Arun Kumar Awasthi (IAUWR)

Transcription

1 Differential emission measure distribution and thermal characteristics during a B8.3 flare on July 04, 2009 Arun Kumar Awasthi Ins%tute of Astronomy University of Wroclaw, Poland awasthi@astro.uni.wroc.pl, arun.awasthi.87@gmail.com Collaborators: Barbara Sylwester 2, Janusz Sylwester 2 and Rajmal Jain 3 2. Solar Physics Division, Space Research Centre, Polish Academy of Sciences, Wroclaw, Poland 3. Kadi Sarva Vishwavidyalaya, Gandhinagar, Gujarat, India Arun Kumar Awasthi (IAUWR) July 27, 2016 Acknowledgement: The research leading to these results has received funding from the European Community s Seventh Framework Programme (FP7/ ) under grant agreement no (F- CHROMA). Also, this has the support of the Polish NCN grant 2011/01/B/ST9/05861 and from the European Commissions Seventh Framework Programme under the grant agreement No (eheroes project). SOL T04:37

2 OUTLINE v IntroducWon Ø X-ray emission during solar flares Ø DifferenWal Emission Measure: Thermal CharacterisWcs v SOL T04:37 Ø ObservaWons Ø Thermal CharacterisWcs of the flare plasma derived by: o Single Gaussian DEM[T] o Power-law DEM[T] o Withbroe-Sylwester Inversion Ø Thermal EnergeWcs Ø Summary Arun Kumar Awasthi (IAUWR) SOL T04:37 27/07/2016

3 IntroducWon Solar Flares Energy Release processes during a flare o Solar flare is one of the most impulsive phenomena occurring in the atmosphere of our Sun, releasing typically ergs of energy in 10 3 s. Underlying physical processes: A Glance o Powered by magnewc reconnecwon o Electrons are accelerated to high speed, generawng a burst of radio energy as well as impulsive loop-top hard x-ray emission. o Non-thermal electrons are channelled down to strike the chromosphere emifng hard x-rays. o Beams of accelerated protons cause nuclear reacwons that result in gamma-ray spectral lines and energewc neutrons. o Chromospheric evaporawon, accompanied by a slow, gradual increase in sog x-ray radiawon. Arun Kumar Awasthi (IAUWR) SOL T04:37 27/07/2016 (1/18)

4 Arun Kumar Awasthi (IAUWR) SOL T04:37 27/07/2016 (2/18) High energy emission IntroducWon Solar Flares ü A typical M-class solar flare can be observed across almost enwre electromagnewc spectrum. ü X-ray emission during solar flares mainly originates from corona and upper chromosphere. ü X-ray spectrum observed during a flare can serves as the best probe of studying various plasma processes of thermal and nonthermal origin. Aschwanden (2005) ü Thermal emission Ø Isothermal Ø MulW-thermal ü Non-thermal emission Ø Energies much larger than mean thermal energy of the background plasma Spectral Inversion of the flare emission probes various energy release mechanisms occurring in the different layers of solar atmosphere.

5 Arun Kumar Awasthi (IAUWR) SOL T04:37 27/07/2016 (3/18) Emission measure IntroducWon Inversion Problems in Flares o The study of thermal characteriswcs of the flare plasma by the inversion of observed X-ray spectrum is made by forward-fifng model photon flux generated by: Isothermal Emission Measure MulW-thermal plasma through assuming a funcwonal form of DEM[T]. Uncertainces: o DEM[T] is known with large uncertainwes owing to the inevitable inversion problem. o Several funcwonal forms are available to forward-fit the observed spectra. Craig & Brown (1976)

6 Arun Kumar Awasthi (IAUWR) SOL T04:37 27/07/2016 (4/18) SOL T04:37 Observacons Solar Photometer in X-rays (SphinX) SphinX -> kev - Temporal and spectral cadence -> 6μs and 0.4 kev. A spectrophotometer designed to observe the solar corona in SXRs. Flown on board the Russian CORONAS- PHOTON satellite on 2009 January 30. Employed three Si PIN diode detectors to record X-rays in the energy range kev. hpp:// / sphinx_l1_catalogue/ SphinX_cat_main.html

7 SOL T04:37 Observacons Solar Photometer in X-rays (SphinX) & SOXS SOXS -> 4-25 kev - Temporal and spectral resoluwon -> 3s and 0.7 kev. hpps:// Flown on-board GAST-2 satellite on May 08, Employed two semiconductor devices, namely, a silicon (Si) PIN (4 25 kev) and a Cadmium Zinc Telluride (CZT) detector (4 56 kev). The energy resoluwon of the Si detector is 0.8 kev while that for CZT detector is 1.7 kev. Temporal cadence is 3 s during quiet and gradual phase of the flare while 100 ms during the rise to the peak phase. Arun Kumar Awasthi (IAUWR) SOL T04:37 27/07/2016 (5/18)

8 Arun Kumar Awasthi (IAUWR) SOL T04:37 27/07/2016 (6/18) SOL T04:37 Observacons Solar Photometer in X-rays (SphinX) SOL T04:37, is the only event common recorded from Solar X-ray Spectrometer (SOXS, Indian) and SphinX (Polish) instruments. X-Ray light-curve of AR as seen by SphinX

