quiet-sun magnetism - probing deep photospheric layers ... · quiet-sun magnetism probing deep...

Quiet-Sun MagnetismProbing Deep Photospheric Layers with High Magnetic Sensitivity

Andreas Laggand the GREGOR/GRIS team1

Max-Planck-Institut fur SonnensystemforschungGottingen, Germany

1 Kiepenheuer Institut fur Sonnenphysik (KIS), Freiburg; Leibniz-Institut fur Astrophysik Potsdam (AIP); Germany

Instituto de Astrofsica de Canarias (IAC), Tenerife, Spain

Hinode-10 Meeting

NagoyaSep-05 2016

1 / 311

Motivation

RelevanceQS magnetism covers>90% of solar surface(even during maxima);15% in inter-networkcrucial to understandthe solar globalmagnetisme.g. origin:local (surface) dynamoor cascade from globaldynamo?

2 / 31M. Rempel (MURaM)

Controversial Findings Strength: few Gauss 200 Gauss kilo-Gauss?

Summary angular distributions (Tab. 2 from Steiner & Rezaei, 2012)

4 / 311

2

1

2

Controversial Findings Strength: few Gauss 200 Gauss kilo-Gauss?

Summary of observations

5 / 31

Reasons for Non-Conclusive Results Low B weak signals

Reason 1: Sensitivity of polarimeters

B=50G, INC=70 deg

Wavelength []

0.40.60.81.0

I

0.00100.0005

0.00000.00050.0010

Q/I C

6301.0 6301.5 6302.0 6302.5 6303.00.0040.002

0.0000.0020.004

V/I C

Fe1 Fe1Fe1 Fe1

6 / 31

Reasons for Non-Conclusive Results Low B weak signals

Reason 1: Sensitivity of polarimeters

B=50G, INC=70 deg

Wavelength []

0.40.60.81.0

I

0.00100.0005

0.00000.00050.0010

Q/I C

6301.0 6301.5 6302.0 6302.5 6303.00.0040.002

0.0000.0020.004

V/I C

Fe1 Fe1Fe1 Fe1

6 / 31

add noise: 103IC

Reasons for Non-Conclusive Results Difference: Sensitivity to B and B||

Reason 2: Bias introduced by Zeeman effect

B=50G, INC=70 deg

Wavelength []

0.40.60.81.0

I

0.00100.0005

0.00000.00050.0010

Q/I C

6301.0 6301.5 6302.0 6302.5 6303.00.0040.002

0.0000.0020.004

V/I C

Fe1 Fe1Fe1 Fe1

7 / 31

add noise: 103IC

Stenflo (2013) noise leads to more horizontal fields apparent flux: 25 higher in Bh

Reasons for Non-Conclusive Results Cancellation & Methods

Reasons 3+4: Cancellation & Methods

Signal cancellationinsufficient spatial resolution for Zeemandiagnostics

500 km

Analysis methodsZeeman vs. Hanleselection of profiles(-level)inversions

ME vs. height dependentfilling factor

direct techniques (e.g. lineratio)

8 / 31Hinode GREGOR / Solar-C

Reasons for Non-Conclusive Results Height dependence of Bv vs. Bh

Reason 5: Height dependent Bv & Bh

Bv vs. Bhdepends strongly on

spectral line selectionanalysis method (heightdependent inversion vs. ME)heliocentric angle (higheropacity at limb)

small scale dynamo

MHD: P() sin (e.g. Vogler & Schussler, 2007)height dependent(Rempel, 2014) Rempel (2014)

9 / 31

Dilemma: How to solve the controversies?

Possible solutions?

