Quasars, Black Holes & Host Galaxy Evolution

1. Quasars, Black Holes & Host Galaxy Evolution (Quasar Metal Abundances) Fred HamannUniversity of Florida

2. Why quasars? Why high redshifts? Why metal abundances? • MBHsph  SMBH growth linked to galaxy (spheroid) formation • Massive spheroids today have (mostly) old stellar pops. • Quasars mark the locations when and where the spheroids formed • Their metallicities trace the amount of star formation: • When did the star formation occur during SMBHgalaxy evolution? • How much star formation occurred before the visible quasar epoch?

3. Outline: • Metallicity diagnostics & results • Implications for SMBHgalaxy evolution • Significance of Fe/ • Trends with z, L, L/Ledd, Mass • Future Prospects

4. Broad Line Region (BLR) metallicities: Quasars have (broad) metal emission lines.  Prior star formation! Even for quasars at z > 6! Shields 1976 Baldwin & Netzer 1978 Davidson & Netzer 1979 Uomoto 1984 ~ Solar metallicities +/- 1 dex Composite of z > 4 quasars (Hamann & Ferland 1999, Constantin et al. 2002) Problem: As C/H increases, Tgas decreases, and CIV/Ly  constant.

5. Shields (1976): Assume Nitrogen has secondary enrichment: N/O  O/H (as in galactic HII regions and stellar data) Use N III] 1750, N IV] 1486, etc., to avoid saturation issues (but weak and hard to measure) Hamann & Ferland (1992, 1993, 1999), Ferland et al. (1996): Include stronger UV lines: NV/CIV and NV/HeII  fainter quasars & larger samples Saturation/thermalization issued unavoidable Extensive photoionization simulations, with N/O  O/H

6. Ionizing flux H density Hamann et al. (2002): Locally Optimally-emitting Cloud (LOC) model of BLR (Baldwin et al. 1995)  the BLR is stratified, a wide range in nH, H coexist  not dependent on a particular choice Calculate line strengths & ratios for each nH, H, Z

7. Add line emission over each LOC grid  line ratios versus Zgas : The metallicity dependence of these ratios is due mainly to N/O  O/H Hamann et al. (2002)

8. Nagao et al. (2006): Include more lines, with sensitivities to nH, H, temperature (Zgas)  less dependent on N lines and N/O  O/H  Find “best” solution for each quasar by tuning the weighted sums over LOC distrib. to match each quasar spectrum.

9. Nagao et al. (2006)  > 5000 SDSS quasars Zgas ~ 4-5 Zo Dietrich et al. (2003)  Obtained spectra the old fashioned way.

10. Warner et al. 2002 High redshift examples: This quasar at z ~ 4.2 has many well-measured diagnostics We estimated: Zgas ~ 2 Zo Pentericci et al. 2002 Zgas Zo at redshift 6.28 based on NV/CIV, lower limit on NV/HeII

11. How much metal-rich gas? From what stellar population? LOC models suggest quasar MBLR ~ 1000 Mo(Baldwin et al. 2003) But the amount of accretion over a quasar lifetime is  MBH If the BLR is continuously replenished by accretion, then the reservoir of metal-rich gas has mass: Mgas MBH ~ 109 Mo Stellar mass needed to enrich this gas: Mstars few  109 Mo  at least ~bulge-size stellar pops.

12. In our models, the NV ratios often suggest 1.5 to 2x higher Zgas than NIII]. Measurement error? (In “well-measured” - high EW - cases all the N lines agree.) (Dietrich et al. 2003)  Need independent checks

13. Much larger scales: 102 to 104 pc Narrow Line Region (NLR) metallicities: Groves et al. (2006): ~23,000 low-redshift Seyfert 2s from SDSS Visible emission-line ratios, e.g., [NII] 6584 Adopt: nH ~ 1000 cm3, secondary N enrichment  All but 40 have Zgas Zo  Typical values: Zgas ~ 2 - 4Zo Also: Storchi Bergmann & Pastoriza 1989 Storchi Bergmann et al. 1998, Nagao et al. 2002, Groves et al. 2004

14. Narrow Line Region (NLR) metallicities: Nagao et al. (2006): High-z quasar 2s and radio galaxies UV emission-line ratios (same lines at BLR) Adopt: nH ~ 102 or 105 cm3, secondary N enrichment  Zgas= 0.2 to 5 Zo depending on nH

