The Mean Ultraviolet Spectrum of a Representative Sample of Faint - - PowerPoint PPT Presentation

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The Mean Ultraviolet Spectrum of a Representative Sample of Faint - - PowerPoint PPT Presentation

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Tokyo Spring Cosmic Lyman-Alpha Workshop: The Mean Ultraviolet Spectrum of a Representative Sample of Faint z~3 Lyman Alpha Emitters Kimihiko Nakajima (ESO/UCL) In collaboration with R. Ellis (ESO/UCL) , T .

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SLIDE 1

Tokyo Spring Cosmic Lyman-Alpha Workshop:

  • The Mean Ultraviolet Spectrum of

a Representative Sample of Faint z~3 Lyman Alpha Emitters

Kimihiko Nakajima (ESO/UCL)

  • In collaboration with
  • R. Ellis (ESO/UCL), T

. Fletcher (UCL), B. Robertson (UCSC),

  • I. Iwata (Subaru), A. Inoue (Osaka Sangyo U.)
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SLIDE 2
  • 2
  • )
  • Galaxies governed Reionization process?

Neutral fraction of IGM Electron scattering Optical depth

ρSFR←UV

History of cosmic star-formation

Efficiency of ionizing photon production Fraction of ionizing photons that escape into IGM

Background

Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima

  • 2
  • )
  • )
  • 1-QHII

τ

Robertson et al. 2015

  • See also Faisst 2016, Talks on Wednesday
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SLIDE 3

Lyα emitters (LAEs) as Probes of Early galaxies

Stark et al. 2011, ApJL, 728, L2

3 4 5 6 7 8 Redshift

Fraction of LAEs in all star-forming galaxies

EoR

  • Low-mass, metal-poor, young star-forming galaxies
  • Typical in early universe

Background

Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima

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SLIDE 4

Lyα emitters (LAEs) as Probes of Early galaxies

Stark et al. 2011, ApJL, 728, L2

3 4 5 6 7 8 Redshift

Fraction of LAEs in all star-forming galaxies

EoR

  • Low-mass, metal-poor, young star-forming galaxies
  • Typical in early universe
  • Intense nebular lines, e.g. [OIII]5007,4959

Background

z=3.1 LAEʼs MOSFIRE K spectrum Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima

Nakajima et al. 2016

  • See also Nakajima&Ouchi 2014, Erb+2016, Kojima+2017, Talk by D. Erb
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SLIDE 5

Lyα emitters (LAEs) as Probes of Early galaxies

Stark et al. 2011, ApJL, 728, L2

3 4 5 6 7 8 Redshift

Fraction of LAEs in all star-forming galaxies

EoR

  • Low-mass, metal-poor, young star-forming galaxies
  • Typical in early universe
  • Intense nebular lines, e.g. [OIII]5007,4959

Background

z=3.1 LAEʼs MOSFIRE K spectrum Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima

Nakajima et al. 2016

  • See also Nakajima&Ouchi 2014, Erb+2016, Kojima+2017, Talk by D. Erb

Roberts-Borsani et al. 2016 See also Smit+2014,2015

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SLIDE 6

LAEs present Hard Ionizing Spectrum

LBGs

(Bouwens et al. 2016)

More efficient production

  • f ionizing photons

LAEs Background

Typical Characteristics of LAEs ?

ξion Based on Hydrogen recombination lines

Nakajima et al. 2016

Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima

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SLIDE 7

Number of photons emitted above energy E

Nature of Ionizing Spectrum Examined by UV spectrum

Our Work

Harder Softer

Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima

Refer also to Talk by K. Schmidt

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SLIDE 8

UV line diagnostics of ξion

Nakajima et al. 2017 in collaboration with VUDS (A&A in press, arXiv:1709.03990) See also Stark+2014, Gutkin+2016

EW(CIII]) = --------------- ∝ ------------------ = f(Z,U,ξion(age)) Flux(CIII]) fλ,1909 Nion(>24.4eV) LUV

Smaller ξion

Our Work

Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima 1Myr 10Myr 100Myr Age

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SLIDE 9

VLT/VIMOS (11hrs) Observation Identifying Lyα from ~70 Faint z=3 LAEs

Our Work

Nakajima et al. 2018, MNRAS in press (arXiv:1801.03085)

