Top Tweets for #coss18
I have to leave Prague today, so no tweets from me on the last day of #CoSS18. Was great fun to see so many friends and collaborators again, and I even got a new project idea or two. Now looking forward to finally get back to Irvine tomorrow.
Makarova: Discovered a dwarf galaxy (upper left, Mv~-14 mag) with a smaller dwarf nearby (lower right, Mv~9.5 mag). Both have consistent distances of ~9 Mpc. That makes this a good candidate of a “satellite of a satellite/dwarf” galaxy. (Cc @coralrosew ;-) ) #CoSS18
Lidia Makarova now talks about “lost satellites”, and observational searches for dwarf satellite galaxies in nearby galaxy groups. Shows a nice fly-through around the local volume showing the positions of known galaxies. Many new dwarfs in LV were discovered recently. #CoSS18
.@benfamaey: Discusses evidence for Dark Matter from CMB and large scale structure, then introduces the idea of superfluid dark matter. Would combine successes of MOND and LCDM, but with some difference to both which makes it testable. #CoSS18
Back from lunch, and we’re going to hear from @benfamaey about alternatives to Cold Dark Matter in the light of the mass discrepancy-acceleration relation. Starts by pointing out the surprising diversity as well as regularity in disk galaxies. #CoSS18
Haslbauer: TDG candidates are almost all found close to a host galaxy, consistent with a tidal origin. Shows some examples where you still see a tail and have phase-space correlated TDG candidates. #CoSS18
Moritz Haslbauer now talks about dark-matter-free galaxies in the Illustris simulation, i.e. tidal dwarf galaxy candidates. He finds about 100 if requiring minimum stellar mass. That’s compared to tens of thousands of „dark matter containing“ (DMC) dwarf galaxies. #CoSS18
.@lellifede concludes with a quick discussion of how MOND predicted RAR & BTFR … not only before the observational data of the SPARC sample existed, but actually before @lellifede was even born. Asks if we love in LCDM universe, why is MOND getting any predictions right? #CoSS18
.@lellifede: Baryonic Tully Fisher Relation can be easily derived from the Radial Acceleration Relation (not vice versa). Finds that intrinsic perpendicular scatter inBTFR is extremely small, of order 6%. #CoSS18
.@lellifede: All disk galaxies in the SPARC sample follow essentially the same Radial Acceleration Relation if you plot their baryonic vs. total measured acceleration. The relation is consistent with no intrinsic scatter. Shows this video here: https://t.co/ktmaFb6OBQ #CoSS18
.@lellifede: Introduces the SPARC dataset of disk galaxies. Get the data here: https://t.co/vvGfGmzblC #CoSS18
We’re back from lunch at #CoSS18, and now @lellifede talks about three empirical laws of galaxy rotation. Starts by highlighting the local history in Prague of studying the empirical laws of planetary motion by Brahe and Kepler.
Back from my talk. Couldn’t help myself but call out the insane gender bias at this conference. Not sure what the organizers thought of that, but it’s a problem, and if you want to talk about problems in cosmology then expect to be called out on this one, too. #CoSS18
Karachentsev’s summary slide at #CoSS18
Karachentsev: Cosmological simulations predict substantial fractions of dark matter to be distributed in voids and filaments, which probably explains the observed under-density in the local volume which only considers mass around luminous galaxies. #CoSS18
Karachentsev: There are possible explanation for why the local density seems smaller than the global, cosmologically expected one. Substantial amounts of dark matter might be distributed beyond the viral radii of galaxies, in filaments, or we live in a giant local void. #CoSS18
Karachentsev: Present data are not sufficient to measure dark matter density accurately on scales beyond 40 Mpc. #CoSS18
Karachentsev: Shows density within spherical shells, highlights that our immediate neighborhood is a substantial mass over-density, but that on a scale of 20-40 Mpc we are living in an under density of dark matter. #CoSS18
Karachentsev: To measure densities of galaxies, you need to measure their distances very accurately. Consider all galaxies within the Local Volume of 11 Mpc radius. Why 11 Mpc? "It is the distance accessible with one HST orbit, which makes it a natural scale." #CoSS18
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