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 E-mail: 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 (FP7/2007-2013) under grant agreement no. 606862 (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. 284461 (eheroes project). SOL2009-07-04T04:37
OUTLINE v IntroducWon Ø X-ray emission during solar flares Ø DifferenWal Emission Measure: Thermal CharacterisWcs v SOL2009-07-04T04:37 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) SOL2009-07-04T04:37 27/07/2016
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 10 27 10 32 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) SOL2009-07-04T04:37 27/07/2016 (1/18)
Arun Kumar Awasthi (IAUWR) SOL2009-07-04T04:37 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.
Arun Kumar Awasthi (IAUWR) SOL2009-07-04T04:37 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)
Arun Kumar Awasthi (IAUWR) SOL2009-07-04T04:37 27/07/2016 (4/18) SOL2009-07-04T04:37 Observacons Solar Photometer in X-rays (SphinX) SphinX -> 1.2-15 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 1.2 15.0 kev. hpp://156.17.94.1/ sphinx_l1_catalogue/ SphinX_cat_main.html
SOL2009-07-04T04:37 Observacons Solar Photometer in X-rays (SphinX) & SOXS SOXS -> 4-25 kev - Temporal and spectral resoluwon -> 3s and 0.7 kev. hpps://www.prl.res.in/~soxs-data Flown on-board GAST-2 satellite on May 08, 2003. 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) SOL2009-07-04T04:37 27/07/2016 (5/18)
Arun Kumar Awasthi (IAUWR) SOL2009-07-04T04:37 27/07/2016 (6/18) SOL2009-07-04T04:37 Observacons Solar Photometer in X-rays (SphinX) SOL2009-07-04T04:37, is the only event common recorded from Solar X-ray Spectrometer (SOXS, Indian) and SphinX (Polish) instruments. X-Ray light-curve of AR 11024 as seen by SphinX
Arun Kumar Awasthi (IAUWR) SOL2009-07-04T04:37 27/07/2016 (7/18) SOL2009-07-04T04:37 Observacons SphinX & SOXS GOES
SOL2009-07-04T04:37 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) SOL2009-07-04T04:37 27/07/2016 (8/18)
SOL2009-07-04T04:37 Observacons EUV emission: STEREO A STEREO-A Arun Kumar Awasthi (IAUWR) SOL2009-07-04T04:37 27/07/2016 (9/18)
SOL2009-07-04T04:37 Observacons EUV emission: STEREO B STEREO-B Ø Accompanied by Erupcon Arun Kumar Awasthi (IAUWR) SOL2009-07-04T04:37 27/07/2016 (10/18)
Arun Kumar Awasthi (IAUWR) SOL2009-07-04T04:37 27/07/2016 (11/18) ü We derive the best-fit DEM[T] for input X-ray spectrum in three energy bands: 1. 1.6-5.0 kev (Low-energy part of SXR) 2. 5.0-8.0 kev (High-energy part of SXR) 3. Combined (1.6-8.0 kev) SXR spectrum. ü FuncWonal form of DEM[T] is assumed to be single Gaussian SOL2009-07-04T04:37 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
Arun Kumar Awasthi (IAUWR) SOL2009-07-04T04:37 27/07/2016 (12/18) SOL2009-07-04T04:37 Best-fit DEM[T]: Synthesized Spectra Single Gaussian funcwonal form of DEM[T] ----------------------------------------------- Energy DEM p (10 49 ) T p ----------------------------------------------- 1.6-5.0 1.72 6.89 5.0-8.0 1.66 6.91 1.6-8.0 1.68 6.89
Arun Kumar Awasthi (IAUWR) SOL2009-07-04T04:37 27/07/2016 (13/18) SOL2009-07-04T04:37 Best-fit DEM[T]: Observacons Single Gaussian funcwonal form of DEM[T]
Arun Kumar Awasthi (IAUWR) SOL2009-07-04T04:37 27/07/2016 (14/18) SOL2009-07-04T04:37 Best-fit DEM[T] Power-law funcwonal form of DEM[T] T min =0.5 kev (fixed)
Arun Kumar Awasthi (IAUWR) SOL2009-07-04T04:37 27/07/2016 (15/18) SOL2009-07-04T04:37 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 ).
Arun Kumar Awasthi (IAUWR) SOL2009-07-04T04:37 27/07/2016 (16/18) WS DEM inversion SOL2009-07-04T04:37 Best-fit DEM[T]
Arun Kumar Awasthi (IAUWR) SOL2009-07-04T04:37 27/07/2016 (17/18) SOL2009-07-04T04:37 Best-fit DEM[T] WS DEM inversion: DEM evoluwon SphinX only SphinX + SOXS
Arun Kumar Awasthi (IAUWR) SOL2009-07-04T04:37 27/07/2016 (17/18) SOL2009-07-04T04:37 Best-fit DEM[T] DEM inversion: SOL2010-11-15T22:30 (B8.3) Aschwanden (2013) Hannah & Kontar (2012)
Arun Kumar Awasthi (IAUWR) SOL2009-07-04T04:37 27/07/2016 (18/18) Thermal EnergeWcs SOL2009-07-04T04:37 Thermal Energeccs Iso-thermal Energy MulW-thermal Energy
Summary Arun Kumar Awasthi (IAUWR) SOL2009-07-04T04:37 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 13.0 5.5 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 (1.6-5.0 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.
The research leading to these results has received funding from the European Community s Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 606862 (F-CHROMA) This work was supported by the grant of Polish Ministry of Science and Higher Education No. 3243/7.PR/14/2015/2 (2014-2016)