Illuminating the Dark Ages: Luminous Quasars in the Epoch of Reionisation Bram Venemans MPIA Heidelberg Workshop The Reionization History of the Universe Bielefeld University, March 8-9 2018
History of the Universe Big Bang Years after the Big Bang 0 400 000 100 million 1 billion 13.8 billion Dark Ages Today Credits: NRAO 1000 100 10 6 0 Redshift
Recombination Big Bang History of the Universe Years after the Big Bang 0 400 000 100 million 1 billion 13.8 billion Dark Ages Today Credits: NRAO 1000 100 10 6 0 Redshift
History of the Universe Recombination Big Bang Formation of first luminous sources Years after the Big Bang 0 400 000 100 million 1 billion 13.8 billion Dark Ages Today Credits: NRAO 1000 100 10 6 0 Redshift
The Epoch of Reionisation (EoR) Recombination Big Bang Formation of first luminous sources Years after the Big Bang 0 400 000 100 million 1 billion 13.8 billion Dark Ages Today Credits: NRAO 1000 100 10 6 0 Redshift
Constraints on reionisation from CMB Neutral Ionized Neutral fraction xhi, Neutral fraction 1 0 11 1.0 0.8 0.6 0.4 0.2 Planck XLVII 2016 CMB + ksz + z 6 quasars Redshift Redshift 10 9 8 7 2 1 0.5 0.6 0.7 0.8 0.9 Time (Gyr)? 6 Planck XLVII 2016
The first sources: galaxies in the EoR z=8.6 8.6 8.8 8.8 9.5 9.5 11.9 Example of galaxies in the Hubble Ultra Deep Field: very faint (mag 26) difficult to confirm their distance nearly impossible to measure properties JWST (launch 2019) Bouwens+ 2016
High luminosity objects: quasars - powered by accreting black holes - brightest sources in universe - UV/optical spectrum: power-law cont. by accretion disk + broad emission lines - line width+continuum black hole mass
Quasars: beacons in the early Universe Luminous quasar are found up to! > 7: >10 9 M black holes exist within first Gyr Hosted by starburst galaxies (SFR > 100 M /yr) Study the formation of massive galaxies Excellent probes of the Epoch of Reionisation
Quasars: sources of UV photons Lyα + luminous + very blue + high escape fraction Wavelength (Å) Lusso+ 2015
High-! quasar luminosity function! = 6 Willott+ 2010 Onoue+ 2017
Ionising photon production of quasars Probability factor ~20 Needed to keep Universe reionised at! ~ 6 Willott+ 2010 Onoue+ 2017 Log ionising photon emission density
Probes of the Intergalactic Medium (IGM)
Quasars: probes of the EoR Use quasars to X-ray the early Universe Investigate redshift evolution of absorption in the Lyα forest ionised region around quasars (near zone) damping wing 08/03/2018 Luminous Quasars in the Epoch of Reionisation, Bielefeld University Bram Venemans
Quasar absorption due to Lyα forest Credits: B. Keel, N. Wright Strong absorption at! > 6 Fan+ 2006
Probing the neutral IGM 8400 Wavelength (Å) 8600 8800 10 8 6 4 6 4 2 0 SDSS J1030+0524 Lyβ Flux density Flux (10-18 erg cm -2 s -1 A -1 ) 2 0 10 8 6 4 2 0 5.80 5.90 6.00 6.10 6.20 6.30 Redshift Redshift Wavelength 8400 8600 8800 6 SDSS J1148+5251 4 2 0 Lyα 5.8 5.9 6.0 6.1 6.2 6.3 Lyβ Lyα 5.80 5.90 6.00 6.10 6.20 6.30 Redshift e.g. White+ 03
Evolution of the optical depth Optical depth Redshift
