Spectro-polarimetric study to constrain accretion-ejection properties of MCG-5-23-16 using IXPE and NuSTAR observations

We conducted a study on the X-ray polarization properties of MGC-5-23-16 by analyzing long-term monitoring data from { NuSTAR} jointly with { IXPE} observations in May and November 2022. The re-analysis of { IXPE} data gives model-dependent polarization degree, PD (%) = 1.55±0.99 and 1.31±0.95 in the energy band $2-8$ keV, agrees with previous studies within error bars. The model-independent analysis of PD poses an upper limit of ≤3.8 (1σ level) for the same energy band. The observed upper limit of PD, along with broadband spectral analysis ($3-79$ keV), allowed us to derive corona geometry (i.e. length and height) and the accretion disk inclination (~ 33^∘). Additional { NuSTAR} observations were also analyzed to gain insights into the accretion flow properties of the source and to estimate the expected polarization during those epochs with PD ~ 4.3%. The radius and height of the corona exhibited to vary between 28.2±3.1 - 39.8±4.6 rₛ and 14.3±1.7-21.4±1.9 rₛ, with a mass outflow rate from the corona measuring 0.14±0.03-0.2±0.03 Eddington rate (MEdd). The estimated PD values were nearly constant up to a certain radial distance and height of the corona and then decreased for increasing corona geometry. The spectral analysis further provided an estimate for the mass of the central black hole ~ 2× 10⁷ M_ and the velocity of the outflowing gas ~ 0.16-0.19c. Our modeling of the disk-corona-outflows and polarization connection can be extended and validated with data from recently launched India's first X-ray Polarimeter Satellite, offering potential applications to other sources.