M87: The Rosetta Stone of AGN Jets

Transcription

1 M87: The Rosetta Stone of AGN Jets Image credit: W. B. Sparks (STScI) Masa Nakamura (ASIAA) Collaborators: K. Asada (ASIAA), D. Meier (JPL), D. Garofalo (CSUN), C. Norman (JHU) EHT Jan. 2012

2 Outline Examination of magnetic acceleration & collimation zone in the M87 jet; how does the jet become relativistic? Structural transitions of AGN jets constrained by the mass of SMBHs; a stationary feature may play a role Future prospects of the sub-mm VLBI project to explorer the SMBH & the origin of the M87 jet

3 Observational Aspects Best candidate for studying relativistic jets Nearby: D 16 Mpc (1 mas = 0.08 pc) FR I: Misaligned BL Lac ( θ view 14 ; Wang & Zhou 2009) (6.6 ± 0.4) 10 9 M SMBH mass: (Gebhardt et al. 2011) VLBA resolution: 20 RS at 43 GHz Sub-mm VLBI resolution: 3 RS at 345 GHz (w/ GL) VLBA Movie at 43GHz (C. Walker, NRAO) 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,...), indicating a role of B-fields In situ particle acceleration (Fermi-I diffusive shock processes) HST Movie (J. Biretta, STScI)

4 Observational Aspects (cont.) X-ray: XMM-Newton M87 M87 Forman et al. (2005) Radio: VLA M87 Image credit: X-ray (NASA/CXC/KIPAC/N. Werner, E. Million et al); Radio (NRAO/AUI/NSF/F. Owen) Owen et al. (2000) X-ray observations reveal the property of ISM, as well as interactions between the jet and ISM Transferring the enormous energy in the nucleus on the circumgalactic environment (from 10-4 to 105 pc)

5 A New Components After the TeV Flaring NASA, ESA, and J. Madrid (McMaster Univ.) CORE Abramowski et al., ApJ, in press HST-1 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 evidently splits into two roughly equally bright knots: superluminal (c1; 4.3c) and trailing sub-luminal (c2; 0.47c) components during Q. HST-1 as an origin of superluminal knots (Cheung et al. 2007)? (e.g., Biretta et al. 1999)

6 Quad RMHD Shock Model VC1, VC2, Contact discon. (CD) Reverse slow (RS) (g cm -3) Forward fast (FF) VC1 0.97c VC2 0.67c t (y r) *FWHM ratio (HST/VLA) is about 0.75 at knot A (Sparks et al. 1996): Different magnetic pitch & flow speed are applied Biretta et al. (1999) *Slow-mode MHD Shocks are not suitable for a DSA CD RS RF FS FF ! V 0.99c, VEast 0.79c 1.0 z (pc) V,app 6.0c, VEast,app 0.84c, Assuming θ 14, 2 MN, Garofalo, & Meier (2010)!" (g cm-3) Cheung et al. (2007) app 4.3c 0.47c Assuming θ 14, Forward slow (FS) Reverse fast (RF) app 5 0 MN, Garofalo, & Meier

7 B-fields and Helical Structures M87: VLA F I A B C A pair (forward/reverse)? DW DE G (HST-1) E EF Conical streamline Owen et al. (1989) Biretta & Meisenheimer (1993) Sparks et al. (1996) Transverse field component is dominant in some knots (HST-1, D, A, and C) Sudden changes in B-vector orientation strongly imply the existence of MHD fast/slow-mode waves (w/ high Pol. 20% at inter-knot regions) Presence of four shocks, instead of two, is due to the presence of Bφ (equivalent to B in the simpler planer oblique shocks) may be favored

8 START the Exhaust Inspection of the Jet Engine Image Credit: W. Steffen Note: VLBI radio core includes the jet ACZ & a stationary shock in Marscher s view...

9 Puzzle Remains Unsolved for 2 Decades Apparent speed (V/c) Reid et al. (1989) Junor & Biretta (1995) Biretta et al. (1995) Biretta et al. (1999) Cheung et al. (2007) Kovalev et al. (2007) Distance from the nucleus: z (arcsec) N2 L HST-1 D E F AB C Junor et al. (1999) log r (arcsec) 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 real flow speed at all?

