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Polarizationofsolarflaresat45and90GHz
DouglasF.Silva1,PauloSimões2,AdrianaValio1(akaA.Silva)
1-CRAAM–MackenzieUniversity,Brazil2-UniversityofGlasgow,UK
ChromoAID–March15-18,2016–Boulder,CO(USA)
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*
Flareemissionatmmduetogyrosynchrotronfromacceleratedelectrons*
Wavepropagationmode
i. Ordinaryii. Extraordinary:
i. RCP:N(+)Bii. LCP:S(-)B
* Stronglyaffectedbythepropagationconditions*
Observedcircular
polarizationat45and90GHzwithoppositesign
Flareradioemissionandpolarization
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*
Kundu&Vlahos(1979):Relationbetweentotalfluxandpolarizedfluxdependsontheratioofthemagneticintensityatlooplegs
S2
S1
S1 S2
B1>B2
Asymmetricmagneticloop
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* Radioobservationofthreesolarflares:i. Radiospectra;ii.
Polarizationdegreeat45and90GHz.
* Complementaryobservationsatotherwavelengths:i. XRay;ii.
UVimages;iii. Magnetograms.
* Qualitative comparison with numerical simulations of
radioemissioninflaring3Dmagneticloops(Simões2009).
Determinethemagneticfieldconfigurationandenergydistributionofacceleratedparticles
Goal
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* RSTN:2.7,5,8.8,and15.4GHz* POEMAS (POlarized Emission of
Millimeter
ActivityontheSun):45and90GHz*
SST(SubmillimeterSolarTelescope):212GHz
Radioobservation
ElLeoncitoObservatory(CASLEO)intheArgetinaAndes
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* Novelty:circularpolarizationmeasurements*
Frequencies:45and90GHz* Wholesolardisk(HPBW1.5°)*
Timeresolution:10ms* Sensibility:2–3K* CASLEO,Argentina*
Data:Nov2011–Dec2013
POEMAS
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3Solarflares
Flare GOESclass Location Polat45GHz Polat90GHz
17Feb2013 M1.9 N12E17 -8% +9%
13May2013 X2.8 N08E89 +7% -10%
05Nov2013 M1.0 S12E47 +35% -10%
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NumericalSimulation(Simões2009)
* Gyrosynchrotronemission-Ramaty(1969)
andRamatyetal.(1994).
* Injectionofacceleratedelectronsintothe
magneticloop
* Energydistributionofacceleratedelectrons
* Radiativetransfer
*
Resultsforflaringsource:v Radiospectrav Emissionmapswithtotalfluxandpolarizationfor
severalradiofrequencies*
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NumericalsimulationINPUTS
* Magneticloop* Magneticfieldintensityalongtheloop*
Length:1-3x109cm*
Position(longitude,latitude):locationofflareinUVimages*
Azimuth(magnetograma):magneticfield* Inclination:0o*
Ambientthermalelectrons:* Density:1x1010cm-3* Temperature:10MK*
Nonthermalelectrons:* Spectralindex* Density:5x107cm-3*
Energycutoffs:10keV–20MeV
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Explos„oSolarM1 .9
Flare–17Feb2013(M1.9)
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Radiospectra+154718.0
1 10 100[F R E QU N C IA ]
1
10
100
1000
s.f.u
.[10
-22W
m-2Hz-1]
F requÍnc iadepico=4 7GHZ
alfa=-2.3 7702
+154722.0
1 10 100[F R E QU N C IA ]
1
10
100
1000
s.f.u
.[10
-22W
m-2Hz-1]
F requÍnc iadepico=23 .GHz
alfa=-1.2 7918
+154722.0
1 10 100[F R E QU N C IA ]
1
10
100
1000
s.f.u
.[10
-22W
m-2Hz-1]
F requÍnc iadepico=23 GHz
alfa=-1.2 7918
+154724.0
1 10 100[F R E QU N C IA ]
1
10
100
1000
s.f.u
.[10
-22W
m-2Hz-
1]
F requÍnc iadepico=16 GHz
alfa=-1.1 9256
+154725.0
1 10 100[F R E QU N C IA ]
1
10
100
1000
s.f.u
.[10
-22W
m-2Hz-
1]
F requÍnc iadepico=15 GHz
alfa=-1.2 6095
+154727.0
1 10 100[F R E QU N C IA ]
1
10
100
1000s.f.u
.[10
-22W
m-2Hz-
1]
F requÍnc iadepico=13G Hz
alfa=-1.3 3153
-
RCPandLCP
-Pol@45GHz
+Pol@90GHz
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SDOAIA_317117 -F eb-2013 15:47 :11.34 0UT
-420 -400 -380 -360 -340 -320 -300X(ar csec s)
280
300
320
340
360
380
400
Y(ar
csec
s)
UV(171A)andMagnetogram
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Simulationresults
*
Asymmetricmagneticfield:-3100Ginonefootpointand3800Gontheother.*
Position:Lat18º,Long-22º* Anglewrtsolarequator:5º
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Flare–13May2013(X2.8)
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Radiospectra
-
RCPandLCP
+Pol@45GHz
-Pol@90GHz
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SDO_AIA_17113-Ma io -2013 16:0 3:59. 340UT
-1000 -950 -900 -850X(ar csec s)
0
100
200
300
400
Y(ar
csec
s)
UV(171A)andMagnetogram
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Simulationresults
*
Asymmetricmagneticfield:3200Ginonefootpointand-3420Gontheother.*
Position:Lat15º,Long-80º* Anglewrtsolarequator:70º
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Flare–5Nov2013(M1.0)
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Radiospectra
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+Pol@45GHz
-Pol@90GHz
RCPandLCP
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UV(171A)andMagnetogram
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Simulationresults
*
Asymmetricmagneticfield:-4500Ginonefootpointand3000Gontheother.*
Position:Lat-15º,Long-47º* Anglewrtsolarequator:-60º
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Summary
Parameter17Feb2013 13May2013 5Nov2013
Obs Model Obs Model Obs Model
Magneticfield
-1500and
1400G
-3100and3800G
-1300and1200G
3200and–3480G
-1300and1200G
3000and-4500G
Latitude&Longitude 12°,-17° 18°,-22° 8°,-89° 15°,-80°
-12°,-47° -15°,47°
Pol45GHz -0.08 -0.03 +0.07 +0.096 +0.35 +0.11
Pol90GHz +0.09 +0.027 -0.10 -0.045 -0.18 -0.39
Spectralindex 2-3 3.5 2-3.4 3.5 1.8–3.5 3.5
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S1 S2B1>B2
Conclusions*
Oppositesignofpolarizationat45and90GHzduetoasymmetric
magneticloop
* Sourcesatdifferentlooplegs
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Thankyou!
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IAUSymp328:Livingaroundactivestars
* October17-21,2016* MaresiasBeachHotel*
Maresias,SP,Brazil
* Abstractsubmission®istration:
16March2016(Today!)* www.sab-astro.org.br/IAUS328
