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Solving QuasarsSolving Quasarspart Ipart I
Martin ElvisHarvard-Smithsonian Center for Astrophysics
in particular…
Understanding Quasar Atmospheres
Elvis M., 2000, Astrophysical Journal 545, 63
Fermilab Colloqium 29 October 2003
QuasarsQuasars** unsolved after 40 years unsolved after 40 years
Once were a `hot topic’ Were the first to start the downfall of Steady State Cosmology
- via ‘evolution’: change in density with cosmic time
Now astronomers have moved on to easier problems – Large scale structure, Dark Energy and Gamma-ray bursts
Quasar studies continue to generate many papers …but little understanding?
Discovered in 1963
Quasars are the most powerful continuous radiation sources in the Universe
* Note for the pedantic: By ‘quasars’ I mean all types of ‘activity’ in galaxies
Fermilab Colloqium 29 October 2003
What’s the problem?What’s the problem?
Enormous array of detail
We have no images of a quasar atmosphere
Would need 1000 times sharper pictures than Hubble or Chandra <100as
Must rely on spectra: span all wavelengths: X-ray optical - radio
Superficial understanding
Fermilab Colloqium 29 October 2003
Why Study Quasars?Why Study Quasars?
We live on a planet A star gives us life Galaxies dominate the Universe … but why do quasars matter? Here are 4 answers:
Fermilab Colloqium 29 October 2003
Outside the wavelength range that our eyes are sensitive to
1. An Astronomer’s Answer1. An Astronomer’s Answer
Radio
Gamma-ray
X-ray
Quasars dominate the night sky
Fermilab Colloqium 29 October 2003
2. An Astrophysicist’s Answer2. An Astrophysicist’s Answer
Gravity powered, not fusion. via Black Holes 106 - 109 as massive as the
Sun. Gas heats up falling toward it, like a spacecraft on re-entry.
Billions of times brighter than stars. Can outshine a whole galaxy
Emit strongly from radio to -rays. How do they do that?
Make galaxy length jets
Fermilab Colloqium 29 October 2003
The power available from gravity for heating is all too obvious following the Columbia tragedy
3. A Cosmologist’s Answer3. A Cosmologist’s Answer
Emit up to 1/5 of power in Universe: Important input, may dominate in some places, times.
Quasars lie at the hearts of galaxies:
Galaxy mass and quasar black hole mass are tightly connected. Maggorrian et al, Ferrarese & Merritt, Gephardt et al.
How? Should be governed by different processes.
Already exist at t<1Gyr (z=6)FIRST survey discovery, Becker et al.
½ Gyr from WMAP reionization at z=20
special role in early Universe?
reionization, seeding galaxies…
element creation, star formation catalyst via dust creation?
4. A Physicist’s Answer4. A Physicist’s AnswerEject bulk gas at 99.50% speed of light
=10
similar to proton in Fermilab Tevatron 99.88%c
Impacts gas of intergalactic medium.->what emerges?
Accelerates e- to ~1000 -> TeV photons
X-rays come from region of Strong Gravityseen in 6.4 keV `Fe-K’ (=Fe Lyman-) emission line?
Wilms et al., 2002, MNRAS, 328, L27
6.4 keV
GR redshift?
MCG -6-30-15 (XMM)
Reynolds C.
Reynolds C.
Fermilab Colloqium 29 October 2003
What What dodo we know? we know?High level theory rapidly gave a clear picture
massive black holeLynden-Bell 1969
accretion diskLynden-Bell 1969, Pringle & Rees 1972,Shakura & Sunyaev
1972
relativistic jet Rees 1967 [PhD], Blandford & Rees 1974
All established just 10 years after discovery
Fermilab Colloqium 29 October 2003
does not connect to the atomic physics
features observed in quasars
This theory describes a naked quasarThis theory describes a naked quasar
Leaves us with no way to order observations, nothing to test
Fermilab Colloqium 29 October 2003
Atomic features in Quasar AtmospheresAtomic features in Quasar Atmospheres
High ionization: e.g. CIV, OVI
Low ionization: e.g. MgII, H.