Evolution of the optical depth Optical depth GP (z) ¼ 1:8 ; 10 5 h 1 1=2 m b h 2 1 þ z 0:02 7 3=2 n H i n H (Gunn & Peterson 1965) Redshift
X HI from Lyα forest 10-3 Neutral Hydrogen <F HI > V 10 3 Absorption saturates at X HI ~ 10-4 fraction X HI 10-4 10 4 gure 6 5.0 5.5 z 6.0 6.5! e.g. Fan+ 2006
Lyα absorption saturates 30 hour spectrum with the VLT of a quasar at!=7.1 Barnett+ 2017
Weak constraints on X HI from Lyα forest X HI 10-4 Barnett+ 2017
Dark pixel statistics Count fraction of zero flux pixels upper limit on X HI + Not dependent on model or quasar spectrum Reionisation ending at!~6 McGreer+ 2015
Quasar ionisation regions HI HII R NZ
Quasar ionisation regions Quasar near zone: HI R NZ ~ X HI -1/3 (t Q L) 1/3 (e.g. Fan+ 2006) HII X HI neutral H fraction t Q quasar age L quasar luminosity R NZ
Quasar ionisation region Distance to quasar (Mpc) Normalised flux density R p R NZ Lyα at! Q Wavelength Eilers+ 2017 Patzer Co!oquium December 8th, 2
Quasar ionisation region Near zone sizes scaled to same luminosity Fan+ 2006 Carilli+ 2010 BV+ 2015
Quasar ionisation region Decreasing near zone, increasing X HI at!=6 7 X HI few % at "=7 factor 6.5 Fan+ 2006 Carilli+ 2010 BV+ 2015
However: near zone ionisation front New simulations show: R NZ ~ L 1/2.35 R NZ (proper Mpc) R NZ ~ L 1/3 Simulations M 1450 Eilers+ 2017 see also Bolton & Haehnelt 2007
Shallower trend with redshift Recent publications: New observations Higher S/N Homogeneous analysis Better systemic redshifts R NZ (Mpc) + simulations show same trend for neutral and ionised IGM 10 8 6 4 2 0 neutral IGM ionised IGM Eilers+ 2017 5.8 6.0 6.2 6.4 Redshift 6.6
Shallower trend with redshift Recent publications: New observations Higher S/N Homogeneous analysis Better systemic redshifts + simulations show same trend for neutral and ionised IGM R NZ (Mpc) 10 8 6 4 2 0 ionised IGM Eilers+ 2017 5.8 6.0 6.2 6.4 Redshift 6.6
Near zone size as function of age ~10% of quasars have a very small R NZ No evidence for proximate DLAs Short quasar lifetime of t Q < 10 5 yr R NZ (Mpc) Quasar lifetime 1 Myr? Inconsistent with rapid growth of black holes Log t Q (years) Eilers+ 2017
IGM damping wing Damping wing of the IGM: sensitive to neutral fractions >0.1 challenge: unknown intrinsic spectrum see, e.g., Miralda-Escude 1998
Tentative detection of damping wing J1120+0641 at!=7.1 shows a damping wing signature (Mortlock+ 11): X HI = 0.4 +/- 0.2 However, claim disputed Bosman & Becker 2015: no need for damping wing Mortlock+ 2011; see also Bolton+ 2011; Greig+ 2016
Principle Component Analysis Wavelength Davies+ 2018 Model red side of spectrum to predict blue side Use! 2 quasars as training set
Damping wing modeling Model IGM neutral fraction and quasar age simultaneously log t Q (years) X HI Davies+ 2018; Bolton+ 2011
Evolution of neutral Hydrogen fraction Neutral xhi, Neutral fraction X HI 11 1.0 0.8 0.6 0.4 0.2 10 Planck XLVII 2016 CMB + ksz + z 6 quasars 9 Redshift Redshift 2 1 8 0.5 0.6 0.7 0.8 0.9 Time (Gyr) Time (Gyr) 7 6
Evolution of neutral Hydrogen fraction Neutral xhi, Neutral fraction X HI 11 1.0 0.8 0.6 0.4 0.2 10 Planck XLVII 2016 CMB + ksz + z 6 quasars 9 Redshift Redshift 2 1 8 z =7.1 QSO damping wing 0.5 0.6 0.7 0.8 0.9 Time (Gyr) Time (Gyr) 7 6
