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Some Heuristic Viewpoints on the 3C273 Jet Physics

Some Heuristic Viewpoints on the 3C273 Jet Physics. W.-P. LIU (1, 2) and Z.-Q. SHEN (1) 1.Shanghai Astronomical Observatory of CAS 2.The Graduate School of CAS. http://www.astro.soton.ac.uk/~jester/images/Marshall3C273rgb.jpg. Metaphysics on this project.

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Some Heuristic Viewpoints on the 3C273 Jet Physics

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  1. Some Heuristic Viewpoints on the 3C273 Jet Physics W.-P. LIU (1, 2) and Z.-Q. SHEN (1) 1.Shanghai Astronomical Observatory of CAS 2.The Graduate School of CAS http://www.astro.soton.ac.uk/~jester/images/Marshall3C273rgb.jpg

  2. Metaphysics on this project • 1. Observation and Model are two faces of one coin. • 2. Creating a good problem is more important than solving it. • 3. Accepting the contradiction is the most effective way to solve the contradiction. • 4. Science has no border, but scientists and telescopes have border. We should have our own national telescopes (at least partially take part in) .

  3. Outline • I. Creating a problem • II. Some heuristic viewpoints on the problem • III. Conclusion and Future work on this project

  4. I. Creating a problem

  5. IR 取自U06 http://cass.ucsd.edu/public/tutorial/Quasars.html Observations of the 3C273 Jet • Z=0.158，3C273 was the first quasar discovered (Schmidt 1963). Nobel Prize in the future if he’s alive long enough. • The 3C273 Jet has been studied extensively from the radio (e.g., Conway et al. 1993; An 2004, PhD thesis), infrared (e.g., Jester et al.2005; Uchiyama et al. 2006, hereafter U06; Jester et al. 2007,hereafter J07), optical (e.g., Jester et al. 2001; 2005), to the X-rays (e.g., Marshall et al. 2001; Sambruna et al. 2001, hereafterS01; Jester et al. 2006, hereafter J06). • A TeV flux upper limit has also been obtained by shallow H.E.S.S. observations (Aharonian et al. 2005). • The 10”-long radio jet has a knotty morphology, with the first bright knot at about 12 -13” from the central engine and increasing radio intensity toward a terminal bright hot spot about 22-23” from the nucleus (Flatters & Conway 1985; U06).

  6. 取自U06 Three-bands Image of the 3C273 jet

  7. 取自U06 Composite Image The increasing lower-energy emissions and decreasing high-energy emissions with the increasing separation from the nucleus (U06).

  8. Data of the 3C273 Jet

  9. Jester et al. 2006 Two-component Nature of Spectrum • Based on the spectral energy distributions (SEDs) of these knots and hot spots in the 3C273 jet, many researchers have identified two-component nature (U06; J06; S01), namely (1) the low-energy component extending from radio to optical, and (2) the high-energy component responsible for the emission including X-ray.

  10. Jester et al. 2006 The Possible Radiation Mechanisms of the 3C273 Jet • Synchrotron emission is considered to be the dominant radiation mechanism from radio through optical bands, i.e., the low-energy component (S01;U06), but the radiation mechanism of X-ray emission is still perplexing.

  11. So far, there have been three candidates forthe origin of the X-rays (S01): • (a) synchrotron emission which another much more energetic population of particles emit (Roeser et al. 2000; Aharonian 2002; Bai & Lee, 2003; U06); • (b) inverse Compton scattering of synchrotron photons from low energy component, i.e. Self-Synchrotron Compton (SSC) model; • (c) inverse Compton scattering of photons which are external to the jet， such as inverse Compton scattering of cosmic microwave background photons model (hereafter IC/CMB).

  12. Tavecchio et al. 2000 Equipartition Condition and SSC SSC emission from electrons in an equipartition magnetic field can usually account for the X-ray emission from hot spots (J07, Harris & Krawczynski 2006). The contribution from SSC X-rays in the3C273 jet is not significant (S01, J06), so we provisionally ignore SSC effect on the X-ray emission. Doppler factor1，need a lower magnetic field than equipartition field of synchrotron component. The magnetic fieldequipartition field , need a lower Doppler factor (debeamed) than unit. This results in a much larger and implausible total jet power. (Sambruna et al. 2001; Dermer & Atoyan 2004; Tavecchio et al. 2000, Schwartz et al. 2000, Tavecchio, Maraschi, & Ghisellini 1998 )。

  13. Double Synchrotron Model • U06 described the wide radio-to-X-ray spectrum with their double power-law models (eq. (1) of U06, low-energy component with an exponential cutoff), but they required an additional assumption that the two power-law indices were different and their formula was partly man-made rather than derived from any clear physical insight. • The double synchrotron emission model also does not clearly point out the direct connection of the two populations of source particles, and the second, the ultra-energetic particles that emit X-ray photons calls for a radical rethink of the physics of relativistic jet that black holes drive (Urry 2006)

  14. One Plausible Mechanism • Among the suggested mechanisms for the high-energy component, we adoptIC/CMB if there is a bulk relativistic motion on kilo-parsec scales (S01). Indeed, VLBI observations have detected apparent superluminal motions in the parsec-scale jet with apparent velocities about 6-10 c (e.g., Unwin et al. 1985). And X-ray/optical emission remains asymmetric, implying the presence of relativistic bulk motion on kilo-parsec scales (S01) too.

