Radio astronomical probes of Cosmic Reionization and the 1 st luminous objects Chris Carilli, NRL, April 2008  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: early massive galaxy and SMBH formation  Neutral Intergalactic Medium (IGM) – HI 21cm telescopes, signals, and challenges USA – Carilli, Wang, Wagg, Fan, Strauss Euro – Walter, Bertoldi, Cox, Menten, Neri, 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 Cosmic Reionization Last phase of cosmic evolution to be tested Bench-mark in cosmic structure formation indicating the first luminous structures

Barkana and Loeb 2001 Constraint I: Gunn-Peterson Effect z

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

Constraint II: CMB large scale polarization -- Thomson scattering during reionization   Scattering CMB local quadrapole => polarized   Large scale: horizon scale at reioniz ~ 10’s deg  Signal is weak: TE ~ 10% TT EE ~ 1% TT  e = / ~ l /mfp ~ l n e  e  (1+z)^2 Hinshaw et al 2008

Constraint II: CMB large scale polarization -- Thomson scattering during reionization   Rules-out high ionization fraction at z> 15  Allows for finite (~0.2) ionization to high z  Most action occurs at z ~ 8 to 14 Dunkley et al. 2008

 GP => pushing into near-edge of reionization at z ~ 6  CMB pol => substantial ionization fraction persists to z ~ 11 Fan, Carilli, Keating ARAA 06 GP => First light 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

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: > 100 z>6: 20 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 2.4mJy

Dust => Gas: L FIR vs L’(CO)  non-linear => increasing SF eff (SFR/Gas mass) with increasing SFR  FIR-luminous high z QSO hosts have massive gas reservoirs (>1e10 M o ) = fuel for star formation Index=1.5 1e11 M o 1e3 M o /yr z ~ 6 QSO hosts ~ Star formation ~ Gas Mass

Highest redshift SDSS QSO (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

Radio to near- 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

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) VLA IRAM VLA

Dense, warm gas: CO excitation similar to starburst nucleus T kin > 80 K n H2 ~ 1e5 cm^-3 CO excitation ladder 2 NGC253 MW

J : VLA imaging of CO3-2  Separation = 0.3” = 1.7 kpc  T B = 35K => Typical of starburst nuclei, but scale is 10x larger rms=50uJy at 47GHz CO extended to NW by 1” (=5.5 kpc) 1” 0.4”res 0.15” res

[CII] traces PDRs associated with star formation [CII] 158um fine structure line: dominant ISM gas cooling line

[CII] 158um at z=6.4 [CII] PdBI Walter et al.  z>4 => FS lines redshift to mm band  L [CII] = 4x10 9 L o (L [NII] < 0.1 L [CII] )  [CII] similar extension as molecular gas ~ 6kpc => distributed star formation  SFR ~ 6.5e-6 L [CII] ~ 3000 M o /yr 1” [CII] + CO 3-2 [CII] [NII] IRAM 30m

Gas dynamics: Potential for testing M BH - M bulge relation at high z -- mm lines are only direct probe of host galaxies M dyn ~ 4e10 M o M gas ~ 2e10 M o M bh ~ 3e9 M o => M bulge ~1e12 M o (predicted) z=6.42 z<0.5

Low z IR QSOs: major mergers AGN+starburst? Low z Optical QSOs: early- type hosts Z~6 FIR - L bol in QSO hosts FIR luminous z ~ 6 QSO hosts follow relation establish by IR- selected QSOs at low z => (very) active star forming host galaxies? Wang + 08, Hao 07

Downsizing: Building a giant elliptical galaxy + SMBH at t univ < 1Gyr  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  Evolves into giant elliptical galaxy in massive cluster (3e15 M o ) by z= Li, Hernquist, Roberston.. z=10 Rapid enrichment of metals, dust, molecules Rare, extreme mass objects: ~ 100 SDSS z~6 QSOs on entire sky Integration times of hours to days to detect HyLIGRs

(sub)mm: high order molecular lines. fine structure lines -- ISM physics, dynamics cm telescopes: low order molecular transitions -- total gas mass, dense gas tracers The need for collecting area: lines  FS lines will be workhorse lines in the study of the first galaxies with ALMA.  Study of molecular gas in first galaxies will be done primarily with cm telescopes SMA ALMA will detect dust, molecular and FS lines in ~ 1 hr in ‘normal’ galaxies (SFR ~ 10 M o /yr = LBGs, LAEs) at z ~ 6, and derive z directly from mm lines., GBT

cm: Star formation, AGN (sub)mm Dust, molecular gas Near-IR: Stars, ionized gas, AGN Arp 220 vs z The need for collecting area: continuum A Panchromatic view of galaxy formation SMA

