Galaxy Cluster Gas Motions with X-ray Surveyor: Probing the Small Scales
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Transcript of Galaxy Cluster Gas Motions with X-ray Surveyor: Probing the Small Scales
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Coma
200 kpc
A2319
200 kpc
GALAXY CLUSTER GAS MOTIONS WITH X-RAY SURVEYOR:
PROBING THE SMALL SCALES
John ZuHone, MIT Kavli Institute
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6.4 6.5 6.6
0.1
110
norm
aliz
ed c
ount
s s−
1 keV
−1
Energy (keV)
data and folded model
sekiya 6−Jun−2011 12:36
vturb = 0 km/svturb = 100 km/svturb = 300 km/svturb = 1000 km/s
6.7
w
xyz
jk
e
po
Perseus simulated spectrum (wabs*bapec)
He-like Fe line at E0 ≈ 6.7 keV
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ASTRO-H
• 3’x3’ FOV
• ~5 eV spectral resolution
• ~1’ spatial PSF
X-RAY SURVEYOR
• 5’x5’ FOV
• ≲ 5 eV spectral resolution
• ~1” spatial PSF
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TURBULENCE IN COMAComa
200 kpc
ZuHone, Markevitch, & Zhuravleva 2015 (arXiv:1505.07848)
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WHY COMA?
Churazov et al 2012
• bright and nearby
• large core radius
• no central AGN
• likely to be turbulent
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Inertial Range
Dissipation Scale
Injection Scale P(k) ~ k-α
k
P(k)
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3’x3’
1.5’ ≈ 40 kpc
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“strip” “big cross” “small cross”
“fill” “checkerboard”
arXiv:1505.07848
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ERRORS• cosmic variance errors
• Natural variations in the velocity field
• Decrease with more baselines
• measurement errors
• Statistical errors on line shift and width from Poisson statistics (increase with increasing line width, decrease with increasing exposure)
• Systematic errors on the line shift from gain uncertainty
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VARYING DISSIPATION
SCALESCurves are essentially
indistinguishable
arXiv:1505.07848
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10 kpc 20 kpc
100 kpc50 kpc
5’x5’
1” ≈ 0.5 kpc
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σstat = 0 km/s σstat = 20 km/s
POWER SPECTRA Reblocked to 4”x4” pixels
M = 0.3
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σstat = 40 km/s σstat = 80 km/s
POWER SPECTRA Reblocked to 4”x4” pixels
M = 0.3
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SLOSHINGA2319
200 kpc
ZuHone, Miller, Simionescu, & Bautz 2015 (arXiv:1508.04426)
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DIGGING INTO THE VELOCITY FIELD
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SIMULATED SPECTRA
Model: Thermal broadening only
exposure time = 200 ks
Model: Thermal and Gaussian
velocity broadening
exposure time = 200 ks
arXiv:1508.04426
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VELOCITY DISTRIBUTIONS: ASTRO-H
arXiv:1508.04426 (cheating! ignored PSF scattering)
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VELOCITY DISTRIBUTIONS: X-RAY SURVEYOR
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BUT WHY X-RAY SURVEYOR?
• < 1” resolution of Chandra resulted in discovery of cold fronts
• Need nearly equivalent resolution to study thermodynamic and kinematic properties near interface
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SUMMARY• With Astro-H, we will finally start to get a handle on gas kinematics in galaxy
clusters
• But limited resolution will only get us so far—just the basic properties of the velocity field on large scales
• With an X-ray Surveyor:
• We can potentially get at the dissipation scale in Coma, so long as we can keep the measurement errors down
• Larger effective area and higher spatial resolution would enable us to more precisely nail down the characteristics of the velocity field in sloshing cores