Poster P15: Bounds on graviton mass from galaxy clusters


Sajal Gupta, Indian Institute of Science Education and Research kolkata


In the last few years, there has been a resurgence of interest in obtaining observational bounds on the graviton mass, following the detection of gravitational waves, because of the versatility of massive graviton theories in resolving multiple problems in cosmology and fundamental physics. 
In our works,” Limit on graviton mass using stacked galaxy cluster catalogs from SPT-SZ, Planck-SZ and SDSS-redMaPPer” and “Bound on the graviton mass from Chandra X-ray cluster sample”, we have presented new strong bounds on graviton mass. In the former study, we derived the gravitation acceleration in Yukawa-like fall off potential and extracted galaxy clusters parameters from three disparate surveys, which include catalogs from 2500 sq. degree SPT-SZ survey, the Planck all-sky SZ catalog, and a redMaPPer selected catalog from 10,000 sq. degree of SDSS-DR8 data. Finally, from a Chi-Square analysis, we obtained 90% c.l. limits, which were mg < 4.73×10^−30 eV, 3.0×10^−30 eV, and 1.27 × 10^−30 eV for SPT, Planck and SDSS. These limits are about five times more stringent than the previous best bound from galaxy clusters. In the latter work, we used temperature and gas density profiles of 12 relaxed galaxy clusters, which we obtained from Chandra X-ray observations. For determining graviton mass limits, we first calculated the total dynamical mass from the hydrostatic equilibrium equation in Yukawa gravity and then compared it with the corresponding mass in Newtonian gravity. We calculated a 90 % c.l upper limit of mg < 3.46 × 10^−29 eV on the graviton Compton wavelength/ mass for each of the 12 clusters in the sample. 




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