Cosmology nature of dark matter cosmic geometry large scale structure

1. X-ray Astronomy in the Next Decade90% of the matter in the universe can only be seen via x-ray observations main science themes and the role of x-ray observations • Cosmology nature of dark matter cosmic geometry large scale structure • Galaxy formation and evolution- • Extreme environments of astrophysics massive black holes end stages of stellar evolution • Amount of and distribution of dark matter in “spherical systems” • How do AGN influence their galaxy and how does this change with cosmic time • direct observation of star formation rates, chemical abundances and galactic winds over a wide range of redshifts • How does accretion work, physics of black holes and neutron stars Thanks to : C. Done, Y. Ueda, T. Boller, J. Tueller

2. Meeting Summary - AGN • It is not possible to properly review the wide variety of observations, theory and instrumental technique • I will focus on what are ( I believe) are the important science problems and “Forget the technology” I will not give specific numbers (e.g. energy resolution, spatial resolution, sensitivity) this has been well covered in the talks on specific missions I personally believe that we have the technology to make major steps forward As Suzaku has shown even ‘small’ improvements can have major science implications Chandra Obs of Hydra-A Direct evidence for AGN influence on cluster scales

3. Properties of active galaxies • Energy due to accretion onto a Massive Black Hole (but other processes may be at work) exact mechanism which produces radiation is not known • strong dynamical evidence for MBH from optical velocity data and x-ray timing data mass estimates are accurate to ~ 2-4. • Strong connections between the host galaxy and MBH masses • The Eddington ratio ranges from <10-7 to >1 • Relativistic effects very important in radio loud AGN -what is the role of jets in the energy budget of the sources ?

4. 4 Main areas of AGN research • What is nature of the source of energy • Accretion • Spin • ? • Physics of matter close to a black hole (e.g. strong gravity) • Affect of AGN on formation and structure of the universe • physics of the radiation- what produces the photons (thermal, non-thermal, relativistic phenomena) Major issue : how to we communicate to our colleagues the importance of high energy astrophysics. I think that our theme should be How the universe came to be the way it is “Without x-rays life itself would be impossible”

5. What are the fundamental questions? • 1) How do AGN "work"- e.g. how is energy produced/extracted and transformed into radiation. What is the role of relativistic effects • 2) How is the MBH connected to host galaxy • how do they form and affect the galaxy • how do they affect the formation and structure of the universe • 3) What is the origin of the wide range of apparent types? - what causes the difference (Unified Models) • 4) How do they evolve with cosmic time? (Mass, luminosity, number) • 5) What can we learn about strong gravity ? • 6) What is the nature/geometry of the central regions ? (winds, disks, torus, jets) • 7) What is the source of the material responsible for accretion and how does it accrete

6. Big questions: strong gravity • Accreting BH: huge X-ray luminosity close to event horizon • Bright emission from region of strong spacetime curvature • Spectral distortions depend on velocity, geometry and GR • Observational constraints on strong gravity if we know velocity/geometry! • Need to understand accretion!

7. The sensitivity of missions circa 1980 • For AGN Chandra,XMM are well matched to Hubble and Spitzer for imaging but not for spectroscopy • For next generation (JWST, ALMA, TMT) x-ray astronomy needs much better sensitivity

8. Active Galaxies in the post XMM/Chandra Era Why are active galaxies interesting in the x-ray? • AGN - most numerous class of extragalactic x-ray source (above F(x)>10-14 ergs/cm2/sec) - can be seen out to z~6 by XMM and Chandra • "x-ray" (0.1-100 keV) band has ~0.05-0.3 (1.0?) of the total energy • x-rays originate very close to the supermassive black hole (MBH) - x-ray band most "rapidly" variable of all wavelength bands x-ray band • x-ray band has the only spectral signature that originates close to MBH • the "Fe K" line • X-ray band is the most efficient way of finding AGN • Many/most x-ray selected AGN cannot be detected by optical techniques • Significant x-ray radiation from jets (in plane of sky and in "Blazars" ) • All types of AGN are luminous x-ray sources (Bl Lac, Quasar, Seyfert I/II, LINER, NLAGN. BLRG......) • Intrinsic luminosity covers an extremely wide range <1040ergs/sec (Ho et al 2001)- 1047 ergs/sec (Fabian et al 1997)

