Abstract
We update constraints on cosmic opacity by combining recent SN Type Ia data with the latest measurements of the Hubble expansion at redshifts between 0 and 2. The new constraint on the parameter ϵ parametrising deviations from the luminosity-angular diameter distance relation (dL = dA(1+z)2+ϵ), is ϵ = −0.04−0.07+0.08 (2-σ). For the redshift range between 0.2 and 0.35 this corresponds to an opacity Δτ < 0.012 (95% C.L.), a factor of 2 stronger than the previous constraint. Various models of beyond the standard model physics that predict violation of photon number conservation contribute to the opacity and can be equally constrained. In this paper we put new limits on axion-like particles, including chameleons, and mini-charged particles.
Highlights
In this paper we have focused on two scenarios for exotic particles which can significantly modify the propagation of photons as they pass through magnetic fields
Measurements of cosmic opacity are a strong tool to constrain such scenarios, as interactions between photons and exotic particles in the magnetic fields of the intergalactic medium leads to a new source of cosmic opacity
The Etherington relation implies that, in a cosmology based on a metric theory of gravity, distance measures are unique: the luminosity distance is (1+z)2 times the angular diameter distance
Summary
In reference [15], the authors use Type Ia SN brightness data (namely the SCP Union 2008 compilation [16]) in combination with measurements of cosmic expansion H(z) from differential aging of luminous red galaxies (LRGs) [17, 18] to obtain constraints on non-trivial opacity, at cosmological scales. In reference [15] this constraint was improved (and extended over a wider redshift range, but for a general parameterised form for τ ) by using, instead of measurements of the BAO scale at these two redshifts, measurements of cosmic expansion H(z) from differential aging of LRGs at redshifts z 2 This method of distance determination relies on the detailed shapes of galaxy spectra but not on galaxy luminosities, so it is independent of τ. We will apply similar constraints on different parametrisations of τ which correspond to particular models of exotic matter-photon coupling, namely axion-like particles (ALPs), chameleons, and mini-charged particles (MCPs) Before moving to these models, we briefly update the above constraint on ǫ using the latest H(z) data [23], which include two extra data points at redshifts z = 0.48 and z = 0.9, as well as the latest determination of H0 [24]. Move on to study more general parametrisations of cosmic opacity, tailored for particular models of exotic matter coupled to photons
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