Moriond Cosmology Conference, La Thuile, 18th March 2018 eboss Lyman-α Forest Cosmology Matthew Pieri and BOSS & eboss Lyα Working Groups
Quasar Spectra and Lyman α Forest Quasar Intergalactic medium Line-of-sight probe of the IGM Gas with 1.. 10 traces dark matter on large scales Largely photoionized HI / 1.7 H and Departures from this UV background modulation Strong lines f = CF = Ce HI credit: Andrew Pontzen Small scale physics metal absorption
Quasar Spectra and Lyman α Forest Quasar Intergalactic medium Line-of-sight probe of the IGM Gas with 1.. 10 traces dark matter on large scales Largely photoionized HI / 1.7 H and Departures from this UV background modulation Strong lines f = CF = Ce HI credit: Andrew Pontzen Small scale physics metal absorption
Quasar Spectra and Lyman α Forest Quasar Intergalactic medium Line-of-sight probe of the IGM Gas with 1.. 10 traces dark matter on large scales Largely photoionized HI / 1.7 H and Departures from this UV background modulation Strong lines f = CF = Ce HI credit: Andrew Pontzen Small scale physics metal absorption
Baryon Acoustic Oscillations A useful ruler on the sky measured in the CMB (Eisenstein et al 2005, Cole et al. 2005) Trace expansion over time BIG ~100 Mpc/h comoving credit: David Kirkby
Baryon Acoustic Oscillations A useful ruler on the sky measured in the CMB (Eisenstein et al 2005, Cole et al. 2005) Trace expansion over time BIG ~100 Mpc/h comoving credit: David Kirkby
Baryon Acoustic Oscillations A useful ruler on the sky measured in the CMB (Eisenstein et al 2005, Cole et al. 2005) Trace expansion over time BIG ~100 Mpc/h comoving credit: David Kirkby
The Sloan Digital Sky Survey III and IV Dedicated 2.5m SDSS telescope at Apache Point, New Mexico, USA 1000 fibres per field Spectral resolution R = 2000 SDSS-III/BOSS 2009-2014 SDSS-IV/eBOSS 2014-2019 Final BOSS sample: 158k analysis quasars with z > 2.1
Measuring Structure in the Lyman α Forest Measure continuum to obtain delta (z) = f C F 1 Adds line of sight distortion So only small-scales possible along LOS (e.g. McDonald et al 2004) High quasar densities and 3D needed to get large scales
First Detection of BAO in the Lya Forest First year measure of large-scale 3D (Slosar et al. 2011) 1st BAO in Data Release 9 (Busca et al. 2013 and Slosar et al. 2013) Also BAO in quasar-lyα forest cross-correlation (Font-Ribera et al 2014)
Line of Sight Separations and Redshift Space Distortions Sum over all pairs of deltas (A) = X i,j2a note that w ij i j µ = r k r r rǁ μ μ
BOSS-Lyα Forest Mocks Mocks needed To test analysis and potential systematics Not to provide covarience matrix Gaussian Random Fields not N-body Same GRF to draw quasar positions gives Lyα auto and quasar-lyα cross Currently two sets of mocks being developed by Etourneau & Le Goff and Farr & Font
DR12 Lyα Forest Autocorrelation V near LOS Near LOS Intermediate to LOS Transverse to LOS Bautista et al (2017)
DR12 QSO-Lyα Cross-correlation V near LOS Near LOS Intermediate to LOS Transverse to LOS du Mas des Bourboux et al (2017)
DR12 Cosmological Constraints Hubble param Angular diameter distance 2.3sig tension with Planck-based models
extendedboss (eboss) Emission line galaxies, new LRGs (see Julian s talk) New quasar sample - no z cut ~500k quasars between 1<z<2 New quasars z>2 for Lyα BAO Also boost to S/N of faint z>2 quasars from BOSS eboss Lyα analysis sample growth in numbers: BOSS (DR12) eboss now (DR14) eboss end (DR16) Lyα auto 158k 174k (+16k reobs) ~194k (+36k reobs) Quasar-Lyα Cross 234k 266k (+16k reobs) ~306 (+36 reobs)
Intermediate Redshift Quasars Sample for clustering BAO (see Hector and Pauline s talks) Lyα Forest not observable but carbon-iv forest is New potential BAO tracer (MP 2014) Weaker signal but higher quasar number density Potential contaminant of Lyα BAO CIV interesting in its own right Lyα forest carbon forest MP (2014)
Carbon Absorption BAO 1st Measurement (Blomqvist et al 2018) Marginal (1.7sig) BAO detection with ~9% precision Final eboss: ~7% precision Final DESI: 3% precision Value: redshift overlap with galaxy clustering to confirm consistency
More Tracers in Data More Lyα forest at lower wavelengths in the Lyman-β forest For use in both the Lyα auto and quasar-lyα cross
DR14 Sample Growth (including Lyman-β) Lyα Auto: mean improvement 0.64 Quasar-Lyα Cross: mean improvement 0.59 De Sainte Agathe et al in prep Blomqvist et al in prep
More Tracers in Data More Lyα forest at lower wavelengths in the Lyman-β forest For use in both the Lyα auto and quasar-lyα cross Magnesium-II absorption to z>0.3 and and crosscorrelation with CMASS, LRG, QSO. Tentative BAO measurement Galaxies in absorption
BAO from Galaxies in Absorption Connection between DLAs & galaxies is standard Sample Parks et al (2017) Strong and blended Lyα are circumgalactic Discovered from metals in composite spectra (MP++ 2010, MP+ +2014) Confirmed in Lyman break galaxy comparison Further supported by bias similar to DLAs
BAO from Galaxies in Absorption Preliminary and not including all data DLA SLA 7% on par BAO 9% on perp BAO 5% on par BAO V near LOS Near LOS 8% on perp BAO Combined gives competitive constraints on par BAO (Hubble param).. but 25% covariance with the Lyα Auto Intermediate to LOS Blomqvist et al in prep Transverse to LOS
Cosmology with 1D Power spectrum 1D power a probe of light particles Like neutrinos Σm ν < 0.12 ev (BOSS + CMB; Palanaque-Delabrouille + 2015) Σm ν < 0.14 ev (BOSS + XQ100 + CMB; Yèche + 2017)
Cosmology with 1D Power spectrum 1D power a probe of light particles Like neutrinos Σm ν < 0.12 ev (BOSS + CMB; Palanaque-Delabrouille + 2015) Σm ν < 0.14 ev (BOSS + XQ100 + CMB; Yèche + 2017) And Warm dark matter Pure WDM Mixed DM Sterile neutrino Baur + (2016, 2017) In tension with excess X-ray emission from galaxies Pure CDM CDM-like HDM-like
Next Generation Massive IGM Surveys DESI BAO error WEAVE BAO error
Summary Intergalactic gas in quasar absorption a large scale structure tracer Probe BAO in 2 key measurements: Hydrogen Lyα forest auto-correlation & the cross with quasars Final BOSS results indicate >2.3 sigma tension with Planck based concordance cosmology eboss key analyses ongoing, but significant boost in data Carbon forest BAO at intermediate z - potential for cross checks Push to use all absorption tracers including promising use of galaxies in absorption