Taotao Fang Soft X-ray Emission from the Warm-Hot Intergalactic Medium UC Berkeley
Soft X-ray Emission from the Warm-Hot
Intergalactic Medium
Taotao Fang
UC Berkeley
Collaborator: R. Croft, W. Sanders, J. Houck,
R. Dave, N, Katz, D. Weinberg, L. Hernquist
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
–
– b
= 0.6, m
= 0.02 h -2
= 0.4
• 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:
M ISSING B ARYON E XPLORER
A mission to locate baryons…
…on the road to completing our picture of the Universe
In Partnership With: Missing Baryon Explorer
Energy Range
Energy Resolution
40 – 2000 eV
4 eV (FHWM)
Angular Resolution 4.9 arcmin
Field of View
29.5’ x 29.5’
Features Selected deep pointings
All-sky survey
Guest observer program
Configuration and Detection Limits
Instrument Astro-E2
A (cm 2 ) 35
Constellation-X XEUS
3,000
Ω
FOV
Ω
PIXEL
2.9’x2.9’
0.48’ x 0.48’
R 100
RAΩ
FOV
(cm 2 deg 2 )
7
EW (ev) 138.0
2.5’x 2.5’
5’x5’
400
2,083
8.0
40,000
1x1
2”x2”
500
5,556
4.9
MBE
200
29.5x29.5
4.9x4.9
150
6439
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.