Fermilab Colloqium 29 October 2003
All studied separately with separate telescopes
Compton gamma-ray Observatory
Chandra
Hubble
MMT
Sub-millimeter array
VLA
Quasars have no temperatureQuasars have no temperatureWhipple 10 meter
Blind men and the elephant. Manga VIII Hokusai, Katsushika (1760-1849)
Wall, Tree, Rope, Spear, Snake, Fan
Not having the complete picture can be misleading
Fermilab Colloqium 29 October 2003
we need a ‘low theory’we need a ‘low theory’ that deals with the multitude of quasar details
Just as there are textbooks on ‘Stellar Atmospheres’ we need the subject of ‘Quasar Atmospheres’ Takes more than 1 step. First build an observational paradigmobservational paradigm
i.e. what do the observations drive require of any theory?
These optically thin features are all interconnected
= `quasar atmosphere’
Fermilab Colloqium 29 October 2003
A Paradigm for Quasar AtmospheresA Paradigm for Quasar Atmospheres
Accretion disk
Broad Absorption LinesReflection features
Thin Vertical wind
Narrow absorption lines X-ray `warm’ absorbers
Broad Emission Lines
hollow cone
Supermassive black hole
Elvis M., 2000, Astrophysical Journal 545, 63
X-ray/UV ionizing continuum
Accelerating bi-conical wind
NB: Independent of Unification Jets are not included
no absorption lines
A Geometric & Kinematic solutionc.f. Rees relativistic jets for blazars/radio sources
Can now re-construct this model using data not in Elvis 2000
Quasar AtmosphereQuasar Atmosphere
Fermilab Colloqium 29 October 2003
Take a lesson from lab plasmas: use all the dataTake a lesson from lab plasmas: use all the data
NSTX diagnostic instruments cover everything
NSTX at PPPL
National Spherical Torus eXperiment
Princeton Plasma Physics Laboratory
2mm interferometer
X-ray PHA
X-ray crystal spectrometer
Radiometer
Thomson scattering
Far infrared tangential
Interferometer/polarimeter
Visible spectrometer
Vacuum UV survey spectrometer
Grazing incidence spectrometer
Tangential bolometer array
Single channel visible
Bremsstrahlung detector
Polarimeter
X-ray pinhole camera
Soft X-ray arrays
Fast tangential X-ray camera
Reflectometer array
Infrared cameras
Princeton AGN Physics with the SDSS, 29 July 2003
12,277 Papers on Quasars since 196312,277 Papers on Quasars since 1963** *ADS to 4/18/03, refereed only , search on abstract containing ‘quasar’ | ‘AGN’
1/day. Now 2 per day = 5% of all astronomy papers
SpamSpam!! Need filters---
1. Physical measurementsMass, length, density. Not ratios, column densities
2. Favor absorption: advice from Steve Kahn c.1985
1-D spatial integral, not 3-D;
blueshift = outflow
3. Use Polarization Non-spherical geometry
With these filters just a dozen papers define the structure of quasar atmospheres.