9. The last 6 years - XMM and Chandra • Vast improvement in • grasp • high spectral resolution • multiwavelength capability • angular resolution • sensitivity XMM/Chandra are ideally suited for • extending previous studies to fainter, higher redshift, higher • and lower luminosity systems • detailed studies of many bright low redshift objects. • critical progress in the temporal/spectral domain Combined with other facilities • building up a complete picture of the multiwavelength spectrum of active galaxies as a function of redshift, type and luminosity probing the evolution of quasars over the lifetime of the Universe. • examine structure of the central engine in Seyfert galaxies via observations of their multiwavelength spectral properties and time dependent spectral signatures

10. Some of the new unexpected results (a biased list) • narrow absorption lines are strongest features in grating obs of Seyfert I galaxies- • total opacity dominated by edges-low E emission lines are weak • Almost certainly due to winds carrying significant energy/momentum • Extended line emission from OVII and Fe K (NGC4151, Circinus) • Extended soft x-ray regions (NGC4945,Circinus etc) Chandra images. • Fe K lines are very complex- lots of velocity structure • Narrow +broad Fe K lines are common- but not ubiquitous • ionized Fe K lines detected -Chandra grating obs. • Seyfert II galaxies are photoionization dominated--grating observations • Majority of AGN in the universe do not have strong optical lines or bright optical nuclei- • XMM and Chandra deep fields • Serious difference between optical and x-ray classification schemes (SAX, XMM and Chandra serendipitous sources) • X-ray selected AGN evolve very differently than optically selected objects peaking at z~1 • Direct x-ray detection of cold material via resonance absorption • lack of strong absorption features in Bl Lacs- grating • first features in power density spectra (XTE and XMM)-lack of simple correlation between UV and X-ray • "real" soft excess have been detected XMM-EPIC

11. What have been the new exciting observations?(Suzaku additions ) • Reality of reflection and broad lines - broad band spectra allow ‘unique’ deconvolution of continuum No simple relation between reflection and Fe K lines • Confirmation of Complex time variability across wide energy range • Confirmation of complex shape of Fe K lines Iron line Profile of MCG -5-23-16 Simultaneous Suzaku and XMM Observation- notice the excellent agreement on Fe K line shape Ratio to =1.8 PL EPIC-PNSuzaku XIS Fe K Core (peak energy at 6.397 keV - within 10eV for PN and XIS) Red-wing Fe K (at 7.06 keV) Fe K edge (at 7.1 keV)

12. Black Hole Finder? The Seyfert II Galaxy NGC 4945 ASCA Ginga Photons/cm s2 keV AXAF/XMM energy band energy band Black hole finder Energy (keV) AGN viewed edge-on through the optically thick torus Chandra results show that many AGN lie in the nuclei of optically normal galaxies The present paradigm for AGN consists of a black hole, accretion disk, and a physically thick region of obscuration (“the torus”) Most lines of sight to the AGN are “blocked” by the torii which has an effective column density >1023atms/cm2, The torii are optically thick in the near-IR,optical, UV and soft x-ray band A detection in the hard x-ray band of a source with Lx>1040.5. ergs/s is a direct indictor of a AGN

13. What is required to make progress ?? Relation of soft to hard x-ray flux The requirements to answer the major questions are NOT THE SAME- thus requiring either several missions or a wide range of capabilities • The evolution of AGN and the x-ray background • Chandra and XMM have probed the z=0.5-3.0 universe in the restframe 1-20 keV band- however models of the x-ray background indicate that they may have missed up to 50% of the sources • Need the 15-50 kev band at z<1 • Many AGN have high absorbing columns • I.e. they can be “hidden” from line of sight in optical, UV, soft X-ray • Hard X-ray band (> 15 keV) is one window where opacity is low needed to make a census of AGN Models of XRB background highly sensitive to spectral assumptions(Ueda) -2 models that accurately predict 2-10 kev Log N-Log S have factor of 2 difference in 20-100 kev band

14. Luminosity Function in 20-200 Compared to 2-10 kev • See systematic trend of more sources at lower luminosity in 20-200 keV survey -e.g. 2-10 keV survey miss a large fraction of sources at L<1043 ergs/sec at z=0 20-200 keV 2-10 keV Ratio of 20-100/2-10 luminosity function 2 4 6 8 Hard x-ray survey reaching to z~1 is crucial for AGN evolution and luminosity function .

15. Nature of Hard X-ray selected sources • Followed up Swift BAT selected sources with XMM, Suzaku and XRT • Wide range of x-ray spectra • Many of the Ids have • no optical evidence for activity in literature even though they are very low z bright galaxies Obvious why soft and hard x-ray band are uncorrelated

16. What is Needed ACCURATE MEASURE OF OBSCURATION: • Required in order to accurately determine the AGN contribution to the energetics of the host galaxy emission • Properly calculate the obscured:unobscured AGN ratio vs X-ray luminosity-true census of AGN in universe PROPERTIES OF THE CENTRAL ENGINE: • Study high accretion rate processes (many luminous sources are likely to be growing their black holes at close to the Eddington limit) • Compare the accretion and obscuration properties of obscured and unobscured AGN • Constrain relativistic vs ‘thermal’ processes AGN FEEDBACK IN THE FORMATION OF MASSIVE GALAXIES: • Measure the properties of outflowing gas and estimate their effect on the formation of massive galaxies and the enrichment of the intra-galactic medium • Observe the direct effects of relativistic particles “TRACING THE BLACK-HOLE GROWTH OF MASSIVE GALAXIES”

17. Origin of X-ray Background E-2 200 keV BAT UL • Pre-Chandra results indicate that the background was made up of the superposition of a huge number of very faint sources- • by 1980 it was clear that the number of objects required to make up the XRB exceeded (in surface density) that of known AGN by >10 • However the x-ray spectra of the objects detected (clusters of galaxies, active galaxies, blazars etc) showed that none had the spectrum of the x-ray background out to 200 keV (!)- • this is the so-called "spectral paradox" Spectrum of bright sources from Swift ------------

18. A possible answer Spectrum of individual objects sums to XRB spectrum • The main assumption - most of the flux is produced by supermassive black holes in the center of galaxies containing large amounts of dust and gas and thus having x-ray spectra dominated, at low energies, by photoelectric absorption. • Suitable algebraic superposition- just the right number of objects, evolving the rightway with redshift, with the right distribution of column densities can produce the volume emissivity, log N-log S and the x-ray spectrum. • Such models are remarkably flexible. (Ueda)

19. AGN Evolution Swift BAT and Integral sources Radio loud Blazar Compton thick • Strong selection effects- low luminosity sources more absorbed than high luminosity sources • Differential evolution of low vs high z sources N(H) Z=1 L(x) 20-100 kev • Probable evolution of N(H)/L distribution with redshift- numbers are very uncertain • z~1 is where ‘most’ of XRB originates • to get to Log L(x)=43 at z=1 requires a sensitivity of ~2x10-15 ergs/cm2/sec in 20-200 keV band • NEED HARD X-RAY Imaging UN-Absorbed fraction 0.1 1 1 1 Z=0.6 Z=0.25 Log L(x) 2-10 kev 42 43 44 45 46

20. NeXT Has the capability to resolve ~50% of XRB in 20-40 keV band Fraction of Compton thick AGNs NeXT limit ~40-50% XRB 10-30 keV Survey 2-8 keV Survey • With ~100 srcs/deg^2 - 2-4 sources per NeXT field of view at 3x10-14 ergs/cm2/sec • Need ~100 fields to perform survey with exposure of 100ks per field to ‘solve’ XRB Ueda+ 03 BAT NeXT

21. How the Observable Universe Came to Be • Dark matter evolution in the universe now understood • it is not at all understood how ‘baryonic structures’ (galaxies, groups, clusters) form. • For models to fit the data additional physics (beyond gravity and hydrodynamics) is required (heating, cooling, mass and metal injection, gas motions etc) • Up until now this has been parameterized in ‘semi-analytic’ models - just so stories • The critical problem in all of astrophysics is to put physics into these stories • Ideas and material stolen from M.Begelman, TJ Cox, D. Croton, T. DiMatteo, I. George, C. Martin, J. Ostriker, V. Springel, C. Steidel, S. White… Semi-analytic modeling

22. Formation of Large Scale structure 1/2 stars formed The standard theory of the formation of structure by the evolution of dark matter halos has been remarkably successful But it has several “missing pieces”/problems • How does gas become galaxies, clusters and groups? • What is the origin of the “feedback” process that controls efficiency of conversion of gas in to stars and governs the star formation rate in the universe? • Do galaxies actually form via cooling and what is the interaction with star formation ? • How is the chemical evolution of galaxies connected with their formation ? z Growth of galaxy mass vs redshift 50% of mass created at z<1 (Drory et al 2004, astro-ph 412167)

23. Strong relation of Galaxy to Black hole and SF to BH Growth Star forming history vs accretion history Marconi+ 04 Black holes create and are influenced by their environment

24. How the universe came to be the way it is What has changed in the last 4 years • We now know (Barger et al 2004, Heavens et al 2004, Conselice et al 2004, lots more) that • at z>1.5 the universe is very different from today • Most stars in the universe formed from 0.3<z<1.5 • The epoch of black holes is z~1 • Cluster evolution is doing something quite interesting at z~1 • We need to study the z~1 universe (AGN, clusters and galaxy/star formation) in great detail • Only x-ray astronomy can measure how, where and when most of the energy that controlled how universe formed was produced Barger et al 2005 Ettori et al 2004

25. When did the stars form? • Recent work (e.g Bell et al 2004, Heavens et al 2004, Rudnick et al 2003) shows that ~1/2 of all stars form at z<1 • Integration of the SFR rate would give the 1/2 mass redshift at z~1.5 • This agrees with the new x-ray data for AGN reinforcing the co-evolution of black holes and galaxies Stellar mass density Stellar mass density/year

26. The AGN History of Universe- X-ray Selected AGN • Even including upper limits there is less energy emitting per unit volume at z>1 X-ray luminosity density/sec Barger et al 2005 X-ray selected AGN have a similar evolution to total star formation rate at z<2 type I AGN, all objects Open box- assigning all objects without a redshift to to redshift bin

27. Comparison of Energy Densities and Evolution • Optical samples miss most of the energy radiated by BHs at z< 2 • Most of the AGN luminosity is due to M~10 7+/-1 M objects • The x-ray data show that lower mass black holes evolve later and grow more than more massive objects. 5x When BHs get their mass z Marconi et al 2004 Energy densities from AGN from Optical (---) x-ray (-------) surveys Accretion rate per unit time Each line is the growth of a Massive BH vs z

28. Formation of structure in the Universe • Detailed numerical calculations of the formation of structure via the collapse of gravitational perturbations in a LCDM universe (Springel et al 2003, White et al 2004) cannot ‘produce’ the present day universe without invoking ‘feedback’ (the injection of energy, heat momentum) • Similar results are obtained in analytic work (Ostriker and colleagues) • The nature of the feedback is not clear, but must be related to star formation and AGN - the only possible sources with sufficient energy

29. Calculation of K band galaxy luminosity function in N body simulation Gravity+ hydrodynamics no AGN+ starburst+ reionization - get low luminosity range ‘right’ Gravity+ hydrodynamics +AGN+ starburst+ reionization - get it all ‘right’ Gravity+ hydrodynamics only- get it all wrong- low luminosity, slope, high luminosity slope and number and mass in galaxies Thanks to V. Springel and S. White Blue lines are data-black models

30. Springel 2004

31. AGN Heating and Groups • the x-ray luminosity and entropy profiles (Lapi et al, Dave et al, Borgani et al) cannot be produced by pure gravitational effects • - the effects of star formation and cooling are not sufficient to produce the observed entropy profiles • AGN heating (both internal and pre-heating) of same order to solve the galaxy formation problem ‘works’ to solve entropy problem - may not solve cooling flow problem • ------------ just hydro • ------------ star formation • ------------ AGN +SFR entropy L(X) L(X) entropy

32. The first black holes

33. Winds In AGN • This maybe the mechanism by which AGN ‘heat’ the universe • In >1/2 of all high S/N Chandra/XMM observations of AGN one detects ouflowing winds • In deep fields ~15% of luminous galaxies are x-ray sources (high duty cycle) • V~500-2000km/sec • Mass and energy flux in wind is rather uncertain (Chelouche 2005) but may reach Lwind~0.1Lradiation • Maybe more mass/momentum at higher ionization states Log N(H) Kaastra et al 2003 Log ionization Need to obtain time resolved, high resolution spectra for a large number of objects to get accurate estimates of mass and energy flux in wind and dependence on AGN parameters

34. What is needed? Mass outflow from high resolution spectra • High resolution spectra of objects to understand the winds, the evolution and total energy - only x-ray spectra can determine whether AGN can influence structure formation in the universe • High resolution at E= 6 kev in the rest frame to detect the momentum majority of the wind. • High resolution spectra for extended sources to see the velocity structure in clusters and groups and determine the relative importance of winds or jets Courtesy Ian George

