AR_final file_2018-19

the observational constraints on the model parame- ters by using the data from CMB, baryonic acous- tic oscillation (BAO) measurements, the recently measured new local value of the Hubble constant from the Hubble Space Telescope, and large scale structure (LSS) information from the abundance of galaxy clusters. The DM-photon coupling pa- rameter Γ γ is constrained to Γ γ ≤ 1 . 3 × 10 − 5 (at 95% C.L.) from the joint analysis carried out by using all the mentioned data sets. The neutrino mass scale P m ν upper bounds at 95% C.L. are obtained as P m ν ∼ 0 . 9 eV and P m ν ∼ 0 . 4 eV with and without the LSS data, respectively. We observe that the DM-photon coupling cause signif- icant changes in the best fit value of N eff but yields statistical ranges of N eff compatible with the stan- dard predictions, and we do not find any evidence of dark radiation. Due to non conservation of pho- tons in our model, we also evaluate and analyze the effects on the BAO acoustic scale at the drag epoch. The DM-photon coupling model yields high values of Hubble constant, consistent with the lo- cal measurement, and thus, alleviates the tension on this parameter. This work has been done in collaboration with Rafael C. Nunes, and Santosh kumar Yadav. Cosmological implications of scale-independent energy-momentum squared gravity: Pseudo non- minimal interactions in dark matter and relativistic relics In this work, we introduce a scale-independent energy-momentum squared gravity (EMSG) that allows different gravitational couplings for differ- ent types of sources, which may lead to scenarios with many interesting applications/implications in cosmology. We study a modification of the cold dark matter (ΛCDM) model, where photons and baryons couple to the spacetime as in general rel- ativity, while the cold dark matter and relativistic relics (neutrinos and any other relativistic relics) couple to the spacetime in accordance with EMSG. This scenario induces pseudo non minimal interac- tions on these components, leading to modification at both the background and perturbative levels. A consequence of this scenario is that the dimension- less free parameter of the theory may induce di- rect changes on the effective number of the rela- tivistic species, without the need to introduce new extra species. In order to quantify the observa- tional consequences of the cosmological scenario, we use the cosmic microwave background Planck data (temperature, polarization, and lensing power spectrum) and baryonic acoustic oscillations data. We find that the free model parameter is too small to induce statistically significant corrections on the ΛCDM model due to EMSG. We deduce that the model presented here is quite rich with promis- ing cosmological applications/implications that de- serve further investigations. This work has been done in collaboration with Ozgur Akarsu, Niham Katirchi, Rafael C. Nunes, and M. Sami. Badam Singh Kushvah Halo orbit of regularized circular restricted three- body problem with radiation pressure and oblateness In this work, computation of the halo orbit for the KS-regularized photogravitational circular re- stricted three-body problem is carried out. This extends the idea of Srivastava et al. (Astrophys. Space Sci. 362 : 49, 2017), which only concen- trated on the (i) regularization of the 3D-governing equations of motion, and (ii) validation of the mod- elling for small out-of-plane amplitude ( A − z = 110 . 000 km ) assuming the third-order analytical ap- proximation as an initial guess with and without differential correction. This motivated us to com- pute the halo orbits for the large out-of-plane am- plitudes and to study their stability analysis for the regularized motion. The stability indices are described as a function of out-of-plane amplitude, mass reduction factor and oblateness coefficient. Three different Sun planet systems: the Sun Earth, Sun Mars and the Sun Jupiter are chosen in this study. Stable halo orbits do not exist around the L 1 point, however, around the L 2 point, stable halo orbits are found for the considered systems. This work has been done in collaboration with Vineet K. Srivastava, Jai Kumar, and Padmdeo Mishra. Trajectory of asteroid 2017 SB20 within the CRTBP Regular monitoring the trajectory of asteroids to a future time is a necessity, because the variety of known probably unsafe near-Earth asteroids are in- creasing. The analysis is performed to avoid any in- cident or whether they would have a further future threat to the Earth or not. Recently a new Near Earth Asteroid (2017 SB20) has been observed to cross the Earth orbit. In view of this, we obtain the trajectory of asteroid in the circular restricted ( 197 )