10 Superluminal Motions Upstream of HST-1 3 years monitoring of the M87 jet using European VLBI Network (EVN) at 1.6GHz!""# &'((')*+,-+./0 "!""!""$!""% "!"" 1"" 2"" $"" &'((')*+,-+./0 Asada, MN, et al. (2011)

11 A Missing Link Found! Apparent speed (V/c) Distance from the nucleus: z (arcsec) Reid et al. (1989) N2 L HST-1 D E F AB C Junor & Biretta (1995) Biretta et al. (1995) Biretta et al. (1999) Cheung et al. (2007) Kovalev et al. (2007) Asada et al. (2011) Junor et al. (1999) log r (arcsec) Distance from the nucleus: z (pc) Asada, MN, et al. (2011) 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 ( z r a, 1 <a 2 ) (Zakamska et al. 2008; Komissarov et al. 2009): γθ 1 Acceleration/collimation occurs slowly (Tchekhovskoy et al. 2008; Komissarov 2009): γ z (a 1)/a We need to determine the jet structure (a)!

12 Global Structure of the M87 Jet VLBA at 43 GHz VLBA at 15 GHz EVN at 1.6 GHz MERLIN at 1.6 GHz Parabolic streamline (confined by the ISM): Bondi radius z r 1.73±0.05 jet radius r [r s ] Over-collimation Conical streamline (unconfined, freely expanding): z r 0.96±0.1 ISCO distance from the core z [r ] s The jet maintains the parabolic stream with over 10 5 rs A transition of streamlines presumably occurs at an ISM transition beyond the gravitational influence of the SMBH Stationary feature HST-1 as a consequence of the jet recollimation due to the pressure imbalance w/ the ISM Asada & MN (2012), ApJL

13 Sub-to Superlumial Transition Deprojected distance from the nucleus: z (pc) Apparent speed: app. (V app. /c) Reid et al. (1989), VLBI 1.6 GHz Biretta et al. (1995), VLA 15 GHz Biretta et al. (1999), HST Kellermann et al. (2004), VLBA 15 GHz Cheung et al. (2007), VLBA 1.6 GHz Kovalev et al. (2007), VLBA 15 GHz Asada et al. (2011), EVN 1.6 GHz N2 L HST-1 D E F ABC Deprojected distance from the nucleus: z (mas) Jet opening angle: (deg.) MN, Asada, et al. Expected slope on the stream line: z r α Owen et al. (1980, 1989), VLA 15 GHz Junor & Biretta (unpublished), VLBA 609 MHz Reid et al. (1989), VLBI 1.6 GHz Junor et al. (unpublished), VSOP + VLBA 5 GHz Junor & Biretta (1995), VLBI 22 GHz Junor et al. (1999), VLBI 43 GHz Asada et al. (2010), EVN 1.6 GHz Asada et al. (2010), VLBA 15 GHz Ly et al. (2007), VLBA 43 GHz cf. Ejection point (BP82) θ z 0.43± Deprojected distance from the nucleus: z (mas) Q. Do they exhibit an asymptotic acceleration from non-relativistic (0.01c) to relativistic speed (0.99c) over an extremely large scale Rs? Q. What determines a peak of proper motions as well as a transition from parabolic to conical streamlines?

14 Magnetic Acceleration & Collimation (MAC) Zone Lorentz factor:! Reid et al. (1989), VLBI 1.6 GHz Biretta et al. (1999), HST Kellermann et al. (2004), VLBA 15 GHz Cheung et al. (2007), VLBA 1.6 GHz Kovalev et al. (2007), VLBA 15GHz Asada et al. (2011), EVN 1.6 GHz Walker et al. (2008), VLBA 43 GHz Acciari et al. (2009), VLBA 43 GHz z 2/a z (a 1)/a a = Speed: " (V/c) Specific Kinetic Energy: Spine? Sheath? Reverse shocks Reid et al. (1989), VLBI 1.6 GHz Biretta et al. (1999), HST Kellermann et al. (2004), VLBA 15 GHz Cheung et al. (2007), VLBA 1.6 GHz Kovalev et al. (2007), VLBA 15GHz Asada et al. (2011), EVN 1.6 GHz Walker et al. (2008), VLBA 43 GHz Acciari et al. (2009), VLBA 43 GHz Deprojected distance from the nucleus: z (mas) MN, Asada et al Deprojected distance from the nucleus: z (mas) We identified the jet MAC zone powered by TAW in real astrophysical jet system - The Lorentz factor follows the power-law slope constrained by the parabolic stream ( γθ 1) - Sub-luminal motions at around mas scale is likely to be a trans-alfvénic flow The jet kinetic energy increases as a conversion from Poynting flux - Estimation of the jet total power by Poynting flux: L j = erg s 1 - The system possesses the axial current flowing: I z = A

