The mystery of the distance of galaxies that apparently lacking dark matter

Hosein Haghi

Physics Department, Institute for advanced studies in basic sciences (IASBS)

Abstract: Recently, van Dokkum et al. reported the detection of a couple of ultra-diffuse dwarf (UDG) galaxies lacking dark matter (NGC 1052-DF2 and NGC 1052-DF4). If correct, this could be one of the most important discoveries in Extragalactic Astrophysics and represents a possible challenge to our understanding of the properties of these galaxies and galaxy formation in general. They used surface brightness fluctuation technique yielding a distance of about 20 Mpc implying these galaxies to be dark matter deficient with the larger than expected size, and brighter and larger than expected globular clusters system. But, if the galaxy is a factor of two or three closer to us than the adopted distance of 20 Mpc nearly all the unusual properties vanish. Several authors asked whether these galaxies could be at a smaller distance. Different distance measurement methods that have been applied on these galaxies so far, yielding a distance in the range 10 to 20 Mpc implying it to be “normal” or “dark matter deficient” galaxies. In this talk, first, I will briefly review the current challenge in determining the distance of these galaxies. Then, I will give you a brief report on our recent publication on the IMF-induced intrinsic uncertainties on measuring the ultra-diffuse galaxy distances based on the surface brightness fluctuation technique. 

یکشنبه 22 فروردین 1400، ساعت 19:00

Sunday 11 April 2021 – 19:00 Tehran Time

اتاق سمینار مجازی –Virtual Seminar Room

https://vc.sharif.edu/ch/cosmology

گزینه ورود به صورت مهمان – Enter as a Guest