Astronomy Tea Talk at Caltech

Mondays, Cahill 312

Tea:4 pm, Talk: 4:05 pm

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H0 with explosive transients

Suhail Dhawan (Stockholm University)

Jany 27, 2020

The Hubble constant sets the absolute distance scale of the universe. Recent, precision measurements of the Hubble constant with the local distance ladder are in tension with the value inferred from the cosmic microwave background, assuming the standard cosmological model. This tension could suggest possible evidence for non-standard cosmologies, e.g. additional neutrino species or phantom dark energy. However, it could also be due to something more mundane like unknown sources of systematic errors. In this talk, I will show results from our recent and ongoing work on testing for systematic uncertainties from the Type Ia supernova wrung of the distance ladder. Strongly lensed transients (e.g. supernovae, quasars) are a robust and exciting independent route to measure the Hubble constant. I will talk about our recent work on measuring time delays, lensing magnification and extinction properties of the first resolved, strongly lensed Type Ia supernova and talk about ongoing and future work to discover more such systems. Another promising method to measure H0 is using gravitational wave (GW) standard sirens (GW equivalent of standard candles). Here, I will summarise a recent study on using the electromagnetic counterpart of GW standard sirens and implications for H0 from the first GW source with an identified EM counterpart, GW170817.

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