Taotao FangUC Berkeley

Collaborator: R. Croft, W. Sanders, J. Houck, R. Dave, N, Katz, D. Weinberg, L. Hernquist

Soft X-ray Emission from the Warm-Hot Intergalactic Medium

Baryon Phase Diagram:

Dave et al. (2001), Croft et al. (2001)

Cosmic X-ray Background

• Total Cosmic X-ray background (0.5 - 2 keV):~ 6. - 8. 10-12 ergs cm-2 s-1 deg-2

• Contribution from discrete sources:74 - 94 % (Mushotzky et al. 2000)

• Contribution from WHIM:likely ~ 5% (simulations from Croft et al. 2000,

Phillips et al. 2001) • Metal line emission account for a significant portion of WHIM

emission!

Simulating X-ray emission

• Parallel TreeSPH simulation by Dave, Katz, Weinberg & Hernquist (see Dave et al. 2001, Croft et al. 2001 for details).

• CDM with a cosmological constant = 0.6, m= 0.4 b= 0.02 h -2

• The simulation volume: a cube of side-length 50 h-1 Mpc

• The spatial resolution is 7 h-1 kpc

• Density-depended metallicity

Enlarged Region of Area (A) and (B):

(A) (B)

Cross-correlation of metal emission with nearby galaxies

Auto-correlation:

In Partnership With:

MISSING BARYON EXPLORER

A mission to locate baryons…

…on the road to completing our picture of the Universe

Missing Baryon Explorer Energy Range 40 – 2000 eVEnergy Resolution 4 eV (FHWM)Angular Resolution 4.9 arcminField of View 29.5’ x 29.5’Features Selected deep pointings All-sky survey Guest observer program

Configuration and Detection Limits

Instrument Astro-E2 Constellation-X XEUS MBE

A (cm2) 35 3,000 40,000 200

ΩFOV 2.9’x2.9’ 2.5’x 2.5’ 1x1 29.5x29.5

ΩPIXEL 0.48’ x 0.48’ 5’x5’ 2”x2” 4.9x4.9

R 100 400 500 150

RAΩFOV

(cm2 deg2)7 2,083 5,556 6439

EW (ev) 138.0 8.0 4.9 4.5

MBE view of a 10º x 10º sky region

MBE sky coverage:

This plot shows the fraction of the sky probed by MBE with at least one detectable emission line.

Summary

• Cosmological simulations: quantitative predictions of the physical properties of the WHIM gas and its observational signatures.

• X-ray emission: mapping 3-D distribution of the WHIM gas. By combining imaging/spectroscopy measurement, X-ray

emission shall provide direct evidence of the WHIM gas. • Cross-correlation with nearby galaxies: X-ray emission lines

show strong cross-correlation with nearby large scale structure. Angular correlation: WHIM gas tends to cluster strongly at small angle.

• Future prospective: high spatial/spectral resolution X-ray telescopes.