July 11 X-Ray Gratings Workshop

Capella Grating Data and the Emission Line Project - An Update

Priya Desai (CfA)

Nancy Brickhouse

Jeremy Drake

Dave Huenenmoerder

Randall Smith

Andrea Dupree

Vinay Kashyap

July 11 X-Ray Gratings Workshop

Outline

• What is the Emission Line Project (ELP)?

• Some results and existing problems – Using Capella grating data

• Future Plans

July 11 X-Ray Gratings Workshop

What is the Emission Line Project?

- Collaborative effort organized by CXC

-To use the calibration data to identify potential atomic data problems that can be addressed theoretically or in the laboratory-mostly Capella

- Primary Goals:

- to improve the plasma spectral models used to

analyze and fit X-ray spectra.

- catalog of observed spectral lines

July 11 X-Ray Gratings Workshop

Publications related to the ELP• Chen, G.X., Smith, R.K., Brichouse, N.S.,Wargelin, B.J., Phys Rev

A, 2006, 74, 042709 • Gu, M.F., Gupta, R., Peterson, J.R., Sako, M. , 2006, ApJ, 649, 979• Keenan, F.P., Drake, J.J., Chung, S., Brickhouse, N. S., Aggarwal,

K.M., 2006, ApJ, 645, 597• Ishibashi, K., Dewey, D.,Huenenmorder, D., Testa, P., ApJ, 644,

L1171• Desai, P., et al ,2005, ApJ, 625, L59• Ness, J.U., Brickhouse, N.S., Drake, J.J., Huenenmorder, D., 2003,

ApJ, 598, 1277• Campbell,S.M., Brickhouse, N.S.,2001, AAS, 199.1313C • Ayres, T. R., 2001,ApJ, 549, 554A

July 11 X-Ray Gratings Workshop

Some Results

• Fe XVIII and Fe XIX EUV to X-ray discrepancies

• Line Identifications

• Ne IX G -ratios in Capella

July 11 X-Ray Gratings Workshop

Capella :X-rays

LETG 355 ks

HETG/HEG 300 ks

HETG/MEG 300 ks

-- Fe XVIII(resonance)

Fe XVIII

Desai et al. 2005

• For the strongest lines, the codes agree: discrepancies are 30% for Fe XVIII and a factor of 2 for Fe XIX. X-ray

Fe XVIII

Fe XIX

EUV FUV

• All X-ray/EUV line ratios are larger than predicted (by all codes).

Fe XVIII and Fe XIX X ray to EUV discrepancies

• Why Capella ?

• Atomic Physics

July 11 X-Ray Gratings Workshop

Interstellar Absorption? Partially ionized

Hydrogen => more Helium

Gu et al. 2006

NH=1.6e18

NH=7.2e18

NH=1.6e19

July 11 X-Ray Gratings Workshop

Interstellar Absorption?

NH=1.8e18cm-2

NH=7.2e18NH=1.6e19

July 11 X-Ray Gratings Workshop

Fe XVI line ratios

NH=7.2e18

NH=1.6e19

NH=1.8e18

Predicted line ratio (335.1/360.8)

July 11 X-Ray Gratings Workshop

Fe XVI line ratios

NH=1.8e18cm-2

NH=7.2e18cm-2

NH=1.6e19cm-2

l

335.4 /360.8

335.

4/63

.7

• 335/63.7

July 11 X-Ray Gratings Workshop

Blending with FeXIX in the Ne IX triplet region

Model Fe XIX lines from HULLAC(1% accuracy)

July 11 X-Ray Gratings Workshop

Blending with FeXIX in the Ne IX triplet region

With EBIT λ measurements (Brown et al. 2002, 5-10 mÅ)

July 11 X-Ray Gratings Workshop

Fe XIX Model Wavelengths Kotochigova et al. 2005

With this Fe XIX model we can match the positions of all features in the spectrum.

Derived T from Capella in better agreement

G-ratio agrees with LLNL EBITmeasurements of Wargelin (PhD Thesis 1993)

New Ne IX G-ratio calculations (Chen et al. 2006, PRA)

Recent Results

July 11 X-Ray Gratings Workshop

New Calculated G-ratios

• Ness et al Ne IX G- ratios don’t predict the correct temperature

• Chen et al improved calculations bring it more in line with observations

July 11 X-Ray Gratings Workshop

Future Plans

• A lot of work in theory and lab astro • Catalog of emission lines• Access to Users

Blending with Fe XIX in the Ne IX Spectral Region

Model Fe XIX wavelengths from HULLAC (1% accuracy)

With EBIT λ measurements (Brown et al. 2002, 5-10 mÅ)

Fe XIX Model Wavelengths from Dirac-Fock-Sturm Method

Kotochigova, in progress

With this Fe XIX model we can match the positions of all features in the spectrum.

Ne IX “R-ratio” and “G-ratio”

• Classic He-like diagnostics• “R-ratio” = f/i is density-sensitive.• “G-ratio” = (f + i)/r is temperature-

sensitive.

f = forbidden 1s2 1S0 - 1s2s 3S1

i = intercombination 1s2 1S0 - 1s2p 3P2

1s2 1S0 - 1s2p 3P1

r = resonance 1s2 1S0 - 1s2p 1P1

July 11 X-Ray Gratings Workshop

But there still is a problem!

• Fe XVI calculations

July 11 X-Ray Gratings Workshop

Improved wavelength calculations

• Provides substantial cleaning up of the

13.0-13.8 Angs Ne IX region

July 11 X-Ray Gratings Workshop

July 11 X-Ray Gratings Workshop

July 11 X-Ray Gratings Workshop

July 11 X-Ray Gratings Workshop