15. AALs Observed Wavelength Associated Absorption Line (AAL) metallicities: AALs appear in ~25% of quasars Probably form at a wide range of radii: ~10 to >104 pc A simpler analysis: Measure ionic column densities Apply ionization correction No assumptions about secondary N Foltz et al. 1986 Also posters: Nestor, Simon, Misawa, Ganguly

16. Associated Absorption Line (AAL) metallicities: • Early results: Zgas Zo and N/C  solar are typical (for bona fide near-quasar absorbers) Petitjean et al. 1994, Wampler et al. 1993, 1996, Savaglio et al. 1997, Hamann 1997, Tripp et al. 1995, 1997, Savage et al. 1998, … • Best/most recent: D’Odorico et al. 2004 6 AAL quasars at redshifts 2.1 to 2.6 VLT/UVES spectra, resolution ~7 km/s 5 out of 6 have Zgas = 1 to 3 Zo • In progress: Leah Simon et al. 200x, poster n AAL quasars at redshifts 2 - 4 at Keck, VLT, Magellan…

17. Other Indicators of star formation in quasar hosts: mm, sub-mm, CO, … For example: ~30% of high-redshift, optically luminous quasars are ULIRGs based on mm and sub-mm (Cox et al. 2006, Beelen et al. 2006) Inferred SFRs ~ 1000 Mo/yr Dust masses 108 to 109 Mo  Enriched gas masses ~ 1010 to 1011 Mo  Stellar pop. masses ~ few  1010 to 1012 Mo …formed prior to the quasar epoch. • SF coincident with quasar  SF that preceded the quasar

18. Understanding Zgas Zo near quasars: Galaxy Evolution Massive spheroids today are old and metal rich: Zstars ~ 1 to 3 Zo The gas that produced this population must have had Zgas > Zstars toward the end of the evolution. Age (Gyr) log Zstars Central re/8 in field ellipticals (Trager et al. 2000)

19. Quasar Z’s are consistent with normal galactic chemical evolution… Friaca & Terlevich 1998 (and many others) if most of this star formation occurred before the quasar epoch, with 70% conversion of gas into stars.

20. In physically motivated models, e.g., to explain MBHsph a major merger triggers a starburst and funnels gas toward the SMBH AGN (& SN) feedback halts the star formation… obscured visible The visible/luminous quasar appears after the starburst, with central Zgas ~ 2-3 Zo Kauffmann & Haehnelt 2000, Granato et al. 2004 Di Matteo et al. 2004, Hopkins et al. 2005, Springel et al. 2006

21. In this GADGET-2 simulation, 8 galaxies merge to make an enormousstarburst, then a quasar at z = 6.54 Li et al. 2006

22. …before the quasar becomes bright/observable at z = 6.54 (final MBH 2  109 Mo) The total SFR reaches 104 Mo/yr, creating a stellar mass of 1012 Mo Li et al. 2006

23. …leaving these metallicity distributions in gas and stars at the quasar epoch z = 6.54. • Near solar on large scales, super-solar in dense pockets. • with Zgas ~ 2-3 Zo expected in the nucleus Li et al. 2006 Di Matteo et al. 2004

24. solar Non-AGN data: Quasars metallicities are like massive SF galaxies: Zgas ~ 2-3 Zo e.g., in this SDSS sample of 53,000 at z ~ 0.1 (HII region emission-line diagnostics) Tremonti et al. 2004

25. Trends in the quasar data …can further constrain evolution models: 1)No significant trends with redshift, e.g., in these BLR studies Nagao et al. (2006)  Dietrich et al. (2003)

26. Trends in the quasar data: 2)More luminous quasars are more metal rich (based on BLR data). Nagao et al. (2006) Hamann & Ferland (1999)

27. Trends in the quasar data: 3)The fundamental trends are with Mass or L/Ledd Shemmer et al. (2004) find a stronger relationship to L/Ledd than to L or MBH, (based on 92 AGN with H SMBH masses)  higher Z at earlier evolutionary stages?

