Fermilab Colloqium 29 October 2003 Solving Quasars part I in particular… Understanding Quasar Atmospheres Martin Elvis Harvard-Smithsonian Center for Astrophysics Elvis M., 2000, Astrophysical Journal 545, 63 Fermilab Colloqium 29 October 2003 Quasars* unsolved after 40 years Discovered in 1963 Quasars are the most powerful continuous radiation sources in the Universe 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? * Note for the pedantic: By ‘quasars’ I mean all types of ‘activity’ in galaxies Fermilab Colloqium 29 October 2003 What’s the problem? We have no images of a quasar atmosphere Would need 1000 times sharper pictures than Hubble or Chandra <100mas Must rely on spectra: span all wavelengths: X-ray - optical - radio • Enormous array of detail • Superficial understanding Fermilab Colloqium 29 October 2003 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 1. An Astronomer’s Answer Outside the wavelength range that our eyes are sensitive to Radio Gamma-ray Quasars dominate the night sky X-ray Fermilab Colloqium 29 October 2003 2. 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. The power available from gravity for heating is all too obvious following the Columbia tragedy Emit strongly from radio to g-rays. How do they do that? Billions of times brighter than stars. Can outshine a whole galaxy Make galaxy length jets 3. A Cosmologist’s Answer 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. Emit up to 1/5 of power in Universe: Important input, may dominate in some places, times. 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? Fermilab Colloqium 29 October 2003 4. A Physicist’s Answer Eject bulk gas at 99.50% speed of light G=10 similar to proton in Fermilab Tevatron 99.88%c Impacts gas of intergalactic medium.->what emerges? Accelerates e- to g~1000 -> TeV photons X-rays come from region of Strong Gravity seen in 6.4 keV `Fe-K’ (=Fe Lyman-a) emission line? MCG -6-30-15 (XMM) Reynolds C. GR redshift? 6.4 keV Reynolds C. Wilms et al., 2002, MNRAS, 328, L27 Fermilab Colloqium 29 October 2003 What do we know? High level theory rapidly gave a clear picture massive black hole Lynden-Bell 1969 accretion disk Lynden-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 This theory describes a naked quasar does not connect to the atomic physics features observed in quasars Leaves us with no way to order observations, nothing to test Fermilab Colloqium 29 October 2003 Atomic features in Quasar Atmospheres High ionization: e.g. CIV, OVI Low ionization: e.g. MgII, Hb. All studied separately with separate telescopes Quasars have no temperature Whipple 10 meter Compton gamma-ray Observatory Chandra Hubble MMT Sub-millimeter array VLA Fermilab Colloqium 29 October 2003 Wall, Tree, Rope, Spear, Snake, Fan Not having the complete picture can be misleading Blind men and the elephant. Manga VIII Hokusai, Katsushika (1760-1849) Fermilab Colloqium 29 October 2003 we need a ‘low theory’ that deals with the multitude of quasar details These optically thin features are all interconnected S = `quasar atmosphere’ • Just as there are textbooks on ‘Stellar Atmospheres’ • we need the subject of ‘Quasar Atmospheres’ • Takes more than 1 step. • First build an observational paradigm i.e. what do the observations drive require of any theory? Fermilab Colloqium 29 October 2003 A Paradigm for Quasar Atmospheres Elvis M., 2000, Astrophysical Journal 545, 63 A Geometric & Kinematic solution c.f. Rees relativistic jets for blazars/radio sources Quasar Atmosphere Accelerating bi-conical wind hollow cone Broad Absorption Lines no absorption Reflection features NB: Independent of Unification lines Jets are not included Thin Vertical