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Fabrizio Nicastro (Harvard-Smithsonian Center for Astrophysics)

Missing Baryons: the First Mass Measurement Detection of WHIM Filaments along the Lines of Sight to MKn 421 and 1ES 1028+511. Fabrizio Nicastro (Harvard-Smithsonian Center for Astrophysics). Collaborators: S. Mathur, M. Elvis, J. Drake, F. Fiore, T. Fang. J. Bergeron, H. Marshall, Y. Krongold,

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Fabrizio Nicastro (Harvard-Smithsonian Center for Astrophysics)

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  1. Missing Baryons: the First Mass MeasurementDetection of WHIM Filaments along the Lines of Sight to MKn 421 and 1ES 1028+511 Fabrizio Nicastro (Harvard-Smithsonian Center for Astrophysics) Collaborators:S. Mathur, M. Elvis, J. Drake, F. Fiore, T. Fang. J. Bergeron, H. Marshall,Y. Krongold, D. Weinberg, A. Fruscione & The XTE-ASM Team: R. Remillard, A. Levine, H. Bradt, E. Morgan (Nicastro et al., 2004, Nature, submitted Nicastro et al., 2004, ApJ, submitted) The Environments of Galaxies: from kpc to Mpc, Crete - 2004 (F. Nicastro)

  2. Overview The Missing Baryons Problem The WHIM at z > 0: the lines of sight to Mkn 421 (Nicastro et al., 2004, ApJ, submitted) and 1ES 1028+511 (Nicastro et al., 2004, in prep.) First Measurement of Ωb(OVII) (Nicastro et al., 2004, Nature, submitted) Future Prospects The Environments of Galaxies: from kpc to Mpc, Crete - 2004 (F. Nicastro)

  3. (Rauch et al., 1998; Weinberg et al., 1997) maybe conservative by a factor 2-7, due to uncertainty in the meta-galactic radiation field (Burles & Tytler, 1998) (Bennet et al., 2003) The Baryon Budget at High z • From Observations of the Lya Forest at z=2: • Standard Bib Bang Nucleosynthesis, combined with observed light-element ratios, and CMB anisotropies measurements give: &  At High z, consistency on the estimated Baryon density The Environments of Galaxies: from kpc to Mpc, Crete - 2004 (F. Nicastro)

  4. Baryons are Missing at Low z (Fukugita, Hogan & Peebles, 1997) Galactic ‘damped’ Ly The Environments of Galaxies: from kpc to Mpc, Crete - 2004 (F. Nicastro)

  5. The Baryon Content in the Universe Mass Fraction vs Volume Fraction (Cen & Ostriker, 1999) Warm-Hot gas dominates Mass at low z Cool (Ly) gas dominates Volume at all z The Environments of Galaxies: from kpc to Mpc, Crete - 2004 (F. Nicastro)

  6. Chandra OVIII CVI NeIX OVII How to detect the WHIM Background QSO Emission (lines): A 2x2x5 Mpc3 Filament (4.5’ x 11’, at z=1): L ~ 6 x 1039 erg/s/sr at z = 1  F ~ 10-24 erg/s/cm2 Cf. Chandra limit ~10-18 in 2-4 months for point source The Environments of Galaxies: from kpc to Mpc, Crete - 2004 (F. Nicastro)

  7. WHIM is Faint • EW(OVII) ≲40 mÅ  NOVII≲1016 cm-2.Requires ≳100 ct/res.el. In Chandra-LETG or XMM-RGS • Exceptionally high quality X-ray spectra of background AGN are needed, implying either very large exposures or bright states, or both. The Environments of Galaxies: from kpc to Mpc, Crete - 2004 (F. Nicastro)

  8. Our Strategy (Chandra Cycles 4-5 and Newton-XMM Cycles 2-3) • Blazars flare to > 10 times normal • Trigger ToO (from Rossi-XTE ASM) • Outbursts last 1-2 weeks • 1st TOO on 2002 October 27: 100 ks ACIS-LETG • 2nd TOO on 2003 June 6: 100 ks HRC-LETG • Spectacular Results! The Environments of Galaxies: from kpc to Mpc, Crete - 2004 (F. Nicastro)

