Astronomy Twitter Journal Club tackled supernova progenitors for its 10th meeting, inspired by this year’s Nobel Physics Prize, which was awarded to Saul Perlmutter, Brian Schmidt and Adam Riess. Congratulations!
The discussion was chaired by Matt Burleigh and he set the tone of the meeting straightaway:
Convince me there’s nowt wrong with SN Ia as standard candles…
@Matt_Burleigh so, what don’t you like about using 1a’s to measure the expansion of the universe? – @kashfarooq
@kashfarooq If we don’t know the progenitor, then can we be certain they are standard candles? What corroborating evidence is there? So I would ask cosmologists, is acceleration of universe firmly established, is Nobel prize premature or deserved? – @Matt_Burleigh
Can we find one locally?
There’s still a SN 1a in the nearby galaxy M101. Have they searched for progenitors there? – @AdrianusV
yes, I believe so, and see nothing. Which fits with some kind of WD binary (not supermassive star) – @Matt_Burleigh
Are they good standard candles?
what if SNIa evolve with redshift, mimicking acceleration signal? They are standard candles, assumed to have same luminosity. What if brighter in past? – @Matt_Burleigh
presumably achieved by measuring the distance to those galaxies by another method… circular argument? – @Matt_Burleigh
The hunt for a progenitor
Chandra data seems to suggest that WD (white dwarf) accretion SN not as common as expected. – @kashfarooq
yep. And searches for double WDs find none with right masses and periods to merge in a Hubble time. Its worrying. If you take the frequency of SNIa in other galaxies, then we should have found a progenitor by now…. – @Matt_Burleigh
@AdrianusV yerrrrrsssssss…. #speculative – @Matt_Burleigh
Other evidence for acceleration
has the accelerating expansion of the Universe got any other evidence? or is it just type 1a? @kashfarooq
GRBs and some evidence for MWB (microwave background). But I assume neither as good as SNIa since new dark energy experiments will use SNIa – @Matt_Burleigh
@Matt_Burleigh so you are not convinced, then? – @kashfarooq
@kashfarooq convinced of what? SNI as standard candles? Not yet but I don’t dispute other evidence also points to accelerating univ – @Matt_Burleigh