Evidence of Magnetic Acceleration & Collimation in AGN Jets

18 Pages·2012·9.75 MB·English

Evidence of Magnetic Acceleration
& Collimation in AGN Jets
Image credit: W. Sparks (STScI)
Masanori Nakamura (ASIAA)
Collaborators: K. Asada (ASIAA), J. Biretta (STScI), A. Doi (JAXA), D. Garofalo (CSUN),
M. Inoue (ASIAA), D. Meier (JPL), H. Nagai (NAOJ), C. Norman (JHU), W. Sparks (STScI)
NAASC Jets2012@Charlottesville, VA, Mar. 2012
SUMMARY of THIS TALK
๏ A constraint of magnetic acceleration & collimation (MAC) zone
in the M87 jet; how does the flow become relativistic?
→ MAC zone may not be defined by only MHD jet theory (positions of re-
collimation shocks in self-similar solutions)
๏ Structural transitions of AGN jets scaled by M ; stationary features (re-
●
collimation shocks) may play a role
→ An intrinsic correlation w/ the M -σ relation and a potential connection to
●
VHE emission regions
Paraboloidal structure: Re-collimation & accumulating Conical structure:
a
z r , 1 < a 2 azimuthal B-field z r (γθ 1)
∝ ≤ ∝ ∼
p z b p 0
ism − ism
∝ ∇ ∼
Magnetic Acceleration & Collimation (MAC) Zone
TAW
I
SMBH B Stationary knot
φ
R
BH
∼
0.5 0.6
8
10.0 M /10 M − pc
BH
⊙
￿ ￿MN & Norman
M87 Observations
• The “Rosetta Stone” for studying relativistic jets
x 10 of BH diameter
• Nearby: D 16 Mpc (1 mas 0.078 pc 125 r ) 0.1 light year
s
∼ ∼ ∼
• FR I: Misaligned BL Lac ( θ 1 4 ; Wang & Zhou 2009)
view ◦
∼
• SMBH mass: ( 6 . 6 0 . 4 ) 1 0 9 M (Gebhardt et al. 2011)
± ×
⊙
• VLBA res. : 20 r at 43 GHz
s
• Sub-mm VLBI res.: 3 r at 345 GHz (w/ GLT)
s
x 3 of BH diameter
VLBA 43GHz (Hada et al. 2011)
• Well studied at wavelengths from radio to X-ray
• Proper motions (sub/super-luminal feature)
• Polarization (20 - 60%; ordered B-fields)
• Substructure (limb-brightened, knots, wiggles,...)
• In situ particle acceleration at knots
• HST-1 (Biretta et al. 1999): the site of flaring
NASA, ESA, and J. Madrid (McMaster Univ.)
CORE HST-1
Bright Dim Bright Dim
M87 Observations
• The “Rosetta Stone” for studying relativistic jets
x 10 of BH diameter
• Nearby: D 16 Mpc (1 mas 0.078 pc 125 r ) 0.1 light year
s
∼ ∼ ∼
• FR I: Misaligned BL Lac ( θ 1 4 ; Wang & Zhou 2009)
view ◦
∼
• SMBH mass: ( 6 . 6 0 . 4 ) 1 0 9 M (Gebhardt et al. 2011)
± ×
⊙
• VLBA res. : 20 r at 43 GHz
s
• Sub-mm VLBI res.: 3 r at 345 GHz (w/ GLT)
s
x 3 of BH diameter
VLBA 43GHz (Hada et al. 2011)
• Well studied at wavelengths from radio to X-ray
• Proper motions (sub/super-luminal feature)
• Polarization (20 - 60%; ordered B-fields)
• Substructure (limb-brightened, knots, wiggles,...)
• In situ particle acceleration at knots
• HST-1 (Biretta et al. 1999): the site of flaring
NASA, ESA, and J. Madrid (McMaster Univ.)
CORE HST-1
Bright Dim Bright Dim
A New Components After the TeV Flaring
Abramowski et al. (2012) VLBA: Cheung et al. (2007)
• A flaring from radio through optical to X-ray (factor 50)
∼
bands (Harris et al. 2006) at HST-1, indicating a site for TeV
γ-ray emissions (Harris et al. 2009)
• HST-1c: two roughly equally bright knots: superluminal and
trailing sub-luminal components during 2005 - 2006
(Cheung et al. 2007) → Quad relativistic MHD shocks
(foward/reverse fast/slow) by MN, Garofalo, & Meier (2010)
VLBA + EVN : Giroletti et al. (2012)
A New Components After the TeV Flaring
Abramowski et al. (2012) VLBA: Cheung et al. (2007)
• A flaring from radio through optical to X-ray (factor 50)
∼
bands (Harris et al. 2006) at HST-1, indicating a site for TeV
γ-ray emissions (Harris et al. 2009)
• HST-1c: two roughly equally bright knots: superluminal and
trailing sub-luminal components during 2005 - 2006
(Cheung et al. 2007) → Quad relativistic MHD shocks
(foward/reverse fast/slow) by MN, Garofalo, & Meier (2010)
VLBA + EVN : Giroletti et al. (2012)
Puzzle Remains Unsolved for 2 Decades
Distance from the nucleus: z (arcsec) Junor et al. (1999)
10-3 10-2 10-1 1 101 log r (arcsec) -1 0 1
8
N2 L HST-1 D E F ABC
Reid et al. (1989)
Biretta & Junor (1995)
Biretta et al. (1995)
Biretta et al. (1999)
6
Kellermann et al. (2004)
) Cheung et al. (2007)
c
/
V Kovalev et al. (2007)
(

