Cosmology Seminars

The Cosmology seminars are weekly seminars dedicated to Cosmology and Astroparticle Physics. Please write to the contact below to join the mailing list to be updated on upcoming seminars.

Time: Wednesdays 14:15-15:15 Helsinki time, unless otherwise noted.

Place: All seminars in 2022 will be held remotely via Zoom. Zoom invitations will be sent out on the Cosmology seminars mailing list.

Format: 45′ + 15′ for questions

Contact: Sami Raatikainen

Scheduled Seminars

Spring Term

  • 27.04.2022 Dra┼żen Glavan (Prague, Inst. Phys.)
    Title: TBA

    Abstract: TBA
  • 16.02.2022 Philip J. Bull (Queen Mary, U. of London)
    Title: TBA

    Abstract: TBA
  • 09.02.2022 Lukas Witkowski (Paris, Inst. Astrophys.)
    Title: TBA

    Abstract: TBA
  • 02.02.2022 Jacopo Fumagalli (Paris, Inst. Astrophys.)
    Title: TBA

    Abstract: TBA
  • 26.01.2022 (at 16:15) Dillon Brout (Harvard-Smithsonian Ctr. Astrophys.)
    Title: The Recent Results From The Pantheon+ Sample and SH0ES Analysis

    Abstract: It has now been 5 years since the last main analyses of the Hubble constant and cosmic acceleration by the SH0ES and Pantheon teams. Since then, both the datasets of cepheid calibrators and Type Ia supernovae have more than doubled in size. Meanwhile there have also been critical leaps in our understanding of systematics and improvements to calibration. In this talk I will detail the progress made towards a 1km/s/Mpc measurement of the Hubble constant and measurements of dark energy.
  • 19.01.2022 Pierre Sikivie (Florida U.)
    Title: Cold dark matter caustics [video]

    Abstract: On a sunny breezy day, sharp lines of light dance on the bottom of a swimming pool. They are due to folds – sometimes called ‘caustics’, or ‘catastrophes’ – in the wavefront of light from the Sun. Caustics also arise naturally in the distribution of dark matter in space. The dark matter density is very large at the location of a caustic. I’ll show that the late infall of cold dark matter onto isolated galaxies, such as our own, produces discrete flows throughout the galactic halo, and associated caustics. One set of caustics are topological spheres surrounding the galaxy. Another set are rings in the galactic plane. Caustic rings are closed tubes whose cross-section is a D_{-4} catastrophe. I’ll argue on theoretical and observational grounds that the caustic ring radii a_n (n=1,2,3..) obey the approximate law: a_n goes like 1/n. There is evidence for these rings in the distribution of bumps in the rotation curves of spiral galaxies, including our own Milky Way. The implications for dark matter searches will be discussed.