Transcript
IISER Pune
Blobs in AGN Jets
Mayur Shende
IISER Pune
January 20, 2016
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 1 / 10
IISER Pune
Introduction
Focus - relativistic jet initiation in blazars
Specifically, episodic jets (as opposed to winds)
To begin with- study data from episodic blobs in the radio galaxy 3C120
Interesting points about 3C 120:
Episodes of radio blob ejection correspond to dips in X-ray luminosity(e.g., Marscher et al 2002, Chatterjee et al 2009)Episodes of radio blob ejection correspond to enhancement in (Fermi)gamma rays (Casadio et al 2015)
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 2 / 10
IISER Pune
Introduction
Focus - relativistic jet initiation in blazars
Specifically, episodic jets (as opposed to winds)
To begin with- study data from episodic blobs in the radio galaxy 3C120
Interesting points about 3C 120:
Episodes of radio blob ejection correspond to dips in X-ray luminosity(e.g., Marscher et al 2002, Chatterjee et al 2009)Episodes of radio blob ejection correspond to enhancement in (Fermi)gamma rays (Casadio et al 2015)
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 2 / 10
IISER Pune
Introduction
Focus - relativistic jet initiation in blazars
Specifically, episodic jets (as opposed to winds)
To begin with- study data from episodic blobs in the radio galaxy 3C120
Interesting points about 3C 120:
Episodes of radio blob ejection correspond to dips in X-ray luminosity(e.g., Marscher et al 2002, Chatterjee et al 2009)Episodes of radio blob ejection correspond to enhancement in (Fermi)gamma rays (Casadio et al 2015)
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 2 / 10
IISER Pune
Introduction
Focus - relativistic jet initiation in blazars
Specifically, episodic jets (as opposed to winds)
To begin with- study data from episodic blobs in the radio galaxy 3C120
Interesting points about 3C 120:
Episodes of radio blob ejection correspond to dips in X-ray luminosity(e.g., Marscher et al 2002, Chatterjee et al 2009)Episodes of radio blob ejection correspond to enhancement in (Fermi)gamma rays (Casadio et al 2015)
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 2 / 10
IISER Pune
Introduction
Focus - relativistic jet initiation in blazars
Specifically, episodic jets (as opposed to winds)
To begin with- study data from episodic blobs in the radio galaxy 3C120
Interesting points about 3C 120:
Episodes of radio blob ejection correspond to dips in X-ray luminosity(e.g., Marscher et al 2002, Chatterjee et al 2009)
Episodes of radio blob ejection correspond to enhancement in (Fermi)gamma rays (Casadio et al 2015)
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 2 / 10
IISER Pune
Introduction
Focus - relativistic jet initiation in blazars
Specifically, episodic jets (as opposed to winds)
To begin with- study data from episodic blobs in the radio galaxy 3C120
Interesting points about 3C 120:
Episodes of radio blob ejection correspond to dips in X-ray luminosity(e.g., Marscher et al 2002, Chatterjee et al 2009)Episodes of radio blob ejection correspond to enhancement in (Fermi)gamma rays (Casadio et al 2015)
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 2 / 10
IISER Pune
Introduction
Questions:
What are these blobs?
These blobs contain energetic electrons (γ = 105 − 106) confinedwithin a small region
How large are they?
Typical sizes 0.2 − 1.6pc
What are the magnetic fields associated with them (using observationsof synchrotron radiation)?Can these fields confine them (if they are tangled)?
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 3 / 10
IISER Pune
Introduction
Questions:What are these blobs?
These blobs contain energetic electrons (γ = 105 − 106) confinedwithin a small region
How large are they?
Typical sizes 0.2 − 1.6pc
What are the magnetic fields associated with them (using observationsof synchrotron radiation)?Can these fields confine them (if they are tangled)?
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 3 / 10
IISER Pune
Introduction
Questions:What are these blobs?
These blobs contain energetic electrons (γ = 105 − 106) confinedwithin a small region
How large are they?
Typical sizes 0.2 − 1.6pc
What are the magnetic fields associated with them (using observationsof synchrotron radiation)?Can these fields confine them (if they are tangled)?
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 3 / 10
IISER Pune
Introduction
Questions:What are these blobs?