d
e
e 4
p
s

t
n
e
r
a
p
p
A
2
0
10-2 10-1 1 101 102 103
Distance from the nucleus: z (pc)
• Superluminal motions begin at HST-1, lying about 1” ( 80 pc) from the nucleus
∼
• Many VLBI observations show sub-luminal motions upstream of HST-1
• Visible pc-scale features may reside in slower layers near the surface (Biretta et al. 1999)
or possibly standing shocks and/or instability patterns ( )?
Kovalev et al. 2007
➡ Q. No “systematic” acceleration towards HST-1 exists although collimation occurs
asymptotically? Or proper motions do not correspond to the flow speed at all?
Superluminal Motions Upstream of HST-1
3 years monitoring of the M87 jet using European VLBI Network (EVN) at 1.6GHz
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Asada, MN, et al.
A Missing Link Found
Distance from the nucleus: z (arcsec)
10-3 10-2 10-1 1 101 log r (arcsec) -1 0 1
8
N2 L HST-1 D E F ABC
Reid et al. (1989)
Biretta & Junor (1995)
Biretta et al. (1995)
Biretta et al. (1999)
6
Kellermann et al. (2004)
) Cheung et al. (2007)
c
/
V Kovalev et al. (2007)
(

d
e
e 4
p
s

t
n
e
r
a
p
p
A
2
0
10-2 10-1 1 101 102 103
Distance from the nucleus: z (pc)
Junor et al. (1999)
✓ Yes, We found final pieces of the puzzle, but how they will match into the MHD jet?
• The (bulk) acceleration (γ) and collimation (θ) are correlated in a parabolic streamline
a
( z r , 1 < a 2 ) ( ): γθ 1
Zakamska et al. 2008; Komissarov et al. 2009 ￿
∝ ≤
(a 1)/a
• Acceleration/collimation occurs slowly (Tchekhovskoy et al. 2008; Komissarov 2009): γ z −
∝
a
We need to determine the jet structure ( )
A Missing Link Found
DDiissttaannccee ffrroomm tthhee nnuucclleeuuss:: zz ((aarrccsseecc))
1100--33 1100--22 1100--11 11 110011 log r (arcsec) -1 0 1
88
NN22 LL HHSSTT--11 DD EE FF AABBCC
RReeiidd eett aall.. ((11998899))
BBiirreettttaa && JJuunnoorr ((11999955))
BBiirreettttaa eett aall.. ((11999955))
BBiirreettttaa eett aall.. ((11999999))
66
KKeelllleerrmmaannnn eett aall.. ((22000044))
)) CChheeuunngg eett aall.. ((22000077))
cc
//
VV KKoovvaalleevv eett aall.. ((22000077))
((
d d Asada, MN, et al.
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ee 44
pp
ss

tt
nn
ee
rr
aa
pp
pp
AA
22
00
1100--22 1100--11 11 110011 110022 110033
DDiissttaannccee ffrroomm tthhee nnuucclleeuuss:: zz ((ppcc))
Junor et al. (1999)
✓ Yes, We found final pieces of the puzzle, but how they will match into the MHD jet?
• The (bulk) acceleration (γ) and collimation (θ) are correlated in a parabolic streamline
a
( z r , 1 < a 2 ) ( ): γθ 1
Zakamska et al. 2008; Komissarov et al. 2009 ￿
∝ ≤
(a 1)/a
• Acceleration/collimation occurs slowly (Tchekhovskoy et al. 2008; Komissarov 2009): γ z −
∝
a
We need to determine the jet structure ( )