Atomic Physics Explains the Universe

Randall SmithSmithsonian Astrophysical Observatory

Building Structure

Relaxing Structure

Fabian et al., Nature, 1984

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 heated.

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, 1994)

Spectra from Real Structure

Peterson et al. 2003: Cluster cooling flows don’t cool.

36 ksec

20 ksec

40 ksec

38 ksec

38 ksec

26 ksec

54 ksec

29 ksec

39 ksec

33 ksec

36 ksec

50 ksec

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.’

Lesson: 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?

After de Plaa et al 2007

We cannot match the observed 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)…

Lesson: 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.

compilation– CHIANTI v6.0 used for non-X-ray emitting ions

New Instruments/Missions

Astro-H: Planned launch in 2014 with 32 pixel silicon microcalorimeter

Astro-H 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 GSFCJay 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 m

9.1 m

TES size 50 µm x 50 µm 35 µm x 35 µm 20 µm x 20 µm 12 µm x 12 µm

Absorber size 75 µm x 75 µm 57 µm x 57µm 42 µm x 42 µm 34 µm x 34 µm

What energy resolution is achievable ?

• Mn K1 & K2 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 2-10MK.

• Strong lines from Fe, O, N, Na, Ne, Ni, Ca, Cr, Ar, Mg, Si, S

• 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

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.

IXO: From The Decadal to Cosmic Visions