NGC 1275

Lore & Background

NGC 1275 was discovered by German-British astronomer William Herschel on 17 October 1786. The galaxy comprises a central type-cD galaxy and a high velocity system (HVS) that lies in front of it, moving at 3000 km/s toward the dominant system. The HVS is not affecting the cD galaxy as it lies at least 200 thousand light-years away, but tidal interactions are disrupting it, and ram pressure from the intracluster medium is stripping its gas and producing large amounts of star formation within it.

An active supermassive black hole at the center powers strong jets of particles into the Perseus Cluster, heating the surrounding gas to 60 million degrees Celsius and causing it to emit X-ray light. The central galaxy contains a massive network of spectral line emitting filaments, apparently dragged out by rising bubbles of relativistic plasma from the active nucleus. These long gaseous filaments stretch beyond the galaxy into the multimillion-degree X-ray–emitting gas of the cluster, each thread containing about one million solar masses of gas, only 200 light-years wide, and extending up to 20,000 light-years.

The filaments pose a problem: they are much cooler than the surrounding intergalactic cloud, and it is unclear how they have persisted without warming, dissipating, or collapsing to form stars. One possibility is that weak magnetic fields, about one-ten-thousandth the strength of Earth's field, exert enough force on the ions to keep them together. NGC 1275 contains 13 billion solar masses of molecular hydrogen infalling from the intracluster medium in a cooling flow, feeding its active nucleus and fueling star formation. High-resolution observations of a rotating disk of molecular gas around the central black hole indicate a central mass of approximately 800 million solar masses.

Reader's Guide

NGC 1275 is significant as a prominent member of the Perseus Cluster and a nearby example of a Seyfert galaxy with an active supermassive black hole. Its dual-galaxy structure, with a high velocity system merging into the cluster, provides a laboratory for studying galaxy interactions and ram-pressure stripping. The massive network of cool gas filaments extending into the hot intracluster medium challenges models of gas dynamics and magnetic field support, offering insights into how such structures persist. The central black hole's jets heat the cluster gas, influencing the evolution of the entire cluster. The detection of three supernovae within the galaxy underscores its ongoing stellar activity. Observations of the molecular gas disk have allowed precise measurement of the central black hole's mass, contributing to the understanding of supermassive black hole demographics. The galaxy's cooling flow, feeding both star formation and the active nucleus, makes it a key object for studying the interplay between black hole accretion and galaxy evolution.

Did You Know?

• The central black hole has a mass of approximately 800 million solar masses.
• Three supernovae have been observed in NGC 1275: SN 1968A, SN 2005mz, and SN 2024xav.
• The galaxy's gas filaments are only 200 light-years wide but extend up to 20,000 light-years.