A compact symmetric ejection from the low mass AGN in the LINER galaxy NGC 4293

We conducted a Very Long Baseline Array (VLBA) observation of the low mass active galactic nucleus (AGN) in galaxy NGC 4293 (z = 0.003). The object is associated with a low-ionization nuclear emission-line region (LINER). Its black hole mass is estimated as similar to 10(5) or similar to 10(7)M(circle dot). The VLBA 1.5 GHz image shows an inverse symmetric structure with two discrete radio blobs separated by an angular distance of similar to 120 mas, corresponding to similar to 7 parsec. Furthermore, its integrated radio spectrum has a turnover at the frequency of similar to 0.44 GHz. Based on the compactness and spectrum, the nuclear radio source in NGC 4293 belongs to a sample of (megahertz) peaked spectrum (PS/MPS) radio sources with compact symmetric morphologies. NGC 4293 has 1.4 GHz radio power of only similar to 10(20) W, Hz(-1) with the VLBA observation, which is consistent with local AGNs but lower than the current PS samples. One of the two blobs has a steep radio spectrum alpha = -0.62 +/- 0.08 (S-nu proportional to nu(+alpha)), while the other one has an inverted spectrum alpha = 0.32 +/- 0.10. The VLBA 1.5 GHz luminosity ratio of the two blobs is 3.23 and both blobs show lateral-flowing structures where the hotspots reside at the edge of each radio lobe. This can be explained as jet interactions with dense circumnuclear medium. We estimate the black hole mass of NGC 4293 through the Fundamental Plane of black hole activity, which constrains the black hole mass to be less than or similar to 10(6) M-circle dot. It supports that the object is a low-mass AGN and a potential candidate for accreting and ejecting IMBHs.

Automated summary

The research team conducted VLBA observations on the low-mass active galactic nucleus (AGN) in galaxy NGC 4293 and estimated its black hole mass. The observation revealed a symmetric structure with two discrete radio blobs and the distance between them was determined. The integrated radio spectrum showed a turnover and the radio power was lower compared to current samples. One of the blobs had a steep spectrum while the other had an inverted spectrum.