The jet and resolved features of the central supermassive black hole of M 87 observed with EHT. (arXiv:2205.04623v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Miyoshi_M/0/1/0/all/0/1">Makoto Miyoshi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kato_Y/0/1/0/all/0/1">Yoshiaki Kato</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Makino_J/0/1/0/all/0/1">Junichiro Makino</a>
We report our independent image reconstruction of the M 87 from the public
data of the Event Horizon Telescope Collaborators (EHTC). Our result is
different from the image published by the EHTC. Our analysis shows that (a) the
structure at 230 GHz is consistent with those of lower frequency VLBI
observations, (b) the jet structure is evident at 230 GHz extending from the
core to a few mas, though the intensity rapidly decreases along the axis, and
(c) the unresolved core is resolved into bright three features presumably
showing an initial jet with a wide opening angle of about 70 deg.
The ring-like structures of the EHTC can be created not only from the public
data, but also from the simulated data of a point image. Also, the rings are
very sensitive to the FOV size. The u-v coverage of EHT lack about 40
micro-asec fringe spacings. Combining with a very narrow FOV, it created the 40
micro-asec ring structure. We conclude that the absence of the jet and the
presence of the ring in the EHTC result are both artifacts owing to the narrow
FOV setting and the u-v data sampling bias effect of the EHT array. Because the
EHTC’s simulations only take into account the reproduction of the input image
models, and not those of the input noise models, their optimal parameters can
enhance the effects of sampling bias and produce artifacts such as the 40
micro-asec ring structure, rather than reproducing the correct image.
We report our independent image reconstruction of the M 87 from the public
data of the Event Horizon Telescope Collaborators (EHTC). Our result is
different from the image published by the EHTC. Our analysis shows that (a) the
structure at 230 GHz is consistent with those of lower frequency VLBI
observations, (b) the jet structure is evident at 230 GHz extending from the
core to a few mas, though the intensity rapidly decreases along the axis, and
(c) the unresolved core is resolved into bright three features presumably
showing an initial jet with a wide opening angle of about 70 deg.
The ring-like structures of the EHTC can be created not only from the public
data, but also from the simulated data of a point image. Also, the rings are
very sensitive to the FOV size. The u-v coverage of EHT lack about 40
micro-asec fringe spacings. Combining with a very narrow FOV, it created the 40
micro-asec ring structure. We conclude that the absence of the jet and the
presence of the ring in the EHTC result are both artifacts owing to the narrow
FOV setting and the u-v data sampling bias effect of the EHT array. Because the
EHTC’s simulations only take into account the reproduction of the input image
models, and not those of the input noise models, their optimal parameters can
enhance the effects of sampling bias and produce artifacts such as the 40
micro-asec ring structure, rather than reproducing the correct image.
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