Fabrizio Nicastro (INAF-OAR/CfA) Have we Detected the Missing Baryons? FUV and X-Ray Evidence of the WHIM Fabrizio Nicastro (INAF-OAR/CfA) Collaborators: S. Mathur (OSU), R. Williams (OSU), M. Elvis (CfA), J. Drake (CfA), F. Fiore (INAF-OAR), Y. Krongold (IA-UNAM) 12/8/2018 Oustanding Questions for the Santandard Cosmological Model (IC, London)

Outline The Missing Baryons problem and N-body simulations solution The WHIM in the UV-FUV The Controversial X-Ray Detections(?) The Way Forward: Short- & Long-Term Prospects 12/8/2018 Oustanding Questions for the Santandard Cosmological Model (IC, London)

(59 ± 9) % of Baryons are Missing (Nicastro et al., 2005, Nature, 433, 495) >76 5.7 1.7 4.6 29 4.8 46 54 % of b 12/8/2018 Oustanding Questions for the Santandard Cosmological Model (IC, London)

Warm-Hot gas dominates Mass at low z The Solution:WHIM ? Warm-Hot gas dominates Mass at low z Find the ‘Missing Baryons’ and verify theory Ecology of the Universe: dZ/dz - Absolute (needs UV) and Relative Metallicities. - Galaxy Superwinds (SN) vs AGN winds, jets - Nucleosynthesis Heating History of the Universe: dT/dz Cosmological parameters > 103 systems needed LG-WHIM is a biased measure - Need z>0 WHIM absorbers to measure Wb Local Group WHIM and Galaxy formation Read WHIM Science goals; Why is the WHIM important (Cen & Ostriker, 2006) 12/8/2018 Oustanding Questions for the Santandard Cosmological Model (IC, London)

WHIM Strength & Detectability Pure Collisional Coll. + Phot (z=1, =5) Size: R ~ 1 Mpc, Density: nb ~ 10-6-10-5 cm-3, Temperature: T ~ 105-6 K, Ion Fraction: ξOVII ~ 1, ξOVI < 0.2, Metallicity: Z ~ 0.1 Z๏ => NOVII ~ nbξOVIIZOR ~ 2x(1014-1015) cm-2 => WOVII ~ 0.8-8 (1+z) mA => NOVI ~ nbξOVIZOR < 5x(1013-1014) cm-2 => WOVI < 60-600 (1+z) mA Contrast: FUV: 1032/(0.06-0.6) ~ 2000-20000 ~ (0.1-1) x RFUSE/HST-STIS X-Rays: 22/(0.0008-0.008) ~ 3000-30000 ~ (10-100) x RChandra/XMM 12/8/2018 Oustanding Questions for the Santandard Cosmological Model (IC, London)

The WHIM in the FUV: 10-20 % of the Missing Mass Cen & Fang, 2006 b(OVI) = 0.22 %, i.e. ~ 10 % Missing Baryons (with ZO ~ 0.1 Z) Also: BLAs (Richter et al., 2006): btherm(HI) > 45 km/s (Cf b(HI) ~ 10-50 km/s in Ly-Forest) b(BLA) = 0.27 %, i.e. ~ 10 % Missing Baryons 12/8/2018 Oustanding Questions for the Santandard Cosmological Model (IC, London)

The WHIM in X-Rays: 80-90 % of the Missing Mass? Local Group WHIM? <z>=0.011 WHIM <z>=0.027 Chandra TOOs: F(0.5-2)=2x10-4 erg s-1 CPREs=5300 (Nicastro et al., 2005, Nature, 433,495; Nicastro et al., 2005, ApJ; Williams et al., 2005, ApJ, in press) 0.8 mA 8 mA 12/8/2018 Oustanding Questions for the Santandard Cosmological Model (IC, London)

dNWHIM(OVII)/dz & bWHIM(OVII) Cen & Fang, 2006 Fang et al., 2002 12/8/2018 Oustanding Questions for the Santandard Cosmological Model (IC, London)

The Controversy (1) Differences are due to different assumptions Nicastro et al., 2005a,b claim statistical significances of 3.5 and 4.8 for the two systems, based on F-tests (that do not properly account for the number of trial redshifts). Kaastra et al., 2006 perform MonteCarlo tests and conclude that: P=40 % and P=6 % of falsely detect the two systems. Nicastro et al., 2007 perform new MonteCarlo and confirm P=0.05 % and P < 0.01 % for the two systems (i.e. 3.5 and > 3.9 respectively). Differences are due to different assumptions 12/8/2018 Oustanding Questions for the Santandard Cosmological Model (IC, London)

No conclusive evidence, yet, for X-Ray WHIM The Controversy (2) Rasmussen et al., 2006 show no evidence of the absorption lines seen by Chandra in a high S/N XMM-Newton RGS spectrum of Mkn 421 RLETG ~ 2.4 x RRGS Bottom Line: No conclusive evidence, yet, for X-Ray WHIM 12/8/2018 Oustanding Questions for the Santandard Cosmological Model (IC, London)

The Way Forward: Short-Term FUV: Systematic search of BLAs and OVI on archival STIS and archival and new FUSE KOS in 2009: deep observations of BLAs and moderate-to-high-z OVI X-Rays: Only pursuable way with Chandra and XMM: Multi-Ms observations of higher-z, strategically selected (i.e. BLAs, OVI, or pilot X-ray spectra) bright targets On quiescent targets RGS slightly better than Chandra whwre both RGSs are present, because of high LETG background LETG is the only instrument at > 40 A: sensitivity at C 4 times better than at O ES: 1ES 1028+511 (z=0.361: 10x Mkn 421) Approved 100 ks FUSE Proposed 300 ks Chandra 12/8/2018 Oustanding Questions for the Santandard Cosmological Model (IC, London)

Long-Term Prospects & high spectral resolution Long Term: mapping the WHIM up to z~1: Needs large throughput & high spectral resolution Tens to hundreds systems would enable: b ® and dN/dz to better than few/tens % WHIM density in galaxy voids vs galaxy overdensities Multi-phase studies ® ® ® Hundreds to Thousands of Systems would enable: b ® and dN/dz to better than few tenth of % Cosmological Parameters Dark-Matter Maps Metallicity History: dZ/dz (Ecology of the Universe) (needs UV) ® IGM/galaxy/AGN Feedback Heating History of the Universe (dT/dz) ® 12/8/2018 Oustanding Questions for the Santandard Cosmological Model (IC, London)

Pharos distant beacons as cosmological probes A GRB MIDEX mission concept R > 2500 @ 0.5 keV (RLETG=400) Aeff > 600 @ 0.5 keV (ALETG=20 cm2) 1 arcmin ASM localization Slew in 30-60 s ‘The “Pharos” of Alexandria, one of the Seven Wonders of the ancient world, was the tallest building on Earth (120m). Its mysterious mirror, whose reflection could be seen more than 55 km off-shore fascinated scientists for centuries.’ Fast on this; Read ‘Pharos’ of Alexandria Fabrizio Nicastro & Martin Elvis On behalf of the Pharos Team (CfA, MIT, GSFC, MSFC, OAR-INAF, IASF-INAF) 12/8/2018 Oustanding Questions for the Santandard Cosmological Model (IC, London)

EDGE Explorer of the Diffuse emission and GRB Explosions Piro, L., Den Herder, J.W. & Ohashi, T., for the Edge collaboration 12/8/2018 Oustanding Questions for the Santandard Cosmological Model (IC, London)

WHIM Absorption: Pharos vs Edge Fluence(0.3-2 keV) = 10-5 ergs cm-2 ~ 2-17/year Fluence(0.3-2 keV) = 10-6 ergs cm-2 ~ 10-70/year Stress that even at 1e-6 we do a lot! And a lot better than with the best calorimeter 12/8/2018 Oustanding Questions for the Santandard Cosmological Model (IC, London)

WHIM in Emission: Edge FOV=3’ A filament is in the FOV and O lines are clearly present 12/8/2018 Oustanding Questions for the Santandard Cosmological Model (IC, London)

High-z Galaxy ISM GRB Redshifts in X-Rays F=2 10-6 z=1, NH=1E21, NeII and OI, dz/z=10-4 ! NeII@14.6Å=>29.2Å OI@23.5Å NeII@14.6Å “Edge” 12/8/2018 Oustanding Questions for the Santandard Cosmological Model (IC, London) Talk by Nicastro

Conclusions Up to 10-20 % of the Missing Baryons Mass has been found in the FUV: OVI & BLAs The only two tentative X-Ray (Chandra) detections of WHIM (+ possibly the LG-WHIM) give a cosmological mass density of WHIM consistent with expectations (within large errors due to low number statistics) However, such detections are controversial ==> no conclusive evidence, yet, for the bulk of the Missing Baryons mass Only way forward with current facilities is long integrations of, smartly selected, targets: bright in soft X, low Galactic NH, presence of BLAs, or OVI, galaxies concentrations, pilot X-ray observations Long-Term Prospects: Need Large Throughput & high Spectral Resolution in the Soft X-Ray: PHAROS & EDGE 12/8/2018 Oustanding Questions for the Santandard Cosmological Model (IC, London)