Pulsar Magnetosphere: a New View from PIC Simulations Gabriele - - PowerPoint PPT Presentation

▶
pulsar magnetosphere a new view from pic simulations
SMART_READER_LITE
LIVE PREVIEW

Pulsar Magnetosphere: a New View from PIC Simulations Gabriele - - PowerPoint PPT Presentation

Feb 08, 2023 22 likes •1.02k views

March 28th 2017 - Annual NewCompstar Conference, Warsaw (Poland) Pulsar Magnetosphere: a New View from PIC Simulations Gabriele Brambilla NASA Goddard Space Flight Center (MD-USA) - Universit degli Studi di Milano (Italy) Im a PhD student

slide-1
SLIDE 1

Pulsar Magnetosphere: a New View from PIC Simulations

March 28th 2017 - Annual NewCompstar Conference, Warsaw (Poland)

Gabriele Brambilla

NASA Goddard Space Flight Center (MD-USA) - Università degli Studi di Milano (Italy)

I’m a PhD student and I work with: Kostas Kalapotharakos Andrey Timokhin Alice Harding Demos Kazanas

Many of the figures are obtained using VisIt - Childs et al. 2012

My Italian supervisor is: Pierre Pizzochero

slide-2
SLIDE 2

Pulsars are expected to have a magnetosphere because their strong magnetic field overcomes gravity

B

PULSAR

slide-3
SLIDE 3

Pulsars are expected to have a magnetosphere because their strong magnetic field overcomes gravity

B Ω

PULSAR

slide-4
SLIDE 4

Pulsars are expected to have a magnetosphere because their strong magnetic field overcomes gravity

B Ω

PULSAR

inclination angle

slide-5
SLIDE 5

Pulsars are expected to have a magnetosphere because their strong magnetic field overcomes gravity

B Ω E

PULSAR

inclination angle

slide-6
SLIDE 6

Pulsars are expected to have a magnetosphere because their strong magnetic field overcomes gravity

B Ω E

PULSAR

Goldreich and Julian 1969 inclination angle

slide-7
SLIDE 7

Pulsars behaves like a dynamo; currents dissipate, emitting light when particles are accelerated

www.physicsforums.com Google images

slide-8
SLIDE 8

Pulsars behaves like a dynamo; currents dissipate, emitting light when particles are accelerated

www.physicsforums.com Google images

slide-9
SLIDE 9

Pulsars behaves like a dynamo; currents dissipate, emitting light when particles are accelerated Particle’s acceleration produces light

  • > dissipation/resitivity

www.physicsforums.com Google images

E·B≠0

slide-10
SLIDE 10

Force-free simulations highlighted the presence of a current sheet, where particles could be accelerated by magnetic reconnection

Contopoulos et al. 1999

  • inc. angle 0°
slide-11
SLIDE 11

Force-free simulations highlighted the presence of a current sheet, where particles could be accelerated by magnetic reconnection

Contopoulos et al. 1999

Magnetic reconnection

see Magnetic Reconnection, by Priest & Forbes, 2000

  • inc. angle 0°
slide-12
SLIDE 12

Force-free simulations highlighted the presence of a current sheet, where particles could be accelerated by magnetic reconnection

Contopoulos et al. 1999

Magnetic reconnection

see Magnetic Reconnection, by Priest & Forbes, 2000

  • inc. angle 0°
slide-13
SLIDE 13

Force-free simulations highlighted the presence of a current sheet, where particles could be accelerated by magnetic reconnection

Contopoulos et al. 1999

Magnetic reconnection

Spitkovsky 2006

see Magnetic Reconnection, by Priest & Forbes, 2000

  • inc. angle 0°
  • inc. angle 60°
slide-14
SLIDE 14

Force-free simulations highlighted the presence of a current sheet, where particles could be accelerated by magnetic reconnection

Contopoulos et al. 1999

Magnetic reconnection

Spitkovsky 2006

see Magnetic Reconnection, by Priest & Forbes, 2000

  • inc. angle 0°
  • inc. angle 60°
slide-15
SLIDE 15

Force-free simulations highlighted the presence of a current sheet, where particles could be accelerated by magnetic reconnection

Contopoulos et al. 1999

Magnetic reconnection

Spitkovsky 2006

see Magnetic Reconnection, by Priest & Forbes, 2000

  • inc. angle 0°
  • inc. angle 60°
slide-16
SLIDE 16

Dissipative solutions also point to the current sheet for reproducing the emission of the gamma-ray pulsars

Abdo et al 2013

Vela AKA J0835-4510

slide-17
SLIDE 17

Dissipative solutions also point to the current sheet for reproducing the emission of the gamma-ray pulsars

