On the Role of Galaxies and AGN in Reionising the IGM: - PowerPoint PPT Presentation

On the Role of Galaxies and AGN in Reionising the IGM: spectroscopic survey of 5<z<7 galaxies in QSO fields s Koki Kakiichi University College London With Richard Ellis, Nicolas Laporte, Adi Zitrin, Anna-Christina Eilers, Emma Ryan-Weber, Romain Meyer, Brant Robertson, Dan Stark, Sarah Bosman Sakura CLAW @ Tokyo 2018

Epoch of Cosmic Dawn & Reionization Gunn & Peterson (1965) paper z=1100 (CMB) first stars assemble to reionization z~20-30 first galaxies z~6-18 “Long-standing questions in observational cosmology” 50 years old problem! When did reionization happen? What reionized the Universe?

What reionized the universe? Problem 1 ✔ Hubble+Planck Becker+2015 Robertson+2015 1. HST galaxy demographics can drive reionisation but “Unknown f esc ” Robertson+15

What reionized the universe? Problem 2 Transmission spikes Gunn-Peterson trough UV background Temperature Becker+15 Also Bosman & Chardin’s talks 2. Huge variation of the intergalactic Lyman alpha optical depth at z>5.5 Difficult with faint galaxies.. Luminous systems? thermal fluctuations?

Testing what reionized the universe: Probing the direct influence of galaxies on the Ly α forest at z>5 Becker+2015 z>6 Spectroscopic survey of Ly α emitting galaxies in QSO fields Galaxy spectra QSO QSO absorption spectra Ly α Ly α emission & absorption HII HI Post-reionized IGM small-scale absorbers “Ly α probing Ly α ” A reionisation-era extension of idea in Keck Baryonic Structure Survey (Steidel et al) e.g. Rudie+12, Turner+14 and Quasar Probing Quasar Survey (Hennawi & Prochaska et al) e.g. Prochaska+13, Schmidt+17

Keck spectroscopy of 5<z<7 galaxies around the Ly ɑ forest of a background QSO field Survey design: DEIMOS spectroscopy of bright LBGs (r- and i-dropouts, z mag < 25.5) in the foreground of well-known QSO z~6 (Keck/ESI QSO spectra) SDSS J1148+5251 QSO z=6.4189 Kakiichi+2018 (arXiv:1803.02981)

Ly α emitting Lyman-break galaxies in J1148+5251 QSO field “Direct mapping of the physical state of the IGM around galaxies at z~6” Ly 𝛾 Ly ɑ Cosmological hydrodynamic simulation + simple radiative transfer Ionising UV radiation from galaxies → more Ly α transmission spikes around galaxies but the individual associations are “ stochastic "

Ly α emitting Lyman-break galaxies in J1148+5251 QSO field “Direct mapping of the physical state of the IGM around galaxies at z~6” Ly 𝛾 Ly ɑ Cross-correlate… ?

Ly α emitting Lyman-break galaxies in J1148+5251 QSO field “Direct mapping of the physical state of the IGM around galaxies at z~6” galaxy - Lya forest pixel r Lya transmitted flux Cross-correlate… ? exp(- 𝞄 ) r

Ly α emitting Lyman-break galaxies in J1148+5251 QSO field “Direct mapping of the physical state of the IGM around galaxies at z~6” galaxy - Lya forest pixel r Lya transmitted flux Cross-correlate… ? exp(- 𝞄 ) r

Ly α emitting Lyman-break galaxies in J1148+5251 QSO field “Direct mapping of the physical state of the IGM around galaxies at z~6” galaxy - Lya forest pixel r Lya transmitted flux Cross-correlate… ? exp(- 𝞄 ) r

Ly α emitting Lyman-break galaxies in J1148+5251 QSO field “Direct mapping of the physical state of the IGM around galaxies at z~6” galaxy - Lya forest pixel r Lya transmitted flux Cross-correlate… ? exp(- 𝞄 ) r