Cosmic Stromgren Sphere Accurate host 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  GP => f(HI) >  If f(HI) ~ 0.001, then ~ 1e4 yrs – implausibly short given QSO fiducial lifetimes (~1e7 years)?  Probability arguments + size evolution suggest: f(HI) > 0.05 Wyithe et al =t qso /4e7 yrs 90% probability x(HI) > curve P(>x HI ) Fan et al 2006

ESO OI  Not ‘event’ but complex process, large variance: z reion ~ 14 to 6  Good evidence for qualitative change in nature of IGM at z~6 Fan, Carilli, Keating ARAA 2006

ESO OI Saturates, HI distribution function, pre-ionization? Abundance? 3 , integral measure? Local ionization? Geometry, pre- reionization?  Current probes are all fundamentally limited in diagnostic power  Need more direct probe of process of reionization Local ioniz.?

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

Experiments under-way: pathfinders 1% to 10% SKA MWA (MIT/CfA/ANU) LOFAR (NL) 21CMA (China) SKA

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

Signal II: 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  Lya ~ 1e7  21cm => neutral IGM opaque to Lya, but translucent to 21cm Signal III: 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 III: Cosmic web before reionization: HI 21Forest Perhaps easiest to detect Only probe of small scale structure Requires radio sources: expect 0.05 to 0.5 deg^-2 at z> 6 with S 151 > 6 mJy? 159MHz

Signal IV: 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 Wyithe et al Mpc Prediction: first detection of HI 21cm signal from reionization will be via imaging rare, largest CSS, or absorption toward radio galaxy.

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 = non-thermal = featureless over ~ 100’s MHz  Signal = fine scale structure on scales ~ few MHz 10’ FoV; SKA 1000hrs Signal/Sky ~ 2e-5 Cygnus A 500MHz5000MHz  Simply remove low order polynomial or other smooth function  Xcorr/power spectral analysis in 3D – different symmetries in freq

 TIDs – ‘fuzz-out’ sources  ‘Isoplanatic patch’ = few deg = few km  Phase variation proportional to ^2 Solution:  Reionization requires only short baselines (< 1km)  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 Chippendale & Beresford 2007

Focus: Reionization (power spec,CSS,abs) Very wide field: 30deg Correlator: FPGA-based from Berkeley wireless lab Staged engineering approach: GB05 8 stations  Boolardy08 32 stations C.Carilli, A. Datta (NRAO/SOC), J. Aguirre (U.Penn)

PAPER: Staged Engineering Broad band sleeve dipole + flaps 8 dipole test array in GB (06/07) => 32 station array in WA (2008) to 256 (2009) FPGA-based ‘pocket correlator’ from Berkeley wireless lab S/W Imaging, calibration, PS analysis: AIPY + Miriad/AIPS => Python + CASA, including ionospheric ‘peeling’ calibration 100MHz200MHz BEE2: 5 FPGAs, 500 Gops/s

CygA 1e4Jy PAPER/WA -- 4 Ant, July 2007 RMS ~ 1Jy; DNR ~ 1e4 Parsons et al e4Jy

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

END

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.

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 ?

Building a giant elliptical galaxy + SMBH by z=6.4 M stars =1e12M o M BH = 2e9M o Enrichment of heavy elements, dust starts early (z > 8) Rare, extreme mass objects: ~ 100 SDSS z~6 QSOs on entire sky Integration times of hours to days to detect HyLIGRs

Destination: Moon! RAE  No interference  No ionosphere  Only place to study PGM  Recognized as top astronomy priority for NASA initiative to return Man to Moon (Livio 2007)  NASA concept study: DALI/LAMA (NRL + MIT ++)

Limitations of measurements CMB polarization  e = integral measure through universe => allows many reionization scenarios Difficult measurement (10’s degrees, uK) result 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 => First light occurs in ‘twilight zone’, opaque for obs <0.9  m

[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! J1623

Signal I: Global (‘all sky’) reionization signature Signal ~ 20mK < 1e-4 sky Possible higher z absorption signal via Lya coupling of T s -- T K due to first luminous objects Feedback in Galaxy formation No Feedback Furlanetto, Oh, Briggs 06