Abdo et al 2013

Vela AKA J0835-4510

slide-18
SLIDE 18

Dissipative solutions also point to the current sheet for reproducing the emission of the gamma-ray pulsars

Abdo et al 2013

Vela AKA J0835-4510

slide-19
SLIDE 19

Dissipative solutions also point to the current sheet for reproducing the emission of the gamma-ray pulsars

Abdo et al 2013

Vela AKA J0835-4510

slide-20
SLIDE 20

Dissipative solutions also point to the current sheet for reproducing the emission of the gamma-ray pulsars

Brambilla et al 2015 Abdo et al 2013

Vela AKA J0835-4510

Kalapotharakos et al 2014

slide-21
SLIDE 21

In PIC codes, particles moved by the fields form the currents that act on the fields themselves

slide-22
SLIDE 22

In PIC codes, particles moved by the fields form the currents that act on the fields themselves

slide-23
SLIDE 23

In PIC codes, particles moved by the fields form the currents that act on the fields themselves

slide-24
SLIDE 24

In PIC codes, particles moved by the fields form the currents that act on the fields themselves

Birdsall & Langdon 1985 Plasma Physics via Computer Simulation (New York: McGraw-Hill)

slide-25
SLIDE 25

In PIC codes, particles moved by the fields form the currents that act on the fields themselves

Birdsall & Langdon 1985 Plasma Physics via Computer Simulation (New York: McGraw-Hill)

slide-26
SLIDE 26

In PIC codes, particles moved by the fields form the currents that act on the fields themselves

Birdsall & Langdon 1985 Plasma Physics via Computer Simulation (New York: McGraw-Hill)

slide-27
SLIDE 27

In PIC codes, particles moved by the fields form the currents that act on the fields themselves

Birdsall & Langdon 1985 Plasma Physics via Computer Simulation (New York: McGraw-Hill)

slide-28
SLIDE 28

In PIC codes, particles moved by the fields form the currents that act on the fields themselves

Birdsall & Langdon 1985 Plasma Physics via Computer Simulation (New York: McGraw-Hill)

slide-29
SLIDE 29

In PIC codes, particles moved by the fields form the currents that act on the fields themselves

Birdsall & Langdon 1985 Plasma Physics via Computer Simulation (New York: McGraw-Hill)

Pulsar & PIC Chen et al. 2014, Philippov et al. 2014, Belyaev 2015

slide-30
SLIDE 30

With our PIC code we reproduced the force free limit

  • nce we inject enough particles everywhere

Kalapotharakos et al 2017 (in prep.)

Jtotal

IR 1GJ

slide-31
SLIDE 31

With our PIC code we reproduced the force free limit

  • nce we inject enough particles everywhere

Force Free

Kalapotharakos et al 2017 (in prep.)

Jtotal

IR 1GJ

slide-32
SLIDE 32

With our PIC code we reproduced the force free limit

  • nce we inject enough particles everywhere

Force Free PIC

Kalapotharakos et al 2017 (in prep.)

Jtotal

IR 1GJ

slide-33
SLIDE 33

With our PIC code we reproduced the force free limit

  • nce we inject enough particles everywhere

Force Free PIC

Kalapotharakos et al 2017 (in prep.)

Jtotal

IR 1GJ

slide-34
SLIDE 34

With our PIC code we reproduced the force free limit

  • nce we inject enough particles everywhere

Force Free PIC

Kalapotharakos et al 2017 (in prep.)

Jtotal

IR 1GJ

slide-35
SLIDE 35

With our PIC code we reproduced the force free limit

  • nce we inject enough particles everywhere

Force Free PIC

Kalapotharakos et al 2017 (in prep.)

Jtotal

IR 10GJ

slide-36
SLIDE 36

With our PIC code we reproduced the force free limit

  • nce we inject enough particles everywhere

Force Free PIC

Kalapotharakos et al 2017 (in prep.)

Jtotal

IR 20 GJ

slide-37
SLIDE 37

With our PIC code we reproduced the force free limit

  • nce we inject enough particles everywhere

Force Free PIC

Kalapotharakos et al 2017 (in prep.)

Jtotal

IR 30 GJ

slide-38
SLIDE 38

With our PIC code we reproduced the force free limit

  • nce we inject enough particles everywhere

Force Free PIC

Kalapotharakos et al 2017 (in prep.)

Jtotal

IR 40 GJ

slide-39
SLIDE 39

With our PIC code we reproduced the force free limit

  • nce we inject enough particles everywhere

Force Free PIC

Kalapotharakos et al 2017 (in prep.)

