Active Galaxies

• Definition – – Amount of Energy– Type of Energy

• Non-thermal• Polarized

• Other characteristics– Emission spectra

• Hydrogen – Balmer series & Lyman alpha (121.6 nm), UV• N V (124.0 nm)• C IV (154.9 nm)• O VI (103.5 nm)• Forbidden emission lines

• Synchrotron radiation

F()=Fo

between 0.7 and 1.2

Active galaxy general characteristics -– L>1037 W (>10 billion L)

– Non-thermal emission– Excessive amount of IR, UV, radio, x-ray– Small region of rapid variability– Bright nucleus– Explosive appearance/Jets– Broad emission lines

ULIRG

• Very high redshift (z)

• Very young/early galaxies

• Lots of IR/dust

• Lots of star formation

• Earliest of all galaxies?

Seyferts

• Characteristics– Bright nuclei, 100 billion L

– Spiral like (90%)• 10% Normal spirals have Seyfert characteristics

– Non-thermal, synchrotron continuum– Two different types

• Type I– More common

– Wide spectral features – high velocity

– More luminous

– UV, x-ray

• Type 2– Narrow emission lines– Strong in IR

• Range of types, 1.5, 1.7, etc.

Model?– Accretion disk (non-thermal)

• High energy photons (x-ray, uv)

– Black hole– Jets

• Radio, or boosted to higher energies

– Dust – IR source for type 2– High/low velocity clouds

Type 1

Type 1.5

Type 2

Radio Galaxies

• 1% of all galaxies

• 10% of active

• Level of emission is used to classify

• Two groups– Compact– Extended

• Jets – synchrotron, bipolar outflow• Lobes, 50-3000 kpc, electrons, protons

• 3 types of extended radio galaxies– Classical double lobes

• High luminosity• cD galaxies, ellipticals

– Wide-angle tails, bent tails– Narrow tail sources

• Low luminosity, high velocity galaxies

• Compact sources have different energy profile ( ~ 0)

Cygnus A

Radio, x-ray images

100 kpc

M87

3 billion M

Black hole

M87X-ray radio both

Quasars

• Quasi-stellar objects (QSOs)• Characteristics

– Star-like appearance– Broad emission lines– Absorption lines, especially if z>2– Other absorption features

• Broad features with velocities up to 0.2 c• Low velocity sharp lines – absorption/emission• Lyman – alpha forest – wide range of velocities

• Most quasars visible light sources, or higher energy (x-ray, gamma-ray)

• Non-thermal spectrum (a between 0, 1.6)• Variable – quick• High z values

– Quasar evolution– Brightness varies with z (brighter at high z)– Very few at very high z– Peak at z~2.5 (1000x more/volume than

today)– Peak of 1 QSO per 100 Mpc3

Unified Model

• Look at model for Seyferts – Can be applied to all types of active galaxies– Must have a black hole!

– Million – billions of M

– Infall rates of 100 M /year needed

– High luminosities – short lived

History?

Step 1. First objects formed – what were they?ULIRG or Quasars or regular Galaxies?ULIRG Rare, hard to findQSOs – stand out, but not common at very high zMost distant object observed, z=10 (maybe)

Step 1a. Formation of first galaxies, z=5-8?With massive black holes? First QSOs formed also (not all galaxies are QSOs)

Step 2. Peak of QSO formation at z=2.5

Step 3. QSOs start to fade

Not feeding them enough

Step 4. QSOs become Seyferts? Or Radio?

Less powerful, logical step

Seyfert phase – relatively short

Whole AGN phase – few billion years?

Step 5. Normal, boring galaxies, with no major activity

Feeding the Monster

Black hole powers AGNs

Can you over feed a black hole?

Yes!

Radiation pressure limits infall

Eddington Luminosity –

LEdd = 3 x 104 (MBH/M) L

Abell 1835 IR1916 z=10!Much smaller than MW!

Most distant object?

Most distant QSO

SDSS J1148+5251z=6.42

Gravitational Lensing

How many quasars?

Lynx arc