Evolution of neutral Hydrogen fraction Neutral xhi, Neutral fraction X HI 11 1.0 0.8 0.6 0.4 0.2 10 Planck XLVII 2016 CMB + ksz + z 6 quasars 9 Redshift Redshift 2 1 8 z =7.1 QSO damping wing 0.5 0.6 0.7 0.8 0.9 Time (Gyr) Time (Gyr) 7 6
New quasar at record redshift:!=7.54! Age of universe: 690 Myr à ~10% younger than at!=7.1 Z J1 J H Ks Observed wavelength (µm) 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 f (10 18 erg s 1 cm 2 Å 1 ) Transmission 12 9 6 3 0 0.8 0.4 0.0 Z Ly C IV C III] Mg II J1 J H Ks 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 Observed wavelength (µm) Bañados, BV+ 2018
New quasar at record redshift:!=7.54! Very accurate measurement of systemic redshift BV+ 2017
IGM damping wing at!=7.5 Observed wavelength (µm) 1.02 1.04 1.06 12 2.0 2 1 2 9 1.5 f 6 PDF 1.0 3 0.5 0.27 0.38 0.77 0.94 0 1190 1200 1210 1220 1230 1240 1250 1260 0.0 0.5 1.0 Rest frame wavelength (Å) Lyα at systemic redshift Bañados, BV+ 2018 x HI X HI
Neutral xhi, Neutral fraction X HI Reionisation occurred late? 11 1.0 0.8 0.6 0.4 0.2 Lyα at systemic Redshift redshift 10 9 8 Planck XLVII 2016 CMB + ksz + z 6 quasars Redshift 2 1 J1342 + 0928 damping wing Bañados et al. 2017 0.5 0.6 0.7 0.8 0.9 Time (Gyr) Time (Gyr) C A B Bañados, BV+ 2018 7 6
Conclusions Luminous quasars are ideal objects to study the Epoch of Reionisation Quasar do not contribute to ionising photon density Analysis of Lyα forest suggests reionisation ended around!=6 Size of near zones insensitive to neutral fraction Damping wing in two most distant quasars indicate a highly neutral Universe at!>7
Conclusions Luminous quasars are ideal probes to study the Epoch of Reionisation Quasar do not contribute significantly to the ionising photon rate density Analysis of Lyα forest suggests reionisation ended around!=6 Size of near zones insensitive to neutral fraction Damping wing in two most distant quasars indicate a highly neutral Universe at!>7 Probability factor ~20 Log ionising photon emission density
Conclusions Luminous quasars are ideal probes to study the Epoch of Reionisation Quasar do not contribute significantly to the ionising photon rate density Analysis of Lyα forest suggests reionisation ended around!=6 Size of near zones insensitive to neutral fraction Damping wing in two most distant quasars indicate a highly neutral Universe at!>7 Probability factor ~20 Log ionising photon emission density
Conclusions Luminous quasars are ideal probes to study the Epoch of Reionisation Quasar do not contribute significantly to the ionising photon rate density Analysis of Lyα forest suggests reionisation ended around!=6 Size of near zones insensitive to neutral fraction Damping wing in two most distant quasars indicate a highly neutral Universe at!>7 Probability factor ~20 Log ionising photon emission density xhi, Neutral fraction 11 1.0 0.8 0.6 0.4 0.2 10 Planck XLVII 2016 CMB + ksz + z 6 quasars Redshift 9 8 2 1 J1342 + 0928 damping wing Bañados et al. 2017 0.5 0.6 0.7 0.8 0.9 Time (Gyr) C A B 7 6