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Old December 15th 17, 05:33 AM posted to sci.astro.research
Steve Willner
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Default A quasar, too heavy to be true

In article ,
jacobnavia writes:
https://www.nature.com/articles/nature25180
[[Mod. note -- Open-access preprint at
https://arxiv.org/abs/1712.01860


The Nature article is still preliminary and has some typos in it.
The preprint doesn't have those, and the figures are better.

Here we report observations of the quasar ULAS J134208.10+092838.61
(hereafter J1342+0928) at a redshift of z=7.54. This quasar has a
bolometric luminosity of 4e13 Lsun and a black hole mass of 8e8 Msun.


It is at 690 My after the supposed "bang".


The big pre-existing black holes of the universe (with 10E4 solar
masses) would have seeded this thing of course.


Fig 2 of the paper shows that seeds need to be 1000 Msun at z=40 or
1E4 Msun (not 10E4) at z=22 or so if the subsequent accretion is at
Eddington rate. Temperature at z=40 is about 112 K (hardly "searing
hot"). I invite you to calculate the Jeans mass at these redshifts.

I don't think anyone knows how the initial seed black holes formed or
what their mass distribution was, but why should it be impossible to
form the seeds as suggested above? At least on current knowledge,
there don't have to be very many of them.

There's also the alternative of super-Eddington accretion. While
there's some evidence for that at lower redshifts, it seems less
likely than high-mass seeds.

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