Age dependence of EM in AR Cores... and... Some thoughts on the Accuracy of Atomic Data Helen Mason, Durgesh Tripathi, Brendan O’Dwyer and Giulio Del Zanna Loops-6, Belgium, June 2013 Photo: Giulio Del Zanna

Characteristic loop structures for solar active regions Large 1MK loops (171A) seem to be ‘almost isothermal’ and ‘spatially resolved’ by present day instruments such as TRACE, EIS, SDO/AIA. Are they? Check with HiC at 171A The hot core loops (3MK?) do not seem to be so well resolved. Look same in SDO/AIA and HiC. We can study their footpoints regions (moss regions). Micro-flare activity and Dynamic core loops – mini-post-flare? Very large ‘Fan’ loops reach far out into the corona, possibly joining remote active regions. SDO/AIA Observations ARE ALL THESE LOOPS HEATED IN THE SAME WAY???

Imaging versus spectroscopic observations Imaging instruments TRACE, EIT, Stereo/EUVI, SDO/AIA, HiC Intensity variations...flows, waves or pulses? Intensity changes – Ne or Te? Several spectral lines contributing to some wavelength bands? High cadence and good spatial coverage Relatively straightforward to analyse SoHO/CDS and SUMER, Hinode/EIS, Coronal visible lines High cadence at expense of spatial coverage...one slit position Uncertainties – jitter, line blending, absolute wavelengths, other instrumental effects – point spread function? A nightmare to analyse, very labour intensive... SUMER – absolute wavelengths relative to chromospheric lines Very good diagnostics: EM, Ne, flows, abundances Spectroscopic Instruments

: : TRACE image – 1” res SOHO/CDS – Mg IX - 6” res CDS and TRACE: off limb AR quiescent loops (1MK) Background subtraction is crucial 1 MK TRACE loops, are isothermal across the loop, but have 0.7 MK footpoints with Ne of around 2 x 10 9 cm -3. Imaging at 1” seems to resolve single flux tubes Del Zanna and Mason (2003), Del Zanna (2003)

Emission measure loci plot using CDS data, showing near isothermal temperature (Del Zanna & Mason, 2003) CDS: ‘warm’ 1MK Quiescent AR Loop

Hinode/EIS spectrum Hinode/EIS spectra are dominated by coronal ions (iron, particularly) Young, Mason et al. (2007, PASJ)

Active region density map Peter Young, 2007 The high quality of the EIS data makes density maps relatively easy to generate

Hinode EIS - temperature and density map for a limb AR Average electron density map from FeXIII lines Temperature map from FeXVI/FeXV Red is Log T = 6.7, yellow is Log T= 6.5 Hot, dense AR cores are clearly seen with EIS. XRT shows ‘dynamic’ activity. O’Dwyer et al, 2011

Impulsive heating, nanoflare trains Klimchuk, Bradshaw, Cargill, Reep Fix: Loop length: 2L = 80 Mm Power: ergs cm -3 s -1 Triangular pulse: width 100 sec. Vary: Delay between nanoflares Diagnostics T max, EM(T max ) EM ~ T a, T < T max EM ~ T b, T > T max

log EM (cm -5 ) log T EM(T) of Inter-moss: Tripathi, Mason and Klimchuk, 2011

HINODE/EIS EM Data points are the average of the EM of regions A, B, C subtracted by the average of EM for Bkg1 and Bkg2 reduced by a factor 4 (see next slide). Theory versus observations: hot core loops Tripathi, Klimchuk & Mason, 2011 EBTEL SIMULATIONS Loop half length = 2.4x10 9 cm Duration of nanoflare = 500s Amplitude = 0.04 erg cm -3 s -1 Repetition time = every 8000s Constant low level heating = erg cm -3 s -1 slope 

Active region First rotation – April 19 th, 2011 Second rotation – May 16 th, 2011 SDO available Active Region First rotation – March 28 th, 2010 Second rotation – April 27 th, 2010 NO SDO available Very carefully selected Inter-moss MCMC method was used to derive the slope and Ratio. Age dependence of EM distribution in AR cores Tripathi, D., O’Dwyer, B. and Mason, H.E., 2013