Ly α emitting Lyman-break galaxies in J1148+5251 QSO field “Direct mapping of the physical state of the IGM around galaxies at z~6” galaxy - Lya forest pixel r Lya transmitted flux Cross-correlate… ? exp(- 𝞄 ) r

Ly α emitting Lyman-break galaxies in J1148+5251 QSO field “Direct mapping of the physical state of the IGM around galaxies at z~6” galaxy - Lya forest pixel r Lya transmitted flux Cross-correlate… well, just take exp(- 𝞄 ) the MEAN Lya transmitted flux around LBGs r

Mean Ly α transmitted flux around LBGs at z~5.8 More Ly α forest transmission (=IGM more ionised) Closer to galaxies “ Tentative ”, but promising, evidence of “ Statistical HI proximity effect ” ?

Mean Ly α transmitted flux around LBGs at z~5.8 10 � 11 10 � 11 h Γ HI ( r ) i h Γ HI ( r ) i 10 � 12 10 � 12 10 � 13 10 � 13 10 � 1 10 � 1 10 � 1 10 � 1 10 0 10 0 10 1 10 1 10 0 10 0 10 1 10 1 log 10 r [pMpc] log 10 r [pMpc] log 10 r [pMpc] log 10 r [pMpc] 10 � 1 10 � 1 h f esc i = 0 . 02 h f esc i = 0 . 02 M lim M lim UV = � 10 UV = � 10 h f esc i = 0 . 05 h f esc i = 0 . 05 M lim M lim UV = � 13 UV = � 13 h f esc i = 0 . 10 h f esc i = 0 . 10 M lim M lim UV = � 15 UV = � 15 h exp( � τ α ( r )) i h exp( � τ α ( r )) i h f esc i = 0 . 20 h f esc i = 0 . 20 M lim M lim UV = � 18 UV = � 18 10 � 2 10 � 2 10 � 3 10 � 3 0 0 1 1 2 2 3 3 4 4 5 5 6 6 0 0 1 1 2 2 3 3 4 4 5 5 6 6 r [pMpc] r [pMpc] r [pMpc] r [pMpc] Spectroscopic survey of Ly α emitting galaxies in QSO fields Galaxy spectra QSO QSO absorption spectra Ly α HII HI Post-reionized IGM

Mean Ly α transmitted flux around LBGs at z~5.8 10 � 11 Ionising radiation from the ‘detected’ h Γ HI ( r ) i 10 � 12 galaxies is too small to explain the 10 � 13 observation (statistical HI proximity effect) 10 � 1 10 � 1 10 0 10 1 10 0 10 1 log 10 r [pMpc] log 10 r [pMpc] 10 � 1 h f esc i = 0 . 02 M lim UV = � 10 h f esc i = 0 . 05 M lim UV = � 13 h f esc i = 0 . 10 M lim UV = � 15 h exp( � τ α ( r )) i h f esc i = 0 . 20 M lim UV = � 18 10 � 2 10 � 3 0 1 2 3 4 5 6 0 1 2 3 4 5 6 r [pMpc] r [pMpc] Spectroscopic survey of Ly α emitting galaxies in QSO fields Galaxy spectra QSO QSO absorption spectra Ly α HII HI Post-reionized IGM

Mean Ly α transmitted flux around LBGs at z~5.8 10 � 11 Ionising radiation from the ‘detected’ h Γ HI ( r ) i 10 � 12 galaxies is too small to explain the 10 � 13 observation (statistical HI proximity effect) 10 � 1 10 � 1 10 0 10 1 10 0 10 1 log 10 r [pMpc] log 10 r [pMpc] Need “ faint unseen galaxies clustering 10 � 1 h f esc i = 0 . 02 M lim UV = � 10 around the detected galaxies ” & h f esc i = 0 . 05 M lim UV = � 13 h f esc i = 0 . 10 M lim UV = � 15 h exp( � τ α ( r )) i their collective ionising radiation h f esc i = 0 . 20 M lim UV = � 18 (modelled by CLF/HOD framework and joint analysis of 10 � 2 luminosity function and angular galaxy clustering, then do RT) 10 � 3 0 1 2 3 4 5 6 0 1 2 3 4 5 6 r [pMpc] r [pMpc] Spectroscopic survey of Ly α emitting galaxies in QSO fields Galaxy spectra QSO QSO absorption spectra Ly α HII HI Post-reionized IGM

Mean Ly α transmitted flux around LBGs at z~5.8 10 � 11 Ionising radiation from the ‘detected’ h Γ HI ( r ) i 10 � 12 galaxies is too small to explain the 10 � 13 observation (statistical HI proximity effect) 10 � 1 10 � 1 10 0 10 1 10 0 10 1 log 10 r [pMpc] log 10 r [pMpc] Need “ faint unseen galaxies clustering 10 � 1 h f esc i = 0 . 02 M lim UV = � 10 around the detected galaxies ” & h f esc i = 0 . 05 M lim UV = � 13 h f esc i = 0 . 10 M lim UV = � 15 h exp( � τ α ( r )) i their collective ionising radiation h f esc i = 0 . 20 M lim UV = � 18 (modelled by CLF/HOD framework and joint analysis of 10 � 2 luminosity function and angular galaxy clustering, then do RT) Slope is shallower if the IGM is ionised by even fainter galaxies 10 � 3 0 1 2 3 4 5 6 0 1 2 3 4 5 6 ‘ clustering bias of ionising sources ’ r [pMpc] r [pMpc] Spectroscopic survey of Ly α emitting galaxies in QSO fields Galaxy spectra QSO QSO absorption spectra Ly α HII HI Post-reionized IGM

From the mean Ly α transmitted flux around LBGs to the average LyC escape fraction 10 � 11 h Γ HI ( r ) i 10 � 12 10 � 13 10 � 1 10 0 10 1 10 � 1 10 0 10 1 log 10 r [pMpc] log 10 r [pMpc] 10 � 1 h f esc i = 0 . 02 M lim UV = � 10 h f esc i = 0 . 05 M lim UV = � 13 h f esc i = 0 . 10 M lim UV = � 15 h exp( � τ α ( r )) i h f esc i = 0 . 20 M lim UV = � 18 10 � 2 10 � 3 0 1 2 3 4 5 6 0 1 2 3 4 5 6 r [pMpc] r [pMpc]

From the mean Ly α transmitted flux around LBGs to the average LyC escape fraction 10 � 11 Luminosity function + LBG clustering h Γ HI ( r ) i 10 � 12 10 � 13 10 � 1 10 0 10 1 10 � 1 10 0 10 1 log 10 r [pMpc] log 10 r [pMpc] 10 � 1 h f esc i = 0 . 02 M lim UV = � 10 h f esc i = 0 . 05 M lim UV = � 13 h f esc i = 0 . 10 M lim UV = � 15 h exp( � τ α ( r )) i h f esc i = 0 . 20 M lim UV = � 18 10 � 2 10 � 3 0 1 2 3 4 5 6 0 1 2 3 4 5 6 r [pMpc] r [pMpc]

From the mean Ly α transmitted flux around LBGs to the average LyC escape fraction 10 � 11 Luminosity function + LBG clustering h Γ HI ( r ) i 10 � 12 10 � 13 10 � 1 10 0 10 1 10 � 1 10 0 10 1 log 10 r [pMpc] log 10 r [pMpc] 10 � 1 h f esc i = 0 . 02 M lim UV = � 10 h f esc i = 0 . 05 M lim UV = � 13 h f esc i = 0 . 10 M lim UV = � 15 h exp( � τ α ( r )) i h f esc i = 0 . 20 M lim UV = � 18 10 � 2 lim M uv 10 � 3 0 1 2 3 4 5 6 0 1 2 3 4 5 6 r [pMpc] r [pMpc]