# Presentation: 161389

## The Iron-Line Complex-RHESSI Measurements

| Brian Dennis
Ken Phillips
Hugh Hudson | David Smith
Richard Schwartz
Kim Tolbert |
| --- | --- |

- RHESSI Workshop
- 4 – 6 June, 2003
- Glasgow, Scotland

## RHESSI Spectra

- RHESSI sees the iron-line complex at ~6.7 keV even with the thin and thick shutters in.
- The peak energy can be determined to <0.1 keV.
- The equivalent width (or line-to-continuum ratio) can also be accurately determined.
- The iron/nickel line complex at ~8 keV can also be detected.

## Slide 3

## Shutters Out

## RHESSI SpectraThin Shutters In (A1)Detector #41-minute accumulations

- RHESSI SpectraThin Shutters In (A1)Detector #41-minute accumulations

## RHESSI Spectra Thin Shutters (A1)Thin + Thick (A3)Detector #41-minute accumulations

## RHESSI Spectra

- Spectra in Thin (A1) & Thin+Thick (A3) Shutter States

- D4

- D1

- D2

- D3

- D5

- D6

- D7

- D8

- D9

## SPEX Spectral Fits-Thermal (Mewe)+Broken Power Law Photon SpectrumThin Shutters InDetector #4

## SPEX Spectral Fits-Thermal (Mewe)+Broken Power Law Photon SpectrumThin Shutters InDetector #4

- SPEX Spectral Fits-Thermal (Mewe)+Broken Power Law Photon SpectrumThin Shutters InDetector #4

## Thermal Fits to RHESSI Spectra

## SPEX Spectral Fits-Power Law +GaussianPhoton SpectrumShutters OutDetector #4

## SPEX Spectral Fits-Broken Power Law Thin & Thick Shutters InDetector #4

- SPEX Spectral Fits-Broken Power Law Thin & Thick Shutters InDetector #4

## SPEX Spectral Fits-Power Law +3 GaussiansThin & ThickShutters InDetector #4

## RHESSI Results

- All Shutters Out
- Gaussian Peak Energy from SPEX using Power-law + N-Gaussians fit from 5 – 30 keV

## RHESSI Results

- Gaussian Peak Energy from SPEX using Power-law + N-Gaussians fit from 5 – 30 keV

## RHESSI Results

- Equivalent Width of ~6.7-keV Peak from SPEX using Power-law + N-Gaussians fit from 5 – 30 keV

## RHESSI Results

- Power-law Index from SPEX using Power-law + N-Gaussians Fit from 5 – 30 keV

## RHESSI Results

- Gaussian Peak Energy from SPEX using Power-law + N-Gaussians fit from 5 – 30 keV

## RHESSI Results

- Power-law Flux from SPEX using Power-law + N-Gaussians Fit from 5 – 30 keV

## Mewe & Chianti Spectra

## Energy of Iron-line complex

- Energy in keV

## Equivalent Width of Iron-Line Complex

## Ionization Equilibrium

- Arnaud & Rothenflug (1985)

- Mazzotta et al. (1998)

- Fe XXV

- Fe XXV

## Conclusions (1)

- RHESSI detects the Fe-line complex at ~6.7 keV.
- Peak energy is high by ~0.1 – 0.2 keV.
- Peak energy varies with counting rate.
- Measured equivalent width is high by ~0.5 – 1.5 keV.
- Equivalent width shows possible evidence of nonthermal component to the continuum.
- RHESSI probably detects the Fe/Ni complex at ~8 keV.
- Great promise for improving separation of thermal and nonthermal components.

## Conclusions (2)

- Chianti & Mewe spectral models differ very significantly.
- Intensity of Fe-line complex is much lower below ~15 MK in Chianti.
- Probable cause is different ionization equilibrium models for Fe:
- Mewe uses Arnaud & Rothenflug (1985)
- Chianti uses Mazzotta et al. (1998)
- Iron abundance can be determined from RHESSI spectra vs. time for each flare.
- GOES temperatures are suspect since they are based on old (~1985) spectral codes (Thomas, private communication).