN) Discovery of Seyferts and Quasars Basic properes , QSOs, BL Lacs, OVVs, LINERs etc. AGN Unificaon SMBH correlaons with host galaxy AGN Acvity with Cosmic Time Implicaons for galaxy formaon

Black Holes is the curvature of space-time by matter. If sufficient exists in a small enough volume space-time is distorted such that even light cannot escape The Schwarzschild Radius

• The radius at which even light cannot escape is known as the event horizon or Schwarzschild radius. • For a non-rotang black hole this is simply when the Kinec Energy = Gravitaonal Energy for a photon

1 GMm mv2 = 2 r 1 GMm mc2 = 2 rS 2GM rS = 2 r s c Types of Black Hole

• Normal – Formed from massive stars going supernovae

MBH ~ 10M! • Super-massive – Formed in galaxy cores during inial collapse?

7"9 MBH ~ 10 M! • Most galaxies are believed to harbour a super-massive black- hole in their cores – Existence of Intermediate Mass Black Holes uncertain Evidence for SMBHs • We find that stars have velocies of >110km/s within 2.5pc of the core of M31 Super-massive BH in M31

• IF they are in circular orbits we can use the Virial theorem to calculate the mass inside r

v2r (110#103 )2 # 2.5#3#1016 M = = CORE G 6.67#10"11 37 6 MCORE =1.4#10 kg = 6.8#10 M!

• In our galaxy – Velocities > 1000 km/s inside 0.01 pc! 6 • => 2 x 10 Msun SMBH Our Galactic Centre Infrared Studies

• Infrared (2 µm) penetrates through the dust • Can use to probe stellar populaons and dynamics in GC • Find central cluster of young massive stars

– Teff ~ 20,000 K – Burst of star formaon 107 years ago? • Or modified by star-star collisions? – Plus repeated bursts in the past (AGB stars present) – Stellar density ~> 106 stars pc–3 – Compare solar neighbourhood: stellar density ~ 0.1 stars pc–3 – Use stars to study kinemacs GM v2R – And mass of central object v2 = ! M = R G Time lapse movie of Galactic Centre over past 12 years Orbital Motions

Proper Motions in Galactic Centre • Measured by speckle and (now) adapve opcs – In IR (2.2 mm) to see through dust • Speckle: many short exposures – Freeze out effects of turbulence in atmosphere – Add coherently to see image! Obs.Tech. • Measures velocies of many stars near GN • From velocies: mass – At 0.01 pc: v ~ 1000 km/s – At 0.04 pc: v ~ 500 km/s • Implicaon: v2R ! constant " M (r < 0.5pc)! constant i.e., Keplerian Central Black Hole • Mass of central object v2R M = G

6 • Mass within 0.01 pc is ~3 x 10 Msun • Keplerian velocies inside of 0.5 pc

7 • Mass within 10 pc is ~3 x 10 Msun 6 -3 • mass density is ~4 x 10 Msun pc

• So, does this necessarily mean a black hole? 12 -3 • If not, mass density is ~4 x 10 Msun pc – Cluster of neutron stars? Mass distribution mass

107

6 3 x 10 Msun Msun

106

4 x 1012 M pc-3 6 -3 4 x 10 Msun pc

105

0.01 0.1 1.0 10.0

Radius (pc) Sgr A* • Radio source in centre of nucleus • Molecular gas disc rotates around it • Stellar cluster centred on it • What is it? – Variable non-thermal radio source 5 – Luminosity < 10 Lsun • Size: 0.3 mas ~ 2.4 AU!!! • Could be a • But it doesn’t move!!! Should be in equilibrium with stellar cluster! v < 200 km/s – Most probably a black hole – Schwarschild radius ~ ~ few GM Rsun R = c2 Flare from black hole • x-ray flare from central locaon • Due to mass falling into the GC super-massive black hole

• Heats up and emits in X- rays before crossing ‘event- horizon’ Quasars & Seyferts

