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SUMMARY:A challenge to the standard cosmological model
DTSTART:20261120T020000Z
DTEND:20261120T030000Z
DTSTAMP:20261107T121500Z
UID:indico-event-5435@indico-tdli.sjtu.edu.cn
DESCRIPTION:Speakers: Subir Sarkar (University of Oxford)\n\nAbstract:\nIn
  the standard ΛCDM model\, the Universe is assumed to be isotropic and ho
 mogeneous when averaged on large scales\, so described by the FLRW metric.
  That the cosmic microwave background has a dipole anisotropy is interpret
 ed as due to our peculiar (non-Hubble) motion because of local inhomogenei
 ty. A similar dipole is then expected in the sky distribution of distant s
 ources. Using catalogues of radio galaxies and quasars\, we find however t
 hat the amplitude of the matter dipole is a factor of 2-3 bigger than expe
 cted\, i.e. the distribution of distant matter is not isotropic in the `CM
 B frame’. This calls into question all analyses of cosmological data\, i
 n particular of Type Ia supernovae\, which assume the FLRW metric to infer
  that the Hubble expansion rate is accelerating\, as if driven by a Cosmol
 ogical Constant Λ or more general dark energy. In fact the inferred accel
 eration is anisotropic and local - so likely an artefact of the local pecu
 liar bulk flow rather than due to the quantum vacuum. [Nature Rev. Phys. 7
 :68\, 2025\; Rev. Mod. Phys. 97:041001\, 2025\; Mon. Not. Roy. Astron. Soc
 . 549:stag844\, 2026]\nSpeaker Bio:\nSubir Sarkar was born & educated in I
 ndia - at the Indian Institute of Technology\, Kharagpur and the Universit
 y of Bombay (PhD 1982). He was a Staff Associate of the Tata Institute of 
 Fundamental Research\, Bombay and has held visiting positions at SISSA\, T
 rieste\; CERN\, Geneva\; Astrophysics\, University of Oxford\, and Rutherf
 ord Appleton Laboratory\, Chilton. Since 1990 he has been at the Rudolf Pe
 ierls Centre for Theoretical Physics\, University of Oxford\, where he was
  head of the Particle Theory Group and since 2021 is Professor Emeritus. H
 e has also been visiting Niels Bohr Professor at Copenhagen University.\nH
 is research interests are at the interface between astrophysics & cosmolog
 y and fundamental physics — including cosmic rays\, dark matter\, inflat
 ion\, neutrino cosmology etc. He also participates in astroparticle experi
 ments such as the IceCube Neutrino Observatory and Cherenkov Telescope Arr
 ay – as well as laser plasma experiments and the Dark Energy Science Col
 laboration of the Rubin Observatory. He was awarded the IUPAP-TIFR Homi Bh
 abha Medal & Prize in 2017 and shared in the 2021 Bruno Rossi Prize of the
  American Astronomical Society to the IceCube Collaboration.\nAlternative 
 online link: https://meeting.tencent.com/dm/6XK4hRdc2ILdID: 185147668 (No 
 Password)\n\nhttps://indico-tdli.sjtu.edu.cn/event/5435/
LOCATION:Tsung-Dao Lee Institute/N6F-N600 - Lecture Room (Tsung-Dao Lee In
 stitute)
URL:https://indico-tdli.sjtu.edu.cn/event/5435/
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