ALMA detection of parsec-scale blobs at the head of kiloparsec-scale jet in the nearby Seyfert galaxy NGC 1068

TL;DR

This study uses ALMA observations to identify parsec-scale blobs at the jet head in NGC 1068, revealing strong magnetic fields and potential cosmic-ray amplification by modest jets in a nearby Seyfert galaxy.

Contribution

First detection of parsec-scale blobs at the jet head in NGC 1068 with detailed magnetic field analysis and implications for cosmic-ray acceleration.

Findings

Detected parsec-scale blobs with strong magnetic fields (~240 μG)

Estimated cosmic-ray power exceeds star formation limits

Implication that modest jets can enhance galactic cosmic-ray content

Abstract

We present Atacama Large Millimeter/submillimeter Array observations at $\approx100$ GHz with $0.05$ arcsec (3 pc) resolution of the kiloparsec-scale jet seen in the nearby Seyfert galaxy NGC 1068, and we report the presence of parsec-scale blobs at the head of the jet. The combination of the detected radio flux ($\approx0.8$ mJy), spectral index ($\approx0.5$), and the blob size ($\approx10$ pc) suggests a strong magnetic field of $B\approx240\,\mu$G. Such a strong magnetic field most likely implies magnetic field amplification by streaming cosmic rays. The estimated cosmic-ray power by the jet may exceed the limit set by the star formation activity in this galaxy. This result suggests that even modest-power jets can increase the galactic cosmic-ray content while propagating through the galactic bulge.