Radio astronomical probes of Cosmic Reionization and the 1st 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

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

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 = 0.084 +/- 0.016

~ l/mfp ~l ne 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 20-50 GHz + 0.2” resol. mol. gas (low order)

Radio observations of z ~ 6 QSO host galaxies

Why QSOs?

Spectroscopic redshifts

Extreme (massive) systems

MB < -26 =>

Lbol > 1e14 Lo

MBH > 1e9 Mo

Rapidly increasing samples:

z>4: > 1000 known

z>5: > 100

z>6: 20

Fan 05

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)

Magorrian, Tremaine, Gebhardt, Merritt…

• 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?

MAMBO surveys of z>2 QSOs

2.4mJy

Dust => Gas: LFIR 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 Mo) = fuel for star formation

Index=1.5

1e11 Mo

1e3 Mo/yr

z ~ 6 QSO hosts

~ Star formation

~ Gas Mass

• Highest redshift SDSS QSO (tuniv = 0.87Gyr)• Lbol = 1e14 Lo

• Black hole: ~3 x 109 Mo (Willot etal.)• Gunn Peterson trough (Fan etal.)

Pushing into reionization: QSO 1148+52 at z=6.4

1148+52 z=6.42: Dust detection

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 07)?

S250 = 5.0 +/- 0.6 mJy

LFIR = 1.2e13 Lo

Mdust =7e8 Mo

3’

MAMBO 250 GHz

1148+5251

Radio to near-IR SED TD = 50 K

FIR excess = 50K dust

Radio-FIR SED follows star forming galaxy

SFR ~ 3000 Mo/yr

Radio-FIR correlation

Elvis SED

1148+52 z=6.42: Gas detection

Off channelsRms=60uJy

46.6149 GHzCO 3-2

• FWHM = 305 km/s• z = 6.419 +/- 0.001• M(H2) ~ 2e10 Mo

• Mgas/Mdust ~ 30 (~ starburst galaxies)

VLA

IRAM

VLA

Dense, warm gas: CO excitation similar to starburst nucleus

Tkin > 80 K

nH2 ~ 1e5 cm^-3

CO excitation ladder 2

NGC253

MW

J1148+52: VLA imaging of CO3-2

Separation = 0.3” = 1.7 kpc

TB = 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] = 4x109 Lo (L[NII] < 0.1 L[CII])

[CII] similar extension as molecular gas ~ 6kpc => distributed star formation

SFR ~ 6.5e-6 L[CII] ~ 3000 Mo/yr

1”

[CII] + CO 3-2

[CII]

[NII]

IRAM 30m

Gas dynamics: Potential for testing MBH - Mbulge relation at high z -- mm lines are only direct probe of host galaxies

Mdyn~ 4e10 Mo

Mgas~ 2e10 Mo

Mbh ~ 3e9 Mo =>

Mbulge ~1e12 Mo (predicted)

1148+5251 z=6.42

z<0.5

Low z IR QSOs: major mergers AGN+starburst?

Low z Optical QSOs: early-type hosts

Z~6

FIR - Lbol 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 tuniv

< 1Gyr Multi-scale simulation isolating most

massive halo in 3 Gpc^3 (co-mov)

Stellar mass ~ 1e12 Mo forms in series (7) of major, gas rich mergers from z~14, with SFR ~ 1e3 - 1e4 Mo/yr

SMBH of ~ 2e9 Mo forms via Eddington-limited accretion + mergers

Evolves into giant elliptical galaxy in massive cluster (3e15 Mo) by z=0

10.5

8.1

6.5

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 Mo/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+/0.001Ly 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

tqso = 1e5 R^3 f(HI)~ 1e7yrsor

f(HI) ~ 1 (tqso/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: <R> = 4.4 Mpc

GP => f(HI) > 0.001

If f(HI) ~ 0.001, then <tqso> ~ 1e4 yrs – implausibly short given QSO fiducial lifetimes (~1e7 years)?

Probability arguments + size evolution suggest: f(HI) > 0.05

Wyithe et al. 2005

=tqso/4e7 yrs

90% probability x(HI) > curve

P(>xHI)

Fan et al 2006

ESO

OI

Not ‘event’ but complex process, large variance: zreion ~ 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: TK, TCMB, Tspin

)1()10

1)((008.0 2/1 δ +

+= HI

S

CMB fz

TT

1e13 Mo

1e9 Mo

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 + 2004

z=12

9

7.6

TB(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-5 -- 1e-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=12 z=819mJy

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 S151 > 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. 2006

5Mpc

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 + 1982)

Coldest regions: T ~ 100z)^-2.6 K

Highly ‘confused’: 1 source/deg^2 with S140 > 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-5Cygnus A

500MHz 5000MHz

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 + 02

QuickTime™ and aCinepak decompressor

are needed to see this picture.

15’

Challenge III: Interference

100 MHz z=13

200 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^-2

0.01 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

100MHz 200MHz

BEE2: 5 FPGAs, 500 Gops/s

CygA 1e4Jy

PAPER/WA -- 4 Ant, July 2007

RMS ~ 1Jy; DNR ~ 1e4

Parsons et al. 2008

1e4Jy

Radio astronomy probing cosmic reionization

•‘Twilight zone’: obs of 1st luminous sources limited to near-IR to radio wavelengths

• Currently -- pathological systems (‘HLIRGs’): coeval formation SMBH+giant ellipt. in spectacular starburst at tuniv<1Gyr

•EVLA, ALMA 10-100x 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 trecomb < tuniv 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) ~ 2e20TS cm^-2 ?

Building a giant elliptical galaxy + SMBH by z=6.4

Mstars=1e12Mo

MBH = 2e9Mo

• 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!

RAE2 1973

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 to 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 LFIR (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 Ts -- TK due to first luminous objects

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Furlanetto, Oh, Briggs 06