NOAA 11193: AIA Rotation 1 19-Apr-2011 Rotation 2 16-May-2011

AR high temperature emission and slope decreases with age: high to low frequency nanoflares? From log T = 6.0 to log T = 6.5 Slope = 2.61 ± 0.32 Ratio = 22 ± 12 From log T = 6.0 to log T = 6.5 Slope = 2.14 ± 0.53 Ratio = 9 ± 4 Log Ne = 9.7 Log Ne = 9.0

AR high temperature emission and slope decreases with age: high to low frequency nanoflares? From log T = 6.0 to log T = 6.5 Slope = 3.01 ± 0.12 Ratio = 50 ± 11 From log T = 6.0 to log T = 6.5 Slope = 2.81 ± 0.17 Ratio = 49 ± 14

Errors in the EM analyses. Observational errors - EIS (or SDO) calibration - Blends Errors in the EM/DEM methods -MCMC -Giulio’s method -EM Loci -EM Pottasch -Other methods Errors in the atomic data -Ionisation balance -Radiative data -electron collision data Other Uncertainties -elemental abundances -equilibrium? How to deal with all of these issues? -CHIANTI – v7.1 (soon V8) -Assess errors on individual lines -Look for consistency in results

Comparison between MCMC and Pottasch EM Methods Tripathi, D. and Ali, S.M., 2013

WARNING: Pottasch EM is only valid if the plasma is multi-thermal MCMC not reliable at low temperatures

Multi-thermal Emission in ARs Del Zanna, Oct 26 SDO/AIA 171A193A335A

Multi-thermal Emission in ARs Del Zanna, 2013 EM for 3MK AR Core loops: Lhs: T_max; rhs: T_eff slope of 3.4 Note consistency of EM for different ion stages of iron

Errors? Gennou et al, 2013: Emission Measure Slope Probability of the true slope given an observed slope  = 3 Uncertainty:  ~ 1.1 Guennou et al. (2013) slope 

CHIANTI An atomic database for astrophysics UK, USA, Italy First database to make atomic data freely available for astrophysics First released in 1996 Just released v7.1 Landi et al, 2013, ApJ, 763 Improved coverage in X-ray range (addressing 94A) Over 1,000 citation CHIANTI V8 – 2013?

New Ionisation Balance (Ni ions)

CHIANTI v.7.1: DW data (Landi & Dere 2013) + identifications of Del Zanna (2012). R-matrix data (Del Zanna+2012) provide increased intensities. They will be available in v.8. CHIANTI V7.1 and CHIANTI V8

G. Del Zanna Scattering calculation for Fe XII calculations: Fe XII Serious problems with the Fe XII spectrum. Many calculations: Flower (1977) Binello et al (several papers) Storey, Del Zanna, Mason (2005) Del Zanna (2012) EUV 4 S 3/2, 2 D 3/2, 2 D 5/2, 2 P 1/2, 2 P 3/2 2 D 3/2 4 P 1/2 4 P 3/2 2 P 1/2 SO

FeXII – Atomic Data re-visited (yet again!!) Mason & Del Zanna - IRIS meeting 2012 New CC Old CC UK APAP Team O’Dwyer, Del Zanna, Badnell, Mason and Storey, 2012, A&A, 537, 22 Atomic data for the X-ray lines of Fe VIII and Fe IX (for SDO/AIA, 94A) Del Zanna, Storey, Badnell and Mason (2012, in press) - new Fe XII atomic data The previous R-matrix calculation (Storey et al. 2004) has been extended to include all main n=4 levels (for the soft X-rays)

This plot shows how the density derived from a single, quiet Sun off-limb data-set has changed with time using the Fe XII λ186.88/λ and Fe XIII λ203.82/λ density diagnostics. The changes are due to improvements in the atomic data models in CHIANTI. CHIANTI - Fe XII density diagnostics

Summary More work needs to be done on EM tracking AR evolution Errors in the various DEM methods need checking carefully New EIS calibration is very important SDO/AIA responses now much better understood Abundances can give problems Atomic data are much better that they were! Benchmarking CHIANTI v7.1+ gives good results Errors need to be judged for each spectral line/transition WE NEED HIGHER SPATIAL RESOLUTION AND HIGHER CADENCE SPECTRAL OBSERVATIONS IRIS, SOLAR-C and Solar Orbiter