Theory Does Meet ( or not? ) VLBI Observations in M87 Color: - - PowerPoint PPT Presentation

Theory Does Meet (or not?) VLBI Observations in M87

EAVW2018, PyeongChang, Korea, Sep. 4-7 2018

MASANORI NAKAMURA (ASIAA)

Color: Lorentz factor

—: Magnetization = 1 —: Jet boundary of F-F model

MN, Asada, Hada+ (2018)

Multi Frequency VLBI (MFV) View

Asada & MN (2012); Hada+ (2013); Asada, MN+ (2014); Hada+ (2016); Asada+ (2017)

★ Our knowledge is still limited even after 100 years…

MN, Asada, Hada+ (2018) (see also Asada & MN 2012; MN & Asada 2013; Hada+ 2011, 2013, 2016)

1 101 102 103 104 105 106

Bondi radius

10-4 10-3 10-2 10-1 1 101 102 103 104 1 101 102 103 104 105 106 107 108 Jet axial distance (de-projected): z (pc) Jet radius: R (rg) Jet axial distance (de-projected): z (rg)

MERLIN 1.8 GHz (AN12) EVN 1.6 GHz (AN12) VLBA 2.3 GHz (H13) VLBA 5 GHz (H13) VLBA 8.4 GHz (H13) VLBA Core 43 & 86 GHz (NA13) VLBA Core 5, 8, 15, 24, 43, & 86 GHz (H13), HSA Core 86 GHz (H16) EHT Core 230 GHz (D12, A15) (Area) FFE parabolic jet (NMF07, TMN08) (Area) FFE genuine parabolic jet (NMF07, TMN08) a = 0.5 (upper edge) - 0.99 (lower edge) VLBA 15 GHz (AN12, H13) VLBA 22 GHz (H13) VLBA 43 GHz (AN12, H13) HSA 86 GHz (H16)

HST-1

Discovery of Jet Collimation Break (JCB)

“parabolic” “conical”

=

• JCB in Various AGN Jets

Hada, …, MN, and Asada (2018)

• Related VLBI results
• 3C 84: Nagai, …MN+ (2014)

Giovannini, …MN+ (2018)

• N6251: Tseng, Asada, MN+ (2016)
• Cyg-A: Boccardi+ (2016a, b)

Nakahara, …MN+, submitted

• Blazers: Algaba, MN+ (2017)
• 3C 273: Akiyama, …MN+ (2018)
• N4261: Nakahara, …MN+ (2018)
• 1H 0323+342: Hada, …MN+ (2018)
• N1052: Nakahara, …MN+, submitted
• …

Doi+ (2018)

• Fig. 1. Distribution of the Lorentz factor for the case with

showing the main features of the steady solution. The red viduates the region shown in Fig. 2. We notice that the stretched.

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t h e s l i g h t l y ( 2 9

Bodo & Tavecchio (2018)

Numerical Sim. vs. Steady FFE Solutions

— Blandford & Payne (1982)-type FFE solution

• - Blandford & Zajek (1977)-type FFE solution

HARM2D (Gammie & McKinney 2003)

a = 0.9375

✓Boundary condition between the magnetically dominated funnel (unbound jet) and coronal (bound wind) is numerically identified up to r/rg = 100 for a = 0.5 - 0.99

— σ = 15 — ur = 0 — σ = 1 —βp = 1

• -Be = 0 (-ut = 1)
• 1. Funnel jet
• 2. Wind
• 3. RIAF

Funnel Jet Velocity

Γ = √−gttut

✓ A clear dependence on the BH spin ✓ Emerging superluminal blobs w/ Γ > 2 (w/ θview < 25°) along

the jet sheath for high spins (discuss later)

a = 0.5 a = 0.7 a = 0.9 a = 0.99

βp = 1

F = r B2

φ

8π

p

1

> p

2

Mf > 1

S

dS S = dv v (M2 − 1), where M ≡ v cs

M > 1

p1 > p2

dS > 0 dp < 0 dv > 0

F = rp

M < 1

(Magneto-)hydrodynamics of Jet Acceleration

• Diverging nozzle (de Laval 1888) in hydro jet: Flow cross section
• pens up at supersonic regime, causing the gas pressure drops

★ Parabolic nozzle may not be effective (not diverging…)?

