Nota de FísicaPublicado
Hubble diagram of gamma-ray bursts and prevalence of energy conditions in Friedmann-Lema\^itre-Robertson-Walker Cosmology
H. Dumet Montoya; Carlos A. Bonilla Quintero; Cristina Furlanetto; Jefferson Morais; Rodrigo Turcati
Datos de la publicación
- Autores
- H. Dumet Montoya; Carlos A. Bonilla Quintero; Cristina Furlanetto; Jefferson Morais; Rodrigo Turcati
- Tipo
- Nota de Física
- Estado
- Publicado
- Fecha de publicación
- 23/10/2006
- Descripción
- The 1997 february 28 Beppo-SAX discovery of the X-ray afterglow of a gamma-ray burst (GRB) allowed the first precise determination of a GRB redshift. This major breakthrough came to confirm the long-standing suspicion in the high energy astrophysics community that GRBs arrive from, and their sources lie at cosmological whereabouts. Since then, the possibility of using them as actual cosmological probes has estimulated the search for self-consistent methods of bringing them into the realm of cosmology. A handful of attempts have been on trial. Since the introduction of the {\sl Amati relation} (Amati et al. 2002), other largely promising techniques have appeared in an attempt to turn GRBs into reliable cosmological probes. These incluide the {\sl Ghirlanda relation} (Ghirlanda et al. 2004), the {\sl Liang-Zhang relation} (Liang \& Zhang 2005), and the recently discovered {\sl Firmani et al. relation} (Firmani et al. 2006a), all of which take into account the most relevant physical properties of gamma-ray bursts (GRBs) as peak energy, jet openning angle, and both time lag and variability. Such discoveries hints at the long-sought {\sl Holy Grail} of creating a cosmic ruler from GRBs observables to be achievable. In this {\sl Letter} we construct the Hubble diagram (HD) for the standard Friedmann-Lema\^itre-Robertson-Walker (FLRW) cosmological model after enforcing it with the general relativistic energy conditions, heeding to investigate whether it still stands on as the leading scenario for cosmology in face of the distance modulus-redshift relation of a sample of GRBs that had their redshifts properly estimated and corrected upon applying on the data analysis the above quoted relations. Our $\chi^2$ analysis support the view that FLRW plus the strong energy condition (SEC) is what better fits the GRB data. But this is not the whole story, since for a cosmological constant $\Lambda \neq 0$ the FLRW+SEC analysis with undefined $p=p(\rho)$ suggests that $\Lambda$ is not constant anyhow, because it does not follows the $p= \omega \rho$ HD, with $\omega=-1$. Thenceforth, one concludes that either the cosmological constant does not exist at all, and consequently one is left with the FLRW+SEC which fits properly the GRBs HD and there is no late-time acceleration, or it does exist but should be time-varying. This all is contrary to current views based on SNIa observations that advocate for an actual constant $\Lambda$ and an accelerating universe. In connection to the results above, this last argumentation would imply that either there is something wrong with the SNIa interpretation regarding cosmic late-time acceleration (Middleditch 2006; Vishwakarma 2005; Santos, Alcaniz \& Rebou\c cas 2006) or we will have to move away from general relativity. We would better to think that general relativity is still the most correct theory of gravity.
- Año
- 2006
- Vínculo con tesis
- No
- Vínculo con beca
- No