  15. Region A corresponds to knot A1 (maximum X-ray flux); region B encloses optical knots A2, B1, and B2; regionC includes knots C1-C3; and region D contains knots D1-D3 (Samburna et al. 2001). Sambruna et al. 2001 Sambruna et al. 2001 Question • J06 presented deeper Chandra observations of the 3C273 jet and found that the X-ray spectra are softer than the radio spectra in nearly all parts of the jet, ruling out the simplest one-zone beamed IC/CMB models for the X-ray emission from the entire jet. Within their two-zone jet model, they still required two different spectral indices for radio and X-ray spectrum of each knot in the 3C273 jet. • S01 divided all the detected knots into four regions, and then quite well fit IC/CMB model to the wide-band SED in each of them, implying the rationality of IC/CMB model for 3C273 jet. Then the question is why IC/CMB model could fitthe regions enclosing some neighboring knots but not individual knot. S01 and J06 did not explain this interesting problem.

  16. 南部阳一郎 小 林 诚 益川敏英 http://news.xinhuanet.com/tech/2008-10/07/content_10161828.htm Similar to this year Noble’s theme:“Symmetry and Breaking”

  17. In for a penny, in for a pound: The Summed Spectrum of all the knots in the 3C273 Jet The FSRQs’ Hard X-ray Contribution to the Hard X-ray Background (partly), which needs to be verified by HXMT. Marelli,M., 2008ATel. A Synchrotron with two break frequencies (Liu & Shen 2007 (LS07), Sahayanathan 2008) for the low-energy component +IC/ CMB (a power law fitting) for the high-energy component. Agreeing with the requirement of FSRQ’s Doppler factors（>6.45, Cao & Bai 2008）

  18. Marelli,M., 2008ATel.1707....1M, Fermi LAT detection of 3C 273 in flaring state

  19. LS07 Jester et al. 2006 CONSTRAINTS A. The summed spectrum of all the knots in the 3C273 jet could be fitted by Syn+IC/CMB model with a electrons energy spectrum index and a Doppler factor; B. The individual knot in the 3C273 jet could not be explained by the Syn+IC/CMB model with a electrons energy spectrum index and/or a Doppler factor. C. The Spectrum difference (esp. Synchrotron Component) of the M87 and 3C273 knots with different viewing angles.

  20. II. How to understand this problem?

  21. Jet as a Stratified Structure(Stream Layers and Viewing Angles) External

  22. A Stratified Model • Based on the difference between the optical and radio polarimetric observations, Perlman et al. (1999) advanced a model of partial energy stratification. They illustrated that the optical-emitting electrons are located closer to the jet axis, while most of the radio-emitting electrons are located nearer the jet surface. • Further promoting this model, we think that even the optical- and radio-emitting electrons themselves may also be (weakly) stratified through the jet's cross section, similar to the spine-sheath structure.

  23. And the advection and diffusion of the populations of particles along the jet with the decrease of the synchrotron lifetime from low energy to high energy would result in spatially stratified (LS07) and conical emission layers (regions) along the jet. Because of cooling process, the stratified effect along the jet may be more obvious for high energy electrons. • This scenario suggests that the observed different radiation from a knot at different frequency is not from a simple electrons component within the same region of that knot, but from a more complicated one whose stratified emission layers roughly correspond to different synchrotron-emitting electrons (and so to different emissions). This is more significant for a jet with small viewing angle.

  24. If the stratified emission layers were almost independent on each other (i.e., different emission regions could have different intrinsic velocities and/or electrons distribution), their Doppler factors may be different. Otherwise the Doppler factors should be similar to each other. • If we further assume that all the conical emission layers had a same intrinsic velocity but electron distribution of each emission layer was asymmetrical to the jet axis, this results in that the equivalent/averaged viewing angle of each emission layer could have two phases, i.e., near and away from line of sight.

  25. Quantitative Analysis

  26. 取自U06 Weak Doppler Factors Distribution

  27. III. Conclusion and Future work on this project

  28. Conclusion • We proposed some heuristic viewpoints to explain the SEDs of the 3C273 knots; • We obtained some physical parameters of the 3C273 Jet: Doppler Factor7.4, Equipartition Filed27micronG; The TeV flux in the 3C273 Jet could be tested by the GLAST. • The external model depends on the stratified synchrotron-emitting electrons layers. It needs to be verified by future multi-bands observations.

  29. Future works on this project • Apply this method to other sources, construct a new classification standard of jets; • The Stratified and Acceleration (bulk and particle) Mechanism.

  30. Thanks We thank the conference organizers and participants. We thank all the teachers for care and nurture to youngers. http://www.shao.ac.cn/tianwu/group4/members/wpl.htm Wen-Po LIU, 2008.07.15, Personal Website Email: xiaopozi@163.com

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