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Paper   IPM / P / 15341
School of Physics
  Title:   Low Redshift Cosmological Data Favours Negative Cosmological Constant
  Author(s): 
1.  K. Dutta
2.  Ruchika.
3.  A. A. Sen
4.  M.M. Sheikh-Jabbari
  Status:   Published
  Journal: Gen Relativ Gravit
  Vol.:  52
  Year:  2020
  Pages:   15
  Supported by:  IPM
  Abstract:
Assuming that the Universe at higher redshifts (z  ∼ 4 and beyond) is consistent with model as constrained by Planck satellite data, we reanalyze the low redshift cosmological data to reconstruct the Hubble parameter as a function of redshift in a model independent way. This enables us to address the H0 and other tensions between low z observations and high z Planck measurement from CMB. From H(z), we reconstruct the energy density and pressure for the "dark energy" sector of the Universe as a function of redshift and find that the dark energy density has a minimum for certain redshift range and that this ρDEmin is negative. This behavior is most simply described by a negative cosmological constant plus a dark energy sector which has a phantom crossing. We discuss possible theoretical and observational implications of such a scenario.

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