Frequency Dependence of Scintillation Arcs Dan Stinebring Oberlin - - PowerPoint PPT Presentation

▶
frequency dependence
SMART_READER_LITE
LIVE PREVIEW

Frequency Dependence of Scintillation Arcs Dan Stinebring Oberlin - - PowerPoint PPT Presentation

Dec 30, 2023 40 likes •332 views

Frequency Dependence of Scintillation Arcs Dan Stinebring Oberlin College 2019 November 4 (Time Variability) Tilted 0355a Roger Foster, GB 140 ft Tilted 0355b Roger Foster, GB 140 ft Tilted 0919a Tilted 0919b Questions

slide-1
SLIDE 1

Frequency Dependence

  • f Scintillation Arcs


Dan Stinebring Oberlin College 2019 November 4

slide-2
SLIDE 2

(Time Variability)

slide-3
SLIDE 3

Tilted 0355a

Roger Foster, GB 140 ft

slide-4
SLIDE 4

Tilted 0355b

Roger Foster, GB 140 ft

slide-5
SLIDE 5

Tilted 0919a

slide-6
SLIDE 6

Tilted 0919b

slide-7
SLIDE 7

Questions

  • Can we distinguish between
  • anisotropic Kolmogorov scattering
  • distributed core + “crack in the

glass”?

  • How is arc morphology affected by
  • bserving frequency (strength of

scintillation)?

slide-8
SLIDE 8
slide-9
SLIDE 9
slide-10
SLIDE 10
slide-11
SLIDE 11

6 µs 90 µs

B1133+16

slide-12
SLIDE 12

6 µs 90 µs

B1133+16

delay is frequency independent

slide-13
SLIDE 13

340 MHz 825 MHz B0628–28

slide-14
SLIDE 14

340 MHz 825 MHz B0818–13

slide-15
SLIDE 15

340 MHz 825 MHz B1508+55

slide-16
SLIDE 16

340 MHz 825 MHz B1540–06

slide-17
SLIDE 17

340 MHz 825 MHz B2021+51

slide-18
SLIDE 18

340 MHz 825 MHz B2045–16

slide-19
SLIDE 19

340 MHz 825 MHz B2327–20

slide-20
SLIDE 20

340 MHz 825 MHz B2310+42

slide-21
SLIDE 21

Concluding Comments

  • Can we distinguish between …
  • Maybe. Needs to be done quantitatively.
  • How is arc morphology affected by
  • bserving frequency (strength of

scintillation?

  • Very strongly. Need to look at frequency


evolution in order to understand models.

slide-22
SLIDE 22

slides not shown …

slide-23
SLIDE 23

Preamble to conjecture:

all (or almost all) of the Kolmogorov ray tracing simulations you’ve seen assume a single thin screen along the LOS

slide-24
SLIDE 24

Conjecture:

rays scattered by a distributed Kolmogorov medium do not produce pronounced scintillation arcs

slide-25
SLIDE 25
  • A. Jussila 2018

Oberlin honors thesis rays random walk in a distributed medium

slide-26
SLIDE 26

The statistical connection between delay and Doppler (in this case) is a selection effect. It’s real, but it needs further quantitative exploration to see what sort of scintillation arcs it produces, if any.

Cordes, Shannon, & Stinebring 2016

slide-27
SLIDE 27

B0628–28 DM = 34 pc cm-3 distance = 320 pc

slide-28
SLIDE 28

B0628–28 DM = 34 pc cm-3 distance = 320 pc

distributed scattering

Conjecture

slide-29
SLIDE 29

B0628–28 DM = 34 pc cm-3 distance = 320 pc

but it’s not there!