Increase spatial resolutionlarger telescope aperture

Increase signal/noise ratiomore photonsbetter polarimetermore sensitive spectral lines

Remove height biasselect lines with narrow and knownformation heightincrease height resolution

Remove model ambiguitiesselect simple, bias-free analysismethod without

10 / 31

GREGOR/GRIS Observations

Recent results from GREGOR / GRIS

11 / 31

GREGOR/GRIS Observations

GREGOR Infrared Spectrograph (GRIS; Collados et al., 2012)

GRIS fact sheetWL-range 12.3msensitivity < 104

/ 120 000 (@1.56m)mounted at 1.5 m GREGORtelescope0.180.30 resolution

12 / 31

GRIS Data Fe I @ 1.56 m

Scan of quiet sun region (2015-Sep-17)

FFT rebinned:0.135 pixelsize

0.20 pixelsize(seeing limited: 0.40)

noise level reduction:4 104 IC

2.7 104 IC no loss in spatial

resolution

spectral binning

2 (oversampling)

2.1 104 IC

02468

1012

02468

1012

02468

1012

0 10 20 30 4002468

1012

0.96

0.99

1.02

1.05

Sto

kes

I

0.0020.0010.000

0.001

0.002

Sto

kes

Q

0.0020.0010.000

0.001

0.002

Sto

kes

U

0.0025

0.0000

0.0025

Sto

kes

V

x [arcsec]

y[a

rcse

c]

13 / 311

2

3

S/N Ratios Comparison to Hinode SOT/SP

Comparison: GRIS vs. SOT/SP: Stokes Maps

02468

1012

02468

1012

02468

1012

0 10 20 30 4002468

1012

0.96

0.99

1.02

1.05

Sto

kes

I

0.0020.0010.000

0.001

0.002

Sto

kes

Q

0.0020.0010.000

0.001

0.002

Sto

kes

U

0.0025

0.0000

0.0025

Sto

kes

V

x [arcsec]

y[a

rcse

c]

02468

1012

02468

1012

02468

1012

0 10 20 30 4002468

1012

0.88

0.96

1.04

1.12

Sto

kes

I

0.0025

0.0000

0.0025

Sto

kes

Q

0.0025

0.0000

0.0025

Sto

kes

U

0.005

0.000

0.005

Sto

kes

V

x [arcsec]

y[a

rcse

c]

14 / 31

GREGOR/[email protected], 0.40 Hinode SOT/SP (deep 12.8s)


Comparison: GRIS vs. SOT/SP: LP/CP Coverage

0

2

4

6

8

10

12

0 10 20 30 400

2

4

6

8

10

12

x [arcsec]

y[a

rcse

c]

15 / 31

V

3Q,U

3Q,U,V

3

GR

EG

OR

/GR

IS4.

8s,

0. 4

0,21

04

Hin

ode

SO

T/S

P12

.8s,

0. 4

0,71

04


Stokes signal levels

Comparison GRIS Hinode SOT/SP

- GRIS [%] LP LP SOT/SP [%] LP LPlevel and or and or

LP CP CP CP LP CP CP CP3 39.7 73.0 33.1 79.7 9.8 49.3 7.7 51.44 18.4 57.0 13.9 61.5 4.2 37.1 3.1 38.25 9.2 44.2 6.2 47.2 2.1 28.5 1.5 29.1

16 / 31

Magnetic Line Ratios (MLRs) The principle

Simple diagnostic techniques: MLR - field strength

Magnetic Line Ratio (Solanki et al., 1992)

MLR =geff(15652)Vmax(15648)g(15648)Vmax(15652)

Requirements:spectral lines identical except for Lande factor2 distinct components:(1) magnetized, (2) field-freesmall gradients in log

not fulfilled for Fe I 1.56 line pair

BUT: similar formation height, narrowformation height range, similar thermalproperties

17 / 31

Magnetic Line Ratios (MLRs) The principle

Simple diagnostic techniques: MLR - field strength

Magnetic Line Ratio (Solanki et al., 1992)

MLR =geff(15652)Vmax(15648)g(15648)Vmax(15652)

Requirements:spectral lines identical except for Lande factor2 distinct components:(1) magnetized, (2) field-freesmall gradients in log

not fulfilled for Fe I 1.56 line pair BUT: similar formation height, narrow

formation height range, similar thermalproperties

17 / 31

Magnetic Line Ratios (MLRs) Profile selection

MLR analysis - select normal profiles

Stok

es V

noise threshold 3 small amplitude asym. a small area asym. A

(43.7% of the profiles)

18 / 31



Stok

es V

noise threshold 3

small amplitude asym. a small area asym. A


18 / 31



Stok

es V

noise threshold 3 small amplitude asym. a

small area asym. A


18 / 31



Stok

es V



18 / 31



Stok

es V


(43.7% of the profiles)18 / 31


Stokes Profiles: Red: MLR0.6, large Vmax, Yellow 3: MLR0.6, small Vmax

19 / 31

yellow: V 3


Stokes Profiles: Red: MLR0.6, large Vmax, Yellow 3: MLR0.6, small Vmax

MLR ~ 0.6

19 / 31

yellow: V 3

Magnetic Line Ratios (MLRs) MLRs for Fe I 15648 / Fe I 15652

MLR Fe I 15648 / Fe I 15652

0.002 0.004 0.006 0.008 0.010 0.012 0.014Vmax(15648.5)

0123probability density [%]

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.01.

