AGN absorbing column densities

We developed a multiple linear regression machine learning algorithm trained with WISE colors, Swift-BAT count rates, soft X-ray hardness ratios, and an MIR-soft X-ray flux ratio. Our algorithm was trained off 451 AGN from the Swift-BAT sample with known NH and has the ability to accurately predict NH values for AGN of all levels of obscuration, as evidenced by its Spearman correlation coefficient value of 0.86 and its 75% classification accuracy.

This is significant as few other methods can be reliably applied to AGN with Log(NH)<22.5. It was determined that the two soft X-ray hardness ratios and the MIR-soft X-ray flux ratio were the largest contributors towards accurate NH determination. We applied the algorithm to 487 AGN from the BAT 150-month catalog with no previously measured NH values.