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Radio astronomical probes of Cosmic Reionization and the 1 st luminous objects Chris Carilli, NRL, April 2008. Brief introduction to cosmic reionization

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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



Dark Ages

  • Last phase of cosmic evolution to be tested

  • Bench-mark in cosmic

    structure formation

    indicating the first

    luminous structures

Cosmic Reionization


Constraint I: Gunn-Peterson Effect

z

Barkana and Loeb 2001


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


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

Hinshaw et al 2008

e = 0.084 +/- 0.016

~ l/mfp ~l nee(1+z)^2


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


Fan, Carilli, Keating ARAA 06 scattering during reionization

GP => First light occurs in ‘twilight zone’, opaque for obs <0.9 m

  • GP => pushing into near-edge of reionization at z ~ 6

  • CMB pol => substantial ionization fraction persists to z ~ 11


Radio observations of z ~ 6 QSO host galaxies scattering during reionization

  • 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)


Why QSOs? scattering during reionization

  • 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


Magorrian, Tremaine, Gebhardt, Merritt… scattering during reionization

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)


MAMBO surveys of z>2 QSOs scattering during reionization

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?


Dust => Gas: L scattering during reionizationFIR vs L’(CO)

z ~ 6 QSO hosts

~ Star formation

1e3 Mo/yr

Index=1.5

1e11 Mo

~ Gas Mass

  • 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


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

  • Highest redshift SDSS QSO (tuniv = 0.87Gyr)

  • Lbol = 1e14 Lo

  • Black hole: ~3 x 109 Mo (Willot etal.)

  • Gunn Peterson trough (Fan etal.)


1148+52 z=6.42: Dust detection scattering during reionization

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 07)?


1148+5251 scattering during reionization

Radio to near-IR SED

TD = 50 K

Elvis SED

Radio-FIR correlation

  • FIR excess = 50K dust

  • Radio-FIR SED follows star forming galaxy

  • SFR ~ 3000 Mo/yr


1148+52 z=6.42: Gas detection scattering during reionization

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)

VLA


CO excitation ladder scattering during reionization

2

NGC253

Dense, warm gas: CO excitation similar to starburst nucleus

Tkin > 80 K

nH2 ~ 1e5 cm^-3

MW


J1148+52: VLA imaging of CO3-2 scattering during reionization

0.4”res

rms=50uJy at 47GHz

1”

0.15” res

  • Separation = 0.3” = 1.7 kpc

  • TB = 35K => Typical of starburst nuclei, but scale is 10x larger

CO extended to NW by 1” (=5.5 kpc)


[CII] 158um fine structure line: dominant ISM gas cooling line

[CII] traces PDRs associated with star formation


[CII] 158um at z=6.4 line

  • 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

IRAM 30m

[CII]

[NII]

1”

[CII] PdBI Walter et al.

[CII] + CO 3-2


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

Mdyn~ 4e10Mo

Mgas~ 2e10 Mo

Mbh ~ 3e9 Mo =>

Mbulge ~1e12 Mo (predicted)

1148+5251 z=6.42

z<0.5


FIR - L linebol in QSO hosts

Z~6

Low z IR QSOs: major mergers AGN+starburst?

Low z Optical QSOs: early-type hosts

Wang + 08, Hao 07

FIR luminous z ~ 6 QSO hosts follow relation establish by IR-selected QSOs at low z => (very) active star forming host galaxies?


Downsizing: Building a giant elliptical galaxy + SMBH at t lineuniv < 1Gyr

z=10

10.5

Li, Hernquist, Roberston..

  • Multi-scale simulation isolating most massive halo in 3Gpc^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

8.1

6.5

  • 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


SMA line

The need for collecting area: lines

cm telescopes: low order molecular transitions -- total gas mass, dense gas tracers

, GBT

(sub)mm: high order molecular lines. fine structure lines -- ISM physics, dynamics

  • 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

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.


The need for collecting area: continuum line

A Panchromatic view of galaxy formation

Arp 220 vs z

SMA

cm: Star formation, AGN

(sub)mm Dust, molecular gas

Near-IR: Stars, ionized gas, AGN


Cosmic Stromgren Sphere line

  • Accurate host 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)



CSS: Constraints on neutral fraction at z~6 line

  • 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

Fan et al 2006

P(>xHI)

90% probability

x(HI) > curve

=tqso/4e7 yrs


OI line

Fan, Carilli, Keating ARAA 2006

  • Not ‘event’ but complex process, large variance: zreion ~ 14 to 6

  • Good evidence for qualitative change in nature of IGM at z~6

ESO


3 line, integral measure?

