Fermi-GBM Observation of GRB 090717034: χ ² Test Confirms Evidence of Gravitational Lensing by a Supermassive Black Hole with a Million Solar Mass

Abstract

Gravitational lensing of gamma-ray bursts (GRBs) can provide an opportunity to probe the massive compact objects in the universe at different redshifts. We have discovered two consecutive pulses in the light curve of GRB 090717034, with the same temporal profile and different count rate, separated by a time interval, which is identified as a gravitationally lensed candidate in the Fermi-GBM GRB catalog. Here, we use the χ 2 minimization method to investigate the similarity of the temporal profile variability of the two pulses as a gravitationally lensed GRB candidate. We find the magnification factor and the time delay between two pulses to minimize the χ 2 function. Then, we perform a Monte Carlo simulation on a sample of mock lensed GRBs and compare the χ 2 of the lensed GRB candidate with the simulation, which confirms this candidate with 1σ confidence level. Assuming that GRB 090717034 is lensed by a pointlike object, the redshifted lens mass is about M L (1 + z) = (4.839 ± 1.148) × 106 M ⊙. The lens of this GRB is a candidate for a supermassive black hole along the line of sight to the GRB.

Observational Evidence for Cosmological Coupling of Black Holes and its Implications for an Astrophysical Source of Dark Energy

“…The prevalence of strong gravitationally lensed γ-ray bursts (GRBs) has been used to estimate the comoving density of intermediate-mass BHs (IMBHs; Paynter et al 2021, see also, e.g., Wang et al 2021;Yang et al 2021;Chen et al 2022;Kalantari et al 2022;Liao et al 2022;Lin et al 2022). GRBs probe IMBHs at scales much greater than the nonlinearity scale of ∼6 Mpc, complementing ∼50 kpc MACHO constraints (Appendix B).…”

Shadow and weak gravitational lensing for Ellis-Bronnikov wormhole*

“…In future studies, the observational data of the gravitational lensing in Refs. [93][94][95][96] may be further employed to obtain constraints on the spacetime parameters of EB and estimate the plasma characteristics.…”

Properties and Patterns of Polarized Gravitational Waves

“…For an extreme Kerr black hole of mass M ∼ 10 6 M at a cosmological distance that has been detected through microlensing of a gamma-ray burst (GRB), such as the source in [30,31], the numerical value of the time delay would be at most |∆ gm | ≈ 10 −3 s. This time delay turns out to be much shorter than the sampling rate of the light curve, which is of the order of 10 −1 s. The sampling rate of the GRB light curve by FERMI satellite is larger than the gravitomagnetic time delay; therefore, the latter is not detectable in this data. However, future gamma-ray detectors with high sampling rate should take into account the possible contribution of the gravitomagnetic term.…”