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Radio astronomical probes of Cosmic Reionization and the 1 st luminous objects

Radio astronomical probes of Cosmic Reionization and the 1 st luminous objects Chris Carilli March 19, 2007 University of Colorado. Brief introduction to cosmic reionization

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Radio astronomical probes of Cosmic Reionization and the 1 st luminous objects

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  1. Radio astronomical probes of Cosmic Reionization and the 1st luminous objects Chris Carilli March 19, 2007 University of Colorado • Brief introduction to cosmic reionization • Objects within reionization – recent observations of molecular gas, dust, and star formation, in the host galaxies of the most distant QSOs, and more… • Neutral Intergalactic Medium (IGM) – HI 21cm telescopes, signals, and challenges USA – Carilli, Wang, Fan, Strauss, Gnedin Euro – Walter, Bertoldi, Cox, Menten, Omont

  2. Ionized Neutral Reionized

  3. Chris Carilli (NRAO) Berlin June 29, 2005 WMAP – structure from the big bang

  4. Hubble Space Telescope Realm of the Galaxies

  5. Dark Ages Epoch of Reionization Twilight Zone • Last phase of cosmic evolution to be tested • Bench-mark in cosmic structure formation indicating the first luminous structures

  6. Constraint I: Gunn-Peterson Effect • End of reionization? • f(HI) <1e-4 at z= 5.7 • f(HI) >1e-3 at z= 6.3 Fan et al 2006

  7. Constraint II: CMB large scale polarization -- Thompson scattering during reionization Page + 06; Spergel 06 TT • Scattered CMB quad. => polarized • Horizon scale => 10’s deg • e = 0.09+/-0.03 • z_reion= 11+/3 TE EE

  8. Fan, Carilli, Keating ARAA 06 Gnedin03 8Mpc • Current observations => zreion = 6 to 11 (+/-3)? • Not ‘event’ but complex process, large variance time/space (eg. Shull & Venkatesan 2006)

  9. Limitations of measurements CMB polarization • e = integral measure through universe => allows many reionization scenarios • Still a 3 result (now in EE vs. TE before) Gunn-Peterson effect • Lya to f(HI) conversion requires ‘clumping factor’ (cf. Becker etal 06) • Lya >>1 for f(HI)>0.001 => low f() diagnostic GP => Reionization occurs in ‘twilight zone’, opaque for obs <0.9 m

  10. Radio observations of z ~ 6 QSO host galaxies • IRAM 30m + MAMBO: sub-mJy sens at 250 GHz + wide fields  dust • IRAM PdBI: sub-mJy sens at 90 and 230 GHz +arcsec resol. mol. Gas, C+ • VLA: uJy sens at 1.4 GHz  star formation • VLA: < 0.1 mJy sens at 20-50 GHz + 0.2” resol.  mol. gas (low order)

  11. Magic of (sub)mm: distance independent method of studying objects in universe from z=0.8 to 10 L_FIR ~ 4e12 x S250(mJy) L_sun SFR ~ 1e3 x S250 M_sun/yr FIR = 1.6e12 L_sun

  12. Why QSOs? • Spectroscopic redshifts • Extreme (massive) systems MB < -26 => Lbol> 1e14 Lo MBH > 1e9 Mo • Rapidly increasing samples: z>4: > 1000 known z>5: 80 z>6: 15 Fan 05

  13. Magorrian, Tremaine, Gebhardt, Merritt… QSO host galaxies – MBH -- Mbulge relation • Most (all?) low z spheroidal galaxies have SMBH: MBH=0.002 Mbulge • ‘Causal connection between SMBH and spheroidal galaxy formation’ • Luminous high z QSOs have massive host galaxies (1e12 Mo)

  14. MAMBO surveys of z>2 QSOs 1e13 Lo 2.4mJy • 1/3 of luminous QSOs have S250 > 2 mJy, independent of redshift from z=1.5 to 6.4 • LFIR =1e13 Lo = 0.1 x Lbol: Dust heating by starburst or AGN?

  15. LFIR vs L’(CO) z>2 1000Mo/yr J1148+525 z=6.42 Index=1 1e11 Mo Index=1.7 • M(H_2) = X * L’(CO), X=4 (Milkyway), X=0.8 (ULIRGs) • Telescope time: t(dust) = 1hr, t(CO) = 10hr

  16. Pushing into reionization: QSO 1148+52 at z=6.4 • Highest redshift quasar known (tuniv = 0.87Gyr) • Lbol = 1e14 Lo • Black hole: ~3 x 109 Mo (Willot etal.) • Gunn Peterson trough (Fan etal.)

  17. 1148+52 z=6.42: Dust detection MAMBO 250 GHz 3’ S250 = 5.0 +/- 0.6 mJy LFIR = 1.2e13 Lo Mdust =7e8 Mo Dust formation? • AGB Winds ≥ 1.4e9yr • tuniv = 0.87e9yr => dust formation associated with high mass star formation:Silicate gains (vs. eg. Graphite) formed in core collapse SNe (Maiolino et al 2007)?

