2019ApJ...879....8S -
Astrophys. J., 879, 8-8 (2019/July-1)
Detection of superluminal motion in the X-ray jet of M87.
SNIOS B., NULSEN P.E.J., KRAFT R.P., CHEUNG C.C., MEYER E.T., FORMAN W.R., JONES C. and MURRAY S.S.
Abstract (from CDS):
Chandra HRC observations are investigated for evidence of proper motion and brightness changes in the X-ray jet of the nearby radio galaxy M87. Using images spanning 5 yr, proper motion is measured in the X-ray knot HST-1, with a superluminal apparent speed of 6.3 ± 0.4c, or 24.1 ± 1.6 mas yr–1, and in Knot D, with a speed of 2.4 ± 0.6c. Upper limits are placed on the speeds of the remaining jet features. The X-ray knot speeds are in excellent agreement with existing measurements in the radio, optical, and ultraviolet. Comparing the X-ray results with images from the Hubble Space Telescope indicates that the X-ray and optical/UV emitting regions co-move. The X-ray knots also vary by up to 73% in brightness, whereas there is no evidence of brightness changes in the optical/UV. Using the synchrotron cooling models, we determine lower limits on magnetic field strengths of ∼ 420 µG and ∼ 230 µG for HST-1 and Knot A, respectively, consistent with estimates of the equipartition fields. Together, these results lend strong support to the synchrotron cooling model for Knot HST-1, which requires that its superluminal motion reflects the speed of the relativistic bulk flow in the jet.
Abstract Copyright:
© 2019. The American Astronomical Society. All rights reserved.
Journal keyword(s):
galaxies: active - galaxies: individual: M87 - galaxies: jets - X-rays: galaxies
Simbad objects:
11
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