Fermilab Colloqium 29 October 2003
1.Physical Measurements: 1.Physical Measurements: BEL Velocity-radius relationBEL Velocity-radius relation
Reverberation mapping shows Keplerian velocity relation in BELs
Pole-on
Keplerian orbits
Mass
Light echo delay (days) Dopple
r w
idth
of
em
. Li
ne
Peterson & Wandel 2000 ApJ 540, L13
Broad Emission Lines close to Keplerian velocities
~1000 rs,
Schwartzchild
radii
Fermilab Colloqium 29 October 2003
1.Physical Measurements:1.Physical Measurements: AngleAngle
Pole-on
Use VLBI + X-ray to get angle of jet to line of sight Rokaki et al. 2003 astroph/0301405
(2) Continuum drops as cos EW=EW0[1/3 cos(1+2cos)]-1 limb darkened disk
H does not H scale height larger than disklike
optical continuumBut BLR is rotating
rotating cylinder?A highly non-equilibrium shape
Simplest solution: BLR is in a rotating wind
Edge-on
Pole-on
SLOW
FAST
Flat disk continuum
Relativistic beaming
isotropic
Con
tin
uu
m/H
f
lux
Rokaki et al. 2003 astro-ph/0301405
(1) Rotation about jet axisc.f. Wills & Browne 1986, Brotherton
1996, McLure & Jarvis 2003
H polarization rotation also implies orbiting gas Smith et al 2002
Fermilab Colloqium 29 October 2003
2. Absorption Features2. Absorption Features
Narrow UV lines
High ionization CIV, OVI High ionization OVII,OVIII
Outflow ~1000 km s-1
Seen in 50% of quasarsSeen in same 50% of quasars
Simplest solution: Same gas, 2 phases
Princeton AGN Physics with the SDSS, 29 July 2003
Winds are common in quasarsChandra HETG: 900ksec NGC3783
new
Narrow X-ray linesnew
Same Outflow ~1000 km s-1 new
Chandra HETGS 850ksec spectrum of NGC 3783
Over 100 absorption features fitted by a 6 parameter model One T~106 K and one T~104 K, in pressure balance to 5%
Krongold, Nicastro, Brickhouse, Elvis, Liedahl & Mathur, 2003 ApJ, in press. astro-ph/0306460
2-phase gas in pressure equilibrium
2. Absorption: More Physics from X-rays2. Absorption: More Physics from X-raysFermilab Colloqium 29 October 2003
2. Absorption: where is the wind?2. Absorption: where is the wind?
Velocity dependent covering factors
Absorber is close to continuum source
absorber is moving transverse
Wind is close to continuum, crosses line of sight
Arav, Korista & de Kool 2002, ApJ 566, 699
Arav, Korista, de Kool, Junkkarinen & Begelman 1999 ApJ 516, 27
Fermilab Colloqium 29 October 2003
A quasar wind is like a flameA quasar wind is like a flame
We are looking through a flow
Apparent lack of change is a common handicap for astronomers
the ‘Static Illusion’
e.g. expansion of the Universe, cluster cooling flows, quasar disks
Fermilab Colloqium 29 October 2003
Emission lines: a thin wind?Emission lines: a thin wind?
Narrow Line Seyfert 1 galaxies (NLSy1s) show
broad, strongly blueshifted
high ionization (CIV) lines Understandable as disk wind redshifted lines hidden by disk Low ionization lines from outer
disk c.f. Collin-Souffrin, Hameury & Joly,1988 A&A 205, 19
Leighly & Moore 2003, ApJ submitted
See: Gaskell 1982
Wilkes 1984
Low ionization
MgII
BELs are rotating, transverse, thin winds
Fermilab Colloqium 29 October 2003
2. Absorption / 1. Physical Measurements:2. Absorption / 1. Physical Measurements:Wind Density,thicknessWind Density,thickness
UV/X-ray absorption responds to continuum changes: photoionized
Nicastro et al. 1999 ApJ, 512, 184
Absorbing wind is dense
But responds with a delay = recombination/ionization time density ne~108 cm- 3 for OVIII