  18. 1148+52 z=6.42: Gas detection 46.6149 GHz CO 3-2 Off channels Rms=60uJy VLA IRAM • FWHM = 305 km/s • z = 6.419 +/- 0.001 • M(H2) ~ 2e10 Mo • Mgas/Mdust ~ 30 (~ starburst galaxies) • C, O production (3e7 Mo) => Star formation started early (z > 10)? VLA

  19. 1148+52 CO Excitation 2 • Tk ~ 100K • nH2 ~ 105 cm-3 => Typical of starburst galaxy nucleus (eg. NGC 253)

  20. 1148+5251 Radio-IR SED TD = 50 K Radio-FIR correlation • FIR excess = 50K dust • Radio-FIR SED follows star forming galaxy • SFR ~ 3000 Mo/yr => form large spheroid in dynamical timescale ~ 1e8 yr

  21. [CII] 158um PDR cooling line detected at z=6.4 PdBI Walter et al. 30m 256GHz Maiolino etal 1” 0.3” • Size ~ 0.5” (~ 2.5kpc) • SFR ~ 6.5e-6 L[CII] ~ 3000 Mo/yr • Enriched ISM on kpc scales • L[CII] = 4x109 Lo • L[CII]/LFIR = 3x10-4 ~ ULIRG

  22. J1148+52: VLA imaging of CO3-2 0.4”res rms=50uJy at 47GHz 1” 0.15” res • Separation = 0.3” = 1.7 kpc • TB = 35K => Typical of starburst nuclei • Merging galaxies? CO extended to NW by 1” (=5.5 kpc) tidal(?) feature

  23. Breakdown MBH - Mbulge relation at high z: SMBH forms first? CO FWHM + size: Mdyn ~ 5e10 Mo (Mgas ~ 2e10 Mo) Expected MBH ~ 2e9 Mo =>Mbulge ~ 1.5e12 Mo x 1148+5251

  24. J1148 z=6.4: gas, dust, star formation • FIR excess ~ 1e13Lo, Md~7e8Mo • Giant molecular gas cloud ~ 2e10Mo, size ~ 5.5kpc • Star formation rate ~ 3000 Mo/yr 1. Radio-FIR SED 2. Gas reservoir + Dust/Gas 3. CO excitation, TB 4. [CII]/FIR ~ ULIRG • Merging galaxy: Mdyn (r<2.5kpc) ~ 5e10 Mo • Early enrichment of heavy elements and dust => star formation started tuniv < 0.5 Gyr • Dust formation in massive stars? • Break-down of M- at high z? • ‘Smoking gun’ for coeval formation of massive galaxy + SMBH within 870 Myr of big bang? • Consistent with ‘downsizing’ in massive galaxy and SMBH formation(Heckman etal. 2004; Cowie et al. 1996)

  25. High z submm detected QSOs: Similar to low z IR-selected QSOs = star formation? Z~6 FIR QSOs Z~6 Low z IR QSOs: major mergers AGN+starburst? Low z Optical QSOs: late-type hosts

  26. The ALMA revolution -- observing normal galaxies into cosmic reionization: Panchromatic view of galaxy formation LFIR = 1e11 Lo ALMA reveals the cool universe: dust and gas -- the fundamental fuel for star formation cm: star formation, AGN (sub)mm dust, molecular gas Near-IR: stars, ionized gas, AGN

  27. Cosmic Stromgren Sphere • Accurate redshiftfrom CO: z=6.419+/0.001 Ly a, high ioniz Lines: inaccurate redshifts (z > 0.03) • Proximity effect:photons leaking from 6.32<z<6.419 White et al. 2003 z=6.32 • ‘time bounded’ Stromgren sphere: R = 4.7 Mpc tqso = 1e5 R^3 f(HI)~ 1e7yrs or f(HI) ~ 1 (tqso/1e7 yr)

  28. Loeb & Rybicki 2000

  29. CSS: Constraints on neutral fraction at z~6? • 9 z~6 QSOs with CO or MgII redshifts:<R> = 4.4 Mpc (Wyithe et al. 05; Kurk et al. 07) • GP => f(HI) > 0.001 • If f(HI) ~ 0.001, then <tqso> ~ 1e4 yrs – implausibly short given QSO fiducial lifetimes (~1e7 years)? • Probability arguments suggest: f(HI) > 0.1 P(>x_HI) Wyithe et al. 2005 90% probability x(HI) > curve =tqso/4e7 yrs

  30. Cosmic ‘phase transition’? • CSS (+ Stromgren surfaces) suggest rapid rise in f(HI) around z ~ 6 to 7? • But cf. Maselli 07: f(HI)  R^-3

  31. Studying the pristine neutral IGM using redshifted HI 21cm observations (100 – 200 MHz) • Large scale structure • cosmic density,  • neutral fraction, f(HI) • Temp: TK, TCMB, Tspin

