Radio astronomical probes of Cosmic Reionization and the 1 st luminous objects Chris Carilli April 3, 2007 MIT  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

Ionized Neutral Reionized

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

Hubble Space Telescope Realm of the Galaxies

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

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

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

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

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 t o 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

 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 GHz + 0.2” resol.  mol. gas (low order) Radio observations of z ~ 6 QSO host galaxies

Magic of (sub)mm: distance independent method of studying objects in universe from z=0.8 to 10 L _FIR ~ 4e12 x S 250 (mJy) L _sun SFR ~ 1e3 x S 250 M _sun /yr FIR = 1.6e12 L _sun obs = 250 GHz

Why QSOs?  Spectroscopic redshifts  Extreme (massive) systems M B L bol > 1e14 L o M BH > 1e9 M o  Rapidly increasing samples: z>4: > 1000 known z>5: 80 z>6: 15 Fan 05

QSO host galaxies – M BH -- M bulge relation  Most (all?) low z spheroidal galaxies have SMBH: M BH =0.002 M bulge  ‘Causal connection between SMBH and spheroidal galaxy formation’  Luminous high z QSOs have massive host galaxies (1e12 M o ) Magorrian, Tremaine, Gebhardt, Merritt…

1/3 of luminous QSOs have S 250 > 2 mJy, independent of redshift from z=1.5 to 6.4 L FIR =1e13 L o = 0.1 x L bol : Dust heating by starburst or AGN? MAMBO surveys of z>2 QSOs 1e13 L o 2.4mJy J

Highest redshift quasar known (t univ = 0.87Gyr) L bol = 1e14 L o Black hole: ~3 x 10 9 M o ( Willot etal. ) Gunn Peterson trough (Fan etal.) Pushing into reionization: QSO at z=6.4

z=6.42: Dust detection Dust formation? AGB Winds ≥ 1.4e9yr t univ = 0.87e9yr => dust formation associated with high mass star formation: Silicate gains (vs. eg. Graphite) formed in core collapse SNe (Maiolino 07)? S 250 = 5.0 +/- 0.6 mJy L FIR = 1.2e13 L o M dust =7e8 M o 3’ MAMBO 250 GHz

z=6.42: Gas detection Off channels Rms=60uJy GHz CO 3-2 FWHM = 305 km/s z = / M(H 2 ) ~ 2e10 M o M gas /M dust ~ 30 (~ starburst galaxies) C, O production (~1e8 M o ) => Star formation started early (z > 8)? VLA IRAM VLA

 T k ~ 100K n H2 ~ 10 5 cm -3 => Typical of starburst galaxy nucleus CO Excitation

J : VLA imaging of CO3-2  Separation = 0.3” = 1.7 kpc  T B = 35K => Typical of starburst nuclei  Merging galaxies? rms=50uJy at 47GHz CO extended to NW by 1” (=5.5 kpc) tidal(?) feature 1” 0.4”res 0.15” res

Testing M BH - M bulge relation at high z CO FWHM + size => M dyn ~ 2e10/(sin  )^2 M o M gas ~ 2e10 M o M bulge ~1e12 M o (predicted)

Radio-IR SED T D = 50 K  FIR excess = 50K dust  Radio-FIR SED follows star forming galaxy  SFR ~ 3000 M o /yr Radio-FIR correlation Elvis SED

[CII] 158um PDR cooling line detected at z=6.4 30m 256GHz Maiolino etal PdBI  L [CII] = 4x10 9 L o  L [CII] /L FIR = 3x10 -4 ~ ULIRG  SFR ~ 6.5e-6 L [CII] ~ 3000 M o /yr  Size ~ 0.5” (~ 2.5kpc)  Enriched ISM on kpc scales 0.3”

SDSS J z=5.8  FIR-luminous QSO host + ‘submm galaxy’ companion  separation = 87kpc  Biased massive galaxy formation at early times? 10” SharkII CSO 850GHz rms= 6mJy L FIR ~ 1e13 L o SFR ~ 2500 M o /yr Radio-FIR correlation Chance projection < 1%

