Tang, Goto et al., 2017, MNRAS, 466,4568 Liu, Goto et al. submitted - - PowerPoint PPT Presentation

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Tang, Goto et al., 2017, MNRAS, 466,4568 Liu, Goto et al. submitted - - PowerPoint PPT Presentation

Feb 11, 2024 166 likes •380 views

Tang, Goto et al., 2017, MNRAS, 466,4568 Liu, Goto et al. submitted Tomo GOTO Tomo GOTO When, and how the Universe was

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Tomo GOTO

Tang, Goto et al., 2017, MNRAS, 466,4568 Liu, Goto et al. submitted

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Tomo GOTO

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When, and how the Universe was reionized? One of the outstanding questions in the

  • bservational cosmology.
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Tomo GOTO

  • ionized

neutral

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p

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Discovery spectra 1 hour (Tang, Goto et al. 2017)

  • 5*1000sec

R~600

Tang, Goto et al., 2017, MNRAS, 466,4568

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Discovery spectra 1 hour (Tang, Goto et al. 2017)

SN~7

  • Follow up spectra

7.5 hour (PI:GOTO) SN~20! y~20.0mag

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SLIDE 11
  • z~6.4

z~5.6 z~6.0 z~5.2 Lyα Nv z~6.6 (Lyα redshift)

Spectrum: Later we will preform 3 methods to probe the phase evolution with the spectrum

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z~6.4 z~5.6 z~6.0 z~5.2 Lyα Nv z~6.6 (Lyα redshift)

Spectrum: Later we will preform 3 methods to probe the phase evolution with the spectrum

Continuum

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SLIDE 15
  • 1. Transmission & Optical depth

Optical depth: " = − %& ' redshi ft redshi ft

Transmission: ' =

()*+,-. ()*+/01

Method1: measuring the transmission and optical depth

  • Transmission
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  • 2. Dark gaps statistics

Method2: counting the gap span by two adjacent peaks

  • ptical depth~2.5

5.89 6.21 6.52 5.58 5.27 Lyα redshift

Higher transmission

Observer, z=0 (ionized) Quasar, z=6.6

Higher transmission Lower transmission Lower transmission Higher transmission

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Gap width(Å) Number of the gaps

Method2: The gaps size(neutral region) is larger at higher redshift

0.20Å 0.66Å 0.80Å

z = 5.48-5.83 z = 5.83-6.18 z = 6.18-6.54

median of the gap width

  • 2. Dark gaps statistics

z>6.1

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  • 3. The dark pixel fraction

Method3: dark fraction = upper limit of the neutral fraction

  • (neutral)

No need to assume the intrinsic flux!

6.07 6.23 6.40 5.91 5.74

Lyα redshift dark pixel not dark pixel

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Method3: dark fraction = upper limit of the neutral fraction

Neutral fraction

  • 3. The dark pixel fraction

z>6.1

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Three abs. tests up to z~6.6

Many thanks for your attention!

We found a bright QSO at z=6.6

1.Transmission: flux~0 at z>6 even with

  • ur high-quality spectrum.
  • 2. Dark gap distribution:

A jump of gap width at 5.8<z<6.2

  • 3. Dark pixel fraction: