Shedding light on the epoch of reionization with the 21cm signal Anne Hutter Catherine Watkinson, Jacob Seiler, Cathryn Trott, Pratika Dayal, Darren Croton, Manodeep Sinha, ARC CENTRE OF EXCELLENCE FOR ALL SKY ASTROPHYSICS IN 3D
The Epoch of Reionization What are the sources of reionization What is the reionization history, and what is their escape fraction of the evolution of ⟨χ HI ⟩? ionizing photons into the IGM? What is the ionization topology, How does reionization afgect the evolution of the sizes and galaxy formation & evolution? location of the ionized regions? Anne Hutter Epoch of Reionization 2
The Epoch of Reionization What are the sources of reionization What is the reionization history, and what is their escape fraction of the evolution of ⟨χ HI ⟩? ionizing photons into the IGM? What is the ionization topology, How does reionization afgect the evolution of the sizes and galaxy formation & evolution? location of the ionized regions? Anne Hutter Epoch of Reionization 3
Observational constraints on reionization ➢ Cosmic Microwave Background optical depth τ = 0.054 ± 0.007 ➢ QSO absorption spectra ➢ Lyman-α emitter luminosity function & clustering Planck 2018 ➢ GRB afterglow spectra Davies+ 2018 Konno+ 2018 IGM damping wing in QSO absorption spectra during reionization Anne Hutter Epoch of Reionization 4
Lyman α emitters (LAEs) in the intergalactic medium IGM f esc = escape fraction of ionizing galaxy photons ( λ<912Å ) HI Lyman α photons emitted ISM (recombination radiation) ISM = interstellar medium Hutter+ 2014 IGM = intergalactic medium Anne Hutter Epoch of Reionization 5
Lyman α emitters (LAEs) in the intergalactic medium IGM f esc = escape fraction of ionizing galaxy photons ( λ<912Å ) HI Lyman α photons emitted ISM (recombination radiation) ionized neutral ISM = interstellar medium Hutter+ 2014 IGM = intergalactic medium Anne Hutter Epoch of Reionization 6
Lyman α emitters (LAEs) in the intergalactic medium IGM f esc = escape fraction of ionizing galaxy photons ( λ<912Å ) dust absorption HI Lyman α photons emitted ISM (recombination radiation) scattering f α = escape fraction of Lyman α ionized photons ( λ=1216Å ) neutral ISM = interstellar medium Hutter+ 2014 IGM = intergalactic medium Anne Hutter Epoch of Reionization 7
Lyman α emitters (LAEs) in the intergalactic medium IGM f esc = escape fraction of ionizing galaxy photons ( λ<912Å ) dust absorption HI Lyman α photons emitted ISM (recombination radiation) scattering f α = escape fraction of Lyman α ionized photons ( λ=1216Å ) absorption by HI LAE selection criteria: L α obs >10 42 erg s -1 neutral EW > 20 Å redshifted out of resonance ISM = interstellar medium Hutter+ 2014 & transmitted through IGM IGM = intergalactic medium Anne Hutter Epoch of Reionization 8
Lyman α emitters (LAEs) in the intergalactic medium intrinsic luminosity IGM f esc = escape fraction of ionizing galaxy photons ( λ<912Å ) dust absorption HI Lyman α photons emitted ISM (recombination radiation) scattering dust attenuation f α = escape fraction of Lyman α ionized photons ( λ=1216Å ) absorption by HI LAE selection criteria: IGM attenuation L α obs >10 42 erg s -1 neutral EW > 20 Å redshifted out of resonance ISM = interstellar medium Hutter+ 2014 & transmitted through IGM IGM = intergalactic medium Anne Hutter Epoch of Reionization 9
Lyman α emitters as probe of reionization Konno+ 2018 dust increases Anne Hutter Epoch of Reionization 10
Lyman α emitters as probe of reionization Konno+ 2018 Ionizing escape fraction increases dust increases Anne Hutter Epoch of Reionization 11
Lyman α emitters as probe of reionization Konno+ 2018 HI in IGM increases Ionizing escape fraction increases dust increases Degeneracy between the ionizing escape fraction , dust attenuation & reionization (Hutter+ 2014) Anne Hutter Epoch of Reionization 12
Lyman α emitters as probe of reionization Konno+ 2018 HI in IGM increases Ionizing escape fraction increases dust z~8.7 EGSY8p7 (Zitrini+2015) z~7.7 EGS-zs8-1 (Oesch+ 2015) increases z~7.5 z~8.7 z~7.5 EGS-zs82 (Roberts-Borsani+ 2016) z~7.7 Degeneracy between the ionizing escape fraction , dust attenuation & reionization (Hutter+ 2014) Anne Hutter Epoch of Reionization 13