• 1943 Carl Seyfert publishes a list of odd galaxies: – Mostly spirals with point-like nuclei – Broad emission lines – Also high ionisaon states (O[VI]) – Doppler interpretaon implied >1000 km/s • Later two classes of Seyferts proposed: – Seyfert Is: Broad hydrogen lines, narrow forbidden lines (e.g., O[III]) – Seyfert IIs: Only narrow lines present • Assumed lines originate from disnct regions: – Broad lines from Broad Line Region – Narrow lines from Narrow Line Region

Galaxies – AS 3011 16 NGC5548 (Seyfert I) NGC3277 (Normal Spiral)

Galaxies – AS 3011 17 Seyfert 1 showing both Broad and Narrow line features

Seyfert 2 showing narrow lines only

Images of both show a spiral galaxy with a very bright central nucleus

18 Discovery of Quasars - Strong radio sources known to correlate with point-like objects - Maarten Schmidt collected the first spectrum for radius source 3C273 -Contained unexplained broad lines, idenfied as redshied hydrogen -Eventually deduced a redshi of 0.16 (Schmidt, Nature, 1963) -Soon other Quasars were discovered with redhiss upto 2 -Current record holder around z=6.0

Galaxies – AS 3011 19 3C273

Opcal jet

Galaxies – AS 3011 20 Typical or QSO spectrum

Steep connuum Broad lines No discernable host galaxy point-like. Observaons -> Properes Point-like = compact Distant = luminous Broad lines = high velocies High excitaon lines = energec Variable = small (<1 lyr)

Galaxies – AS 3011 22 Oen have associated jets visible in rao due to relavisc charged material zipping out along open field lines:

Synchrotron radiaon

Jets oen extend 10-500kpc!

at 1 Gpc Galaxies – AS 3011 23 Emit over all wavelengths:, e.g.,Mk421

24 Other AGN types

Quasars, radio-loud QSO (Quasi-stellar objects), radio quiet Seyfert I(Broad lines) Seyfert II(Narrow lines) Blazers (Highly variable systems), superluminous - BL Lacs (BL Lacertae)=no features - OVV (Opcally violently variable) LINERS - Weak Seyferts (no broad lines)

25 Galaxies – AS 3011 26 Theories Two compeng theories: - Nuclear starbursts - Super-massive black holes Evidence for black holes

• Gas moving at ~10,000 km/s, inconsistent with stellar orbits • Emission lines change in brightness over days to weeks – light travel me implies emission from region only ~ light-weeks across (~0.01 pc) • Hence must have very high density, because 1/2 – fast orbits within very small region: vorbit ~ (G M / r) • Only a black hole can pack this much maer in so densely – the power is generated at a few Schwartzschild radii 2 RS = 2 G Mbh / c (≈ 3 km x Mbh / Msolar) • However SMBHs as central mechanism only adopted following discovery of the GC SMBH and that in M31 and M84 which also exhibits a jet

28 unified model

• The several types may be the same kind of object seen from different angles (Unified Model) – see narrower lines if a spectrum comes from gas orbing further out – fastest stuff is in an accreon disk around the black hole

broad line region narrow line region clouds at ~0.1-1 kpc

accreon torus

(not to scale!) see Seyfert 2 can also see polarized light from see Seyfert 1 near the nucleus if scaered 29 AGN Unification Antonucci, 1993 Quasar

Seyfert 2 galaxy

Torus

Seyfert 1 galaxy

30 Jet !!! Correlaon between SMBH mass and bulge velocity dispersion

31 Correlaon between SMBH mass and Bulge Absolute magnitude AGN acvity AGN acvity much more common in the past. Consistent with bulge formaon preceeding disc formaon The Cosmic Star-formaon History

Constructed from measurements of Hα or UV fluxes at various redshis CSFH v AGN Acvity

AGN acvity does not seem to trace SFH at high-z

1. Data uncertain 2. Redshi axis misleading

…..lets switch to me à CSFH v AGN acvity v Time

.

.

. Pung it together ? U Dark Maer Baryonic Maer SMBHs

0yrs AGN acvity AGN Rapid COLLAPSE/MERGERS merging 5Gyrs

BULGES

AGN no longer acve INFALL Slow merging

DISKS

P-BULGES ACCELERATING DECELERATING 13Gyrs SECULAR ??

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