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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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slide1
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

slide2
Ionized

Neutral

Reionized

slide3
Chris Carilli (NRAO)

Berlin June 29, 2005

WMAP – structure from the big bang

slide5
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

slide6
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

slide7
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

slide8
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)
slide9
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

slide10
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)
slide11
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

slide12
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

slide13
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)
slide14
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?
slide15
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
slide16
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.)
slide17
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)?

slide18
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

slide19
1148+52

CO Excitation

2

  • Tk ~ 100K
  • nH2 ~ 105 cm-3

=> Typical of starburst galaxy nucleus (eg. NGC 253)

slide20
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
slide21
[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
slide22
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

slide23
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

slide24
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)
slide25
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

slide26
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

slide27
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

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)

slide29
CSS: Constraints on neutral fraction at z~6?
  • 9 z~6 QSOs with CO or MgII redshifts: = 4.4 Mpc (Wyithe et al. 05; Kurk et al. 07)
  • GP => f(HI) > 0.001
  • If f(HI) ~ 0.001, then ~ 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

slide30
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
slide31
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
slide32
Multiple experiments under-way: ‘pathfinders’ ~1e4 m^2

LOFAR (NL)

MWA (MIT/CfA/ANU)

SKA 1e6 m^2

21CMA (China)

slide33
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)

slide34
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
slide35
Signal III: 3D Power spectrum analysis

only

LOFAR

 + f(HI)

SKA

McQuinn + 06

slide36
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

slide37
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%)
slide38
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

slide39
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

slide40
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

slide41
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

slide42
Challenge III: Interference

100 MHz z=13

200 MHz z=6

  • Solutions -- RFI Mitigation (Ellingson06)
  • Digital filtering
  • Beam nulling
  • Real-time ‘reference beam’
  • LOCATION!
slide43
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
slide44
Project abandoned: Digital TV

KNMD Ch 9

150W at 100km

slide45
RFI mitigation: location, location location…

100 people km^-2

1 km^-2

0.01 km^-2

(Briggs 2005)

slide47
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
slide48
PAPER: First images/spectra

Cas A 1e4Jy

180MHz

140MHz

Cygnus A

1e4Jy

CygA 1e4Jy

3C348 400Jy

3C392

200Jy

slide49
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 ?

slide50
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
slide52
ALMA first fringes (Emerson +)

ATF, Socorro NM

Saturn 90 GHz March 2, 2007

Using all ALMA electronics

slide53
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

slide56
Signal VI: pre-reionization HI signal

eg. Baryon Oscillations (Barkana & Loeb)

  • Very difficult to detect !
  • z=50 => n = 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

slide57
HCN emission: Dense gas directly associated with star formation

n(H2) > 1e5 cm^-3 (vs. CO: n(H2) > 1e3 cm^-3)

z>2

J1148+52

Solomon et al

z=2.58

70 uJy

index=1

slide58
Line sensitivity

High order, fine structure lines

Low order

slide60
The ALMA revolution
  • Spectral simulation of J1148+5251
  • Detect dust emission in 1sec at 250GHz
  • Detect multiple lines, molecules per band => detailed astrochemistry
  • Image dust and gas at sub-kpc resolution – gas dynamics++

CO

HCO+

HCN

CCH

  • Studying 1st galaxies
  • Detect ‘normal’ (eg. Ly), star forming galaxies at z>6 in few hours
  • Determine redshifts directly from mm spectroscopy for dusty systems

z=6.55

SFR~10Mo/yr

slide61
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?

slide62
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.

slide63
[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!
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