## [astro-ph/0409451] Decay of the vacuum energy into CMB photons

 Authors: Reuven Opher, Ana Pelinson Abstract: We examine the possibility of the decay of the vacuum energy into cosmic microwave background (CMB) photons. It is shown that observations of the primordial density fluctuation spectrum put strong limits on the possible decay rate. When photon creation due to the vacuum energy decay takes place, the standard linear temperature dependence, T(z)=T_0(1+z), where T_0 is the present CMB temperature, is modified. The decay is described by a generic temperature dependence, T(z)=T_0(1+z)^{1-\beta}, of the CMB photons. A strong limit on the maximum value of the decay rate is obtained by placing a maximum value on the \beta parameter: \beta_{max}\approx 3\times 10^{-3}. [PDF]  [PS]  [BibTex]  [Bookmark]

Discussion related to specific recent arXiv papers
Anze Slosar
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Joined: September 24 2004
Affiliation: Brookhaven National Laboratory
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### [astro-ph/0409451] Decay of the vacuum energy into CMB photo

I find this paper quite interesting, since I had similar ideas some time ago... Authors assume dark-energy decays into phtons, and in precombination era these thermalise via photon-baryon interactions. So they place a limit on this process from z_rec (in my understanding of the paper). However, since we have the same volume of vacuum per m^3, these processes should still occur and therefore one would expect a non-thermal feature in the CMB spectrum, on which we have extremelly good constraints and I would expect that this constrains this model much stronger... Any opinions?

Alessandro Melchiorri
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Affiliation: University of Rome
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Ciao Anze,
I did'nt read the paper you mention but, if I remember correctly, in Lima et al. MNRAS 312, 4, 747 2000 they claim that if you have "adiabatic" photon creation you can avoid the CMB black body spectrum bounds in decaying lambda to photon cosmologies.