Capability for Probing the Intergalactic Magnetic Field (IGMF) - - PowerPoint PPT Presentation

Capability for Probing the Intergalactic Magnetic Field (IGMF)

Shinsuke Ideguchi Kumamoto University, Japan

SKA Science W

• rkshop in East Asia 2013 @ Nagoya Univ.

5-7 June 2013

Collaborators:

• K. Takahashi (Kumamoto Univ.), T. Akahori (Sydney Univ.),
• K. Kumazaki (Nagoya Univ.) & D. Ryu (Chungnam National Univ.)

Our Goal

Akahori & Ryu (2010)

Find IGMF in filaments of galaxies by radio telescopes have never been observed affect to many cosmic phenomena

• CMB fluctuation, propagation of UHECR, etc...

may have information of early universe

• based on ideas : the current comic magnetisms originate from primordial MF

~100nG, a few rad/m2 in RM (Akahori & Ryu 2010) In this study: W e forecast the capability for proving the IGMF in filaments assuming “LOFAR, ASKAP & GMRT”

• bservation

Observation

χ = (RM)λ2 + χ0

RM 0.81 rad m2 ls ne cm3 B µG dl Mpc

• Faraday Rotation
• 50

50 100 150 200 250 300 350 0.2 0.4 0.6 0.8 1

Situation needed for observing IGMF IGMF

Foreground

source

Integration along a LOS

slope : RM

W avelength λ2 [m2] Polarization angle [deg.]

Need to distinguish the Galaxy component, IGMF & source

Faraday Dispersion Function (FDF)

Distribution of MF & radio source along a LOS P(λ2) = Q + iU = ∞

−∞

F(φ)e2iφλ2 dφ IGMF

F

• r

e g r

• u

n d source

gap

0.02 0.04 0.06 0.08 0.1 5 10 15 20 25 30

F() [rad m

• 2]

[mJy] Observed polarized intensity Intrinsic polarized intensity

Relation between “observed PI” & “FDF”

φ(r) = 0.81 here

there

neB · dr rad m−2

Faraday depth

(~distance measured by MF)

QU-fitting

Model FDF RMIGMF Diffuse source Compact source

0.02 0.04 0.06 0.08 0.1 5 10 15 20 25 30

F() [mJy] [rad m

• 2]
• bserved Q & U data
• 0.15
• 0.1
• 0.05

0.05 0.1 0.15 0.2 0.001 0.01 0.1 1 10

U 2

• 0.15
• 0.1
• 0.05

0.05 0.1 0.15

Q

• 0.15
• 0.1
• 0.05

0.05 0.1 0.15 0.2 0.001 0.01 0.1 1 10

U 2 parameter set 1 parameter set 2

• 0.15
• 0.1
• 0.05

0.05 0.1 0.15

Q

model Q & U

…

QU-fitting

parameters per each source φ : faraday depth of source δφ: width of source f : peak intensity of source θ : intrinsic polarization angle P(λ2; p1, p2, . . . , pN) = Q(λ2; p1, p2, . . . , pN) + iU(λ2; p1, p2, . . . , pN) = ∞

−∞

F(φ; p1, p2, . . . , pN)e2iφλ2dφ

QU-fitting

Model FDF RMIGMF Diffuse source Compact source

0.02 0.04 0.06 0.08 0.1 5 10 15 20 25 30

F() [mJy] [rad m

• 2]
• bserved Q & U data
• 0.15
• 0.1
• 0.05

0.05 0.1 0.15 0.2 0.001 0.01 0.1 1 10

U 2

• 0.15
• 0.1
• 0.05

0.05 0.1 0.15

Q

• 0.15
• 0.1
• 0.05

0.05 0.1 0.15 0.2 0.001 0.01 0.1 1 10

U 2 parameter set 1 parameter set 2

• 0.15
• 0.1
• 0.05

0.05 0.1 0.15

Q

model Q & U

…

QU-fitting

parameters per each source φ : faraday depth of source δφ: width of source f : peak intensity of source θ : intrinsic polarization angle P(λ2; p1, p2, . . . , pN) = Q(λ2; p1, p2, . . . , pN) + iU(λ2; p1, p2, . . . , pN) = ∞

