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Recent Results on Reionization Chris Carilli (NRAO) Dakota/Berkeley,August 2011. CO intensity mapping during reionization: signal in 3 easy steps Recent results on f(HI) at z > 6 Gunn-Peterson overview Quasar near zones: a new tool J1120+0641 quasar at z=7.1: the Game Changer

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slide1

Recent Results on Reionization

Chris Carilli (NRAO)

Dakota/Berkeley,August 2011

  • CO intensity mapping during reionization: signal in 3 easy steps
  • Recent results on f(HI) at z > 6
    • Gunn-Peterson overview
    • Quasar near zones: a new tool
    • J1120+0641 quasar at z=7.1: the Game Changer
    • [Lya emission from z=7 LBGs: also in the Game]

ESO

slide2

Predicted mean CO brightness temperature in 3 simple steps

  • Cosmic star formation rate density required to reionize the IGM using mean baryon density (Haardt & Madau, Bunker et al.)
    • fescuv = ionizing photon escape fraction ~ 0.06 (MW), up to 0.2 for z~3 LBGs
    • C = IGM clumping factor (recombinations) = 5 to 30 (simulations)
    • Strong increase with z due to increase in mean cosmic baryon density
  • 2. Conversion of star formation rate to IR luminosity based on known properties of galaxies (eg. Kennicutt 1998 and many others)
slide3

3. Conversion of IR luminosity to CO luminosity based on known properties of galaxies (‘K-S law’; Daddi et al. 2010)

  • Roughly linear relationship between L’CO and LFIR for disk galaxies at low and high z
  • Similar slope for merger driven starbursts, with different normalization
  • Disks likely dominate cosmic star formation rate density
slide4

Doing some cosmic algebra => mean brightness temperature of CO emission from the galaxies that reionize the neutral IGM at a given redshift

[Not what we expect to see at all redshifts, but what is required to have reionization occur at that redshift.]

<TBsky>z=8 = 1.1 (0.1/fesc)-1 (C/5) uK

(1+z)3

slide5

Major uncertainties

  • fesc – calibrated with JWST observations of 1st galaxies
  • C – get handle via HI 21m observations (21cm forest absorption?)
  • Line confusion (30GHz = CO 2-1 z=6.7 or 1-0 at z=2.8): requires dual frequency, cross correlation experiment (eg. 15 and 30GHz). Cross correlation with 21cm will also help (Gong, Visbal)
  • Early production of CO and dust (SFR – FIR – L’CO relationships)
slide6

Early production of dust + CO: detections of 12 quasar host galaxies at z~6

M(dust) ~ 108Mo, M(H2) ~ 1010 Mo

z=6.42

0.15” TB ~ 25K

CO3-2 VLA

PdBI

-150 km/s

7kpc

1” ~ 5.5kpc

+

+150 km/s

SFR – FIR – L’CO relationships can be calibrated with ALMA/EVLA/JWST observations of representative z>6 galaxy samples.

slide7

Gunn-Peterson effect

6.4

  • SDSS z~6 quasars
  • Increase of τGP with z
  • Opaque at z>6

z=6.4

5.7

Fan et al 2006

slide8

Gunn-Peterson opacity => f(HI)

  • GP f(HI) (1+z)3/2
  • GP > 5 at z>6 => f(HI) > few x 10-3
  • Note: saturates at low neutral fraction
  • τ depends on clumping factor and resolution

Fan, Carilli, Keating

slide9

Local ionization?

  • GP => likely substantial increase in f(HI) at z~6
  • CMBpol => substantial ionization fraction persisting to z~11
slide10

Quasar Near Zones: J1148+5251

  • Accurate host galaxy redshift from CO: z=6.419
  • Quasar spectrum => photons leaking down to z=6.32
  • ‘time bounded’ Stromgren sphere ionized by quasar

White et al. 2003

6.32

Difference in zhost and zGP => RNZ = 4.7Mpc [fHI Lγ tQ]1/3 (1+z)-1

slide11

HI

HII

Loeb & Barkana

slide12

Quasar Near-Zones: sample of 28 quasars at z=5.7 to 6.5

  • Need: zhost and zGP
  • GP on-set redshift: empirical approach
    • Adopt fixed resolution of 20A
    • Find 1st point when transmission drops below 10% (of extrapolated) = well above typical GP level.
    • => Relative, not absolute measurement

z = 6.1

Wyithe et al. 2010

slide13

Host galaxy redshifts: CO (12), [CII] (3), MgII (14), UV (8)

dz = 0.05 for UV lines

dz = 0.01 for MgII

dz = 0.003 for CO, [CII]

slide14

Quasar Near-Zones: 28 GP quasars at z=5.7 to 6.5

LUV

R Lγ1/3

LUV

  • No correlation of UV luminosity with redshift
  • Correlation of RNZ with UV luminosity
slide15