ne~3x107 cm-3 for FeXVII
X-ray continuum
“OVII edge”
“OVIII edge”
time
R
wind
accretion disk
Black hole
R
To Earth
density + column density (~3x1022 cm-2)
thickness (~1015 cm) < distance to continuum
Absorbing wind is narrow
Fermilab Colloqium 29 October 2003
3. Polarization: X-ray absorbers3. Polarization: X-ray absorbers
Absorption line quasars are highly polarized in optical:
1. Scattering off non-spherical distribution
Edge-on structure
2. Pole-on objects must be unobscured
scatterer & obscurer:
flattened & co-axial
Leighly et al. 1997 ApJ 489, L137
Absorbers are seen edge-on
Fermilab Colloqium 29 October 2003
Flattened, Transverse Wind Flattened, Transverse Wind axisymmetryaxisymmetry
A transverse wind suggests an axisymetric geometry:
bi-cones looking edge-on see
absorbers Wind does not hug disk pole-on: no absorbers absorbers in all quasars
Mathur, Elvis & Wilkes 1995 ApJ, 452, 230
Princeton AGN Physics with the SDSS, 29 July 2003
Absorbing wind is a bi-cone to 1st order
Putting X-ray/UV absorber and BEL togetherPutting X-ray/UV absorber and BEL together
Both are disk winds rising well above the disk plane
Elvis 2000 ApJ 545, 63; Krongold et al. 2003
Similar Pressure:
P( abs ) ~1015 = 104 K x 1011 cm-3
P(BELR)~1015 = 106 K x 109 cm-3
Matching Ionization Parameter, U:T/U( abs ) = 106 = T( abs ) ~106 K/ U( abs ) ~1
T/U(BELR)= 106 = T( abs ) ~104 K/ U(BELR) 0.04
Similar Radius: for NGC 5548
r( abs ) ~1015 - 1018cm recomb. time + NHX
r(BELR)~1016cm CIV reverberation mapping
Keep it simple: Emission and Absorption are 2 phases of the same quasar wind
Similar Temperatures
For low U absorber, BELsnew
They share physical properties:
Fermilab Colloqium 29 October 2003
Components of Quasar AtmospheresComponents of Quasar Atmospheres
High ionization: e.g. CIV, OVI
Low ionization: e.g. MgII, H.
In a 2-phase transverse wind in pressure balance
United
Fermilab Colloqium 29 October 2003
The Final Element:The Final Element:Broad Absorption Lines (BALs)Broad Absorption Lines (BALs)
Old question: Special objects? or Special angle?
QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.
Ferland & Hamann 1999 Annual Reviews of Astronomy & Astrophysics , 37, 487
10% of quasars show BALs with doppler widths ~2%c - 10%c
~10x NALs. Clear acceleration (or deceleration)
Fermilab Colloqium 29 October 2003
Broad Absorption Lines (BALs)Broad Absorption Lines (BALs)
BEL FWHM correlates with BAL velocity (at minimum flux)
V(BAL) ~ 2 FWHM(BEL)
Lee & Turnshek 1995 ApJ 453 L61
Princeton AGN Physics with the SDSS, 29 July 2003
BAL gas knows about BEL gas
More BEL-BAL correlations:
Reichard et al. 2003B
EL
wid
th
BAL width
2:1
BALs from a rotating windBALs from a rotating wind
Redshifted BAL onset Possible occasionally in
a rotation dominated wind
Hall et al. 2002 ApJS, 141, 267
BALs need a rotating wind… like the BELs
BALEm.
line
wavelength
Continuumflu
x
Detachment velocity
blue red
Fermilab Colloqium 29 October 2003
3. Polarization: BAL troughs3. Polarization: BAL troughsOgle et al. 1999 ApJS, 125, 1; Ogle 1998 PhD thesis, CalTech
BAL troughs are highly polarized – scattered light off flattened structure
=> BALs are common. Universal?Scattering solves other BAL problems:
ionization, abundances, NH
Thomson thick: X-ray Fe-K, Compton hump
Ogl
e, P
hD th
esis
, 199
8
Conical wind fits BALs well
Hamann 1998 ApJ 500, 798; Telfer et al. 1998 ApJ 509, 132
Is the BAL wind itself the scatterer?
Bi-cone model Predicts distribution of non-BAL quasar polarization
Fermilab Colloqium 29 October 2003
3. Polarization: VBELR3. Polarization: VBELR
Supported by observations: Emission lines twice as broad in
polarized, non-variable light. non-BAL quasars have
Thomson thick gas at large, BAL, velocities
Don’t see in absorption because out of our line of sight
Large scattering region (but not too large, Smith et al. 2003
MNRAS) with BAL velocities
Young et al. 1999 MNRAS 303, 227
Polarized light2 x width
total light
MKN 509
BAL velocity gas exists in non-BAL quasars
If BALs are cones, all quasars should have BAL gas
Fermilab Colloqium 29 October 2003
One last, crucial, complicationOne last, crucial, complicationAngles are wrong:
BAL velocities too high: ~10,000 km s-1
10 times narrow absorption lines
Requires extreme cone opening angle.
Simple solution: bend wind
Predicts:
1. ‘detached BALs’*
= Lowest velocity where wind bends into our line of sight
= vertical velocity from disk
2. ~10% covering factor
r at r gives 6o divergence angle
radiation forces gas to diverge
Both previously unexplained
BALEm.
line
wavelength
Continuumflu
x
Detachment velocity
*Could this be an ionization effect? v IP?
Fermilab Colloqium 29 October 2003
Quasar Atmospheres, Quasar WindsQuasar Atmospheres, Quasar Winds
60 deg: broad absorption lines
20 deg: no absorption lines
One geometry unites all the features
85 deg: narrow absorption lines
High ionization Broad emission lines Low ionization
Fermilab Colloqium 29 October 2003
Components of Quasar AtmospheresComponents of Quasar Atmospheres
High ionization: e.g. CIV, OVI
Low ionization: e.g. MgII, H.
All atomic features now included
Thompson thick BAL scatterer must also make Compton hump, Fe-K
Fermilab Colloqium 29 October 2003
Putting it all togetherPutting it all togetherinformation filters worked efficiently!
Accretion disk
hollow cone
Supermassive black hole
Elvis M., 2000, ApJ, 545, 63
X-ray/UV ionizing continuum
BALs
Polarization
Accelerating bi-conical wind
Thin quasi-vertical wind
no absorption lines
NALs
BELsWAs
Fermilab Colloqium 29 October 2003
Blind men and the elephant. Manga VIII Hokusai, Katsushika (1760-1849)
Hokusai never saw a live ElephantHokusai never saw a live ElephantNot bad – not 100% right – but gets the idea
This picture of quasar atmospheres is probably in much the same state: needs physics bones
Fermilab Colloqium 29 October 2003
A Quasar Observational ParadigmA Quasar Observational Paradigm
Disk Winds: tie together all the pieces of the quasar atmosphere
Explains features not ‘built in’ BAL covering factor; detachment velocity, Hi ionization BEL blueshifts.
Survived tests X-ray absorber outflow v, 2-phase UV/X-ray absorber, pressure balance
Makes predictions High ionization BEL, X/UV absorber radii, thickness are equal
Creates a research program c.f. Lakatos 1980
Allows tractable physics exploration… Work BACK to origin in accretion disk physics Work OUT to impact on surroundings
Can begin to build a ‘low’ theory of quasar atmospheres
Fermilab Colloqium 29 October 2003
low theory: 2-phase equilibriumlow theory: 2-phase equilibriumKrolik, McKee & Tarter 1981, ApJ, 249, 422
•Photoionized gas tends to have phases
• Not really new:
•Does not work for a static medium
•so abandoned…. a mistake!
•Works fine in a wind. dynamic
•Equilibrium determined solely by: SED & ionization thresholds
•Should be similar from object to object
•No need to assume ‘clouds’
Krongold, Nicastro, Brickhouse, Elvis, Liedahl & Mathur, 2003
Fermilab Colloqium 29 October 2003
low theory: accretion disk physics, IIlow theory: accretion disk physics, IIKrongold et al. in preparation
new
•~106K phase depends critically on SED Nicastro 1999, Reynolds & Fabian 1995
• Use absorber (T,x) to determine unseeable EUV SED
-> Test models of accretion disk
•inner edge ill-defined- boundary condition
•‘plunging region’ Krolik et al.
Krongold, Nicastro, Brickhouse, Elvis, Liedahl & Mathur, 2003
Reynolds & Fabian 1995 MNRAS 273 116
Fermilab Colloqium 29 October 2003
low theory: Why is the wind thin?low theory: Why is the wind thin?
Intermediate level 2D theory Wind driven by UV absorption lines
c.f. O-star winds, CAK ignore gas pressure
3 Zones: Inner, Middle, Outer 1. Inner: over-ionized
Only Compton scattering - insufficient shields gas further out from X-rays =
Murray & Chiang `hitchhiking gas’
2. Middle: UV absorption drives gas wind escapes
3. Outer: shielded from UV, weak initial push from local disk radiation – wind falls back
Risaliti & Elvis 2003, ApJ submitted
wind escapes
Outer: wind falls back
Inner:
`failed wind’
Middle
No wind
Wind
new
•Note: L>LEdd quasars always have winds
•See King & Pounds 2003 astro-ph/0305571
•Reeves et al … ;Chartas et al…
Some BALs are L>LEdd windsweakness
density
Fermilab Colloqium 29 October 2003
Looking Out: quasars as dust factoriesLooking Out: quasars as dust factoriesElvis, Marengo & Karovska, 2002 ApJ, 567, L107
Cooling BEL clouds
Oxygen rich dust
Cooling BEL clouds
Carbon rich dust
Outflowing BEL gas expands and cools adiabatically BEL adiabats track through dust formation zone of AGB stars
Applies to Carbon-rich and Oxygen-rich grains
Princeton AGN Physics with the SDSS, 29 July 2003
Outflows rates ~10 Msol/yr at
L~1047 erg/s
0.1 Msol/yr of dust
assuming dust/gas ratio of Long Period Variables
>107Msol over 108 yr outburst lifetime
Metallicity super-solar even in z=6 BELs• High Z/Zsol should enhance
dust production• Larger dust masses likely
Looking Out: quasars & starburstsLooking Out: quasars & starburstsElvis, King et al., in preparation
Conventionally, starbursts fuel quasar outbursts What if it is the other way around?
Princeton AGN Physics with the SDSS, 29 July 2003
All Quasars have winds
Quasar wind outflow rates ~1 Msol/yr at L~1046 erg/s
shocks on host galaxy ISM
induces starburst
Fuels AGN
Wind
… cycle of AGN/starburst activity?
Quasar Atmospheres, Quasar WindsQuasar Atmospheres, Quasar WindsGood Observational Paradigm:
Quasar Atmospheres are dynamic
Thin, rotating, funnel-shaped disk wind
Prospects:Use quasar atmospheres for accretion disk physics
Dust creation at high zQuasar to Starburst causality
Low Theory beginnings:
2 phase medium
Line driven winds
Fermilab Colloqium 29 October 2003
Postscript: Imaging QuasarsPostscript: Imaging Quasars
At low z sizes are ~0.1 mas
Resolvable with planned ground interferometers
VLT-I, Ohana
Ideal telescopes:
•Image the wind in space and velocity
•5 km-10 km IR 2m interferometer at ‘Dome C’ in Antartica
•½-1km UV space interferometer
= NASA ‘Stellar Imager’
Quasar community should push for “Quasi-Stellar Imager”
Sizes are implicit in:
Peterson et al. 1999 ApJL 520, 659.
Kaspi et al. 2001 ApJ 533, 631
What we really want is to look at quasar atmospheres
SOLVE QUASAR ATMOSPHERES
No more fancy indirect deductions!
Elvis & Karovska, 2002 ApJ, 581, L67
Fermilab Colloqium 29 October 2003