53V

max

(156

48.5

)/3.

00V

max

(156

52.9

)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

prob

abili

tyde

nsity

[%]

20 / 31


Different MLR regions

0.002 0.004 0.006 0.008 0.010 0.012 0.014Vmax(15648.5)

3.0


0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.01.

53V

max

(156

48.5

)/3.

00V

max

(156

52.9

)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

prob

abili

tyde

nsity

[%]

21 / 311

2


Different MLR regions

0.002 0.004 0.006 0.008 0.010 0.012 0.014Vmax(15648.5)

3.0


0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.01.

53V

max

(156

48.5

)/3.

00V

max

(156

52.9

)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

prob

abili

tyde

nsity

[%]

21 / 31

Blue Region:MLR1.2, small Vmax

Yellow Region:MLR0.6, small Vmax

Green Region:MLR1.2, large Vmax

Red Region:MLR0.6, large Vmax

1

2


Different MLR regions - Where?

0 10 20 30 40 5002468

1012

y[a

rcse

c]

0 10 20 30 40 50x [arcsec]

02468

1012

y[a

rcse

c]

0.940.960.981.001.021.041.06

I c

0.00450.00300.00150.00000.00150.00300.0045

V

0 10 20 30 4002468

1012

0.96

0.99

1.02

1.05

Sto

kes

I

x [arcsec]

y[a

rcse

c]

22 / 31MLR1.2, small Vmax (hG) MLR1.2, large Vmax (hG) MLR0.6, small Vmax (kG) MLR0.6, large Vmax (kG)



0 10 20 30 40 5002468

1012

y[a

rcse

c]

0 10 20 30 40 50x [arcsec]

02468

1012

y[a

rcse

c]

0.940.960.981.001.021.041.06

I c

0.00450.00300.00150.00000.00150.00300.0045

V

0 10 20 30 4002468

1012

0.96

0.99

1.02

1.05

Sto

kes

I

x [arcsec]

y[a

rcse

c]

22 / 31MLR1.2, small Vmax (hG) MLR1.2, large Vmax (hG) MLR0.6, small Vmax (kG) MLR0.6, large Vmax (kG)MLR1.2, small Vmax (hG) MLR1.2, large Vmax (hG) MLR0.6, small Vmax (kG) MLR0.6, large Vmax (kG)



0 10 20 30 40 5002468

1012

y[a

rcse

c]

0 10 20 30 40 50x [arcsec]

02468

1012

y[a

rcse

c]

0.940.960.981.001.021.041.06

I c

0.00450.00300.00150.00000.00150.00300.0045

V

0 10 20 30 4002468

1012

0.96

0.99

1.02

1.05

Sto

kes

I

x [arcsec]

y[a

rcse

c]

22 / 31MLR1.2, small Vmax (hG) MLR1.2, large Vmax (hG) MLR0.6, small Vmax (kG) MLR0.6, large Vmax (kG)MLR1.2, small Vmax (hG) MLR1.2, large Vmax (hG) MLR0.6, small Vmax (kG) MLR0.6, large Vmax (kG)

some kG patches (red); surrounded by yellow halo; ubiquitous weak fields (green & blue)

MHD-Simulation Comparison Small scale dynamo run & IMaX run

Test using MHD Quiet Sun simulations (SSD+IMaX run)

23 / 31

0 5 10 15 200

5

10

15

0 5 10 15 200

5

10

15

0.88

0.96

1.04

1.12

Sto

kes

I

0

400

800

1200

mag

netic

field

stre

ngth

[G]

log

=(

0.2,0.8

)

x [arcsec]

y[a

rcse

c]

