by neufer » Thu Sep 03, 2020 5:37 pm
MarkBour wrote: ↑Thu Sep 03, 2020 4:54 am
In that discussion of a stellar mass black hole, I happened to ask if anyone thought that galactic halos were (at least in part), the products of the relativistic jets of the galactic supermassive black hole. @neufer posted a couple of articles in response, and it seemed like he was perhaps supporting the idea, though I didn't see any direct "yea", "nay", or opinion answer from him.
So here, just a few days later is a fascinating APOD about Andromeda's halo. Considering how hard the AMIGA project had to work to observe Andromeda's halo (they had to look at quasars beyond it to study its absorption behavior) I would guess that this is only the second galactic halo we've been able to study in much detail to date. Again, my curiosity about the jets from Andromeda's core contributing to this halo arises. Given billions of years, some of the material from the jets could easily have traveled 1-2 million light years.
- Perhaps...the haloes came first
![Question :?:](./images/smilies/icon_question.gif)
https://www.nature.com/articles/nature07648 wrote:
Cold streams in early massive hot haloes as the main mode of galaxy formation
A. Dekel, Y. Birnboim, G. Engel, J. Freundlich, T. Goerdt, M. Mumcuoglu, E. Neistein, C. Pichon, R. Teyssier & E. Zinger
Nature volume 457, pages451–454(2009)
Abstract:
Massive galaxies in the young Universe, ten billion years ago, formed stars at surprising intensities. Although this is commonly attributed to violent mergers, the properties of many of these galaxies are incompatible with such events, showing gas-rich, clumpy, extended rotating disks not dominated by spheroids. Cosmological simulations and clustering theory are used to explore how these galaxies acquired their gas. Here we report that they are ‘stream-fed galaxies’, formed from steady, narrow, cold gas streams that penetrate the shock-heated media of massive dark matter haloes. A comparison with the observed abundance of star-forming galaxies implies that most of the input gas must rapidly convert to stars. One-third of the stream mass is in gas clumps leading to mergers of mass ratio greater than 1:10, and the rest is in smoother flows. With a merger duty cycle of 0.1, three-quarters of the galaxies forming stars at a given rate are fed by smooth streams. The rarer, submillimetre galaxies that form stars even more intensely are largely merger-induced starbursts. Unlike destructive mergers, the streams are likely to keep the rotating disk configuration intact, although turbulent and broken into giant star-forming clumps that merge into a central spheroid. This stream-driven scenario for the formation of discs and spheroids is an alternative to the merger picture.
[quote=MarkBour post_id=305838 time=1599108858 user_id=141361]
[quote=bystander post_id=305736 time=1598846996 user_id=112005]
[c][b][i] https://asterisk.apod.com/viewtopic.php?t=40907 [/i][/b][/c][/quote]
In that discussion of a stellar mass black hole, I happened to ask if anyone thought that galactic halos were (at least in part), the products of the relativistic jets of the galactic supermassive black hole. @neufer posted a couple of articles in response, and it seemed like he was perhaps supporting the idea, though I didn't see any direct "yea", "nay", or opinion answer from him.
So here, just a few days later is a fascinating APOD about Andromeda's halo. Considering how hard the AMIGA project had to work to observe Andromeda's halo (they had to look at quasars beyond it to study its absorption behavior) I would guess that this is only the second galactic halo we've been able to study in much detail to date. Again, my curiosity about the jets from Andromeda's core contributing to this halo arises. Given billions of years, some of the material from the jets could easily have traveled 1-2 million light years.[/quote]
[list]Perhaps...the haloes came first :?: [/list]
[quote=https://www.nature.com/articles/nature07648]
[size=150][color=#0000FF]Cold streams in early massive hot haloes as the main mode of galaxy formation[/color][/size]
A. Dekel, Y. Birnboim, G. Engel, J. Freundlich, T. Goerdt, M. Mumcuoglu, E. Neistein, C. Pichon, R. Teyssier & E. Zinger
Nature volume 457, pages451–454(2009)
Abstract: [i][color=#0000FF]Massive galaxies in the young Universe, ten billion years ago, formed stars at surprising intensities. Although this is commonly attributed to violent mergers, the properties of many of these galaxies are incompatible with such events, showing gas-rich, clumpy, extended rotating disks not dominated by spheroids. Cosmological simulations and clustering theory are used to explore how these galaxies acquired their gas. Here we report that they are ‘stream-fed galaxies’, formed from steady, narrow, cold gas streams that penetrate the shock-heated media of massive dark matter haloes. A comparison with the observed abundance of star-forming galaxies implies that most of the input gas must rapidly convert to stars. One-third of the stream mass is in gas clumps leading to mergers of mass ratio greater than 1:10, and the rest is in smoother flows. With a merger duty cycle of 0.1, three-quarters of the galaxies forming stars at a given rate are fed by smooth streams. The rarer, [url=https://en.wikipedia.org/wiki/Luminous_infrared_galaxy]submillimetre galaxies[/url] that form stars even more intensely are largely merger-induced starbursts. Unlike destructive mergers, the streams are likely to keep the rotating disk configuration intact, although turbulent and broken into giant star-forming clumps that merge into a central spheroid. This stream-driven scenario for the formation of discs and spheroids is an alternative to the merger picture.[/color][/i][/quote]