15 ISM Gas Pressure External Pressure [dyn cm -2 ] R 2 Bondi + King Model: MN, et al. p ext (p int =B 2 /8 2 ) p ext (p int =B 2 p /8 ) : Magnetic tower (RFP) B 2 min /8 (Owen et al. 1989) B 2 FF /8 (Owen et al. 1989) R 2.3 R L. Stawarz et al. Cusp + King Model: Stawarz, et al. (2006) R 0.6 Falle & Wilson (1985) R R 1.2 Owen et al. (1989) R B R c R Distance from the core (R [pc]) Figure 1. Profiles of the hot gas pressure in M 87 host galaxy, as evaluated Parabolic MHD jet is confined by the stratified by Falle & Wilson A shallow (1985, gradient dashed line), of the Owen external et al. (1989, gas, caused thin solidby line) external gas and in this paper a central (thick solid stellar line). cusp Circles indicate minimum pressure of the knots in the M 87 jet neglecting the relativistic correction (filled ones), and Radial pressure balance: pint (mag.) = pext (gas), assuming the jet Freely Doppler expanding factor δ = 2.7 (conical (open ones). hydrodynamic) The circles disconnected jet is indicating a giant ADAF which extends beyond the from the others converging correspond to into the the HST-1 reconfinement flaring region (the shock upstream (Sanders edge of Bondi radius down to the SMBH (Narayan & Fabian the HST-1 knot). 1983: p In deprojecting ism R b,b<2 distances ) between at HST-1 the knots and the active 2011: p ism R b,b 2 ) core, we assumed the jet viewing angle of θ = 20. Analytical study of RMHD jet supports α 2 for a parabolic jet streamline (Komissarov et al 2009): z r a, 1 <a 2 ( r ) 0.6

16 It s a Classical Issue... QSO 3C 48 VLBA 1.5GHz Jet structural transition: ISM grad : steep to shallow at RB w/ re-collimation : shallow to steep at Rc w/o re-collimation (e.g., Magnetic towers in King atmosphere: MN et al. 2006, 2007, 2008) Un-confined jet Stationary knot Confined jet An et al. (2010) Wilkinson et al. (1991), Nature

17 γ-ray Flares, Superluminal Ejections, & Stationary Features in Blazars γ-ray flares occur after the ejections of superluminal jet components in EGRET blazars at pc-scale distances from the core (Jorstad et al. 2001) The γ-ray and the VLBA radio flux at 15 GHz are significantly correlated in Fermi/LAT blazars, suggesting the pc-scale radio core as likely location of flares (Kovalev et al. 2009) Fermi/LAT γ-ray blazars are more likely to have larger Doppler boosting factors (Savolainen et al. 2010) Fermi/LAT γ-ray blazars have larger apparent opening angles (Pushkarev et al. 2009) Quasi -stationary patterns in VLBI surveys (Jorstad et al. 2001, 2005; Kellermann et al. 2004); 27 sources among 42 EGRET γ-ray bright blazars indicate rather stationary hot spots than very slow flow patterns A significant global maximum in the range of projected distances shorter than 0.5 mas for 30 % of the sources in the sample Jorstad et al. (2001)

18 BL Lac: Britzen et al. (2010) Jorstad et al. (2005) Mahmud et al. (2009)

19 BL Lac: (OJ287) E-vectors ( B-vectors) B dominated Jorstad et al. (2005) B dominated

20 Summary Jets scaled by SMBH(M ): M - σ relation & AGN Unification M87: Rosetta stone of AGN jets Jet MAC nozzle powered by the TAW Transition of streamlines beyond a stationary knot VHE γ-ray emissions & ejections of superluminal knots Paraboloidal structure: z r a, 1 <a 2 p ism z b Re-collimation & accumulating Conical structure: azimuthal B-field z r (γθ 1) p ism 0 Magnetic Acceleration & Collimation (MAC) Zone SMBH TAW B φ I Stationary knot Bondi radius