MHD simulations: SSD+IMaX runRempel (2014): O16bMRiethmuller et al. (2016)


Test using MHD Quiet Sun simulations (SSD+IMaX run)

23 / 31

0 5 10 15 200

5

10

15

0 5 10 15 200

5

10

15

0.96

0.99

1.02

1.05

Sto

kes

I

0

400

800

1200

mag

netic

field

stre

ngth

[G]

log

=(

0.2,0.8

)

x [arcsec]

y[a

rcse

c]

spatial degrading

GREGOR-PSF + 0.25 Gaussian +Lorentzian wings

match contrast, resolution, Ic histogram

spectral degrading

12% straylight

150 mA Gauss

MLR1.2, small Vmax (hG) MLR1.2, large Vmax (hG) MLR0.6, small Vmax (kG) MLR0.6, large Vmax (kG)


MLR (SSD + IMaX run, degraded)

0.002 0.004 0.006 0.008 0.010 0.012 0.014Vmax(15648.5)

3.0


0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.01.

53V

max

(156

48.5

)/3.

00V

max

(156

52.9

)

0

500

1000

1500

2000

mag

netic

field

stre

ngth

[G]

24 / 311


MLR (SSD + IMaX run, degraded)

0.002 0.004 0.006 0.008 0.010 0.012 0.014Vmax(15648.5)

3.0


0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.01.

53V

max

(156

48.5

)/3.

00V

max

(156

52.9

)

0

500

1000

1500

2000

mag

netic

field

stre

ngth

[G]

24 / 31

Blue Region:MLR1.2, small Vmax

Yellow Region:MLR0.6, small Vmax

Green Region:MLR1.2, large Vmax

Red Region:MLR0.6, large Vmax

1


B strength (SSD + IMaX run)

0 500 1000 1500 2000 2500magnetic field strength [G]

100

101

102pr

obab

ility

dens

ity[%

]

0.40MLR 0.850.90MLR 1.60

25 / 31

LP/CP ratio The principle

Simple diagnostic techniques: LP/CP - inclination

LP/CP ratio (Solanki et al.,1992)

LP/CP =

Q2max + U2max

Vmax

1 depends only on ifB sufficiently strong( 1 kG)small gradients

2 depends on and B forweaker fields

0.7

0.8

0.9

1.0

I

0.001

0.000

0.001

Q

0.001

0.000

0.001

U

15650 15655 15660 15665

wavelength []

0.020.01

0.00

0.01

0.02

V

26 / 31

LP/CP ratio LP/CP for Fe I 15648

GRIS: LP/CP for Fe I 15648

0.002 0.004 0.006 0.008 0.010 0.012 0.014Vmax(15648.5)


0.0

0.5

1.0

1.5

2.0

2.5

3.0

Q

2+

U2 /

V(1

5648

.5)

0.0

0.1

0.2

0.3

0.4

0.5

prob

abili

tyde

nsity

[%]

27 / 31


MHD (SSD+IMaX, degraded): LP/CP for Fe I 15648

0.002 0.004 0.006 0.008 0.010 0.012 0.014Vmax(15648.5)


0.0

0.5

1.0

1.5

2.0

2.5

3.0

Q

2+

U2 /

V(1

5648

.5)

0

20

40

60

80

mag

netic

field

incl

inat

ion

[]

28 / 31


B inclination (SSD + IMaX run)

0 20 40 60 80 100 120 140 160 180inclination angle []

0

2

4

6

8

10

12

14pr

obab

ility

dens

ity[%

]

0.40MLR 0.850.90MLR 1.60isotropic

sin()3.22

29 / 31

Summary

Summary: Quiet Sun Stokes Profiles

Noise Statistics: GRISHinodenoise level 2.1 104 0.40)TP: 80% above 3(cf. Hinode 12.8 s scan:51%)CP: 73% above 3(cf. Hinode 12.8 s scan:49%)LP: 40% above 3(cf. Hinode 12.8 s scan:10%)

more reliable inversions arenow possible

MLR & LP/CP ratio

some kG patches resolved (vertical fields)PSF-ring around kG patcheshG patches ubiquitousgood agreement with SSD runs some kG patches missing

Proper PSF deconvolution critical for correctinterpretation of results!