wind Supermassive black hole Narrow absorption lines X-ray `warm’ absorbers Accretion disk Broad Emission Lines X-ray/UV ionizing continuum Can now re-construct this model using data not in Elvis 2000 Princeton AGN Physics with the SDSS, 29 July 2003 Take a lesson from lab plasmas: use all the data 2mm interferometer X-ray PHA NSTX diagnostic instruments cover everything X-ray crystal spectrometer Radiometer NSTX at PPPL Thomson scattering National Spherical Torus eXperiment Far infrared tangential Princeton Plasma Physics Laboratory 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 Fermilab Colloqium 29 October 2003 12,277 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 Spam! • Need filters--- 1. Physical measurements Mass, 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: BEL Velocity-radius relation Reverberation mapping shows Keplerian velocity relation in BELs Peterson & Wandel 2000 ApJ 540, L13 Mass Doppler width of em. Line ~1000 rs, Schwartzchild radii Light echo delay (days) Pole-on Broad Emission Lines close to Keplerian velocities Fermilab Colloqium 29 October 2003 1.Physical Measurements: Angle Use VLBI + X-ray to get angle of jet to line of sight Rokaki et al. 2003 astroph/0301405 (1) Rotation about jet axis c.f. Wills & Browne 1986, Brotherton 1996, McLure & Jarvis 2003 FAST Edge- on Ha polarization rotation also implies orbiting gas Continuum/Ha flux Smith et al 2002 Pole-on Relativistic (2) Continuum drops as cos q beaming EW=EW0[1/3 cosq(1+2cosq)]-1 limb darkened disk isotropic Flat disk continuum Ha does not Ha scale height larger than disklike SLOW optical continuum But BLR is rotating rotating cylinder? Rokaki et al. 2003 astro-ph/0301405 Pole-on A highly non-equilibrium shape Simplest solution: BLR is in a rotating wind Princeton AGN Physics with the SDSS, 29 July 2003 2. Absorption Features Winds are common in quasars new Chandra HETG: 900ksec NGC3783 new Narrow UV lines Narrow X-ray lines High ionization CIV, OVI High ionization OVII,OVIII Same Outflow ~1000 km s-1 new Outflow ~1000 km s-1 Seen in same 50% of quasars Seen in 50% of quasars Simplest solution: Same gas, 2 phases Fermilab Colloqium 29 October 2003 2. Absorption: More Physics from X-rays Krongold, Nicastro, Brickhouse, Elvis, Liedahl & Mathur, 2003 ApJ, in press. astro-ph/0306460 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% 2-phase gas in pressure equilibrium Fermilab Colloqium 29 October 2003 2. Absorption: where is the wind? Arav, Korista & de Kool 2002, ApJ 566, 699 Arav, Korista, de Kool, Junkkarinen & Begelman 1999 ApJ 516, 27 • Velocity dependent covering factors • Absorber is close to continuum source • absorber is moving transverse Wind is close to continuum, crosses line of sight Fermilab Colloqium 29 October 2003 A 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? Leighly & Moore 2003, ApJ submitted • 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 See: Gaskell 1982 Wilkes 1984 outer disk c.f. Collin-Souffrin, Hameury & Joly,1988 A&A 205, 19 Low ionization MgII BELs are rotating, transverse, thin winds Fermilab Colloqium 29 October 2003 2. Absorption / 1. Physical Measurements: Wind Density,thickness Nicastro et al. 1999 ApJ, 512, 184 X-ray continuum UV/X-ray absorption responds to continuum changes: photoionized time “OVII edge” • But responds with a delay • = recombination/ionization time • density ne~108 cm- 3 for OVIII • ne~3x107 cm-3 for FeXVII “OVIII edge” Absorbing wind is dense density + column density (~3x1022 cm-2) wind thickness (~10 15 cm) To Earth Black hole < distance to continuum accretion disk Absorbing wind is narrow DR R Fermilab Colloqium 29 October 2003 3. Polarization: X-ray