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Recalculating SXT Temperature Response Functions

(April, 2010 by Aki Takeda)
(October, 2010, revised: uncertainty analysis added.)
(February, 2011, revised: photospheric abundance added.)

1. Motivation.

As of 30-Apr-2010, our official SXT response function is the one made in 1995 April, and based on the spectral model calculated by Mewe et.al.(1985). New atomic data for the X-ray wavelength range have become available from Chianti atomic database. In order to adopt these new data, we recalculated our SXT temperature response function (expected data number for each analysis filter assuming to observe the isothermal plasma of the temperature range, 5.5 through 8.0 in logTe) using recent Chianti database and software (version 6.0.1).

2. New response functions.

Coronal spectra are calculated on specified elemental abundance and ionization equilibrium. In the latest Chianti database, several kinds and versions of abandance & ionization files are available. These allow us to generate a variety of response functions for different pairs of abundance & ion_eq files.

Our new response functions are calculated with the following two pairs.

Users are allowed to specify one of these response files in the latest software for temperature analysis. The new response files and the software to work with them are downloaded from here.

FYI, our traditional responses and some later work correspond to the following pairs.

3. Comparison of New/Old response files.

New and old response curves for each analysis filter(filter B), in linear and logarithmic scales.

No BackAl.1AlMg BeAl12Mg

Other sre files, and other ratios,

Comparison of line ratio curves derived from the new and old response functions.

AlMg/Al.1Mg/Al.1Al12/Al.1 Be/Al.1Mg/AlMg
Al12/AlMgBe/AlMgAl12/Mg Be/MgBe/Al12

Here are some more check plots (for peace of mind).

- This is the comparison of the sre files, made with sun_coronal_ext.abund and sun_coronal.abund.
- These are to compare Mewe's and Chianti's emission model. Both calculated with the same elemental abundance and ionization equilbrium files. Response curves for AlMg and Be filters, and the corresponding Filter ratios.

4. Step by Step Comparison.

4.1. Elemental abundances

We compared the following 3 abundance files. Plot of comparison among these three files is here. Comparison with other files is here. Text comparison file with other abundances together is here (1,2, and 4 corresponds to the above 3).

4.2. Ionization equilibrium

We will compare the following 3 abundance files. Plots of comparison among these three files for Fe ions. Chianti and Mazzotta_etal and Chianti and Arnaud_Rothenflug.

4.3. Continuum intensity from the isothermal plasma

The temperature dependance of the three atomic processes contributing to the continuum intensities (free-free, free-bound, and two photon) is here. The total continuum intensity (the sum of the three processes) from the 5MK, 2MK, and 1MK isothermal plasma is shown here, and these are the comparison with Mewe's results.

4.4. Line intensities from the isothermal plasma

The Chianti line intensities calculated with coronal_ and hybrid_ abundances are compared with Mewe's calculation in here. The dependance on the electoron density checked using coronal abundance and chianti.ioeq are here.

5. Examples of the temperature analysis



The trend of temperatures derived from the Be/Al12 filter pair : For AR9026 flare kernal, the latest response functions give higher value (up to 50%) than the traditional response file by Mewe. However, the AR6916 has the opposite trend. This difference comes from that two region uses different range of Be/Al12 filter ratio curve, as show in here.

6. Uncertainty of the temperatures and emission measures