Talk given to the "X-ray Vision Workshop" in Washington, DC, October 2015

1. Coma
200 kpc
A2319
200 kpc
GALAXY CLUSTER GAS MOTIONS WITH
X-RAY SURVEYOR:
PROBINGTHE SMALL SCALES
John ZuHone, MIT Kavli Institute

2. 6.4 6.5 6.6
0.1110
normalizedcountss−1
keV−1
Energy (keV)
data and folded model
sekiya 6−Jun−2011 12:36
vturb = 0 km/s
vturb = 100 km/s
vturb = 300 km/s
vturb = 1000 km/s
6.7
w
xyz
j
k
e
po
Perseus simulated spectrum (wabs＊bapec)
He-like Fe line
at E0 ≈ 6.7 keV

3. 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

4. TURBULENCE IN COMA
Coma
200 kpc
ZuHone, Markevitch, & Zhuravleva 2015
(arXiv:1505.07848)

5. WHY COMA?
Churazov et al 2012
• bright and nearby
• large core radius
• no central AGN
• likely to be
turbulent

6. Inertial Range
Dissipation
Scale
Injection
Scale P(k) ~ k-α
k
P(k)

7. 3’x3’
1.5’ ≈ 40 kpc

8. “strip” “big cross” “small cross”
“fill” “checkerboard”
arXiv:1505.07848

9. 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

10. VARYING
INJECTION
SCALES
arXiv:1505.07848

11. VARYING
DISSIPATION
SCALES
Curves are
essentially
indistinguishable
arXiv:1505.07848

12. 10 kpc 20 kpc
100 kpc50 kpc
5’x5’
1” ≈ 0.5 kpc

13. σstat = 0 km/s σstat = 20 km/s
POWER SPECTRA Reblocked to
4”x4” pixels
M = 0.3

14. σstat = 40 km/s σstat = 80 km/s
POWER SPECTRA Reblocked to
4”x4” pixels
M = 0.3

15. SLOSHING
A2319
200 kpc
ZuHone, Miller, Simionescu, & Bautz 2015
(arXiv:1508.04426)

16. LOOKING
ONTOTHE
PLANE
SB T
σμ
arXiv:1508.04426

17. LOOKING
INTOTHE
PLANE
SB T
σμ
arXiv:1508.04426

18. DIGGING INTOTHE
VELOCITY FIELD

19. SIMULATED SPECTRA
Model:
Thermal broadening only
exposure time = 200 ks
Model:
Thermal and Gaussian
velocity broadening
exposure time = 200 ks
arXiv:1508.04426

20. PSF
SCATTERING
arXiv:1508.04426

21. VELOCITY DISTRIBUTIONS:
ASTRO-H
arXiv:1508.04426 (cheating! ignored PSF scattering)

22. VELOCITY DISTRIBUTIONS:
X-RAY SURVEYOR

23. 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

24. 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