tag:blogger.com,1999:blog-7315236707728759521.post488209527177920722..comments2024-03-28T21:52:52.100-06:00Comments on Dispatches From Turtle Island: MACHOsAndrew Oh-Willekehttp://www.blogger.com/profile/02537151821869153861noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-7315236707728759521.post-72989419970629504182016-09-26T12:32:28.797-06:002016-09-26T12:32:28.797-06:00MOND has never had any issues with lensing of whic...MOND has never had any issues with lensing of which I am aware, although obviously it needs to be generalized on a relativistic basis in any case.<br /><br />Lensing would occur based on the modified gravitational pull rather than the GR/Newtonian one without Dark Matter.andrewhttps://www.blogger.com/profile/08172964121659914379noreply@blogger.comtag:blogger.com,1999:blog-7315236707728759521.post-44549120452318029762016-09-19T22:08:27.393-06:002016-09-19T22:08:27.393-06:00Fine tuning problem, right? Though the Standard Mo...Fine tuning problem, right? Though the Standard Model has a fine tuning problem.<br /><br />I thought MOND still had issues with lensing though, no?Ryanhttps://www.blogger.com/profile/07906194112935320590noreply@blogger.comtag:blogger.com,1999:blog-7315236707728759521.post-42607780024444739972016-09-19T19:44:17.102-06:002016-09-19T19:44:17.102-06:00I strongly suspect that MACHOs have all of the def...I strongly suspect that MACHOs have all of the defects of cold dark matter in terms of cusp-core issues, satellite galaxies, scatter around Tully-Fisher relations, etc., if not worse.<br /><br />But, since MACHOs were mostly ruled out pretty early on, there hasn't been a lot of serious investigation of these issues in the case of MACHOs.<br /><br />Also, to be clear about the problem in the WIMP case, it isn't that you can't imagine that dark matter particles couldn't be arrangement in a way that would produce the right rotation curves and dynamics. The problem is with common up with a process that makes minimal assumptions that produces halos of the right shape, and in particular, why the halo distribution shape is so sensitive to baryonic matter distributions and how you get galaxy and matter assembly that produces as many buldgeless galaxies as are seen observationally. <br /><br />You need a mechanism that produces what modified gravity does from pretty much random models of mass assembly that rely very little on the properties of the DM particle itself except its average velocity at thermal freezeout.andrewhttps://www.blogger.com/profile/08172964121659914379noreply@blogger.comtag:blogger.com,1999:blog-7315236707728759521.post-67986807262467611952016-09-19T16:45:35.074-06:002016-09-19T16:45:35.074-06:00Why could MACHOs explain galactic velocity curves ...Why could MACHOs explain galactic velocity curves when WIMP's without self interaction can't? I'd think a MACHO would behave a lot like a really heavy WIMP wouldn't it?Ryanhttps://www.blogger.com/profile/07906194112935320590noreply@blogger.com