These blobs contain energetic electrons (γ = 105 − 106) confinedwithin a small region
How large are they?
Typical sizes 0.2 − 1.6pc
What are the magnetic fields associated with them (using observationsof synchrotron radiation)?Can these fields confine them (if they are tangled)?
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 3 / 10
IISER Pune
Introduction
Questions:What are these blobs?
These blobs contain energetic electrons (γ = 105 − 106) confinedwithin a small region
How large are they?
Typical sizes 0.2 − 1.6pc
What are the magnetic fields associated with them (using observationsof synchrotron radiation)?Can these fields confine them (if they are tangled)?
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 3 / 10
IISER Pune
Introduction
Questions:What are these blobs?
These blobs contain energetic electrons (γ = 105 − 106) confinedwithin a small region
How large are they?
Typical sizes 0.2 − 1.6pc
What are the magnetic fields associated with them (using observationsof synchrotron radiation)?
Can these fields confine them (if they are tangled)?
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 3 / 10
IISER Pune
Introduction
Questions:What are these blobs?
These blobs contain energetic electrons (γ = 105 − 106) confinedwithin a small region
How large are they?
Typical sizes 0.2 − 1.6pc
What are the magnetic fields associated with them (using observationsof synchrotron radiation)?Can these fields confine them (if they are tangled)?
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 3 / 10
IISER Pune
3C 120: VLBA 15 GHz (Casadio et al 2015)
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 4 / 10
IISER Pune
3C 120: VLBA 43 GHz (Casadio et al 2015)
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 5 / 10
IISER Pune
Blob size
Component Size(pc)
C0 0.24C1 0.35E0 0.99E1 1.7E4 1.1E6 1.23E8 0.72E9 0.72D11 0.25D11a 0.19D12 0.11D12a 0.16
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 6 / 10
IISER Pune
Magnetic Fields and Larmor Radii
Magnetic field (calculated assuming observed (GHz) radiation is atsynchrotron critical frequency)
B =2mcωc
3γ2e
Larmor radius corresponding to this magnetic field
rL =γmc2
eB, = (3/2)
γ3c
ωc
How does this Larmor radius compare with blob size?
i.e., can the magnetic field “confine” the synchrotron emittingelectrons?
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 7 / 10
IISER Pune
Magnetic Fields and Larmor Radii
Magnetic field (calculated assuming observed (GHz) radiation is atsynchrotron critical frequency)
B =2mcωc
3γ2e
Larmor radius corresponding to this magnetic field
rL =γmc2
eB,
= (3/2)γ3c
ωc
How does this Larmor radius compare with blob size?
i.e., can the magnetic field “confine” the synchrotron emittingelectrons?
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 7 / 10
IISER Pune
Magnetic Fields and Larmor Radii
Magnetic field (calculated assuming observed (GHz) radiation is atsynchrotron critical frequency)
B =2mcωc
3γ2e
Larmor radius corresponding to this magnetic field
rL =γmc2
eB, = (3/2)
γ3c
ωc
How does this Larmor radius compare with blob size?
i.e., can the magnetic field “confine” the synchrotron emittingelectrons?
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 7 / 10
IISER Pune
Magnetic Fields and Larmor Radii
Magnetic field (calculated assuming observed (GHz) radiation is atsynchrotron critical frequency)
B =2mcωc
3γ2e
Larmor radius corresponding to this magnetic field
rL =γmc2
eB, = (3/2)
γ3c
ωc
How does this Larmor radius compare with blob size?
i.e., can the magnetic field “confine” the synchrotron emittingelectrons?
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 7 / 10
IISER Pune
Magnetic Fields and Larmor Radii
Magnetic field (calculated assuming observed (GHz) radiation is atsynchrotron critical frequency)
B =2mcωc
3γ2e
Larmor radius corresponding to this magnetic field
rL =γmc2
eB, = (3/2)
γ3c
ωc
How does this Larmor radius compare with blob size?
i.e., can the magnetic field “confine” the synchrotron emittingelectrons?
