The Chandra view of the cluster outskirts University of Alabama in Huntsville The Chandra view of the cluster outskirts Andrea Morandi With Ming Sun, William Forman, Christine Jones Honolulu, 08/05/2015 01:29

The Virialization region of clusters Credits: Roncarelli et al. 2007 Gas clumping 𝐶= <ne2> <ne>2 𝑃nt Multi-T T Ion v.s. e - Clusters show the major axis preferentially elongated along the cosmic filaments 01:29

Outskirts of clusters via stacking 320 Chandra Clusters (kT>3 keV, 0.056<z< 1.24), 20 Ms observations Study Xray EM∝∫ 𝐧 𝐞 𝟐 𝐝𝐥 to measure ne, β, fgas out to R100 Detection of the filaments via ICM eccentricities 01:29

EM profiles kT-1/2E(z)-3EM(R/R200) Ez=Hz/H0 01:29

Stacking: method R500 from Yx,500-M500 and then R200 from c-M from simulations Gas density from the stacked EM∝∫ 𝒏 𝒆 𝟐 𝒅𝒍 , no spectral analysis Modelling CXB, local+particle backgr, readout Validation of stacking via mock simulations Systematics: spherical modeling, HE, homogenous ICM, single-temperature spectral fit 01:29

ne profile Eckert et al. 2012 Roncarelli et al. 2006 01:29

β profiles β=- 𝟏 𝟑 dln(ne) dln(r) 01:29

fgas(<R)= Mgas Mtot fgas profiles WMAP 9 Planck fgas(<R)= Mgas Mtot Biases: Stellar fraction – Baryon Deplet. – Multi-T – Clumpiness + Pnt + 01:29

fgas : `missing` baryons or `too many` baryons? Conclusions: Steep ne with β≥1 at R100 Detection of the filaments fgas : `missing` baryons or `too many` baryons? differences in ne between X-ray missions Biases in HE, Clumping, multi-T Cosmology WMAP (Ωb/ Ωm~0.167) v.s. Planck (Ωb/ Ωm~0.155) 01:29