−26 −24 −22 −20 −18 −16 −14

MUV

50 100 150 200 250 300 350 400

No (Shapley + 03 only)

5 10 15 20 25 30 35 40

No

z=3 LBGs (Shapley+03) z∼2 LAEs (Stark+14) z=2-3 LAEs (Erb+14) z=3.1 LAEs (This Work)

Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima

Our target LAEs

LBGs

(Shapely et al. 2003)

MUV

  • 26 -24 -22 -20 -18 -16 -14
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SLIDE 10

VLT/VIMOS (11hrs) Observation Identifying Lyα from ~70 Faint z=3 LAEs

Our Work

Nakajima et al. 2018, MNRAS in press (arXiv:1801.03085)

−26 −24 −22 −20 −18 −16 −14

MUV

50 100 150 200 250 300 350 400

No (Shapley + 03 only)

5 10 15 20 25 30 35 40

No

z=3 LBGs (Shapley+03) z∼2 LAEs (Stark+14) z=2-3 LAEs (Erb+14) z=3.1 LAEs (This Work)

Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima

Our target LAEs

LBGs

(Shapely et al. 2003)

MUV

  • 26 -24 -22 -20 -18 -16 -14
slide-11
SLIDE 11

VLT/VIMOS (11hrs) Observation Identifying rest UV lines in Stacks of 70 z=3 LAEs

Our Work

Rest Wavelength (A)

Nakajima et al. 2018, MNRAS in press (arXiv:1801.03085)

Flux density (cgs per A)

Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima

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SLIDE 12

Strong CIII] Associated with Strong Lyα

Nakajima et al. 2018, MNRAS in press (arXiv:1801.03085)

Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima

Results EW(Lyα) large UV faint Bluer β EW(Lyα) small UV bright Redder β

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SLIDE 13

Stronger LAEs are less chemically enriched galaxies

Nakajima et al. 2018

Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima

Results

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SLIDE 14

Stronger LAEs are less chemically enriched galaxies

Nakajima et al. 2018 Nakajima et al. 2017

ionization state Gas metallicity

Stronger LAEs: Z = 0.05 – 0.2 Zsun Weaker LAEs: Z = 0.1 – 0.5 Zsun

Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima

Results

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SLIDE 15

LAEsʼ Hard ξion is confirmed with UV line analysis

Nakajima et al. 2018

Stronger LAEs: log ξion = 25.68±0.13 Weaker LAEs: log ξion = 25.54±0.09

Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima

Results

@ 1Myr

slide-16
SLIDE 16

Stronger LAEs: log ξion = 25.68±0.13 Weaker LAEs: log ξion = 25.54±0.09

Nakajima et al. 2018

LAEsʼ Hard ξion is confirmed with UV line analysis

Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima

Results

with Hβ with UV lines

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SLIDE 17

ξion as functions of UV luminosity, redshift and Lyα

LBGs: Uniform ξion (~25.2--25.4), independent of MUV, z LAEs: Larger ξion (~25.5--25.7), particularly for faintest LAEs → Analogous to Galaxies in EoR

(Nakajima+16)

Nakajima et al. 2018

  • Refer also to Talks on Wednesday

Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima

Discussion

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SLIDE 18

Deep (20orbits x3) HST/F336W imaging of 51 z=3 LAEs High success rate in securing significant F336W detections (~30%) HST localization suggests minimal (<2%) foreground contamination

LymAn Continuum Escape Survey (LACES): UV Imaging of z=3 LAEs

Work on-going

r detections: individual f

F336W NB497 F160W LyC Lyα Stars

For detections: Individual fesc ranges from 4-60%

fesc~7±2%

P r e l i m i n a r y

  • Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima
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SLIDE 19

LAEs are ideal analogs of sources in Reionization era

Low-mass, Low-metallicity, Young Intense [OIII]5007,4959 Hard Ionizing Spectrum

Galaxies like LAEs could dominate Reionization process

Hard Ionizing Spectrum High Escape Fraction? → To be examined with LACES

r detections: individual f

F336W NB497 F160W LyC Lyα Stars

Summary

Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima