Transcript Document

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
– = 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:
MISSING BARYON EXPLORER
A mission to locate baryons…
…on the road to completing our picture of the Universe
In Partnership With:
Missing Baryon Explorer
Energy Range
40 – 2000 eV
Energy Resolution
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
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.