[ExI] First Picture of a Black Hole!
avant at sollegro.com
Thu Apr 11 01:26:10 UTC 2019
Tomaz Kristan wrote:
> Shouldn't it be the Sagittarius? Much smaller and much closer one?
> Why is that now?
> On Wed, Apr 10, 2019 at 3:38 PM John Clark <johnkclark at gmail.com> wrote:
As John pointed out their angular widths should be about almost equal
at 5:4 for SgrA* vs M-87*. While there is a lot of dust between us and
SgrA*, that shouldn't affect meters-wide radiowaves. So my guess is
that the paper published back in January that suggested that the radio
jet of Sagittarius A* is pointed directly at us is actually correct.
The radio jet pointing directly at us would make the picture of SgrA*
just look like a bright blotch of light with no dark "shadow" apparent
so it would not look much like a "black" hole. Even in the picture
M-87* they have, the shadow is not quite as dark as the peripheral
space suggesting there is some radio emission occurring between it and
And also, I know they billed it as a mere "picture" but would it have
killed them to put in some form of scale or the galactic plane of M-87
or something for reference? The shadow of the BH looks like an ellipse
elongated in the NE to SW direction. That could be the equatorial
plane of the black hole's rotation in which case it would be spinning
pretty fast. But with no frame of reference it might as well be a
photo of a UFO.
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