Evolution of the Highest Redshift Quasars

Transcription

1 Evolution of the Highest Redshift Quasars Xiaohui Fan University of Arizona Collaborators: Becker, Bertoldi, Carilli, Cox, Diamond-Stanic, Hennawi, Ivezic, Jiang, Kelly, Richards, Schneider, Strauss, Vestergaard, Walter, Wang, White, SDSS collaboration

2 What have changed in quasar properties since z~6? Luminous, normal looking quasars existed at z>6, half Gyr after the first star-formation Timescale for formation of the first billion-m sun BH? Timescale for the establishment of AGN structure: do quasar spectra at z~6 really look the same as at z~0? Timescale for the establishment of M-sigma relation? Study of quasar evolution needs: Large survey to increase sample size Deep survey to break redshift/luminosity degeneracy Multiwavelength study to probe different scales of AGN structure

3 Outline Update on high-redshift quasar searches Quasar luminosity function and BH mass function Evolution in accretion properties? Quasar SEDs at high-redshift First signs of cosmic evolution? Star-formation and dust in quasar host galaxies Evolution of M-sigma relation? Summary

4 The Highest Redshift Quasars Today z>4: >1000 known z>5: >60 z>6: 13 (12 SDSS discoveries) SDSS i-dropout Survey: Current Status: >7000 deg 2 23 luminous quasars at 5.7<z<6.4 By this June: Completion of a colorselected flux-limited sample of luminous high-z quasars in the entire SDSS highlatitude area (~8000 deg 2 )

5 The Highest Redshift Quasars Today Other on-going z~6 quasar surveys: AGES (Cool et al.): Spitzer selected, one quasar at z=5.8 FIRST-Bootes (Becker et al.): radio selected, one quasar at z=6.1 QUEST, CFHT: i-dropout surveys similar to SDSS Future IR-based survey: UKIDSS, VISTA, allows detection up to z~8-9. SDSS 2 : faint quasars in the deep SDSS stripe (Jiang, XF et al.), ~10-30 additional z~6 quasars in next three years (three z~6 quasar in pilot obs)

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7 redshift Lyα forest 46,420 Quasars from the SDSS Data Release Three Lyα CIV CIII MgII 1 FeII FeII 0 OIII 4000 A wavelength 9000 A Hα

8 Quasar Density at z~6 From SDSS i-dropout survey Density declines by a factor of ~40 from between z~2.5 and z~6 Cosmological implication M BH ~ M sun M halo ~ M sun rare, 5-6 sigma peaks at z~6 (density of 1 per Gpc 3) Assembly of massive dark matter halo environment? Assembly of supermassive BHs? Fan et al. 2004

9 Simulating z~6 Quasars z=6.2 z=0 Dark matter galaxy Springel et al The largest halo in Millennium simulation (500 Mpc cube) at z=6.2 Virial mass 5x10 12 M_sun Stellar mass 5x10 10 M_sun Resembles properties of SDSS quasars Such massive halos existed at z~6, but.. How to assemble such mass BHs and their host galaxies in less than 1Gyr?? The universe was ~20 t edd old Initial assembly from seed BH at z>>10 Low radiative efficiency or massive seed BH Little or no feedback to stop BH/galaxy growth

10 Evolution of Quasar LF Shape Richards, et al.; Fan et al High-z quasar LF different from low-z Bright-end slope of QLF is a strong function of redshift Transition at z~2.5 (where quasar density peaks in the universe) Different formation mechanism at low and high-z? Faint quasar surveys needed!

11 Probing the Evolution of Faint Quasar SDSS Southern Deep Spectroscopic Survey 270 deg along Fall Equator in the Southern Galactic Cap Down to ~25 mag in SDSS bands with repeated imaging Spectroscopic follow-up using 300-fiber Hectospec spectrograph on 6.5-meter MMT Reaches AGN luminosity at z~2.5 Few hundred faint quasars at z> at z~6 Status after Year One: Large number of z>3 quasar to probe LF evolution Three z~6 quasar to demonstrate target selection

12 BH mass determination at high-z CIV Upper Limit? Fan et al. >1000 quasars at z>3 McLure et al. SDSS DR 1 Virial BH mass estimate using optical spectra: Emission line width to approximate gravitational velocity Bolometric luminosity vs. BLR size scaling relation Accurate to a factor of 3-5 locally Applying virial method to high-z (Vestergaard et al.) Lack of spectral evolution in highredshift quasars quasar BH estimate valid at high-z Using Hβ MgII and CIV for different redshift ranges BH mass at high-z: M sun existed at z~6 Upper envelop of BH mass at several M sun? Negative feedback?