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 7 / 10
IISER Pune
Magnetic Fields and Larmor Radii
γ = 105 and blob size= 0.24pc
Freq(GHz) B(Gauss) rL(pc) Ratio(rL:blob size)
15 3.57 × 10−7 1.55 × 10−4 6.4 × 10−4
37 8.82 × 10−7 6.27 × 10−5 2.6 × 10−4
43 10.25×10−7 5.4 × 10−5 2.25 × 10−4
γ = 106
Freq(GHz) B(Gauss) rL(pc) Ratio(rL:blob size)
15 3.57 × 10−9 0.1550.65
37 8.82 × 10−9 0.0630.26
43 10.25×10−9 0.0540.23
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 8 / 10
IISER Pune
Larmor radius to blob size ratio at 15GHz
γ = 105
Blob size(pc) rL(pc) Ratio
0.24 1.55 × 10−4 6.45 × 10−4
0.72 1.55 × 10−4 2.15 × 10−4
1.698 1.55 × 10−4 9.13 × 10−5
γ = 106
Blob size(pc) rL(pc) ratio
0.24 0.1550.65
0.72 0.1550.22
1.698 0.1550.091
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 9 / 10
IISER Pune
Conclusions
The magnetic fields required to explain the observed GHz emissionrange from 10−7 − 10−9 G assuming γ = 105 − 106
If γ ≈ 105, rL � blob size; i.e., several Larmor radii can fit inside ablob, and the tangled magnetic field can be considered as a goodconfining agent
However, for γ ≈ 106, the Larmor radius is comparable to the blobsize
Hence we need to appeal to additional scattering/confinementmechanisms
Maybe self-generated turbulence?
Thank you for your attention!
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 10 / 10
IISER Pune
Conclusions
The magnetic fields required to explain the observed GHz emissionrange from 10−7 − 10−9 G assuming γ = 105 − 106
If γ ≈ 105, rL � blob size; i.e., several Larmor radii can fit inside ablob, and the tangled magnetic field can be considered as a goodconfining agent
However, for γ ≈ 106, the Larmor radius is comparable to the blobsize
Hence we need to appeal to additional scattering/confinementmechanisms
Maybe self-generated turbulence?
Thank you for your attention!
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 10 / 10
IISER Pune
Conclusions
The magnetic fields required to explain the observed GHz emissionrange from 10−7 − 10−9 G assuming γ = 105 − 106
If γ ≈ 105, rL � blob size; i.e., several Larmor radii can fit inside ablob, and the tangled magnetic field can be considered as a goodconfining agent
However, for γ ≈ 106, the Larmor radius is comparable to the blobsize
Hence we need to appeal to additional scattering/confinementmechanisms
Maybe self-generated turbulence?
Thank you for your attention!
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 10 / 10
IISER Pune
Conclusions
The magnetic fields required to explain the observed GHz emissionrange from 10−7 − 10−9 G assuming γ = 105 − 106
If γ ≈ 105, rL � blob size; i.e., several Larmor radii can fit inside ablob, and the tangled magnetic field can be considered as a goodconfining agent
However, for γ ≈ 106, the Larmor radius is comparable to the blobsize
Hence we need to appeal to additional scattering/confinementmechanisms
Maybe self-generated turbulence?
Thank you for your attention!
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 10 / 10
IISER Pune
Conclusions
The magnetic fields required to explain the observed GHz emissionrange from 10−7 − 10−9 G assuming γ = 105 − 106
If γ ≈ 105, rL � blob size; i.e., several Larmor radii can fit inside ablob, and the tangled magnetic field can be considered as a goodconfining agent
However, for γ ≈ 106, the Larmor radius is comparable to the blobsize
Hence we need to appeal to additional scattering/confinementmechanisms
Maybe self-generated turbulence?
Thank you for your attention!
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 10 / 10
IISER Pune
Conclusions
The magnetic fields required to explain the observed GHz emissionrange from 10−7 − 10−9 G assuming γ = 105 − 106
If γ ≈ 105, rL � blob size; i.e., several Larmor radii can fit inside ablob, and the tangled magnetic field can be considered as a goodconfining agent
However, for γ ≈ 106, the Larmor radius is comparable to the blobsize
Hence we need to appeal to additional scattering/confinementmechanisms
Maybe self-generated turbulence?
Thank you for your attention!
Mayur Shende (IISER Pune) Blobs in AGN Jets January 20, 2016 10 / 10
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