Measuring the velocity bulk flow in presence of chameleon fields

It seems that the local group moves with respect to the cosmic microwave background known as CMB dipole. The bulk flow, the coherent motion of the large part of our visible universe is one of the powerful methods which can explain and reconstruct the apparent motion of our Local Group of galaxies (LG). Although, it is believed that over - density regions, such as Shapley Super cluster are responsible for the peculiar motion; however the exact source of the peculiar motion is still uncertain and it seems that this motion and other types of anisotropies in large scales have a common source. The chameleon fields can be a good candid to explain both types of anisotropy, namely the bulk flow in small scales and other types of anisotropies in large scales. In this paper, we study the bulk in the presence of chameleon fields flow in different scales. While in the past , this has been studied mostly using galaxies as distance indicators, the weight of type Ia supernovae (SNe Ia) has increased recently. We use Union2 catalogue containing 557 type Ia supernovae (SNe Ia) in redshift range, 0٫15 < z < 1٫4. The results indicate that for distances smaller than 150 Mpc, the bulk flow is moving in the (l, b) = (286, 16) direction with amplitude of 273kms −1. This result is consistence with the direction of CMB dipole in (1 - σ) confidence level. In large scales (300h −1Mpc), the convergence between direction of the bulk flowand CMB dipole decreaseswhile the bulk flow tends to the direction of dark energy dipole; thus it seems that chameleon field can be a common source for bulk flow and dark energy dipole. Moreover, we have estimated the chameleon parameter using peculiar velocity of Type Ia supernovae.