Speaker
Description
Due to the technical time delay, greater than $\sim 40$ s, of the XRT instrument on board the Neil Gehrels Swift Observatory satellite, we are not able to observe the x-ray emission occurring less than $\sim 40$ s after a gamma-ray burst (GRB) trigger time. A new strategy is indicated here of using the cosmological dilatation of time in the observer rest frame measured in high redshift GRBs to observe in the GRB cosmological rest-frame their earliest X-ray emission by Swift/XRT even less than $10$ s after the trigger. We illustrate this procedure using $353$ GRBs with well-defined cosmological redshift, based on the \textit{NASA-Swift GRB Table}. We compare and contrast the time delay between the trigger of the source and the first observation by Swift/XRT as measured in the observer frame (OTD) and the corresponding delay measured in GRBs' cosmological rest-frame (RTD). We consider as specific prototypes GRB 090423 at $z=8.2$ with an RTD of $8.2$~s, GRB 090429B at $z\sim 9.4$ with an RTD of $10.1$~s, as well as the GRB 220101A at $z=4.6$ with an RTD of $14.2$~s. This opens a new possibility for probing the first episode of the binary-driven hypernova (BdHN) model linked to the origin and early appearance of the newborn neutron star ($\nu$NS) and the first clear manifestation of a transition from a Jacobi to a Maclaurin sequence prior to the onset of the GRB afterglow.