9 Arun Kumar Awasthi (IAUWR) SOL T04:37 27/07/2016 (7/18) SOL T04:37 Observacons SphinX & SOXS GOES

10 SOL T04:37 Observacons Comparison of SphinX & SOXS Spectrum ü A systemawc difference of a factor of 2.5 is eswmated in the X-ray spectra of 4-8 kev energy band observed by SOXS and SphinX. ü Mrozek et al. (2012) in their study of flares commonly observed by SphinX and RHESSI found a systemawc difference of a factor of 2-6. We prepared combined data by applying (dividing) the empirical normalizacon factor in the records obtained from SOXS. Arun Kumar Awasthi (IAUWR) SOL T04:37 27/07/2016 (8/18)

11 SOL T04:37 Observacons EUV emission: STEREO A STEREO-A Arun Kumar Awasthi (IAUWR) SOL T04:37 27/07/2016 (9/18)

12 SOL T04:37 Observacons EUV emission: STEREO B STEREO-B Ø Accompanied by Erupcon Arun Kumar Awasthi (IAUWR) SOL T04:37 27/07/2016 (10/18)

13 Arun Kumar Awasthi (IAUWR) SOL T04:37 27/07/2016 (11/18) ü We derive the best-fit DEM[T] for input X-ray spectrum in three energy bands: kev (Low-energy part of SXR) kev (High-energy part of SXR) 3. Combined ( kev) SXR spectrum. ü FuncWonal form of DEM[T] is assumed to be single Gaussian SOL T04:37 Best-fit DEM[T] Energy band dependence: Synthesized mulw-thermal X-ray spectrum ü Firstly, we find the best-fit on synthesized mulw-thermal theorewcal photon flux

14 Arun Kumar Awasthi (IAUWR) SOL T04:37 27/07/2016 (12/18) SOL T04:37 Best-fit DEM[T]: Synthesized Spectra Single Gaussian funcwonal form of DEM[T] Energy DEM p (10 49 ) T p

15 Arun Kumar Awasthi (IAUWR) SOL T04:37 27/07/2016 (13/18) SOL T04:37 Best-fit DEM[T]: Observacons Single Gaussian funcwonal form of DEM[T]

16 Arun Kumar Awasthi (IAUWR) SOL T04:37 27/07/2016 (14/18) SOL T04:37 Best-fit DEM[T] Power-law funcwonal form of DEM[T] T min =0.5 kev (fixed)

17 Arun Kumar Awasthi (IAUWR) SOL T04:37 27/07/2016 (15/18) SOL T04:37 Best-fit DEM[T] Withbroe-Sylwester DEM inversion ü A numerical technique which employs maximum likelihood approach. ü The DEM distribuwon in one step of iterawon [j] (DEM j (T )) is eswmated from that derived in the preceding iterawon (DEM j 1 (T )), and by employing a correcwon factor (c i ) as well as weight factor (w i ).

18 Arun Kumar Awasthi (IAUWR) SOL T04:37 27/07/2016 (16/18) WS DEM inversion SOL T04:37 Best-fit DEM[T]

19 Arun Kumar Awasthi (IAUWR) SOL T04:37 27/07/2016 (17/18) SOL T04:37 Best-fit DEM[T] WS DEM inversion: DEM evoluwon SphinX only SphinX + SOXS

20 Arun Kumar Awasthi (IAUWR) SOL T04:37 27/07/2016 (17/18) SOL T04:37 Best-fit DEM[T] DEM inversion: SOL T22:30 (B8.3) Aschwanden (2013) Hannah & Kontar (2012)

21 Arun Kumar Awasthi (IAUWR) SOL T04:37 27/07/2016 (18/18) Thermal EnergeWcs SOL T04:37 Thermal Energeccs Iso-thermal Energy MulW-thermal Energy

22 Summary Arun Kumar Awasthi (IAUWR) SOL T04:37 27/07/2016 ü We find large values of DEMp, however at low Tp for the lower band in comparison to the relawvely lower values of DEMp at higher Tp derived for the best- fit of high energy band part of the spectrum. ü Time evoluwon of the DEM[T] distribuwon employing a W S maximum likelihood DEM inversion algorithm to individual as well as combined observawons from SphinX resulted: a. The best-fit DEM[ T] distribuwon during the flare onset and post-maximum phase has single Gaussian funcwon appearance with a width of 1 MK. This suggests isothermal plasma with the temperature MK. b. During the rise to the peak of the impulsive phase of the flare we find the presence of mulc-thermal plasma as the corresponding best-fit DEM[ T] curves show a double Gaussian form with widths of 1.5 MK. ü Energy eswmated from parameters derived only from spectral inversion of the low-energy part ( kev) of sog X-ray spectrum results in high thermal energy content than that obtained from combined spectral analysis. ü Same eswmated with from only higher energy part of SXR spectra leads to low thermal energy eswmates in comparison to that calculated from combined energy band analysis. ü Pre-assumed funcwonal form of DEM[T] results in an order higher thermal energy content than that eswmated by W-S inversion algorithm.

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24 The research leading to these results has received funding from the European Community s Seventh Framework Programme (FP7/ ) under grant agreement no (F-CHROMA) This work was supported by the grant of Polish Ministry of Science and Higher Education No. 3243/7.PR/14/2015/2 ( )