Geometry, pre-reionization?

Local ionization?

OI

Abundance?

Saturates, HI distribution function, pre-ionization?

Local ioniz.?

  • Current probes are all fundamentally limited in diagnostic power

  • Need more direct probe of process of reionization

ESO


Studying the pristine neutral IGM using redshifted HI 21cm observations (100 – 200 MHz)

1e13 Mo

  • Large scale structure

  • cosmic density, 

  • neutral fraction, f(HI)

  • Temp: TK, TCMB, Tspin

1e9 Mo


Experiments under-way: pathfinders 1% to 10% SKA observations (100 – 200 MHz)

LOFAR (NL)

MWA (MIT/CfA/ANU)

SKA

21CMA (China)


Signal I: observations (100 – 200 MHz) HI 21cm Tomography of IGM Furlanetto, Zaldarriaga + 2004

z=12

9

  • TB(2’) = 10’s mK

  • SKA rms(100hr) = 4mK

  • LOFAR rms (1000hr) = 80mK

7.6


Signal II: observations (100 – 200 MHz) 3D Power spectrum analysis

only

LOFAR

 + f(HI)

SKA

McQuinn + 06


Signal III observations (100 – 200 MHz): 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

  • Lya ~ 1e7 21cm => neutral IGM opaque to Lya, but translucent to 21cm


Signal III: observations (100 – 200 MHz) Cosmic web before reionization: HI 21Forest

19mJy

z=12

z=8

130MHz

159MHz

  • 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?

  • radio G-P (=1%)

  • 21 Forest (10%)

  • mini-halos (10%)

  • primordial disks (100%)


Signal IV: observations (100 – 200 MHz) 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

5Mpc

Wyithe et al. 2006

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

0.5 mJy


Challenge I: observations (100 – 200 MHz) 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


  • Solution: spectral decomposition observations (100 – 200 MHz)(eg. Morales, Gnedin…)

  • Foreground = non-thermal = featureless over ~ 100’s MHz

  • Signal = fine scale structure on scales ~ few MHz

Signal/Sky ~ 2e-5

10’ FoV; SKA 1000hrs

Cygnus A

500MHz

5000MHz

  • Simply remove low order polynomial or other smooth function

  • Xcorr/power spectral analysis in 3D – different symmetries in freq


Challenge II: observations (100 – 200 MHz) Ionospheric phase errors – varying e- content

  • 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

15’

Virgo A VLA 74 MHz Lane + 02


Challenge III: observations (100 – 200 MHz) 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 observations (100 – 200 MHz)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 observations (100 – 200 MHz)

KNMD Ch 9

150W at 100km


RFI mitigation: location, location location… observations (100 – 200 MHz)

100 people km^-2

1 km^-2

0.01 km^-2

Chippendale & Beresford 2007


C.Carilli, A. Datta (NRAO/SOC), J. Aguirre (U.Penn) observations (100 – 200 MHz)

  • 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


PAPER: Staged Engineering observations (100 – 200 MHz)

  • 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


PAPER/WA -- 4 Ant, July 2007 observations (100 – 200 MHz)

RMS ~ 1Jy; DNR ~ 1e4

1e4Jy

Parsons et al. 2008

CygA 1e4Jy


Radio astronomy probing cosmic reionization observations (100 – 200 MHz)

  • ‘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 observations (100 – 200 MHz)


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 and 6.3 GRB =>

  • 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)

RFI = 20 kiloJy !

232MHz 30mJy

229Mhz0.5 Jy

rms(40km/s) = 3mJy

rms(20km/s) = 5 mJy

N(HI) ~ 2e20TS cm^-2 ?


Building a giant elliptical galaxy + SMBH by z=6.4 and QSO (z~5.2)

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! and QSO (z~5.2)

  • No interference

  • No ionosphere

  • Only place to study PGM

RAE2 1973

  • 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 and QSO (z~5.2)

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 and QSO (z~5.2)

  • [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: and QSO (z~5.2) Global (‘all sky’) reionization signature

Signal ~ 20mK < 1e-4 sky

Feedback in Galaxy formation

No Feedback

Possible higher z absorption signal via Lya coupling of Ts -- TK due to first luminous objects

Furlanetto, Oh, Briggs 06


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