Recent astronomical research, utilizing data from the James Webb Space Telescope and other observatories, has provided new insights into supermassive black holes and their impact on host galaxies. One study details the observation of an extensive super-heated gas stream and precessing jets in the galaxy VV 340a, noting its significant role in gas removal and star formation suppression. Concurrently, another study focusing on the Circinus Galaxy revised previous understandings, determining that the majority of infrared emissions from its active galactic nucleus originate from material accreting onto the black hole, rather than from outflows.
Discovery of Extensive Gas Outflow in Galaxy VV 340a
Astronomers, primarily from the University of California, Irvine, have identified an extensive stream of super-heated gas emanating from the galaxy VV 340a, located approximately 500 million light-years away. The findings were published in the journal Science and presented at the 247th Meeting of the American Astronomical Society.
Observations from NASA's James Webb Space Telescope (JWST) revealed clouds of hot gas erupting from both sides of VV 340a. These structures form two long, narrow nebulae, each extending at least three kiloparsecs. Other data indicates the jets themselves extend up to 20,000 light-years (approximately 6.13 kiloparsecs) from the galaxy's center. This length is comparable to the entire thickness of the VV 340a galaxy's disk. This highly energized gas, described as coronal line gas, typically remains confined to tens of parsecs from a black hole, making this observation an exceedance by a factor of 30 or more.
Black Hole Jets and Coronal Gas
Radio observations from the Karl G. Jansky Very Large Array (VLA) detected a pair of plasma jets originating from opposite sides of the galaxy. These jets form when gas near a supermassive black hole reaches high temperatures and interacts with magnetic fields, launching material outward at high speeds. The jets trace a spiral or helical path, indicating "jet precession," a gradual shift in their direction. This marks the first observation of a precessing kiloparsec-scale radio jet driving a massive coronal gas outflow in a disk galaxy.
As the jets expand, they are believed to collide with surrounding galactic material, heating it to high temperatures and expelling it from the core, thereby generating coronal line gas. This type of highly ionized, super-hot plasma is rarely detected far from a black hole or outside its host galaxy. Data from the Keck II Telescope in Hawaii also identified cooler gas extending up to 15 kiloparsecs from the galaxy, potentially representing residual material from earlier jet activity.
Impact on Galaxy and Research Methods
The black hole jets are causing VV 340a to lose approximately 19 to 20 solar masses of gas annually. This process is understood to limit star formation by heating and removing gas necessary for new stars. While such precessing jets are often observed in older, elliptical galaxies where star formation has largely ceased, VV 340a is a relatively young galaxy currently undergoing a merger. This observation suggests that younger galaxies can also experience these feedback episodes, which might suppress star formation even as an ongoing merger could induce future star formation.
The James Webb Space Telescope was instrumental in detecting the coronal gas due to its infrared capabilities, which can penetrate the significant amounts of dust in VV 340a that obscure visible light. The Keck Cosmic Web Imager (KCWI) on the Keck II telescope helped characterize the spear-like structure and model the expelled material. The research was supported by funding from NASA and the National Science Foundation.
Future Research
Researchers plan to investigate other galaxies for similar features to further understand how powerful black hole activity influences galaxy evolution. Higher-resolution radio observations are also planned to investigate whether a second supermassive black hole within VV 340a could be contributing to the observed jet precession.
Revised Understanding of Infrared Emissions in Circinus Galaxy
New observations from NASA's James Webb Space Telescope (JWST), complemented by images from the Hubble Space Telescope, have revised the understanding of infrared light sources near the active supermassive black hole in the Circinus Galaxy. Located approximately 13 million light-years away, the Circinus Galaxy's black hole has been the subject of research published in Nature, which includes a detailed image of its surroundings captured by Webb.
Revisiting Prior Assumptions
Supermassive black holes sustain activity by consuming surrounding matter, which forms a donut-shaped ring known as a torus. Material from the inner walls of the torus accumulates into an accretion disk around the black hole, heating up and emitting light. Historically, distinguishing details within galactic centers has been challenging due to bright starlight and the obscuring density of the torus. Early models of Circinus often attributed the majority of excess infrared emissions from hot dust in active galactic cores to outflows of superheated matter.
Webb's Observational Technique and Key Findings
To differentiate between the torus and outflows, astronomers utilized the Aperture Masking Interferometer (AMI) tool on Webb's Near-Infrared Imager and Slitless Spectrograph (NIRISS) instrument. This technique allows Webb to function as an array of smaller telescopes, creating interference patterns from gathered light. By analyzing these patterns, astronomers can reconstruct detailed information about distant objects with significantly higher resolution, effectively doubling Webb's resolution for this specific observation. This marks the first instance a high-contrast mode of Webb has been used to study an extragalactic source.
The new data indicated that approximately 87% of the infrared emissions from hot dust in Circinus originate from areas closest to the black hole, suggesting that this material is accreting. In contrast, less than 1% of these emissions were attributed to hot dusty outflows. The remaining 12% came from greater distances that could not be previously resolved. The research notes that Circinus' accretion disk has moderate brightness.
Implications and Future Research
This research provides a tested technique for investigating other black holes. While torus-dominated emissions may be characteristic for systems with moderate accretion disk brightness, brighter black holes might exhibit different emission patterns. Future studies will involve collecting data from a statistical sample of black holes to understand the relationship between mass in accretion disks, outflows, and a black hole's power, building a broader catalog of emission data. The James Webb Space Telescope program is a collaboration led by NASA with ESA and CSA.