  9. Mkn 421: LETG Spectrum • ~ 7 Mcts in 2.3 days!! Takes 4-6 months on the brightest QSOs at z = 0.5 (F0.5-2 keV = 50 mCrab) • ~ 5300 ct/r.e., @ 21 Å Enough to detect (at > 3): EWAbs  2 mÅ, @ 21 Å Implying: NOVII  1014.8 cm-2  NH 1019 cm-2, for Z/Z = 0.1  Path Lengths  0.5 Mpc, for =50 The Environments of Galaxies: from kpc to Mpc, Crete - 2004 (F. Nicastro)

  10. Local Group WHIM <z>=0.011 WHIM <z>=0.027 WHIM WHIM and ISM Absorption The Environments of Galaxies: from kpc to Mpc, Crete - 2004 (F. Nicastro)

  11. X-ray WHIM Filaments The Environments of Galaxies: from kpc to Mpc, Crete - 2004 (F. Nicastro)

  12. WHIM Filaments in UV-FUV FUSE HST-GHRS NHI(z=0.011) < 4.7 x 1012 cm-2 NHI(z=0.027) < 8.5 x 1012 cm-2 NOVI(z=0.011) = 3.3 x 1013 cm-2 NOVI(z=0.027) < 1.4 x 1013 cm-2 The Environments of Galaxies: from kpc to Mpc, Crete - 2004 (F. Nicastro)

  13. Ionization Balance For 2 ions from the same element For 2 ions from different elements The Environments of Galaxies: from kpc to Mpc, Crete - 2004 (F. Nicastro)

  14. WHIM Solutions NVI-NVII-based OVII-based The Environments of Galaxies: from kpc to Mpc, Crete - 2004 (F. Nicastro)

  15. WHIM Solutions In Excellent Agreement with WHIM Expectations The Environments of Galaxies: from kpc to Mpc, Crete - 2004 (F. Nicastro)

  16. z=0.151 z=0.330 OVII Absorption toward 1ES 1028+511 (z=0.361) Chandra TOO on 2004, 03/11-13 Exposure = 149 ks Flux (0.5-10 keV) = 2 mCrab ~ 100 cts/res.el. (21-30 Å) NThr(OVII)>8 1015 cm-2 (3) z=0.151 The Environments of Galaxies: from kpc to Mpc, Crete - 2004 (F. Nicastro)

  17. OVII WHIM Number Density Cf. with: (Savage et al., 2002) Derived from Fang, Bryan & Canizares, 2002 The Environments of Galaxies: from kpc to Mpc, Crete - 2004 (F. Nicastro)

  18. Ωb(NOVII>7x1014 cm-2) • Mkn 421 (2 Filaments.): z=0.03 • Combined Mkn421+1ES1028+511 (3 Filaments): zeq(1ES1028+511)= 0.1; fOVII = 0.7 THE ‘MISSING’ BARYONS HAVE BEEN FOUND The Environments of Galaxies: from kpc to Mpc, Crete - 2004 (F. Nicastro)

  19. Summary • 3 X-ray WHIM Filaments detected with Chandra along two different lines of sight down to Nthres(OVII)=7x1014 and 8.8x1015 cm-2 resp. • Missing Baryons: once Lost but now Found: • Metallicity measurements constrain feedback models: [O/H]  -1.46 (z=0.011), [O/H] > -1.32 and [N/O]  0.65(z=0.027) • Chandra or XMM TOOs are the only way to go The Environments of Galaxies: from kpc to Mpc, Crete - 2004 (F. Nicastro)

  20. Chandra approved up to 2010 (possibly longer): collect data from > 5 sightlines towards blazars in outburst: up to z = 0.7 (2 to trigger in Chandra-AO5 & XMM-Newton-AO3 + 2 approved in AO6):  dNWHIM/dz, b (to better than 10 %), TWHIM(z<0.5), dTWHIM/dz, dZ/dz Long Term: mapping the WHIM up to z=1-2: needs high throughput and spectral resolution in X-ray: Constellation-X (R > 2.5 x LETG, A = 50 x LETG), XEUS (R ~ 2.5 x LETG, A = 750 x LETG) Pharos: (Elvis, Fiore et al. 2002 SPIE, astro-ph/0303444), Midex concept (CfA, Obs. Rome, JHU): R > 13 x LETG, A = 25 x LETG, Coverage: 12-150 Å. Slew on source in < 1-3 min.: about 20 Soft-GRB per year with F = 10-5 erg cm-2 (> 0.5 years on the brightest QSOs at z = 1-2). Short and Long Term Prospects The Environments of Galaxies: from kpc to Mpc, Crete - 2004 (F. Nicastro)

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