absorbers Leighly et al. 1997 ApJ 489, L137 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 Absorbers are seen edge-on Princeton AGN Physics with the SDSS, 29 July 2003 Flattened, Transverse Wind axisymmetry Mathur, Elvis & Wilkes 1995 ApJ, 452, 230 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 Absorbing wind is a bi-cone to 1st order Fermilab Colloqium 29 October 2003 Putting X-ray/UV absorber and BEL together Elvis 2000 ApJ 545, 63; Krongold et al. 2003 Both are disk winds rising well above the disk plane They share physical properties: Similar Radius: for NGC 5548 Similar Pressure: r( abs ) ~1015 - 1018cm recomb. time + NHX r(BELR)~1016cm CIV reverberation mapping P( abs ) ~1015 = 104 Kx 1011 cm-3 P(BELR)~1015 = 106 K x 109 cm-3 Similar Temperatures Matching Ionization Parameter, U: new For low U absorber, BELs T/U( abs ) = 106 = T( abs ) ~106 K/ U( abs ) ~1 T/U(BELR)= 106 = T( abs ) ~104 K/ U(BELR) 0.04 Keep it simple: Emission and Absorption are 2 phases of the same quasar wind Fermilab Colloqium 29 October 2003 Components of Quasar Atmospheres High ionization: e.g. CIV, OVI Low ionization: e.g. MgII, Hb. United In a 2-phase transverse wind in pressure balance Fermilab Colloqium 29 October 2003 The Final Element: Broad Absorption Lines (BALs) 10% of quasars show BALs with doppler widths ~2%c - 10%c ~10x NALs. Clear acceleration (or deceleration) Ferland & Hamann 1999 Annual Reviews of Astronomy & Astrophysics , 37, 487 QuickTime™ an d a TIFF (Unc ompress ed) decompre ssor ar e need ed to s ee this p icture . Old question: Special objects? or Special angle? Princeton AGN Physics with the SDSS, 29 July 2003 Broad Absorption Lines (BALs) Lee & Turnshek 1995 ApJ 453 L61 • BEL FWHM correlates with BAL velocity (at minimum flux) • V(BAL) ~ 2 FWHM(BEL) More BEL-BAL correlations: Reichard et al. 2003 BEL width BAL width BAL gas knows about BEL gas Fermilab Colloqium 29 October 2003 BALs from a rotating wind Hall et al. 2002 ApJS, 141, 267 Detachment velocity • Redshifted BAL onset flu Continuum Em. x BAL line • Possible occasionally in a rotation dominated blue red wavelength wind BALs need a rotating wind … like the BELs Fermilab Colloqium 29 October 2003 3. Polarization: BAL troughs Ogle 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 Hamann 1998 ApJ 500, 798; Telfer et al. 1998 ApJ 509, 132 Is the BAL wind itself the scatterer? Ogle, PhD thesis, 1998 Bi-cone model Predicts distribution of non-BAL quasar polarization Conical wind fits BALs well Fermilab Colloqium 29 October 2003 3. Polarization: VBELR Young et al. 1999 MNRAS 303, 227 If BALs are cones, all quasars should have BAL gas • Supported by observations: MKN 509 • Emission lines twice as broad in polarized, non-variable light. Polarized light • non-BAL quasars have 2 x width Thomson thick gas at large, BAL, velocities • Don’t see in absorption because out of our line of sight • Large scattering region total light • (but not too large, Smith et al. 2003 MNRAS) • with BAL velocities BAL velocity gas exists in non-BAL quasars Fermilab Colloqium 29 October 2003 One last, crucial, complication Angles 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 Detachment = vertical velocity from disk velocity 2. ~10% covering factor dr at r gives 6o divergence angle flu Continuum Em. x BAL radiation forces gas to diverge line Both previously unexplained wavelength *Could this be an ionization effect? Dv a IP? Fermilab Colloqium 29 October 2003 Quasar Atmospheres, Quasar Winds One geometry unites all the features High ionization Broad emission lines Low ionization 85 deg: narrow absorption lines 60 deg: broad absorption lines 20 deg: no absorption lines Fermilab