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Radio emission mechanisms Philippe Zarka LESIA & USN, Obs. Paris, CNRS, PSL/SU/UPMC/UPD/SPC/UO/OSUC, France

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Page 1: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

Radio emission mechanisms

Philippe Zarka

LESIA & USN, Obs. Paris, CNRS, PSL/SU/UPMC/UPD/SPC/UO/OSUC, France

Page 2: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

[Zarka et al., JGR 2004 ; Zarka, PSS 2004]

Jupiter radio "zoo"

Voyager-PRA

day

pre-dawn

HOM HOM

bKOM

[Boischot et al., JGR 1981]

T

Galileo-PWS

Voyager-PRA

Page 3: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

[Zarka, JGR 1998, Geophys. Mon. 2000]

Source locations

Page 4: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

[Hess et al., PSS 2014]

• Auroral

[Queinnec & Zarka, JGR 1998 ; … ]

• Io-Jupiter,

satellite-Jupiter ?

Decameter arcs

Page 5: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

[Ryabov et al., A&A 2014 ; … ]

• discrete

• fast drifting with df/dt <0

• quasi-periodic

• complex envelope

Decameter (S-)bursts

Page 6: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

[Wu, SSR 1985 ; Treumann, AAR 2006]

Radiation mechanism

Resonance condition :

• DAM / HOM / bKOM ? : Cyclotron Maser Instability

• Regime of operation : Oblique/Loss-cone-driven or Perpendicular/Shell-driven ?

Growth rate :

Page 7: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

Earth’s AKR

• AKR only in hot plasma cavities

[Roux et al., JGR 1993 ]

• Perpendicular/Shell-driven CMI → associated to acceleration structures

• df/dt >0 and <0

[Baumback & Calvert, 1987]

Page 8: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

Jovian DAM arcs

• Cold plasma dominates (no plasma cavities ?)

[Zarka et al., PSS 2001 ; Su et al., JGR 2003 ; ]

Page 9: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

Oblique/Loss-cone

Perp./S

hell

[Hess et al., JGR 2008]

Jovian DAM arcs

[Frank & Paterson, 1999 ]

• Oblique/Loss-cone-driven CMI has large growth rates

Page 10: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

Jovian DAM arcs

• ExPRES(SERPE) modeling : favours Oblique/Loss-cone-driven CMI

[Hess et al., GRL 2008 ; + to be submitted 2016]

Oblique/Loss-cone

Perp./S

hell

0.6 keV

2.5 keV

10 keV

Page 11: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

Jovian S-bursts• Oblique/Loss-cone-driven emission from Alfvén waves acceleration of electrons

Oblique/Loss-cone

Perp./S

hell

[Hess et al., JGR 2007, GRL 2009]

Page 12: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

Jovian S-bursts• Double-layers / electron & ion holes along IFT …

<E>=0.9 keV

z~0.1 RJ

[Hess et al,, GRL 2009][Su et al., JGR 2003]

[Hess et al,, PSS 2007]

Page 13: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

Jovian S-bursts

Stability of potential drops > 10 min.

• … in motion along the IFT at the local plasma sound velocity

[Hess et al, PSS 2009]

00

T ~ 1.5 eV

T ~ 0.14 eV~ 200 s ?

Page 14: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

Why oblique mode dominant for Jovian DAM ?

A,B

C

CBA

[Mottez et al, PSS 2010]

perpendicular propagation

hot medium cold

Page 15: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

[Cecconi et al., JGR 2009]

[Lamy et al., JGR 2011]

[Lamy et al., JGR 2008]

[Lamy et al., JGR 2013]

• Remote observations : oblique beaming

• In situ observations : quasi-perpendicular emission

→ role of refraction ?

SKR beaming

Page 16: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

[Cecconi et al., JGR 2009]

X mode

O mode

-1.0

-0.5

0.0

0.5

1.0

V

0 5 10 15 20 25 30

f-f (kHz)ce

0.0

0.2

0.4

0.6

0.8

1.0

L

0

5

10

15

20

25

30

0.0 0.5 1.0 1.5 2.0 2.5 3.0

d (R )s

-1.0

-0.5

0.0

0.5

1.0

AR

a

b

c

d

f-f (

kH

z)

ce

T

E

1/

Line

ar p

olar

izat

ion

Circ

ular

pol

ariz

atio

n

E

Axial ratio T=EY/EX V=2T/(1+T2)

[Lamy et al., JGR 2011]

What JUNO will not do

→ no direct source location, no strong constraint on emission mode, except with S/C spin ?

Page 17: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

What JUNO will do• Wave+particle measurements during high latitude sources traversals

→ comparisons with SKR & AKR

[Lamy et al., 2010, 2011, Mutel et al., 2010, Bunce et al., 2010, Schippers et al., 2011, Kurth et al., 2011, Menietti et al., 2011]

08:12 08:24 08:36

A B C08:48 09:00 09:12

Day 2008-291 (h:m)

0

-2

2

4

6

8

10

-4

(f-fc

e)/fc

e (%

)

fcutoff

fCMI

→ fCMI down to several % below fce above aurora at Jupiter ?

Page 18: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

What JUNO will do

• Wave+particle measurements during high latitude sources traversals

1987SoPh..111...59L

→ Max. E field in sources ? (predicted 1-10 V/m) [Zarka, Juno memo 2006] → CMI saturation ? [Zarka, MOP 2009]

→ Identification of saturation mechanism → Feedback on source plasma content → Implications on exoplanets

→ S-bursts envelope ?

[Ryabov et al., A&A 2014]

Page 19: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

What we will do with JUNO

• ExPRES modeling (CMI + geometry + near source refraction) at all latitudes

Page 20: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

What we will do with JUNO

• ExPRES modeling (CMI + geometry + near source refraction) at all latitudes

[Louis et al., PNST 2016]

WORK IN

PROGRESS

Page 21: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

What we will do with JUNO

• ExPRES modeling (CMI + geometry + near source refraction) at all latitudes

[Imai et al., 2011]

Page 22: Philippe Zarka - |LASP|CU-Boulderlasp.colorado.edu/home/mop/files/2016/03/21Zarka.pdf · [Zarka et al., JGR 2004 ; Zarka, PSS 2004] Jupiter radio "zoo" Voyager-PRA day pre-dawn HOM

• ExPRES modeling (CMI + geometry + near source refraction) at all latitudes

Relations between bKOM / HOM / non-Io DAM (QP ? nKOM) Radio beaming & electrons energy

Satellite-Jupiter lead angle ⇒ Unipolar/Dipolar interaction Relation with UV/IR auroral components ?

What we will do with JUNO

Parametric study → Source locations

• Importance of a « perfect » internal B-field model for ExPRES

of a reliable plasma model for ExPRES & ray-tracing (ARTEMIS-P)[Gautier, Thesis 2013]

[cf. Baptiste’s talk]

→ Cross-correlation (interferometric) measurements WAVES-Ground ?

• Importance of support Ground-Based DAM observations

• HOM & bKOM as a SW proxy

• Auroral activity → Jovian plasma (sub)corotation ?