Future instrumental improvementsGREGOR/GRIS: reach diffraction limitSunrise III: increase height resolution

30 / 31

Summary

Bibliography

Asensio Ramos, A. 2009, ApJ, 701, 1032

Asensio Ramos, A. & Martnez Gonzalez, M. J.2014, A&A, 572, A98

Asensio Ramos, A. & Trujillo Bueno, J. 2005,ApJL, 635, L109

Asensio Ramos, A., Trujillo Bueno, J., & LandiDeglInnocenti, E. 2008, ApJ, 683, 542

Berdyugina, S. V. & Fluri, D. M. 2004, A&A,417, 775

Bommier, V., et al. 2005, A&A, 432, 295

Borrero, J. M. & Kobel, P. 2013, A&A, 550, A98

Buehler, D., Lagg, A., & Solanki, S. K. 2013,A&A, 555, A33

Collados, M., et al. 2012, AstronomischeNachrichten, 333, 872

Danilovic, S., van Noort, M., & Rempel, M.2016, A&A, submitted

Faurobert, M., et al. 2001, A&A, 378, 627

Faurobert-Scholl, M., et al. 1995, A&A, 298,289

Ishikawa, R. & Tsuneta, S. 2011, ApJ, 735, 74Kleint, L., et al. 2010, A&A, 524, A37Lagg, A., et al. 2009, in ASP Conf. Ser., Vol.

415, The Second Hinode Science Meeting:Beyond Discovery-Toward Understanding,ed. Lites, B., et al., 327

Lites, B. W., et al. 2008, ApJ, 672, 1237Martnez Gonzalez, M. J., et al. 2008, A&A,

479, 229Martnez Gonzalez, M. J., et al. 2016, A&A

GREGOR issue, acceptedOrozco Suarez, D. & Bellot Rubio, L. R. 2012,

ApJ, 751, 2Orozco Suarez, D., et al. 2007, Publications of

the Astronomical Society of Japan, 59, 837Orozco Suarez, D. & Katsukawa, Y. 2012, ApJ,

746, 182Rempel, M. 2014, ApJ, 789, 132Riethmuller, T., et al. 2016, ApJ, in preparationSchmidt, W., et al. 2012, Astronomische

Nachrichten, 333, 796

Shapiro, A. I., et al. 2011, A&A, 529, A139

Shchukina, N. & Trujillo Bueno, J. 2003, in ASPConf. Ser., Vol. 307, Solar Polarization, ed.Trujillo-Bueno, J. & Sanchez Almeida, J.,336

Solanki, S. K., Ruedi, I. K., & Livingston, W.1992, A&A, 263, 312

Steiner, O. & Rezaei, R. 2012, in ASP Conf.Ser., Vol. 456, Fifth Hinode ScienceMeeting, ed. Golub, L., De Moortel, I., &Shimizu, T., 3

Stenflo, J. O. 2010, A&A, 517, A37

Stenflo, J. O. 2013, The Astronomy andAstrophysics Review, 21, 66

Stenflo, J. O. 2014, in ASP Conf. Ser., Vol. 489,Solar Polarization 7, ed. Nagendra, K. N.,et al., 3

Trujillo Bueno, J., Shchukina, N., & AsensioRamos, A. 2004, Nature, 430, 326

Vogler, A. & Schussler, M. 2007, A&A, 465, L43

31 / 31

MotivationControversial FindingsStrength: few Gauss 200 Gauss kilo-Gauss?

Reasons for Non-Conclusive ResultsLow B weak signalsDifference: Sensitivity to B and B||Cancellation & MethodsHeight dependence of Bv vs. Bh

Dilemma: How to solve the controversies?GREGOR/GRIS ObservationsGRIS DataFei @ 1.56 m

S/N RatiosComparison to Hinode SOT/SP

Magnetic Line Ratios (MLRs)The principleProfile selectionMLRs for Fei 15648 / Fei 15652

MHD-Simulation ComparisonSmall scale dynamo run & IMaX run

LP/CP ratioThe principleLP/CP for Fei 15648

Summary

fd@rm@0:

quiet-sun magnetism - probing deep photospheric layers ... · quiet-sun magnetism probing deep...

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