J0910−0414

J0910−0414, also known as DELS J091054.53−041406.8, is a quasar at a redshift of approximately 6.64. It is observed during the Epoch of Reionization, when the Universe was less than a billion years old. The quasar is notable for its massive supermassive black hole, broad absorption line (BAL) features, intense star formation in its host galaxy and its location within a large-scale overdensity of galaxies.

The systemic redshift of J0910-0414 is 6.6363 ± 0.0003, measured from C II emission of its host galaxy. The central black hole has a estimated mass of 3.6 billion solar masses.

Discovery

J0910-0414 was identified in the Dark Energy Spectroscopic Instrument Legacy imaging surveys during searches for quasars at high redshift. It was subsequently confirmed through spectroscopic observations and identified as a broad absorption line quasar.

The quasar was included in the follow-up observations of reionization-era quasars designed to measure their blackhole masses and properties. Near-infrared spectroscopy allowed Mg II emission line to be used in estmating the mass of its central black hole.

Properties

J0910−0414 has an absolute ultraviolet magnitude of approximately −26.4. It is among the luminous quasars known at redshifts greater than 6.

The black hole mass has been estimated at approximately 3.6 × 109 M☉. The quasar is classified as a BAL quasar because its spectrum contains broad absorption features produced by gas moving along the line of sight. The systemic redshift obtained from the host galaxy is more reliable for determining the velocity of the quasar's environment than measurements based on broad ultraviolet emission lines.

Host galaxy

The host galaxy of J0910−0414 is a massive, actively star-forming galaxy. Observations with the Atacama Large Millimeter/submillimeter Array (ALMA) detected the [C II] 158 μm emission line from the galaxy. This provided a precise measurement of the systemic redshift and information about the kinematics of the gas surrounding the quasar. ALMA observations also detected compact dust emission and several [C II]-emitting galaxies in the surrounding region. The observations indicate that the quasar is located in a dense environment containing both unobscured and dust-obscured galaxies.

Estimates of the star-formation rate of the host vary depending on the observational tracer used. This is partly due to the different regions of the galaxy probed by ultraviolet, infrared and millimetre observations.

Protocluster

J0910−0414 is located in a large overdensity of galaxies interpreted as a protocluster. A 2024 study combined observations from the Subaru Telescope, spectroscopy and ALMA to investigate the environment around the quasar. Twelve Lyman-alpha-emitting galaxies were spectroscopically confirmed around the quasar. ALMA observations also identified three galaxies emitting the [C II] line, including objects that were not prominent in optical observations because of their dust content.

The concentration of galaxies indicates that J0910−0414 resides in an unusually dense region for its epoch. The structure is expected to evolve into a much more massive galaxy cluster as its constituent galaxies and dark matter continue to collapse under gravity.

Later surveys of high-redshift quasar environments have also classified DELS J091054.53−041406.8 as residing in an overdense field of Lyman-alpha emitters.

Nearby galaxies

A galaxy known as LAE-11 has been studied in the proximity zone of J0910−0414. It lies approximately 0.3 proper megaparsecs from the quasar and is therefore close enough for the quasar's radiation to affect its surrounding environment.

Observations with the Subaru Telescope, Hubble Space Telescope and James Webb Space Telescope, together with spectroscopy from Keck Observatory and JWST, detected Lyman-alpha as well as Hβ, [O III] and Hα emission from LAE-11.

LAE-11 shows a double-peaked Lyman-alpha emission profile. Its location provides an opportunity to study the interaction between a galaxy and the radiation field of a luminous quasar during the Epoch of Reionization.

Significance

J0910−0414 provides an example of the rapid growth of a massive black hole and its host galaxy at an early stage of cosmic history. Its large black hole, active star formation and dense environment make it a useful target for studying the formation of massive galaxies and quasars.

The protocluster surrounding the quasar is also important for understanding the relationship between early quasars and large-scale structure. The presence of many galaxies at approximately the same redshift indicates that the quasar is part of a rapidly developing region of the early Universe.

The detection of an extended Lyman-alpha halo adds another way of studying the gas surrounding the quasar. Its extent and kinematics provide information about the cool gas reservoir around the host galaxy and the processes associated with quasar and galaxy growth.

See also

• Quasar
• Supermassive black hole
• Protocluster
• Epoch of Reionization
• Lyman-alpha emitter
• Dark Energy Spectroscopic Instrument
• Atacama Large Millimeter/submillimeter Array
• James Webb Space Telescope