FIR-luminous z~6 QSOs: SFR ~ few e3 M o /yr => form large spheroid in dynamical timescale ~ 1e8 yr Coeval formation of massive galaxy + SMBH within 1 Gyr of big bang? Low z IR QSOs: major mergers AGN+starburst? Low z Optical QSOs: early- type hosts Z~6

Building a giant elliptical galaxy + SMBH by z=6.5  Multi-scale simulation isolating most massive halo in 3 Gpc^3 (co-mov)  Stellar mass ~ 1e12 M o forms in series (7) of major, gas rich mergers from z~14, with SFR ~ 1e3 - 1e4 M o /yr  SMBH of ~ 2e9 M o forms via Eddington-limited accretion + mergers  BH feedback regulates star formation  ISM abundance quickly evolves to solar  Evolves into giant elliptical galaxy in massive cluster (3e15 M o ) by z= M stars =1e12M o M BH = 2e9M o Li, Hernquist, Roberston..

Panchromatic view of galaxy formation: 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 The ALMA revolution -- observing normal galaxies into cosmic reionization L FIR = 1e11 L o

Cosmic Stromgren Sphere Accurate redshift from 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 z=6.32 ‘time bounded’ Stromgren sphere: R = 4.7 Mpc t qso = 1e5 R^3 f(HI)~ 1e7yrs or f(HI) ~ 1 (t qso /1e7 yr) White et al. 2003

Loeb & Rybicki 2000

CSS: Constraints on neutral fraction at z~6?  Nine z~6 QSOs with CO or MgII redshifts: = 4.4 Mpc (Wyithe et al. 05; Fan et al. 06; Kurk et al. 07)  GP => f(HI) >  If f(HI) ~ 0.001, then ~ 1e4 yrs – implausibly short given QSO fiducial lifetimes (~1e7 years)?  Probability arguments suggest: f(HI) > 0.1 Wyithe et al =t qso /4e7 yrs 90% probability x(HI) > curve P(>x _HI )

 CSS => rapid rise in f(HI) around z ~ 6 to 7  Many difficulties (Lidz + 07, Maselli + 07) * f(HI)  R^-3 * pre-QSO reionization => clumpy IGM/ragged edges Cosmic ‘phase transition’?

Studying the pristine neutral IGM using redshifted HI 21cm observations (100 – 200 MHz) Large scale structure  cosmic density,   neutral fraction, f(HI)  Temp: T K, T CMB, T spin 1e13 M o 1e9 M o

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

Signal I: Global (‘all sky’) reionization signature in low frequency HI spectra Ly  coupling: T spin =T K < T CMB IGM heating: T spin = T K > T CMB Gnedin & Shaver 03 All sky => Single dipole experiment with (very) carefully controlled systematics (signal <1e-4 sky), eg. EDGES (Rogers & Bowman 07) 140MHz

Signal II: HI 21cm Tomography of IGM Zaldarriaga z=   T B (2’) = 10’s mK  SKA rms(100hr) = 4mK  LOFAR rms (1000hr) = 80mK

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

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

z=12z=8 19mJy 130MHz radio G-P (  =1%) 21 Forest (10%) mini-halos (10%) primordial disks (100%) Signal IV: Cosmic web before reionization: HI 21Forest Perhaps easiest to detect (use long baselines) Requires radio sources: expect 0.05 to 0.5 deg^-2 at z> 6 with S 151 > 6 mJy? 159MHz

Signal V: Cosmic Stromgren spheres around z > 6 QSOs 0.5 mJy  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 Wyithe et al Mpc

Challenge I: Low frequency foreground – hot, confused sky Eberg 408 MHz Image (Haslam ) Coldest regions: T ~ 100  z)^-2.6 K Highly ‘confused’: 1 source/deg^2 with S 140 > 1 Jy

Solution: spectral decomposition (eg. Morales, Gnedin…)  Foreground = power-law or gently curving over ~ 100 MHz  Signal = fine scale structure on scales ~ few MHz 10’ FoV; SKA 1000hrs Xcorrelation/Power spectral analysis in 3D – different symmetries in freq space Freq Signal Foreground Signal/Sky ~ 2e-5

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

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

VLA-VHF: 180 – 200 MHz Prime focus X-dipole Greenhill, Blundell (SAO); 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

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

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

Destination: Moon! RAE  No interference  No ionosphere (?)

