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Yuna Dan Mieko Takamura Momotaro Nakamura Masaaki Murata Spring School 2018 March 10 2018/3/10 1 Index 1.Introduction 2.How to analyze 3.Result 4.Discussion

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  • Yuna Dan

Mieko Takamura Momotaro Nakamura Masaaki Murata Spring School 2018 March 10

2018/3/10 1

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Index

1.Introduction 2.How to analyze 3.Result 4.Discussion 5.Summary

2018/3/10 2

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1.Introduction

2018/3/10 3

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Neutron stars

  • Typical radius: 10 km
  • Typical mass: 1 solar mass
  • Density:1017kg/m3
  • Magnetic field: 104 – 1011 T

2018/3/10 4

Credit: NASA’s Goddard Space Flight Center

Neutron stars are really extreme objects!

Credit: NASA

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Pulsar

  • Very fast rotating neutron stars
  • Extraction and acceleration of particles by the

powerful magnetic field

  • Production of pulsed electromagnetic emission
  • Loss of energy due to radiation emission:

rotational spindown

2018/3/10 5

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We analyze

2018/3/10 6

THE CRAB VELA GEMINGA Age [years] 964 (Supernova in 1054 A.D.) ~10.000 ~300.000 Distance [ly] ~7180 ~960 ~800 Rotational period [ms] ~33 89 237

Credit: NASA Credit: JAXA Credit: NASA

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The Fermi Gamma-ray Space Telescope

  • Mission type:

Gamma-ray observatory

  • Launch date:

11 June 2008, 16:05 UTC

  • Atitude: 525.9 - 543.6 km
  • Period: 95.33 min

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It is the most sensitive gamma-ray observatory in orbit!

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What’s phaseogram?

  • Phaseogram:

Sum up events that happen at the same phase

  • Phase:

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Physical information

  • n the pulsar!
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Our mission

  • 1. Learn about pulsar, Fermi, the way to analyze and etc…
  • 2. Produce a phaseogram
  • 3. Decide frequencies and frequencies derivatives
  • 4. Analyze something strange

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2.How to analyze

2018/3/10 10

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How to analyze

2018/3/10 11

Download Each Data The selection of exact photons Make Count Map

  • f

The Crab, VELA and Geminga

187 374 563 750 939 1126 1313 1502 1689 1876 8 : 1 : . 15:00.0 20:00.0 25:00.0 30:00.0 35:00.0 40:00.0 45:00.0 5 : . 55:00.0 9:00:00.0
  • 45:00:00.0
  • 43:00:00.0

Energy range 300 30000MeV

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How to get data

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Fermi LAT What can we get? The direction from which photons come. To measure amount of energy of one photon.

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How to define the time

  • What should we think about

to define the correct time:

  • →

Barycentric Collection

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3.Result

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37265-49 102-

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  • 8
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.3827604 .501-

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9

)(()

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  • 2716539 -40

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()

  • )8(
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15043-27 -

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  • 6
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()

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)((

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()

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44826424168

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.)

4681

( .1

44 82

Observation Time is for about 10 Year !!

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2320

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  • )

(01

7

  • 2

.

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)331

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(

.81

  • )2

)3

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71

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.-

)12

(

  • MJD 58051~60

MJD 58061~70 MJD 58071~ 80

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MJD 58071~ 80

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4.Discussion

2018/3/10 27

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Chi-Square test

  • Evaluation of deviation between

experimental data and model

  • N: Number of bins
  • xi: Counts of photons

(experimental data)

  • X: Counts of photons

(model data)

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Number of bins 0 1 i

  • N

Event number xi x

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Statistical test of pulsation

!" ~1 !" ≫ 1

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Phase 0 1 Count of photons Phase Count of photons

↑Model

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How to fit

We tried to know when the event happened with chi square statistics. We discovered the edge in graph. →It is possible that at this time, the event occurred.

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Decide when the event happened

We investigated the edge’s time by changing two line. →The event happened at “58064.5030.066”.

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Compare with other wave area

We checked “The Jodrell Bank Observatory with the 42-ft Lovell Telescope(1400 MHz)” . Reference: Shaw+2017(Atel#10939) →The event happened at 58064.555(3)(MJD) (58064.503(66)) ⇒The two data are consistent within a statistical error.

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https://en.wikipedia.org/wiki/Lovell_Telescope#/media/File:Lovell_Telescope_5.jpg

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What was the event?

We discovered the two things.

  • 1. The gamma ray from the Crab pulsar changed

and the time is consistent in two wave areas.

  • 2. The pulsar’s frequency increased after the event.

⇒We expected that the event was “GLITCH”.

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What is happened on the CRAB?

  • We think …

Starquake

  • n the CRAB.
  • If we assume that the preservation
  • f angular moment is valid…

∆" " ∼ ∆$ $ ∆"=510mm Sedimentation

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STARQUAKE!!!! ≒10km

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5.Summary

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How much did the frequency change?

We investigated how much the frequency changed. →The frequency increased by 14μHz. Question? : We need more study !!

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?

2018-01-02

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We made a histogram of Δν/ν. It shows that the Glitch we discovered is the biggest one.

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Log10(∆"/"×10')

JODRELL BANK

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2m Uplift Earth radius ≒ 106m Magnitude = 9.0Mw 0.01m Sedimentation Radius of neutron star ≒ 104m Magnitude = 23.5Mw

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2018/3/10 39

Thank you for your attention

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Back up

2018/3/10 42

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  • 2018/3/10

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delta_nu v.s. MJD

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Cumlative chi2 v.s. MJD

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  • 2018/3/10

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Glitch recovery (exponential decay in nu- MJD plot)