SIMBAD references

Iron line spectroscopy has been one of the leading methods not only for measuring the spins of accreting black holes but also for testing fundamental physics. Basing on such a method, we present an analysis of a data set observed simultaneously by NuSTAR and NICER for the black hole binary candidate MAXI J1803-298, which shows prominent relativistic reflection features. Various relxill_nk flavors are utilized to test the Kerr black hole hypothesis. The results obtained from our analysis provide stringent constraints on Johannsen deformation parameter α₁₃ with the highest precise to date, namely ${\alpha }_{13}={0.023}_{-0.038}^{+0.071}$ from relxillD_nk and ${\alpha }_{13}={0.006}_{-0.022}^{+0.045}$ from relxillion_nk, respectively, in 3σ credible lever, where the Johannsen metric reduces to the Kerr metric when α₁₃ vanishes. Furthermore, we investigate the best model fit results using Akaike information criterion and assess its systematic uncertainties.