� � 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.) �
� � � � � � � � � � � � � Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima � � Background � � � � � � � Galaxies governed Reionization process?� � � � � Electron scattering � History of cosmic star-formation� Neutral fraction of IGM� � Optical depth� � � � ρ SFR←UV� � 1-Q HII � � � � τ � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 2 � � � ) Robertson et al. 2015� � � � � � See also Faisst 2016, Talks on Wednesday� � � � � � � � � � � � � Fraction of ionizing photons that � Efficiency of ionizing photon production� � � escape into IGM� � � � � � � � � � � � � � � � ) � � � � � � � � � � � � � � 2 � � � � � � ) � � � � � � � � � � � � � � � �
Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima Background � Lyα emitters (LAEs) as Probes of Early galaxies� in all star-forming galaxies� Fraction of LAEs � EoR� 3 4 5 6 7 8� Redshift� Stark et al. 2011, ApJL, 728, L2� Low-mass, metal-poor, young star-forming galaxies� • Typical in early universe� •
� Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima Background � Lyα emitters (LAEs) as Probes of Early galaxies� z=3.1 LAEʼs MOSFIRE K spectrum� in all star-forming galaxies� Fraction of LAEs � EoR� 3 4 5 6 7 8� Redshift� Nakajima et al. 2016� Stark et al. 2011, ApJL, 728, L2� See also Nakajima&Ouchi 2014, Erb+2016, Kojima+2017, Talk by D. Erb� Low-mass, metal-poor, young star-forming galaxies� • Typical in early universe� • Intense nebular lines, e.g. [OIII] 5007,4959� •
� Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima Background � Lyα emitters (LAEs) as Probes of Early galaxies� Roberts-Borsani et al. 2016� z=3.1 LAEʼs MOSFIRE K spectrum� in all star-forming galaxies� Fraction of LAEs � EoR� 3 4 5 6 7 8� Redshift� Nakajima et al. 2016� Stark et al. 2011, ApJL, 728, L2� See also Smit+2014,2015� See also Nakajima&Ouchi 2014, Erb+2016, Kojima+2017, Talk by D. Erb� Low-mass, metal-poor, young star-forming galaxies� • Typical in early universe� • Intense nebular lines, e.g. [OIII] 5007,4959� •
Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima Background � LAEs present Hard Ionizing Spectrum� ξ ion Based on Hydrogen recombination lines� LBGs� LAEs� (Bouwens et al. 2016)� Nakajima et al. 2016� More efficient production� of ionizing photons� Typical Characteristics of LAEs ? �
Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima Our Work � Nature of Ionizing Spectrum � Examined by UV spectrum � emitted above energy E� Number of photons � Harder� Softer� Refer also to Talk by K. Schmidt�
Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima Our Work � UV line diagnostics of ξ ion� Flux(CIII])� N ion (>24.4eV)� EW(CIII]) = --------------- ∝ ------------------ = f ( Z , U ,ξ ion (age))� f λ,1909� L UV� 1Myr 10Myr 100Myr� Age� Smaller ξ ion� Nakajima et al. 2017 in collaboration with VUDS� (A&A in press, arXiv:1709.03990)� See also Stark+2014, Gutkin+2016�
Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima Our Work � VLT/VIMOS (11hrs) Observation� Identifying Lyα from ~70 Faint z=3 LAEs � 400 z=3 LBGs (Shapley+03) 40 z ∼ 2 LAEs (Stark+14) 350 z=2-3 LAEs (Erb+14) 35 z=3.1 LAEs (This Work) N o (Shapley + 03 only) 300 30 LBGs� Our target � 250 (Shapely et al. 2003)� LAEs� 25 N o 200 20 150 15 100 10 50 5 0 0 − 26 − 24 − 22 − 20 − 18 − 16 − 14 -26 -24 -22 -20 -18 -16 -14 � M UV M UV� Nakajima et al. 2018, MNRAS in press� (arXiv:1801.03085)�
Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima Our Work � VLT/VIMOS (11hrs) Observation� Identifying Lyα from ~70 Faint z=3 LAEs � 400 z=3 LBGs (Shapley+03) 40 z ∼ 2 LAEs (Stark+14) 350 z=2-3 LAEs (Erb+14) 35 z=3.1 LAEs (This Work) N o (Shapley + 03 only) 300 30 LBGs� Our target � 250 (Shapely et al. 2003)� LAEs� 25 N o 200 20 150 15 100 10 50 5 0 0 − 26 − 24 − 22 − 20 − 18 − 16 − 14 -26 -24 -22 -20 -18 -16 -14 � M UV M UV� Nakajima et al. 2018, MNRAS in press� (arXiv:1801.03085)�
Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima Our Work � VLT/VIMOS (11hrs) Observation� Identifying rest UV lines in Stacks of 70 z=3 LAEs � Flux density (cgs per A)� Rest Wavelength (A)� Nakajima et al. 2018, MNRAS in press� (arXiv:1801.03085)�
Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima Results � Strong CIII] Associated with Strong Lyα � EW(Lyα) large� UV faint� Bluer β� EW(Lyα) small� UV bright� Redder β� Nakajima et al. 2018, MNRAS in press� (arXiv:1801.03085)�
Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima Results � 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 � Stronger LAEs are less chemically enriched galaxies � ionization state � Gas metallicity � Nakajima et al. 2018� Nakajima et al. 2017� Stronger LAEs: Z = 0.05 – 0.2 Z sun� Weaker LAEs: Z = 0.1 – 0.5 Z sun�
Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima Results � LAEsʼ Hard ξ ion is confirmed with UV line analysis� @ 1Myr� Nakajima et al. 2018� Stronger LAEs: log ξ ion = 25.68±0.13 � Weaker LAEs: log ξ ion = 25.54±0.09 �
Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima Results � LAEsʼ Hard ξ ion is confirmed with UV line analysis� with UV lines� with Hβ� Nakajima et al. 2018� Stronger LAEs: log ξ ion = 25.68±0.13 � Weaker LAEs: log ξ ion = 25.54±0.09 �
� Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima Discussion � ξ ion as functions of UV luminosity, redshift and Lyα� (Nakajima+16)� Nakajima et al. 2018� Refer also to Talks on Wednesday� LBGs: Uniform ξ ion (~25.2--25.4), independent of M UV , z � LAEs: Larger ξ ion (~25.5--25.7), particularly for faintest LAEs� → Analogous to Galaxies in EoR�
Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima Work on-going� LymAn Continuum Escape Survey (LACES):� UV Imaging of z=3 LAEs� 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 � F336W� NB497� F160W� Lyα� Stars� LyC� f esc ~7±2%� y � r a n i m i l e r P For detections: � Individual f esc ranges from 4-60% � r detections: individual f
Tokyo Spring Cosmic Lyman-Alpha Workshop, Tokyo on Mar 27, 2018 – Kimihiko Nakajima Summary� 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 F336W� NB497� F160W� Reionization process� LyC� Lyα� Stars� Hard Ionizing Spectrum� High Escape Fraction? � → To be examined with LACES� r detections: individual f
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