Colloqium 29 October 2003 Components of Quasar Atmospheres Thompson High ionization: e.g. CIV, OVI thick BAL Low ionization: e.g. MgII, Hb. scatterer must also make Compton All atomic features now included hump, Fe-K Fermilab Colloqium 29 October 2003 Putting it all together information filters worked efficiently! Accelerating bi-conical wind BALs Polarization hollow cone no absorption lines Thin quasi-vertical wind Supermassive black hole BELs Accretion disk WAs NALs X-ray/UV ionizing continuum Elvis M., 2000, ApJ, 545, 63 Fermilab Colloqium 29 October 2003 Hokusai never saw a live Elephant Not bad – not 100% right – but gets the idea Blind men and the elephant. Manga VIII Hokusai, Katsushika (1760-1849) This picture of quasar atmospheres is probably in much the same state: needs physics bones Fermilab Colloqium 29 October 2003 A 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 equilibrium Krolik, McKee & Tarter 1981, ApJ, 249, 422 Krongold, Nicastro, Brickhouse, Elvis, Liedahl & Mathur, 2003 •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’ Fermilab Colloqium 29 October 2003 new low theory: accretion disk physics, II Krongold et al. in preparation Krongold, Nicastro, Brickhouse, Elvis, Liedahl & Mathur, 2003 •~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 Reynolds & Fabian 1995 MNRAS 273 116 •‘plunging region’ Krolik et al. Fermilab Colloqium 29 October 2003 new low theory: Why is the wind thin? Risaliti & Elvis 2003, ApJ submitted • Intermediate level 2D theory • Wind driven by UV absorption lines Wind – c.f. O-star winds, CAK Middle wind escapes – ignore gas pressure • 3 Zones: Inner, Middle, Outer No wind • 1. Inner: over-ionized – Only Compton scattering - insufficient Inner: density – shields gas further out from X-rays = Murray & Chiang `hitchhiking gas’ `failed wind’ • 2. Middle: UV absorption drives gas – wind escapes Outer: wind falls back • 3. Outer: shielded from UV, weak initial push from local disk radiation – wind falls back •Note: L>LEdd quasars always have winds weakness Some BALs are L>LEdd winds •See King & Pounds 2003 astro-ph/0305571 •Reeves et al … ;Chartas et al… Princeton AGN Physics with the SDSS, 29 July 2003 Looking Out: quasars as dust factories Elvis, Marengo & Karovska, 2002 ApJ, 567, L107 • 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 Outflows rates ~10 Msol/yr at L~1047 erg/s Oxygen rich dust Carbon rich dust 0.1 Msol/yr of dust Cooling BEL Cooling BEL clouds clouds 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 Princeton AGN Physics with the SDSS, 29 July 2003 Looking Out: quasars & starbursts Elvis, King et al., in preparation • Conventionally, starbursts fuel quasar outbursts • What if it is the other way around? 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? Fermilab Colloqium 29 October 2003 Quasar Atmospheres, Quasar Winds Good Observational Paradigm: Quasar Atmospheres are dynamic Thin, rotating, funnel-shaped disk wind Low Theory beginnings: 2 phase medium Line driven winds Prospects: Use quasar atmospheres for accretion disk physics Dust creation at high z Quasar to Starburst causality Fermilab Colloqium 29 October 2003 Postscript: Imaging Quasars What we really want is to look at quasar atmospheres Elvis & Karovska, 2002 ApJ, 581, L67 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 2mm interferometer at ‘Dome C’ in Antartica •½-1km UV space interferometer Sizes are implicit in: = NASA ‘Stellar Imager’ Peterson et al. 1999 ApJL 520, 659. Kaspi et al. 2001 ApJ 533, 631 Quasar community should push for “Quasi-Stellar Imager” SOLVE QUASAR ATMOSPHERES No more fancy indirect deductions!
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