Title: Active Galactic Nuclei What are Active Galactic Nuclei and Why Does Anyone Care? Julian Krolik
1Active Galactic NucleiWhat are Active Galactic
Nucleiand Why Does Anyone Care? Julian Krolik
- Aneta Siemiginowska
- Harvard-Smithsonian Center for Astrophysics
- Chandra X-ray Center
2Outline
- AGN models.
- What have we learned from Chandra and XMM?
- X-ray Jets
- Absorbers and Outflows
- Emission Lines
- Deep Imaging and X-ray background
- Obscured AGN
- AGN activity
- Questions.
3AGN Properties
- Highly luminous Lbol 1042 1048 ergs s-1
- Compact size ltlt 1pc
- Broad-band continuum emission dL / dlog
n const. From IR to X-rays and
g-rays - Variable stronger variations on smaller
timescales at shorter wavelengths - Weakly polarized 1 linear polarization
- Radio emission in some sources extended
4AGN Models
Supermassive Black Hole M 106 109
Mo
Accretion Powered L hMc2
.
Accretion rate
Efficiency
Eddington Luminosity
Frad Fgrav LEdd1.3 x 1038(M/Mo)
ergs/s
Urry Padovani 1998
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63D Vision
Elvis 2000
Top View
Side NAL
Side BAL
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8What X-rays can tell us?
- Thermal emission from hot gas 105-107 K
gt hot gas is there! - Non-thermal emission synchrotron, Comptonization
gt relativistic plasma!
9What X-rays can tell us?
- X-ray emission regions
- Nucleus unresolved component
- Extended emission on different scales parsec to
hundreds kpc - Jets and radio lobes
- Absorption properties
- Amount of absorbing material
- Outflow/Inflow velocity
- Cold/Warm absorbers
- Ionization State
- Abundance
- Variability
- Scale/Size of the emitting and reprocessing
regions
10NGC253 starburst
Chandra can resolve structures on 1arcsec scale
11Low scattering wings of the Chandra PSF gt
crucial for high dynamic range observations when
looking at faint structures in the vicinity of
strong sources gt discovery of X-ray jets
Discoveries happen even in 21st Century
12X-ray Jets
- Many Chandra observations revealed X-ray jets
associated with quasars gt jets
are common phenomena. - Some jets were discovered in quasars where there
was no previously known radio jet emission.
Examples PKS 1127-145,
B20738393 - Relativistic motion at hundreds kpc distance from
the quasar!
13PKS 1127-145 z1.187
Chandra
HST/WFPC2
300 kpc
Siemiginowska et al 2002
14B2 0738313 z0.63
X-ray/Radio
Radio
Siemiginowska et al 2003
15Jet Models
- Comparison of X-ray, optical and radio data rules
out thermal emission, SSC and simple direct
synchrotron emission as primary source of the
X-ray emission. - Inverse Compton scattering of Cosmic Microwave
Background (IC/CMB) photons on relativistic jet
electrons can describe the observations
gt Required bulk motion Lorentz factors
are higher for lower redshift quasar G bulk
10 vs. G bulk 2-3 - Are higher redshift quasars more likely to have
X-ray jets? (Dan Schwartz Chandra project)
16Absorbers and Outflows
Optical/UV Absorption due to IGM gt Studies of
Matter in the Universe
Pettini 2003
Lya Forest
Damped Lya
17X-ray Absorption IGM
HRC/LETG
PKS 2155-304
Absorption Lines gt due to WHIM
T106 K
Nicastro et al 2002
18X-ray Absorption due to Ionized Gas close to the
nucleus
19MCG 6-30-15
Chandra/HETG
OVII edge
20XMM-Newton/RGS
MCG 6-30-15 Mkn 766 OVII and OVIII broad
emission lines
Emission or Absorption?
21High velocity outflow in PG 1211143
Pounds et al 2003
Velocity of outflowing ionized gas based on the
line broadening 0.09-0.1c
Mg XII Lya
S XVI Lya
Fe XXVI Lya
22Emission Lines
- Originate in the nucleus
- Accreting matter
- Relativistic broadening Fe -line
- BLR clouds
- Originate in the hot gas away from the nucleus
NLR in Syfert 2
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24Zycki (2003)
25A case for a broad line in MCG 6-30-15?
ASCA
Chandra
Lee et al 2002
Fabian 2002
26XMM- Newton Observations of Fe-line in Type 1 AGN
MCG 6-30-15
XMM-Newton EPIC-PN
Reeves 2002 (astro-ph/0211381)
27Deep X-ray Imaging
- Deep Chandra and XMM observations
Gilli 2003 (astro-ph/0303115)
28Source Counts Log N log S
Gilli 2003(astro-ph/0303115)
29Extragalactic X-ray Background 0.2-400 keV
DATA
Making XRB
Gilli 2003(astro-ph/0303115)
Compton Thick
Total
Type 1
Thin
Fabian 2003 (astro-ph/0304122)
30Absorbing Column Density in CDFS
Absorbing Column
Redshift
Luminosity (2-10) keV
Gilli 2003
31Obscured AGN
NGC 6240 BeppoSAX
IRAS 091044109
Large number of obscured sources! What is
the evolution of obscured sources? Why they
have large absorbing columns? What is their
black hole mass distribtion? Are they less
massive?
3C294
A18
Fabian (2003, astro-ph/0304122)
32AGN Activity
- Is the AGN always on? Or its activity is
intermittent? - AGN in clusters
gt evidence for the past activity in forms of
buoyant bubbles?
- Low Luminosity AGN M87, SgrA, IC1459
Perseus A
Fabian 2001
33Galactic Center gt was our Galaxy active
in the past?
Low Mass BH 106 Mo
Baganoff 2003
34Summary
- AGN models
- X-ray Jets
- Absorption vs. Emission
- Source counts and obscured AGN
- AGN activity
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