−∞

F(φ; p1, p2, . . . , pN)e2iφλ2dφ

This Study: Forecast the capability of ongoing telescope for proving the IGMF by QU-fitting through Fisher analysis

Fisher Analysis

Fisher Matrix Covariance Matrix Fjk = 1 2 ∂2χ2 ∂pj ∂pk

χ2 =

N

• l=1

[Yl(p) − Zl]2 σ2

l

Curvature at the fiducial value in parameter space 1σ 2σ

R

Fiducial value

~ (1/C)1/2 = R (Curvature Radius) ~ C (Curvature) diagonal : 1-σ error of parameter non-diagonal : correlation of error p χ2

Model Observed data

σjk = (F−1)1/2

jk

• An observation of a compact source through the Galaxy
• RM of IGMF in filaments is a few rad/m2
• One hour exposure

IGMF

Foreground

Quasar

Assumption

0.02 0.04 0.06 0.08 0.1 5 10 15 20 25 30

F() [rad m

• 2]

P(2) 2 [m

2]

ASKAP GMRT LOFAR

0.5 1 1.5 2 0.001 0.01 0.1 1 10

Results Ⅰ 1-σ confidence region

RMIGMF =3.0 rad/m2 f=0.1 mJy

fc (0.1) δφc (0.4)

L A AL AGL

short wavelength (ASKAP) long wavelength (LOFAR) RMIGMF (3.0) δφc (0.4)

5 10 15 20 25 30 35 40 2 4 6 8 10

(A : ASKAP, G : GMRT, L : LOFAR) RM=0 is not excluded

0.2 0.4 0.6 0.8 1 1.2 10 20 30 40 50

Results Ⅱ

RMIGMF (5.0) δφc (0.4)

5 10 15 20 25 30 35 40 2 3 4 5 6 7 8 9 10

RMIGMF =5.0 rad/m2 f=0.1 mJy RMIGMF =3.0 rad/m2 f=0.5 mJy

1 2 3 4 5 6 7 8 9 1.5 2 2.5 3 3.5 4 4.5

RMIGMF (3.0) δφc (0.4)

1-σ confidence region

RMIGMF =3.0 rad/m2 f=0.1 mJy

RM=0 is excluded RM=0 is excluded

Larger RMIGMF / Brighter source make it easier to detect the IGMF

Results Ⅲ

RM=1.0 rad/m2

Compact source intensity [mJy]

(A : ASKAP, G : GMRT, L : LOFAR) A AL AGL

The Galaxy intensity [mJy]

RM=3.0 rad/m2

Necessary source intensities for detecting IGMF (3-σ CL) IGMF is detected in the up-right regions of the lines

0.001 0.01 0.1 1 10 100 0.001 0.01 0.1 1 10 100 0.001 0.01 0.1 1 10 100 0.001 0.01 0.1 1 10 100

The Galaxy intensity [mJy] Compact source intensity [mJy]

Results Ⅲ

RM=1.0 rad/m2

Compact source intensity [mJy]

(A : ASKAP, G : GMRT, L : LOFAR) A AL AGL

The Galaxy intensity [mJy]

~0.09mJy [RM=1]

Intensity of the Galaxy (high latitude)

RM=3.0 rad/m2

Necessary source intensities for detecting IGMF (3-σ CL) IGMF is detected in the up-right regions of the lines

0.001 0.01 0.1 1 10 100 0.001 0.01 0.1 1 10 100 0.001 0.01 0.1 1 10 100 0.001 0.01 0.1 1 10 100

The Galaxy intensity [mJy] Compact source intensity [mJy]

~0.03mJy [RM=3]

SUMMARY

IGMF may affect to many phenomena in the universe W e forecast the capability of ongoing telescope for proving IGMFs of filaments by QU-fitting through Fisher analysis Assuming very simple model as the Galaxy component and RM

• f the IGMF is a few rad/m2, the IGMF can be detected by
• bserving some compact source with intensities more than

0.03mJy by LOFAR & ASKAP By using seamless data with SKA, we would be able to detail discussion for IGMFs