An international team of astronomers has unveiled significant new insights into a remarkable quasar, J1601+3102, which has been found to host a large extended radio jet. The discovery, reported in a study published on November 25 on the arXiv preprint server, sheds light on the behavior and structure of extremely radio-loud quasars, particularly at high redshifts. This finding not only enhances our understanding of quasar evolution but also challenges assumptions about the role of supermassive black hole (SMBH) mass in generating powerful radio jets.
Quasars, or quasi-stellar objects (QSOs), are among the most luminous and distant objects in the universe. These active galactic nuclei (AGN) are powered by accretion of matter onto SMBHs at their centers, emitting energy across a wide range of wavelengths, from radio to X-rays. Their extreme luminosity and distance make them critical tools for studying the universe’s early history, galactic evolution, and the mechanisms governing SMBHs.
J1601+3102, an exceptionally radio-loud quasar, was first discovered in 2022 at a redshift of 4.9, placing it at a time when the universe was less than 1.5 billion years old. Its radio flux density is measured at 69 millijanskys (mJy), and it has an extraordinary bolometric luminosity of approximately 26×101426 \times 10^{14} erg/s. Notably, it also exhibits a steep spectral index, distinguishing it from other radio-loud quasars.
In a recent study led by Anniek Joan Gloudemans of the Gemini Observatory, astronomers sought to explore the properties of J1601+3102 in greater detail. The team used the Low Frequency Array (LOFAR), a powerful radio telescope network designed to operate at low radio frequencies, and complemented their observations with data from the Gemini Near-Infrared Spectrograph (GNIRS). By integrating these tools, the researchers constructed high-resolution images and spectra of the quasar, unveiling its intricate structure.
The LOFAR images revealed a remarkable extended radio structure in J1601+3102. The quasar’s radio morphology includes three distinct components: a northern radio lobe, a southern radio lobe, and a central core. The northern lobe, located approximately 29,000 light-years from the quasar’s optical position, exhibits a total flux density of 50.6 mJy. The southern lobe, at a distance of about 185,800 light-years, shows a flux density of 10.5 mJy. Combined, these features indicate that the quasar’s radio jet spans an incredible 215,000 light-years at minimum.
Astronomers believe the true size of the radio jet may be even larger. Projection effects caused by the viewing angle could make the jet appear shorter than it is. This discovery sets a new record: J1601+3102 now holds the distinction of having the most extended radio jet ever observed in a quasar at a redshift above 4.0.
The team also measured the mass of the SMBH at the core of J1601+3102, estimating it to be around 450 million times the mass of the Sun. This mass is relatively modest compared to SMBHs found in other high-redshift quasars, which often exceed several billion solar masses. This observation is particularly significant because it suggests that an exceptionally massive black hole is not a prerequisite for generating powerful and extended radio jets. Instead, other factors, such as the efficiency of accretion processes or the orientation of magnetic fields, may play more critical roles in jet formation and propagation.
The findings offer crucial insights into the nature of high-redshift quasars and their radio jets. Quasars like J1601+3102 provide a unique window into the early universe, as their light has traveled billions of years to reach us. By studying such objects, astronomers can better understand the interplay between SMBHs, their host galaxies, and the surrounding environment during the universe’s formative years.
The study of J1601+3102 also raises intriguing questions about the mechanisms underlying jet formation. Powerful radio jets are a hallmark of some AGN, but their origin remains a topic of active research. While factors such as black hole spin, accretion rates, and magnetic fields have been proposed as key drivers, the discovery of a massive jet in a quasar with a relatively modest SMBH mass suggests that these processes may be more complex than previously thought.
Future research on J1601+3102 and similar objects will likely focus on refining models of jet formation and investigating the role of environmental factors. Advanced telescopes, such as the upcoming Square Kilometre Array (SKA), will enable astronomers to probe radio jets in even greater detail, potentially uncovering the physical processes that govern their extraordinary energy output and structure.