# The ALMA Discovery of the Rotating Disk and Fast Outflow of Cold Molecular Gas in NGC 1275

## TL;DR

This study uses ALMA observations to reveal a rotating cold gas disk and fast outflows in NGC 1275, providing insights into AGN feeding and jet launching mechanisms at unprecedented spatial resolution.

## Contribution

First detection of a massive cold molecular gas disk on 100 pc scales in a BCG, linking it to the AGN jet axis and revealing complex cold gas structures consistent with recent simulations.

## Key findings

- Detected a ~10^8 solar mass molecular gas disk within 100 pc.
- Observed blue-shifted absorption indicating outflows at 300-600 km/s.
- Resolved complex cold gas filaments inconsistent with simple infall models.

## Abstract

We present ALMA Band 6 observations of the CO(2-1), HCN(3-2), and HCO$^{+}$(3-2) lines in the nearby radio galaxy / brightest cluster galaxy (BCG) of NGC 1275 with the spatial resolution of $\sim20$ pc. In the previous observations, CO(2-1) emission was detected as radial filaments lying in the east-west direction. We resolved the inner filament and found that the filament cannot be represented by a simple infalling stream both morphologically and kinematically. The observed complex nature of the filament resembles the cold gas structure predicted by recent numerical simulations of cold chaotic accretion. A crude estimate suggests that the accretion rate of the cold gas can be higher than that of hot gas. Within the central 100 pc, we detected a rotational disk of the molecular gas whose mass is $\sim10^{8} M_{\sun}$. This is the first evidence of the presence of massive cold gas disk on this spatial scale for BCGs. The disk rotation axis is approximately consistent with the axis of the radio jet on subpc scales. This probably suggests that the cold gas disk is physically connected to the innermost accretion disk which is responsible for jet launching. We also detected absorption features in the HCN(3-2) and HCO$^{+}$(3-2) spectra against the radio continuum emission mostly radiated by $\sim1.2$-pc size jet. The absorption features are blue-shifted from the systemic velocity by $\sim$300-600~km~s$^{-1}$, which suggests the presence of outflowing gas from the active galactic nucleus (AGN). We discuss the relation of the AGN feeding with cold accretion, the origin of blue-shifted absorption, and estimate of black hole mass using the molecular gas dynamics.