Bipolar blobs as evidence of hidden AGN activities in the low-mass galaxies

TL;DR

This paper presents evidence of a hidden black hole in a low-mass galaxy using bipolar Hα blobs and introduces a new method to detect active black holes in such galaxies, especially where traditional methods are ineffective.

Contribution

It provides a novel approach to identify active black holes in low-mass, low-metallicity galaxies by analyzing bipolar emission features and photoionization models.

Findings

Detected a hidden black hole with a mass of ~7.2×10^5 solar masses.

Identified bipolar Hα blobs as evidence of AGN activity.

Developed a new method to find black holes in environments where BPT diagrams fail.

Abstract

We report the evidence of a hidden black hole (BH) in a low-mass galaxy, MaNGA 9885-9102, and provide a new method to identify active BH in low mass galaxies. This galaxy is originally selected from the MaNGA survey with distinctive bipolar H$\alpha$ blobs at the minor axis. The bipolar feature can be associated with AGN activity, while the two blobs are classified as the H II regions on the BPT diagram, making the origins confusing. The Swift UV continuum shows that the two blobs do not have UV counterparts, suggesting that the source of ionization is out of the blobs. Consistent with this, the detailed photoionization models prefer to AGN rather than star-forming origin with a significance of 5.8$\sigma$. The estimated BH mass is $M_{\rm BH}\sim$7.2$\times 10^5 M_\odot$ from the $M_{\rm BH}-\sigma_*$ relationship. This work introduces a novel method for detecting the light echo of BHs, potentially extending to intermediate mass, in low metallicity environments where the traditional BPT diagram fails.