Two new diagnostics of dark energy

By V. Sahni, A. Shafieloo, A. Starobinsky. 2008

488 citations recorded by the source corpus.

We introduce two new diagnostics of dark energy (DE). The first, Om, is a combination of the Hubble parameter and the cosmological redshift and provides a null test of dark energy being a cosmological constant {lambda}. Namely, if the value of Om(z) is the same at different redshifts, then DE{identical_to}{lambda}, exactly. The slope of Om(z) can differentiate between different models of dark energy even if the value of the matter density is not accurately known. For DE with an unevolving equation of state, a positive slope of Om(z) is suggestive of phantom (w -1). The second diagnostic--acceleration probe q--is the mean value of the deceleration parameter over a small redshift range. It can be used to determine the cosmological redshift at which the universe began to accelerate, again without reference to the current value of the matter density. We apply the Om and q diagnostics to the Union data set of type Ia supernovae combined with recent data from the cosmic microwave background (Wilkinson Microwave Anisotropy Probe 5) and baryon acoustic oscillations.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/63a4f9661228fb4dc60b3f500ce42b58e79a05de

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In Astronomy and Astrophysics

Citations in the corpus

DESI 2024: reconstructing dark energy using crossing statistics with DESI DR1 BAO data (2024, methodology): “The Om ( z ) diagnostic [93] was specifically tailored to efficiently distinguish dark energy models from a cosmological constant, and is defined as For ΛCDM one has simply Om ( z ) = Ω m , 0 .”
Observational probes of cosmic acceleration (2012, methodology): “As a complement to parameterized models, one can attempt to construct non-parametric “null tests” for a cosmological constant or scalar field models (Sahni et al., 2008).”
Hubble Parameter and Baryon Acoustic Oscillation Measurement Constraints on the Hubble Constant, the Deviation from the Spatially Flat ΛCDM Model, the Deceleration–Acceleration Transition Redshift, and Spatial Curvature (2017, unknown): “Therefore, we have H z H z1 1 1 , 9m0 0 2 3W = - + - ⎡ ⎣ ⎢⎢ ⎛ ⎝⎜ ⎞ ⎠⎟ ⎤ ⎦ ⎥⎥ ( ) [( ) ] ( ) which is a redshift-independent constant if flat-ΛCDM is the correct description of the universe and so can be used to test the model (Sahni et al. 2008).”