28. Warner et al. 2006measured MBH (via CIV) in 578 AGN Create sub-samples to isolate trends with L and MBH … (Each sub-sample has ~150 quasars)

29. L  1047 ergs/s MBH 109 Mo Composite spectra for fixed L and MBH(Warner et al. 2006) the underlying trend is mass-Z, possibly also driving the Baldwin Effect

30. These line ratios (metallicity) scale with MBH not Luminosity Mass  Metallicity is the main relation. (L = constant) (MBH = constant)

31. UV spectral index A physical explanation for the Baldwin Effect, driven by MBH : Metallicity increases with increasing MBH SED becomes softer with increasing MBH Korista et al. (1998), Warner et al. (2006)

32. Aside: MBH from CIV versus H CIV and H yield similar MBHon average, e.g., in composites. with no systematic bias (Warner et al. 2003) All sources with both CIV and H in Warner et al. sample

33. NLR massmetallicity trend: Groves et al. (2006):Z in the NLR increases with galaxy mass (in their Seyfert 2 sample) 2x increase in O/H Galaxy mass 

34. solar Lower mass galaxies expel their gas before it can be enriched to high metallicities. We might expect massmetallicity in quasars based on the well-known massmetallicity trend in galaxies: Bender et al. 1993 Tremonti et al. 2004

35. Summary: What’s next? Quasar environs are metal rich, Zgas 1-5, out to the highest redshifts. Enriched by at least bulge-size stellar pops. (1010 Mo), but maybe by the entire spheroid involved in MBH sph High quasar metallicities require major star- forming episodes before the visible quasar epoch: major merger  ULIRG/starburst  transition object?  quasar Quasars in more massive hosts are more metal rich, …with an added dependence on L/Ledd (age)? AALs and NLR lines at high redshifts Compare quasar Z’s to host galaxy properties (mass, age, Zstars, etc.) Transition objects (strong FIR, sub-mm) might be younger… Sort out trends with Mass or L/Ledd Fe/ and other ratios…

36. Fe/ as a “clock” Hamann & Ferland 1999

37. Hamann & Ferland 1999

38. Log Metallicity Understanding Zgas Zo near quasars: Massive/dense environments evolve quickly and are metal rich at all redshifts Quasars can uniquely probe galactic nuclei Pettini 2001

40. Quasar metal abundances as probes of host galaxy evolution: • How “mature” are the surrounding stellar pops (at different redshifts)? • When did the first major star formation begin, relative to SMBH growth & quasar activity? Dependence on LAGN , MBH & L/Ledd : • Does metallicity (star formation) correlate with L, MBH & L/Ledd ? • NLS1s, Baldwin Effect, broad line ratios…  AGN physics

41. Specifically targeted low L sources at high redshift 578 type I AGN measured at 950 <  < 2050 Ǻ including 26 NLS1s Dietrich et al. (2002-04) Warner, Hamann, & Dietrich (2002-04)

42. ( ) ( ) 2 0.7 FWHM(CIV) L(1450A) 1000 km/s 1044 ergs/s + MBH = 1.4  106 Mo Peterson & Wandel (2000) Kaspi et al. (2000) Vestergaard (2002,04) There can be large differences between CIV and H FWHMs in a given source, But in composites, CIV is ~ 2 broader, consistent with reverberation and ~2x smaller RBLR All sources with both CIV and H measured (narrow H components removed)

43. A -26 B C

44. A B C

45. Composite Spectra Sorted by SMBH mass Sorted by Luminosity Baldwin Effect plus changing NV line ratios 0 1000 1200 1400 1600 1800 2000 Rest Wavelength 1000 1200 1400 1600 1800 2000 Rest Wavelength

46. Fit the lines to deblend & measure line ratios

47. NV and possibly NIII] line ratios increase with MBH ? Log Z/Zo Log Z/Zo

48. NV and possibly NIII] line ratios increase with MBH ? Log Z/Zo Log Z/Zo Metallicity, based on N/O  O/H (Hamann & Ferland 1999, Hamann et al. 2001), is above solar and increases with MBH

49. Log Z/Zo AGN metallicity, from average of several Nitrogen line ratios... ...is above solar, and increases with both MBH and L.

50. How “mature” are the surrounding stellar pops (at different redshifts)? • When did the first major star formation begin, relative to SMBH growth & quasar activity? High metallicities (even at the highest redshifts, Dietrich et al. 2003)  substantial conversion of gas  stars (>70% in simple closed box with “normal” galactic IMF) Major star formation before bright/visible AGN phase, accompanying SMBH growth(Dietrich & Hamann poster, and 2004). Stellar pop. masses > 104 to 105 Mo (>3x MBLR)(Baldwin et al. 2003)probably > MBH (>109 Mo)