35. What are the spectral signatures- Very High Velocity Outflows Need high spectral resolution at E~6 keV

36. How Do the AGN Influence their environment? • Radio jets/double sources • Mechanical winds • Radiation • Each one of these has visible and testable effects • radiation effects have to occur (Sazonov et al 2004) and can photo-ionize and Compton heat the gas in the host galaxy to kT~2x107k- almost exactly what is needed for the ‘entropy’ problem. • However the gas is only heated at R< 0.5-10 kpc and thus can strongly effect spheroid evolution but not groups or clusters. M=108 M=109 R(kpc)

37. Direct Evidence From Chandra Images of Influence of Black holes on their Environment- the effect of relativistic particles • Chandra x-ray image of Cygnus-A Cluster of Galaxies with AGN in center (Wilson et al 2002)- notice the structure related to the radio source X-ray temperature Map of Perseus cluster- AGN at the center 131 kpc Fabian et al. 2003

38. Observable consequences of AGN heating in a gaseous environment A3667 (z = 0.055) • Turbulence/velocity shear from line shapes • transport properties/dissipation • Precise abundances • Radiative energy of nucleus • magnetic field from IC scattering ( hard emission) • Thermal state of the gas • Optical depth of gas (resonance scattering) allows details of velocity 1000 km/s A2256 (z = 0.058) 1000 km/s Astro_E2 simulations of cluster velocity field

39. How Can We Tell is the Fe Line is really broad • In NGC3783 (Reeves et al ) the XMM long look data do not have a “need” for a broad Fe K line but apparently require a complex highly ionized absorber. • Such absorption components must contain features due to Fe K shell transitions seen as a “sea” of Fe resonance absorption lines from a variety of ionization states Such features are diagnostic and remove the ambiguity from cold or ionized absorbers or reflection features XRS

40. Physics of the Central Region • Only x-ray astronomy has the diagnostics to determine what is occurring near the Black hole • Need • broad band pass, • high signal to noise • High spectral resolution

41. Probing the Central Regions of Black Holes Possible geometries near the black hole • The x-ray spectral features due to reprocessing (Fe-K line complex, Compton reflector) are probes of the matter distribution near the black hole (Reynolds and Novak 2003) Theoretical spectra from an ionized accretion disk Ballantyne et al High spectral resolution at high S/N is crucial

42. Components of the X-ray AGN Spectrum • The high energy cutoff and power law slope contains information on the nature of the continuum and its origin (Comptonization?? • The origin of the ‘soft excess’ is not clear- it is due to reprocessing, absorption by a relativistic wind, or is it a continuum component • The ‘Compton hump” and Fe K line come from reprocessing of the x-rays by ‘cold’ material -somewhere

43. Shape of Fe K line The detailed line shape carries Information about spin of the BH , geometry and distribution of material near the black hole (Reynolds and Novak 2003) Line shape as a function of geometry Line shape as a function of inclination from a rapidly spinning black hole Line shape as a function of black hole spin

44. Time variability of Fe K line • It is not expected that the line shape will be stationary- the disk has many instabilities and the detailed variation of the line shape with time carries much information • The prime requirement is high signal to noise -with sufficient energy resolution XMM/Suzaku data have just barely enough S/N to detect such events Reynolds and Armitage 2004

45. Time behavior of Fe K line in NGC3516 Iwasawa, Miniutti & Fabian 2004 Strong gravity and black hole physics Broad iron lines as probes of strong gravity - power of line variability - orbiting structure on disk and probes of time-like paths in metric - relativistic reverberation and probes of null paths in metric * Demographics of black hole mass and spin - implications for SMBH formation - strong gravity and spin across the whole mass range

46. Physics of Accretion Reflection spectrum interpretation Thermal disc interpretation Boller 2002,3 Tanaka 2004 Gallo 2004 Fabian 2004 1H0707-495 Photons cm-2 s-1 keV-1 Energy [keV] Energy [keV] • Comparison of models of disk which fit present data are rather different • Need high spectral resolution to distinguish amongst the large range of reasonable possibilities

47. High Spectral Resolution Breaks Model degeneracies Reflection model fitted with thermal emission from the disc Thermal model fitted with ionized reflection from the disc

49. Summary • Black holes are critical components of the universe • What is needed to enhance our understanding is • Broad band pass • High sensitivity • High spectral resolution “NeXT” and beyond

50. 1 Ms simulation: z=1.06 lensed SCUBA gal • Evidence of emission from an outflowing wind (some SCUBA galaxies show evidence of large-scale outflows): feedback in the formation of massive galaxies • X-ray spectra of the brightest obscured quasars can achieve this quality in ~100 ks exposures