Evolution of QPO During Discovery Outburst of MAXI J1834-021: Estimation of Intrinsic Parameters from Spectro-Temporal Study

The Galactic transient black hole candidate (BHC) MAXI~J1834-021 was detected for the first time by MAXI/GSC on February 05, 2023 and it was active for next $\sim 10$~months. A monotonic evolution of low-frequency QPOs from higher to lower frequencies is observed in the middle-phase of the outburst. We study this evolution of the QPO with the propagating oscillatory shock (POS) model, and it suggests the presence of a receding shock. The POS model fit also estimates the mass of the source to be $12.1\pm 0.3M_{\odot }$. We also study the boradband ($0.5$-$70$~keV) nature of the source using archival data of NICER and NuSTAR on March 10, 2023 with the both phenomenological (combined disk blackbody plus powerlaw) and physical ($\mathit{\text{nthComp,}}\mathit{\text{kerrbb,}}\mathit{\text{TCAF}}$) models. The mass of the BHC estimated by the $\mathtt{\text{kerbb}}$ and $\mathtt{\text{TCAF}}$ models is found to be consistent with POS model fits as well as reported in our recent work. Combining all these methods, we predict mass of the source as $12.3_{-2.0}^{+1.1}{M}_{\odot }$. The $\mathtt{\text{kerbb}}$ model fit also estimates the spin, distance, and inclination of the source to be $0.13_{-0.02}^{+0.03}$, $9.2_{-0.9}^{+0.4}$~kpc, and ${80}^{\circ }.0$${}_{-6.0}^{+2.7}$, respectively. The combined spectral study suggests harder spectral state of the source with a higher dominance of the sub-Keplerian halo accretion rate over the Keplerian disk rate. The consistency of the observed frequency of the QPO with that of obtained from the $\mathtt{\text{TCAF}}$ model fitted shock parameters, confirms shock oscillation as the origin of the QPO.