• Magnetic nozzle (Camenzind 1987)

in MHD jet: Reduction of the Bp line density at the outer layer in the funnel ➡ “Differential bunching” toward the jet axis (by the hoop stress of Bφ)

}

Acceleration efficiency (conversion of Poynting-to-Matter energy flux) increases w/ larger ξ ( e.g.100% in ξ = 2; “force-free”)

S

S

Bp(R) ∝ R−ξ

R

10-1 1 101 102 10-4 10-3 10-2 θ ( ) |Br | r/rg=100 r/rg=50 r/rg=10 t/tg=12000 a=0.5 10-1 1 101 102 10-2 10-1 1 101 102 103 θ ( ) dψ/dθ r/rg=10 r/rg=50 r/rg=100 t/tg=12000 a=0.5 10-1 1 101 102 10-4 10-3 10-2 θ ( ) |Br | r/rg=100 r/rg=50 r/rg=10 t/tg=12000 a=0.99 10-1 1 101 102 10-2 10-1 1 101 102 103 θ ( ) dψ/dθ r/rg=10 r/rg=50 r/rg=100 t/tg=12000 a=0.99

Differential Bunching in Different Spins

✓ Differential bunching does not operate at around the jet

stagnation surface, but it becomes strong toward the downstream and when the BH spin increases

✓ Deviation from ξ = 2 and its variation: ξ(r)

Low spin High spin ξ ∼ 0.5

ξ ∼ 1

Trailing Blobs in Underlying Bulk Flow?

M87 KaVA 23GHz (Niinuma+ 2014)

• HSA 86GHz (Hada+ 2016)

★We don’t know where/how SL knots are formed in AGNs…

R . 10 rg R & 10 rg(∼ RL)

• Sausage instability (m = 0); pressure/current

driven?➡ jet funnel/ambient boundary

• Origin of superluminal knots (not only at the

HST1-d [MN+ 2010, MN & Meier 2014], but also at the very vicinity of the BH)

• Consistency check with simultaneous obs.!
• : varying core (> mm)
• : stable core (< mm/sub-mm)
• “Shock-in-jet” hypothesis and HE/VHE event

can be examined (vs. Gap model [Hirotani+])

• The location of the stagnation surface

depends on the BH spin (Pu, MN+ 2015) ➡ VLBI core (ν→∞) may not reach the EH ➡ How about Sgr A*? βplasma < 0.5 Bφ/ΓBz < √ 2

(for RFP; e.g., Freidberg 1982) (c.f., Kadomtsev 1966)

a = 0.9

VLBA, HSA core@86GHz sub-mm core@340GHz? sub-mm core@690GHz?

Innermost Structure of the M87 Jet

— σ = 1 —βp = 1 — ur = 0

VLBA core@43GHz EHT core@230GHz

1 101 102 103 104 105 106 107 108 10-3 10-2 10-1 1 101

Bondi radius

10-4 10-3 10-2 10-1 1 101 102 103 104 Jet axial distance (de-projected): z (rg) Γβ Jet axial distance (de-projected): z (pc)

VLA 15 GHz (B95) HST (B99, M13) VLBA 1.7 GHz (C07) VLBA 1.7 GHz/EVN 5 GHz (G12) EVN 1.6 GHz (A14) VLBI 1.6 GHz (R89) VLBA 15 GHz (K04, K07) VLBA 15 GHz (M16) KaVA 22 GHz (H17) (Area) VLBA 43 GHz (L07) VLBA 43 GHz (M16) HSA 86 GHz / VLBA 43 GHz (H16) FFE parabolic jet (NMF07, TMN08) a = 0.5 a = 0.7 a = 0.9 a = 0.99 GRMHD simulaiton (M06, a=0.9375) GRMHD simulation (P13, a=0.7-0.98) GRMHD simulation (This paper, a=0.5-0.99)

HST-1

Observations vs. Theory

10-3 10-2 10-1 1 101 102 1 101 102 Γβ Beaming factor: δ3-α

★ A high-cadence VLBI monitoring (< a week) may fjnd a faster motion (> 0.3 mas/week)???

β = cos θv

★ Global high-res simulations to understand the highly non-linear evolution

Cui, Hada+

GMVA

EHT KaVA/VLBA monitor

Topics to Be Examined w/ MFV

➡

EHT (+GLT): Is there any robust feature of “jet birth region” (down/up-stream of the jet stagnation)?

➡

GMVA/HSA (+GLT): Variation under the persistent limb-brightened feature, origin of SL knots

➡

EAVN/KaVA: Faster SL knots w/ high-cadence monitoring (vs. MHD jet theory/simulation)

Summary

Bunching of Poloidal Magnetic Flux

Funnel Jet

J e t Stagnation S u r f a c e Funnel E d g e Spine Sheath

Corona / Wind RIAF

MN+ (2018)

Our parabolic jet model can be primarily applicable to LLAGNs and/or BL Lacs, in which the RIAF (at sub- Eddington regime; mdot < 10−2) falls into the central SMBH. We, however, suggest that the internal structure of a magnetically driven funnel jet (close to SMBH) seems to be general; parabolic jet may also be expected even in radio loud quasars (mdot > 10−2). A faster jet sheath may be universal if the MHD acceleration and collimation play a fundamental role in AGN jets (see also Algaba, MN, Asada & Lee 2017 for some hints of wider jet radii than z ∝ R2). Origin and evolution of AGN jets (collimation / acceleration of bulk flows, forming superluminal knots, etc.) can be extensively examined by MFV w/ EA facilities (EAVN/KaVA, GLT, JCMT). M87 will provide a solid understanding of relativistic AGN jets in coming years; stay tuned!