[seminar] Astro Journal Club on February 8th, Wednesday, 3 p.m.

[Lana Ceraj]

Dear all,


this Wednesday we continue with our Astro Journal Club at 3 p.m. (sharp) in the seminar room F-201 of the Physics Department. Krešimir is going to talk about the dynamics of the Local Group of galaxies. 

Presenter: Krešimir Tisanić

Title: The dipole repeller

Authors: Hoffman Y., Pomarede D., Tully R.B., Courtois H.M.

Abstract:
Our Local Group of galaxies is moving with respect to the cosmic microwave background (CMB) with a velocity of v_CMB = 631 +- 20 kms^-1 and participates in a bulk flow that extends out to distances of ~20,000 kms^-1 or more. There has been an implicit assumption that overabundances of galaxies induce the Local Group motion. Yet underdense regions push as much as overdensities attract, but they are deficient in light and consequently difficult to chart. It was suggested a decade ago that an underdensity in the northern hemisphere roughly 15,000 kms^-1 away contributes significantly to the observed flow. We show here that repulsion from an underdensity is important and that the dominant influences causing the observed flow are a single attractor — associated with the Shapley concentration — and a single previously unidentified repeller, which contribute roughly equally to the CMB dipole. The bulk flow is closely anti-aligned with the repeller out to 16,000 +- 4,500 kms^-1. This ‘dipole repeller’ is predicted to be associated with a void in the distribution of galaxies.

Link: http://www.nature.com/articles/s41550-016-0036 


If you have recently read interesting astrophysics paper you would like to present, please contact me via e-mail: lceraj at phy.hr <mailto:lceraj at phy.hr>


See you on Wednesday.

Cheers,
Lana

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