13 BH mass distribution Mass L BOL L BOL /L Edd SDSS: DR3 Vestergaard, XF et al. in prep.

14 Evolution of Eddington Ratio Luminous quasars at all redshifts have L bol /L edd ~ Luminosity dependence (expected) L bol /L edd ~ 1 at several L * Redshift dependence: At constant luminosity: L bol /L edd increase by ~3 from z=1 to z=5 At z>4, all quasars basically shining at Eddington Next step: Full MF Extend to low-l To what extent is quasar evolution driven by accretion rate changes? Vestergaard, XF et al. in prep.

15 The Lack of Evolution in Quasar Emission Line Properties Ly a Ly a forest NV OI SiIV Fan et al.2004 Rapid chemical enrichment in quasar vicinity Quasar env has supersolar metallicity : no metallicity evolution Does this lack of evolution in rest-frame UV also apply to other wavelength?

16 High Metallicity at high-z Strong metal emission consistent with supersolar metallicity NV emission multiple generation of star formation from enriched pops Fe II emission type II SNe some could be Pop III? Does this lack of evolution in rest-frame UV also apply to other wavelength? Barth et al Nagao et al. 2006

17 Quasar spectral energy distribution BLR hot dust Dust torus disk Spitzer Cool Dust in host galaxy

18 Evolution of Quasar SEDs: X-ray to radio To the first order, average SEDs of z~6 quasar consistent with low-z template However, detailed analysis might be indicating first signs of SED evolution: Dust properties (Spitzer and extinction) Fraction of radio-loud quasars X-ray - optical flux ratio? A population of lineless highz quasars? Jiang, XF et al. 2006a

19 Hot dust in z~6 Quasars Lack of evolution in UV, emission line and X-ray disk and emission line regions form in very short time scale But how about dust? Timescale problem: running out of time for AGB dust Spitzer observations of z~6 quasars: probing hot dust in dust torus (T~1000K) Two unusual SEDs among 13 objects observed. dust No hot dust?? Jiang, XF et al. 2006a

20 Where did the hot dust go? typical J μm 4.8μm 5.6μm J0005 (z=5.85): SED consistent with disk continuum only No similar objects known at low-z formation of the first dust? Larger sample 8.0μm Host dust contribution 24μm luminosity Jiang, XF 2006a

21 Supernova Dust in z~6 quasar? (Maiolino et al. 2004) SDSS J1048 (z=6.2) Highest-z Low-BAL Typical SED at near UV moderate dust But blue in far-uv SED suggesting unusual dust extinction Age of the universe < 1Gr No time for dust from evolved low intermediate mass stars Dust extinction produced by SN dust fits the data

22 Evolution of Radio-loudness Match all SDSS quasars to FIRST and NVSS catalog: For the whole fluxlimited sample, radioloud fraction doesn t strongly depend on luminosity or redshift However, this seems to be an artifact of marginal distribution Jiang, XF et al. 2006b

23 Radio-loud fraction is a strong function of luminosity and redshift Luminosity dependence: RLF ~ L 0.5 At z~1: RLF changes from 17% (M=-27) to 2% (M=-22) Redshift dependence: RLF ~ (1+z) -1.7 For M=-27: RLF changes from 17% (z=1) to 2% (z=5) log(radio-loud fraction) Log(1+z) Jiang, XF et al. 2006b Mi

24 X-ray properties: evolution? Studies of α ox as function of luminosity and redshift: Luministy dependence Strong degeneracy of L and z mild evolution at high-z? High-z quasars are X-ray bright? (Kelly et al.) No strong evolution? (Steffen et al.) Faint high-z quasars! Redshift dependence

25 Lineless quasars: radio quiet BL Lac or quasars with no BLR? No emission line, radio-quiet quasars at z>4 ~1% of high-z quasars No obvious low-z counterparts No BL Lac signature A separate population of quasars? Ly α distribution Lineless Quasars: EW(Lyα)<10 Log EW (Ly α) Diamond-Stanic et al Fan et al. 2006

26 Probing the Host Galaxy Assembly Dust torus Spitzer ALMA Cool Dust in host galaxy

27 Sub-mm and Radio Observation of High-z Quasars Probing dust and star formation in the most massive high-z systems Advantage: No AGN contamination Negative K-correction for both continuum and line luminosity at high-z Give measurements to Star formation rate Gas morphology Gas kinematics

28 Sub-mm Observations of High-z Quasars Using IRAM and SCUBA: ~30% of radio-quiet quasars at z>4 detected at 1mm (observed frame) at 1mJy level submm radiation in radio-quiet quasars come from thermal dust with mass ~ 10 8 M sun Among z~6 quasars: 5(+2)/19 detected in submm If dust heating came from starburst star formation rate of Arp M sun /year Support for star formation origin of FIR luminosity: z~6 quasars follow starburst galaxy FIR/radio relation No correlation between FIR and UV Heating source still open question Bertoldi et al.