GMRT 230 MHz – HI 21cm abs toward highest z radio galaxy and QSO (z~5.2) rms(20km/s) = 5 mJy 229Mhz 0.5 Jy RFI = 20 kiloJy ! 232MHz 30mJy rms(40km/s) = 3mJy N(HI) ~ 2e20T S cm^-2 ?

Radio astronomy probing cosmic reionization ‘Twilight zone’: obs of 1 st luminous sources limited to near-IR to radio wavelengths Currently -- pathological systems (‘HLIRGs’): coeval formation SMBH+giant ellipt. in spectacular starburst at t univ <1Gyr EVLA, ALMA x sensitivity is critical to study normal galaxies Low freq pathfinders: HI 21cm signatures of neutral IGM SKA: imaging of IGM

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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

PAPER: First images/spectra Cygnus A 1e4Jy Cas A 1e4Jy 3C Jy 3C Jy 140MHz 180MHz CygA 1e4Jy

ALMA first fringes (Emerson +) ATF, Socorro NM Saturn 90 GHz March 2, 2007 Using all ALMA electronics

ALMA Status Antennas, receivers, correlator all fully prototyped and evaluated: best mm receivers and antennas ever! Site construction well under way: Observation Support Facility and Array Operations Site North American ALMA Science Center (C’Ville): gearing up for science commissioning and operations (successful international operations review Feb 2007) Timeline: Q1 2007: First fringes at ATF (Socorro) Q1 2009: Three antenna array at AOS Q3 2010: Start early science (16 antennas) Q4 2012: Full operations

Signal VI: pre-reionization HI signal eg. Baryon Oscillations (Barkana & Loeb) Very difficult to detect !  z=50 => = 30 MHz  Signal: 30 arcmin, 50 mk => S _30MHz = 0.1 mJy  SKA sens in 1000hrs: T _fg = 20000K => rms = 0.2 mJy z=50 z=150

HCN emission: Dense gas directly associated with star formation n(H 2 ) > 1e5 cm^-3 (vs. CO: n(H 2 ) > 1e3 cm^-3) z=2.58 Solomon et al index=1 70 uJy J z>2

Stratta, Maiolino et al. 2006: extinction toward z=6.2 QSO and 6.3 GRB => Silicate + amorphous Carbon dust grains (vs. eg. Graphite) formed in core collapse SNe?

Sources responsible for reionization  Luminous AGN: No  Star forming galaxies: maybe -- dwarf galaxies (Bowens05; Yan04)?  mini-QSOs -- unlikely (soft Xray BG; Dijkstra04)  Decaying sterile neutrinos -- unlikely (various BGs; Mapelli05)  Pop III stars z>10? midIR BG (Kashlinsky05), but t recomb < t univ at z~10 GP => Reionization occurs in ‘twilight zone’, opaque for obs <0.9  m Needed for reion.

[CII] -- the good and the bad  [CII]/FIR decreases rapidly with L FIR (lower heating efficiency due to charged dust grains?) => luminous starbursts are still difficult to detect in C+  Normal star forming galaxies (eg. LAEs) are not much harder to detect!

J1148 z=6.4: gas, dust, star formation FIR excess ~ 1e13L o, M d ~7e8M o Giant molecular gas cloud ~ 2e10M o, size ~ 5.5kpc Star formation rate ~ 3000 M o /yr 1. Radio-FIR SED 2. Gas reservoir + Dust/Gas 3. CO excitation, T B 4. [CII]/FIR ~ ULIRG Merging galaxy: M dyn (r<2.5kpc) ~ 5e10 M o Early enrichment of heavy elements and dust => star formation started t univ < 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)

L FIR vs L’(CO)  M(H_2) = X * L’(CO), X=4 (Milkyway), X=0.8 (ULIRGs)  Telescope time: t(dust) = 1hr, t(CO) = 10hr Index=1.7 Index=1 1e11 M o z>2 J z= M o /yr