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Title: Relativistic electrons and magnetic fields of the M87 jet on the ∼10 Schwarzschild radii scale

We explore energy densities of the magnetic fields and relativistic electrons in the M87 jet. Since the radio core at the jet base is identical to the optically thick surface against synchrotron self-absorption (SSA), the observing frequency is identical to the SSA turnover frequency. As a first step, we assume the radio core has a simple uniform sphere geometry. Using the observed angular size of the radio core measured by the Very Long Baseline Array at 43 GHz, we estimate the energy densities of magnetic fields (U{sub B} ) and relativistic electrons (U{sub e} ) on the basis of the standard SSA formula. Imposing the condition that the Poynting power and kinetic power of relativistic electrons should be smaller than the total power of the jet, we find that (1) the allowed range of the magnetic field strength (B {sub tot}) is 1 G ≤ B {sub tot} ≤ 15 G and that (2) 1 × 10{sup –5} ≤ U{sub e} /U{sub B} ≤ 6 × 10{sup 2} holds. The uncertainty of U{sub e} /U{sub B} comes from the strong dependence on the angular size of the radio core and the minimum Lorentz factor of non-thermal electrons (γ {sub e,min})more » in the core. It is still unsettled whether resultant energetics are consistent with either the magnetohydrodynamic jet or the kinetic power dominated jet even on the ∼10 Schwarzschild radii scale.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4]
  1. Korea Astronomy and Space Science Institute, 776 Daedukdae-ro, Yusong, Daejon 305-348 (Korea, Republic of)
  2. Department of Earth and Space Science, Osaka University, Toyonaka 560-0043 (Japan)
  3. INAF—Istituto di Radioastronomia, via Gobetti 101, I-40129 Bologna (Italy)
  4. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, 229-8510 Sagamihara (Japan)
Publication Date:
OSTI Identifier:
22357044
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 786; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ENERGY DENSITY; GALAXIES; MAGNETIC FIELDS; RELATIVISTIC RANGE; SCHWARZSCHILD RADIUS; SELF-ABSORPTION; SURFACES; SYNCHROTRON RADIATION