Quasar Near-Zones: RNZ vs redshift

[normalized to M1450 = -27]

RNZ = 7.3 – 6.5(z-6)

z>6.15

<RNZ> decreases by factor 2.3 from z=5.7 to 6.5

If CSS => fHI increases by factor ~ 10 (eg. 10-4 to 10-3)

slide16

Alternative hypothesis to Stromgren sphere: Quasar Proximity Zones (Bolton & Wyithe)

  • RNZ measures where density of ionizing photon from quasar > background photons (IGRF) =>
  • RNZ [Lγ]1/2 (1+z)-9/4
  • Increase in RNZ from z=6.5 to 5.7 is then
  • due to rapid increase in mfp during overlap/
  • ‘percolation’ stage of reionization
  • Either case (CSS or PZ) => rapid
  • evolution of IGM from z ~ 5.7 to 6.5
slide17

Local ionization?

QNZ

Q-NZ: support substantial increase in f(HI) at z ~ 6 to 7

ESO

slide18

Breaking news: highest redshift quasar, z=7.1

  • Clear GP absorption trough: τ > 5 => IGM opaque to Lya
  • How to form 109 Mo black hole in 750Myr?

Mortlock ea.

z=6.2, 6.4

slide19

z=7.1 quasar near zone

  • Small ~ 2Mpc
  • Continues trend for decreasing NZ size
slide20

z=7.1 quasar: Damped Lya profile

  • N(HI) > 1020.5 cm-2
  • Substantially neutral IGM: f(HI) > 0.1 at 2Mpc distance or
  • Damped Lya galaxy at 2Mpc (probability ~ 5%) (Bolton ea.)

0.5

f(HI)=0.1

1.0

N(HI)=4e20 cm-2 at 2.6Mpc

slide21

Gunn-Peterson effect

6.4

z=6.4

5.7

Fan et al 2006

slide22

Local ionization?

Q-DLA

QNZ

Q-DLA = Best evidence to date for very rapid rise in neutral fraction from z=6 to 7, ie. ‘cosmic phase transition’

ESO

slide23

CMB large scale polarization

  • Rules-out high ionization fraction at z > 15
  • Allows for small (≤ 0.2) ionization to high z
  • Most action occurs at z ~ 7 to 15
  • Challenge: systematics extracting large scale signal

Dunkley et al. 2008

slide24

END

ESO

slide25

LBG galaxies at z=7: Lya spectroscopy

Observed increase in fraction of Lya detections of LBG with z

slide26

Schenker ea

  • LBG at z=7: fewer detected in Lya than expected
  • Expect 9, detect 3 (two independent samples) =>
  • Attenuation of Lya emission by wings of DLA due to neutral IGM or
  • Change in galaxy properties from z=6 to 7
  • More interlopers than they thought

Pentericci ea

slide28

Local ionization?

LBG-DLA

Q-DLA

Q-NZ

Cosmic phase transition! Numerous lines of evidence support a very rapid rise in neutral fraction at z ~ 6 to 7

slide29

END

ESO

slide30

What is ALMA? Tenfold improvement (or more), in all areas of (sub)mm astronomy, including resolution, sensitivity, and frequency coverage.

  • antennas: 54x12m, 12x7m antennas
  • frequencies: 80 GHz to 720 GHz
  • res = 20mas res at 700 GHz
  • rms = 13uJy in 1hr at 230GHz

ALMA Control Building

  • What is the EVLA? similar ten-fold improvement in most areas of cm astronomy
  • frequencies = 1 to 50 GHz
  • 8 GHz BW => 80x old
  • res = 40mas res at 43GHz
  • rms = 6uJy in 1hr at 30GHz

ALMA+EVLA = Order magnitude improvements from 1GHz to 1 THz!

slide31

ALMA Status

  • Antennas, receivers, correlator in production: best submm receivers and antennas ever!
  • Site construction well under way: Observation Support Facility, Array Operations Site, 5 Antenna interferometry at high site!
  • Early science call Q1 2011

5 antennas on high site

EVLA Status

  • Antenna retrofits 70% complete (100% at ν ≥ 18GHz).
  • Early science in March 2010 using new correlator (2GHz)
  • Full receiver complement completed 2012 + 8GHz