Ionization topology with the 21cm signal n 1 Distribution of atoms in states F=0 and F=1 is given by the n 0 spin temperature T s & controls intensity of the 21cm signal 21cm SIGNAL (maps) During the Epoch of Reionization the 21cm signal traces the neutral hydrogen density. Ionized regions appear as holes. Anne Hutter Epoch of Reionization 14
Constraining reionization with 21cm - LAE cross correlations 21 cm galaxies ⟨X HI ⟩ = 0.1 ⟨X HI ⟩ = 0.25 ⟨X HI ⟩ = 0.5 Hutter+ 2017 cross correlation function ξ 21cm,LAE ⟨χ HI ⟩ decreases Lidz+ 2009 21cm-LAE cross correlations trace: ➢ IGM ionization state (amplitude) photoionization ➢ size of ionized regions around rate increases LAEs (turn over) see also Vrbanec+2016, 2019, Sobacchi+ 2016, distance [h -1 Mpc] Heneka+2017, Kubota+2018 Hydro + RT 80h -1 Mpc box Anne Hutter Epoch of Reionization 15
Best survey parameters for detecting 21cm-LAE cross correlations with SKA Hutter+ 2018 ⟨X HI ⟩ = 0.1 ⟨X HI ⟩ = 0.25 ⟨X HI ⟩ = 0.5 Survey Survey luminosity volume limit decreases decreases 1 10 1 10 1 10 1 10 r [h -1 Mpc] r [h -1 Mpc] r [h -1 Mpc] LAE sample variance thermal noise shot noise 21cm sample variance 2 ( k )] [ P LAE ( k ) + σ LAE 2 2 2 δ P 21 ,LAE ( k ) = 2 P 21 , LAE ( k ) + 2 [ P 21 ( k ) + σ 21 ( k )] Anne Hutter Epoch of Reionization 16
Best survey parameters for detecting 21cm-LAE cross correlations with SKA Hutter+ 2018 z = 6.6 Δz = 0.1 ⟨X HI ⟩ = 0.1 ⟨X HI ⟩ = 0.25 ⟨X HI ⟩ = 0.5 HSC: 1.8 deg 2 SILVERRUSH: 21 deg 2 Survey Survey luminosity volume HSC limit SILVERRUSH decreases decreases 1 10 1 10 1 10 1 10 r [h -1 Mpc] r [h -1 Mpc] r [h -1 Mpc] LAE sample variance thermal noise shot noise 21cm sample variance 2 ( k )] [ P LAE ( k ) + σ LAE 2 2 2 δ P 21 ,LAE ( k ) = 2 P 21 , LAE ( k ) + 2 [ P 21 ( k ) + σ 21 ( k )] Anne Hutter Epoch of Reionization 17
Best survey parameters for detecting 21cm-LAE cross correlations with SKA Hutter+ 2018 Survey volume Survey luminosity limit intermediate bright faint L α = 10 42-43 erg s -1 L α = 10 41-42 erg s -1 L α > 10 43 erg s -1 SILVERRUSH HSC 1 10 1 10 1 10 1 10 r [h -1 Mpc] r [h -1 Mpc] r [h -1 Mpc] LAE sample variance thermal noise 21cm sample variance shot noise 2 ( k )] [ P LAE ( k ) + σ LAE 2 2 2 δ P 21 ,LAE ( k ) = 2 P 21 , LAE ( k ) + 2 [ P 21 ( k ) + σ 21 ( k )] Anne Hutter Epoch of Reionization 18
Best survey parameters for detecting 21cm-LAE cross correlations with SKA Hutter+ 2018, 2019 V [Mpc 3 ] V [Mpc 3 ] V [Mpc 3 ] 1 10 1 10 1 10 FoV [deg 2 ] FoV [deg 2 ] FoV [deg 2 ] With current instruments shallow large FoV surveys are achievable FoV > 20 deg 2 and L α > 8x10 42 erg s -1 Anne Hutter Epoch of Reionization 19
The Epoch of Reionization What are the sources of reionization What is the reionization history, and what is their escape fraction of the evolution of ⟨χ HI ⟩? ionizing photons into the IGM? What is the ionization topology, How does reionization afgect the evolution of the sizes and galaxy formation & evolution? location of the ionized regions? Anne Hutter Epoch of Reionization 20
The Epoch of Reionization What are the sources of reionization What is the reionization history, and what is their escape fraction of the evolution of ⟨χ HI ⟩? ionizing photons into the IGM ? GALAXY GALAXY Escape fraction gas of ionizing photons star formation What is the ionization topology, How does reionization afgect the evolution of the sizes and galaxy formation & evolution? location of the ionized regions? Anne Hutter Epoch of Reionization 21
The sources of reionization Star-forming galaxies can UV luminosity function Bouwens+ 2019 provide enough HI ionizing photons to reionize the Universe. e.g. Finkelstein+ 2019, Robertson+2015, Mutch+ 2016, Seiler+ 2019 Contribution from AGN is probably small. e.g. Weigel+ 2015, Parsa+2017, Onoue+2017, Kulkarni+ 2019, Qin+ 2017, Yoshiki+ 2018, Trebitsch+ 2018, Mitra+ 2018 Shedding light on reionization with 21cm 22
The sources of reionization Star-forming galaxies can UV luminosity function Bouwens+ 2019 provide enough HI ionizing photons to reionize the Universe. e.g. Finkelstein+ 2019, Robertson+2015, Mutch+ 2016, Seiler+ 2019 Contribution from AGN is probably small. e.g. Weigel+ 2015, Parsa+2017, Onoue+2017, Kulkarni+ 2019, Qin+ 2017, Yoshiki+ 2018, Trebitsch+ 2018, Mitra+ 2018 The number of ionizing photons is given by N ion = f esc ξ ion ρ UV ˙ Escape fraction UV luminosity of LyC photons density of galaxies ? LyC photon production effjciency Shedding light on reionization with 21cm 23
Recommend
More recommend
