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Atomic Physics Explains the
Randall Smith
Smithsonian Astrophysical Observatory
Building Structure
Relaxing Structure
Most of the mass is in-between
the clusters, with kT ~ 1-10 keV.
Hydrostatic equilibrium plus
radiative cooling implies that at
some point the temperature at
the core must collapse (to ~104 K,
whereupon the gas forms stars).
This is inevitable unless the gas is
However, “No stable heating process
yet devised is able to counteract the
effects of radiative cooling and
account for the observed X-ray
images and spectra.” (Fabian, ARA&A,
Fabian et al., Nature, 1984
Spectra from Real Structure
36 ksec
26 ksec
20 ksec
54 ksec
36 ksec
40 ksec
29 ksec
50 ksec
38 ksec
39 ksec
38 ksec
33 ksec
Peterson et al. 2003: Cluster cooling flows don’t cool.
Heating Structure
Turbulent Structure?
Doesn’t seem like it – in
some cases, line width
limits show that the
turbulent support for
clusters is < 13% of that
needed (Sanders et al.
2010). So any heat input is
relatively ‘gentle.’
We Need a Diagnostic for the Heat Source
• Any heat source will leave a spectral imprint
on the gas – a doppler shift, line broadening,
ion balance.
• High resolution spectra combined with
accurate plasma models are absolutely
necessary if we are to find this source.
Enriching Structure?
We cannot match the
abundances in
clusters to any linear
combination of the
two sources.
Possibly due to
inadequate atomic
models? Argon line
data from mid-80’s
(but so is Sulfur and
Calcium data)…
After de Plaa et al 2007
All X-ray Bright Lines are Important
• AtomDB update (thanks to Adam!)
– All H-like, He-like collisional data now ‘modern’
– DR, RR level-separated rates updated for H-like,
He-like, Li-like and Fe L-shell ions
– Ionization/recombination rates from Bryans et al.
– CHIANTI v6.0 used for non-X-ray emitting ions
New Instruments/Missions
Astro-H: Planned launch in 2014 with 32 pixel silicon microcalorimeter
Effective Area & Resolving Power
Sample Science: A2029
Using redshifted Fe XXV lines, measure the amount of turbulence in the cluster –
something currently only possible with a particular type of cluster.
Expelling Elements in M82
High Spectral Resolution, High Cadence, Imaging
X-ray Microcalorimeter Arrays for Solar Physics
Simon Bandler, Catherine Bailey, Jay Chervenak, Megan Eckart, Fred Finkbeiner,
Caroline Kilbourne, Daniel Kelly, Richard Kelley, F. Scott Porter, Jack Sadleir, Stephen Smith
- X-ray Astrophysics Laboratory at GSFC
Jay Bookbinder, Ed DeLuca, Randall Smith - SAO
Supported by NASA ROSES: Solar & Heliospheric Physics
• Original motivation: RAM - Microcalorimeters to study
dynamics & energetics of solar corona
• Simultaneous imaging, spectroscopy & high cadence
• Pixels need to be small and fast
How small are the pixels ?
42 mm
9.1 mm
TES size
Absorber size
50 µm x 50 µm
75 µm x 75 µm
35 µm x 35 µm
57 µm x 5 7µm
20 µm x 20 µm
42 µm x 42 µm
12 µm x 12 µm
34 µm x 34 µm
What energy resolution is achievable ?
• Mn Ka1 & Ka2 x-rays at 6 keV from an 55Fe internal conversion source
• Instrumental broadening consistent with a gaussian response with 2.13
eV resolution FWHM
Solar X-Ray Spectroscopy
• Excellent selection of lines with formation
temperatures between 2-30MK.
• Density sensitive lines covering temperatures from 210MK.
• Strong lines from Fe, O, N, Na, Ne, Ni, Ca, Cr, Ar, Mg, Si,
• Strong iron emission lines, Fe XVII – XXIV
• Continuum emission between 1.5-10A
• Detection of non-thermal electrons from small flares
• Modeling of X-ray Spectra is well developed and allow
scientists to compare detailed forward models with
state-of-the-art observations.
Hot component has 1% EM of AR component
Hot component has 1% EM of AR component
From The Decadal to Cosmic Visions
The Decadal recognized "IXO’s
high scientific importance" as a
"powerful X-ray telescope that will
transform our understanding of hot
gas associated with stars and
galaxies in all evolutionary stages"
and also states that IXO is "central
to many of the science questions
identified by this survey." The
report summarizes that NASA
should "determine an appropriate
path forward to realize IXO as soon
as possible" if IXO is selected by
ESA as an L-class mission, and
that IXO has been recommended
for approximately $200M in
technology development funding
for this decade.