Jtotal

IR 50 GJ

slide-40
SLIDE 40

We verified that the force free limit is well defined energetically

FF PIC

Radius (RLC)

Kalapotharakos et al 2017 (in prep.)

normalized Poynting flux

slide-41
SLIDE 41

We verified that the force free limit is well defined energetically

FF PIC FF electrodynamics

Radius (RLC) Radius (RLC)

Kalapotharakos et al 2017 (in prep.)

normalized Poynting flux normalized Poynting flux

slide-42
SLIDE 42

We verified that the force free limit is well defined energetically

FF PIC FF electrodynamics

Electromagnetic Energy

FF electrodynamics approach

Radius (RLC)

Injection Rate (GJ flux)

Radius (RLC)

Kalapotharakos et al 2017 (in prep.)

normalized Poynting flux normalized Poynting flux Average Electromagnetic Energy density [arbitrary units]

slide-43
SLIDE 43

With PIC we can explore the different contribution to the currents of the different species

Kalapotharakos et al 2017 (in prep.)

J electrons J positrons

slide-44
SLIDE 44

Tracking individual trajectories we see that the particles are accelerated in the current sheet

slide-45
SLIDE 45

Tracking individual trajectories we see that the particles are accelerated in the current sheet

slide-46
SLIDE 46

Tracking individual trajectories we see that the particles are accelerated in the current sheet

slide-47
SLIDE 47

Tracking individual trajectories we see that the particles are accelerated in the current sheet

slide-48
SLIDE 48

Tracking individual trajectories we see that the particles are accelerated in the current sheet

slide-49
SLIDE 49

With a 3D pic code we can simulate pulsars with an arbitrary inclination angle

0° 30° 60° 85°

∇E

[arbitrary]

∇E

[arbitrary]

∇E

[arbitrary]

∇E

[arbitrary]

slide-50
SLIDE 50

Different injection rates, periods and surface fields cover the range

  • f cutoff energies and luminosities of the Fermi pulsar population

Kalapotharakos et al 2017 (in prep.)

FERMI gamma ray pulsars PIC: different inclination angle and injection rate 15 ° 45 ° 75 °

[ev] [erg]

slide-51
SLIDE 51

We also obtained the force free limit injecting particles only from the surface and the current composition looks different All volume injection star surface injection

Brambilla et al 2017 (in prep.)

Jtotal

slide-52
SLIDE 52

We also obtained the force free limit injecting particles only from the surface and the current composition looks different All volume injection star surface injection

Brambilla et al 2017 (in prep.)

Jtotal

slide-53
SLIDE 53

We also obtained the force free limit injecting particles only from the surface and the current composition looks different All volume injection star surface injection

Brambilla et al 2017 (in prep.)

Jpos

slide-54
SLIDE 54

Summary

  • Macroscopic simulations have shown particular features of the force free

limit

  • Dissipative solutions have shown that the emission in the current sheet is

compatible with the young gamma-ray pulsar emission

  • To understand the dissipation we need kinetic simulations (PIC)
  • Our code works: we are able to reproduce the force free limit and look at

the different species behavior

  • We can follow what the particles are doing
  • We are able to reproduce the “energetics” of FERMI observations
  • We obtain the force free limit also injecting particles only from the surface,

however the contribution of the different species changes (interesting and unexpected!)

slide-55
SLIDE 55
slide-56
SLIDE 56

Philippov et al. 2015

slide-57
SLIDE 57

The magnetosphere can get close to the force-free condition by electron-positron pair cascades

NS SURFACE

  • A. K. Harding
slide-58
SLIDE 58

The magnetosphere can get close to the force-free condition by electron-positron pair cascades

NS SURFACE

e-

  • A. K. Harding
slide-59
SLIDE 59

The magnetosphere can get close to the force-free condition by electron-positron pair cascades

NS SURFACE

e-

  • A. K. Harding
slide-60
SLIDE 60

The magnetosphere can get close to the force-free condition by electron-positron pair cascades

NS SURFACE

e- e±

  • A. K. Harding
slide-61
SLIDE 61

The magnetosphere can get close to the force-free condition by electron-positron pair cascades

NS SURFACE

e- e±

  • A. K. Harding
slide-62
SLIDE 62

The magnetosphere can get close to the force-free condition by electron-positron pair cascades

NS SURFACE

e+ e- e± e-

  • A. K. Harding
slide-63
SLIDE 63

The magnetosphere can get close to the force-free condition by electron-positron pair cascades

NS SURFACE

e+ e- e± e- e± e±

  • A. K. Harding
slide-64
SLIDE 64

The magnetosphere can get close to the force-free condition by electron-positron pair cascades

NS SURFACE

e+ e- e± e- e± e±

  • A. K. Harding
slide-65
SLIDE 65

The magnetosphere can get close to the force-free condition by electron-positron pair cascades

