Being one of only two fundamental properties black holes possess , the spin of supermassive black holes ( SMBHs ) is of great interest for understanding accretion processes and galaxy evolution .
However , in these early days of spin measurements , consistency and reproducibility of spin constraints have been a challenge .
Here we focus on X-ray spectral modeling of active galactic nuclei ( AGN ) , examining how well we can truly return known reflection parameters such as spin under standard conditions .
We have created and fit over 4000 simulated Seyfert 1 spectra each with 375 \pm 1k counts .
We assess the fits with reflection fraction of R = 1 as well as reflection-dominated AGN with R = 5 .
We also examine the consequence of permitting fits to search for retrograde spin .
In general , we discover that most parameters are over-estimated when spectroscopy is restricted to the 2.5 – 10.0 keV regime and that models are insensitive to inner emissivity index and ionization .
When the bandpass is extended out to 70 keV , parameters are more accurately estimated .
Repeating the process for R = 5 reduces our ability to measure photon index ( \sim 3 to 8 per cent error and overestimated ) , but increases precision in all other parameters — most notably ionization , which becomes better constrained ( \pm 45 { \thinspace erg } { \thinspace cm } { \thinspace s } ^ { -1 } ) for low ionization parameters ( \xi < 200 { \thinspace erg } { \thinspace cm } { \thinspace s } ^ { -1 } ) .
In all cases , we find the spin parameter is only well measured for the most rapidly rotating supermassive black holes ( i.e . a > 0.8 to about \pm 0.10 ) and that inner emissivity index is never well constrained .
Allowing our model to search for retrograde spin did not improve the results .