29 Submm and CO observation of z=6.42 quasar: probing the earliest ISM Strong submm source: Dust T: 50K Dust mass: 7x10 8 M sun Strong CO source (multiple transitions) T kin ~ 100K Gas mass: 2x10 10 M sun n H2 ~ 10 5 Gas/dust, Temp, density typical of local SB Bertoldi et al.

30 [CII] detection of z=6.42 quasar [CII] 158μm line: Brightest ISM line Direct probe of SF region J1148 (z=6.42) Both [CII] and L FIR consistent with the brightest local ULIRGs SFR~ 10 3 M sum Mailino et al. 2005

31 High-resolution CO Observation of z=6.42 Quasar Spatial Distribution Radius ~ 2 kpc Two peaks separated by 1.7 kpc CO brightness similar to typical ULIRG SF core. Velocity Distribution CO line width of 280 km/s Dynamical mass within central 2 kpc: ~ M_sun Total bulge mass ~ M_sun < M-sigma prediction VLA CO 3 2 map 1 kpc BH formed before complete galaxy assembly? Channel Maps Walter et al km/s

32 M-σ relation at high-z Host mass from CO 15 CO detections at z>2 Line width all ~ km/s Taking at face value: Strong evolution of M-σ BH forms early Similar results from HST studies of lensed quasar host (Peng et al.) Caveats: Are luminous quasars biased? Are CO observations biased? Need detailed simulations of dust and gas properties of high-z quasar host galaxies Shields et al. 2006

33 Summary: High-z vs. Low-z Quasars LF and BH mass evolution: Flattening of luminosity/mass functions Billion solar mass BH existed at z~6 Average Eddington ratio might be increasing at high-z Are high-z and low-z quasars accreting differently? Spectral evolution: Little or no evolution in continuum/emission line properties Strong evolution in radio, Dust and X-ray properties might be evolving as well. Approaching the epoch of AGN structure formation? BH/galaxy co-evolution ISM of high-z quasar hosts similar to that of local ULIRGs narrow CO line width Large BH in small hosts at high-z? Wish list: 1. Larger sample and fainter quasars to break degeneracy 2. Better models/observations in dust/gas

34 z=6.42: Dust and Gas detection L_FIR = 1.2e13 L_sun, M_dust =7e8M_sun S_250 = 5.0 +/- 0.6 mjy M(H_2) = 2e10 M_sun GHz CO 3-2 Off channels Rms=60uJy Dust formation: 1.4e9yr (AGB winds) > t_univ (8.7e8yr) => dust formed in high mass stars? => silicate grains? C, O production (3e7 M_sun): few e8 yr => Star formation started early (z = 10)?

35 : Masses M(dust) = 7e8 M_sun M(H_2) = 2e10 M_sun M_dyn (r=2.5kpc) = 5e10 M_sun M_BH = 3e9 M_sun => M_bulge = 1.5e12 M_sun Gas/dust = 30, typical of starburst Dynamical vs. gas mass => baryon dominated? Dynamical vs. bulge mass => M σ breaks-down at high z? [SMBH forms first?]

36 : radio-fir SED Beelen et al. S_1.4= 55 +/- 12 ujy T_D = 50 K Star forming galaxy characteristics: radio-fir SED, Gas/Dust, CO excitation and T_B => Coeval starburst/agn? SFR = 1e3 M_sun/yr Stellar spheroid formation in few e7 yrs = e-folding time for SMBH => Coeval formation of galaxy/smbh at z = 6.4?

37 VLA imaging of CO3-2 at 0.4 and 0.15 resolution rms=50ujy at 47GHz CO extended to NW by 1 (=5.5 kpc) tidal(?) feature Separation = 0.3 = 1.7 kpc T_B = 20K Typical of starburst nuclei Merging galaxies?

38 IRAM Plateau de Bure ν 2 (6-5) (3-2) (7-6) FWHM = 305 km/s z = / T kin =100K, n H2 =10 5 cm -3 Typical of starburst nuclei (eg. NGC253, Arp220)

39 PSS J (z=4.12) CO Einstein ring Modeled by starforming disk with 2kpc radius CO line-width 280km/s BH Mass ~10^9 solar Star formation rate 900 solar mass/year 15 detections of CO at z>2 (5/6 known CO sources at z>4 are quasars) Carilli et al. 2003

40 PSS J (z=4.12) CO Einstein ring Modeled by starforming disk with 2kpc radius CO line-width 280km/s BH Mass ~10^9 solar Star formation rate 900 solar mass/year 15 detections of CO at z>2 (5/6 known CO sources at z>4 are quasars Carilli et al. 2003

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