NS SURFACE

e+ e- e± e- e± e±

  • A. K. Harding
slide-66
SLIDE 66

The force free electrodynamics (FFE) is used to describe the magnetosphere

Maxwell + Force Free

Gruzinov 1999

enough charge to screen forces NO inertia

slide-67
SLIDE 67

The force free electrodynamics (FFE) is used to describe the magnetosphere

Maxwell + Force Free

Gruzinov 1999

enough charge to screen forces NO inertia

slide-68
SLIDE 68

The force free electrodynamics (FFE) is used to describe the magnetosphere

Maxwell + Force Free

Gruzinov 1999

enough charge to screen forces NO inertia

+ Maxwell

slide-69
SLIDE 69

The force free electrodynamics (FFE) is used to describe the magnetosphere

Maxwell + Force Free

Gruzinov 1999

enough charge to screen forces NO inertia

+ Maxwell

slide-70
SLIDE 70

The force free electrodynamics (FFE) is used to describe the magnetosphere

Maxwell + Force Free

Gruzinov 1999

enough charge to screen forces NO inertia

+ Maxwell

slide-71
SLIDE 71

The force free electrodynamics (FFE) is used to describe the magnetosphere

Maxwell + Force Free

Gruzinov 1999

enough charge to screen forces NO inertia

+ Maxwell

slide-72
SLIDE 72

The force free electrodynamics (FFE) is used to describe the magnetosphere

+ fields co-rotating with the star

slide-73
SLIDE 73

The force free electrodynamics (FFE) is used to describe the magnetosphere

+ fields co-rotating with the star

+ Goldreich and Julian 1969

slide-74
SLIDE 74

The force free electrodynamics (FFE) is used to describe the magnetosphere

+ fields co-rotating with the star

+ Goldreich and Julian 1969

slide-75
SLIDE 75

Ω µ

slide-76
SLIDE 76

Ω µ

  • µ
slide-77
SLIDE 77

B

Ω µ

slide-78
SLIDE 78

B

Ω µ

slide-79
SLIDE 79

B

  • LEADING EDGE

TRAILING EDGE

slide-80
SLIDE 80

B

  • LEADING EDGE

TRAILING EDGE

slide-81
SLIDE 81

B

  • LEADING EDGE

TRAILING EDGE

slide-82
SLIDE 82

B

  • LEADING EDGE

TRAILING EDGE

RETARDATI ON

slide-83
SLIDE 83

B

  • LEADING EDGE

TRAILING EDGE

RETARDATI ON

slide-84
SLIDE 84

B

  • LEADING EDGE

TRAILING EDGE

RETARDATI ON

slide-85
SLIDE 85

B

  • LEADING EDGE

TRAILING EDGE

RETARDATI ON

slide-86
SLIDE 86

B

  • LEADING EDGE

TRAILING EDGE

RETARDATI ON

ABERRATIO N

slide-87
SLIDE 87

B

  • LEADING EDGE

TRAILING EDGE

RETARDATI ON

ABERRATIO N

slide-88
SLIDE 88

B

  • LEADING EDGE

TRAILING EDGE

RETARDATI ON

ABERRATIO N

slide-89
SLIDE 89

B

  • LEADING EDGE

TRAILING EDGE

RETARDATI ON

ABERRATIO N

slide-90
SLIDE 90

B

  • LEADING EDGE

TRAILING EDGE

RETARDATI ON

ABERRATIO N

slide-91
SLIDE 91
slide-92
SLIDE 92

Ω B α

The most important feature of a rotating dipole is the Light Cylinder (LC)

slide-93
SLIDE 93

Ω B α

The most important feature of a rotating dipole is the Light Cylinder (LC)

slide-94
SLIDE 94

Ω B α

The most important feature of a rotating dipole is the Light Cylinder (LC)

CLOSE

slide-95
SLIDE 95

Ω B α

The most important feature of a rotating dipole is the Light Cylinder (LC)

OPEN CLOSE

slide-96
SLIDE 96

Ω B α

The most important feature of a rotating dipole is the Light Cylinder (LC)

OPEN CLOSE

.

  • I. A. G. Yadigaroglu 

slide-97
SLIDE 97

Ω B α

The most important feature of a rotating dipole is the Light Cylinder (LC)

OPEN CLOSE

.

  • I. A. G. Yadigaroglu 

slide-98
SLIDE 98

Ω B α

The most important feature of a rotating dipole is the Light Cylinder (LC)

OPEN CLOSE

Radiation Field = Poynting Flux

.

  • I. A. G. Yadigaroglu 

slide-99
SLIDE 99

Ω B α

The most important feature of a rotating dipole is the Light Cylinder (LC)

OPEN CLOSE

Radiation Field = Poynting Flux

.

  • I. A. G. Yadigaroglu