  32. Multiple experiments under-way: ‘pathfinders’ ~1e4 m^2 LOFAR (NL) MWA (MIT/CfA/ANU) SKA 1e6 m^2 21CMA (China)

  33. Signal I: Global (‘all sky’) reionization signature in low frequency HI spectra Gnedin & Shaver 03 140MHz IGM heating: Tspin= TK > TCMB Ly coupling: Tspin=TK < TCMB All sky => Single dipole experiment with (very) carefully controlled systematics (signal <1e-4 sky), eg. EDGES (Rogers & Bowman 07)

  34. Signal II: HI 21cm Tomography of IGM Zaldarriaga + 2003 z=12 9 7.6 • TB(2’) = 10’s mK • SKA rms(100hr) = 4mK • LOFAR rms (1000hr) = 80mK

  35. Signal III: 3D Power spectrum analysis only LOFAR  + f(HI) SKA McQuinn + 06

  36. Signal IV: Cosmic Web after reionization Ly alpha forest at z=3.6 ( < 10) Womble 96 N(HI) = 1e13 – 1e15 cm^-2, f(HI/HII) = 1e-5 -- 1e-6 => Before reionization N(HI) =1e18 – 1e21 cm^-2

  37. Signal IV: Cosmic web before reionization: HI 21Forest 19mJy z=12 z=8 130MHz 159MHz • Perhaps easiest to detect (use long baselines) • Requires radio sources: expect 0.05 to 0.5 deg^-2 at z> 6 with S151 > 6 mJy? • radio G-P (=1%) • 21 Forest (10%) • mini-halos (10%) • primordial disks (100%)

  38. Signal V: Cosmic Stromgren spheres around z > 6 QSOs • LOFAR ‘observation’: • 20xf(HI)mK, 15’,1000km/s • => 0.5 x f(HI) mJy • Pathfinders: Set first hard limits on f(HI) at end of cosmic reionization • Easily rule-out cold IGM (T_s < T_cmb): signal = 360 mK 5Mpc 0.5 mJy Wyithe et al. 2006

  39. Challenge I: Low frequency foreground – hot, confused sky Eberg 408 MHz Image (Haslam + 1982) Coldest regions: T ~ 100 (/200 MHz)^-2.6 K Highly ‘confused’: 1 source/deg^2 with S140 > 1 Jy

  40. Solution: spectral decomposition (eg. Morales, Gnedin…) Freq Signal/Sky ~ 2e-5 Signal 10’ FoV; SKA 1000hrs Foreground Xcorrelation/Power spectral analysis in 3D – different symmetries in freq space

  41. Challenge II: Ionospheric phase errors – varying e- content • TIDs – ‘fuzz-out’ sources • ‘Isoplanatic patch’ = few deg = few km • Phase variation proportional to ^2 • Solution: • Wide field ‘rubber screen’ phase self-calibration 15’ Virgo A VLA 74 MHz Lane + 02

  42. Challenge III: Interference 100 MHz z=13 200 MHz z=6 • Solutions -- RFI Mitigation (Ellingson06) • Digital filtering • Beam nulling • Real-time ‘reference beam’ • LOCATION!

  43. VLA-VHF: 180 – 200 MHz Prime focus X-dipole Greenhill, Blundell (SAO Rx lab); Carilli, Perley (NRAO) Leverage: existing telescopes, IF, correlator, operations • $110K D+D/construction (CfA) • First light: Feb 16, 05 • Four element interferometry: May 05 • First limits: Winter 06/07

  44. Project abandoned: Digital TV KNMD Ch 9 150W at 100km

  45. RFI mitigation: location, location location… 100 people km^-2 1 km^-2 0.01 km^-2 (Briggs 2005)

  46. Destination: Moon! RAE2 1973

  47. Focus: Reionization (power spec,CSS,abs) • Very wide field: 2x2 tile(?) • Correlator: FPGA-based from Berkeley wireless lab • Staged engineering approach: GB05 8 stations  Boolardy07 16 stations

  48. PAPER: First images/spectra Cas A 1e4Jy 180MHz 140MHz Cygnus A 1e4Jy CygA 1e4Jy 3C348 400Jy 3C392 200Jy

  49. GMRT 230 MHz – HI 21cm abs toward highest z radio galaxy and QSO (z~5.2) RFI = 20 kiloJy ! 232MHz 30mJy 229Mhz0.5 Jy rms(40km/s) = 3mJy rms(20km/s) = 5 mJy N(HI) ~ 2e20TS cm^-2 ?

  50. Radio astronomy probing cosmic reionization • ‘Twilight zone’: obs of 1st luminous sources limited to near-IR to radio wavelengths • Currently limited to pathological systems (‘HLIRGs’) • EVLA, ALMA 10-100x sensitivity is critical to study normal galaxies • Low freq pathfinders: HI 21cm signatures of neutral IGM • SKA: imaging of IGM

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