HD1
Astronomers at the University of Tokyo reported finding HD1 on the 7th of April 2022. They located this object in the Sextans constellation using data from the Subaru Telescope. The team searched for objects that appeared much brighter in the K band than in the H band. This specific brightness pattern suggested a Lyman-break galaxy redshifted by a factor of around 13. They named it HD1 to reflect its status as an H band dropout. Another similar object, HD2, was found nearby in the Cetus constellation during the same survey.
The light from HD1 traveled for 13.5 billion years before reaching Earth. Scientists estimate the universe began approximately 13.787 billion years ago. This travel time places the observed position of HD1 about 330 million years after the Big Bang. Due to the expansion of space, the current proper distance is roughly 33.288 billion light-years. A previous record holder, GN-z11, had a redshift of 11 and appeared 420 million years after the Big Bang. HD1 pushed the known boundary of the observable universe further back in time.
HD1 displays unusually high brightness compared to other galaxies at this redshift range. It emits significantly more ultraviolet radiation than expected for its epoch. One theory suggests it is an extreme starburst galaxy producing stars at a rate far higher than any previously observed. Another possibility involves a significant population of Population III stars that are massive and luminous. Some researchers propose it could be a quasar hosting a supermassive black hole. Such a scenario would challenge existing models of black hole growth in the early universe.
New spectroscopic studies released in 2024 reclassified HD1 as a passive galaxy. The updated measurements indicate a lower redshift value of z = 4.0. This finding contradicts the initial classification of a high-redshift galaxy near the edge of the observable universe. The original estimate placed the object at approximately z = 13.27. The revised data shifts the timeline from 324 million years after the Big Bang to a later period. This change fundamentally alters our understanding of when such objects existed.
Researchers plan to use the James Webb Space Telescope to verify the true identity of HD1. They also intend to utilize the Nancy Grace Roman Space Telescope and GREX-PLUS space missions for further study. These tools will help identify whether the object is a galaxy, a quasar, or a black hole. The team expects these observations to reveal the first visible Population III stars if they exist. New telescopes could potentially discover over 10,000 galaxies at this early epoch of the Universe.
Common questions
When did astronomers at the University of Tokyo report finding HD1?
Astronomers at the University of Tokyo reported finding HD1 on the 7th of April 2022. They located this object in the Sextans constellation using data from the Subaru Telescope.
How far away is HD1 and when did its light begin traveling to Earth?
The light from HD1 traveled for 13.5 billion years before reaching Earth. Due to the expansion of space, the current proper distance is roughly 33.288 billion light-years.
What theories explain why HD1 displays unusually high brightness compared to other galaxies?
One theory suggests it is an extreme starburst galaxy producing stars at a rate far higher than any previously observed. Another possibility involves a significant population of Population III stars that are massive and luminous or a quasar hosting a supermassive black hole.
Why were new spectroscopic studies released in 2024 reclassifying HD1 as a passive galaxy?
New spectroscopic studies released in 2024 reclassified HD1 as a passive galaxy with a lower redshift value of z = 4.0. This finding contradicts the initial classification of a high-redshift galaxy near the edge of the observable universe which originally placed the object at approximately z = 13.27.
Which telescopes will researchers use to verify the true identity of HD1?
Researchers plan to use the James Webb Space Telescope to verify the true identity of HD1. They also intend to utilize the Nancy Grace Roman Space Telescope and GREX-PLUS space missions for further study.
All sources
14 references cited across the entry
- 1journalPlanck 2018 results. VI. Cosmological parametersPlanck Collaboration — 2020
- 2webKEMPNER Cosmology CalculatorJoshua Kempner — 2022
- 3journalJWST, ALMA, and Keck Spectroscopic Constraints on the UV Luminosity Functions at z~7-14: Clumpiness and Compactness of the Brightest Galaxies in the Early UniverseYuichi Harikane et al. — 2024
- 4webFinding the constellation which contains given sky coordinatesStaff — 2008
- 5newsAstronomers Detect Most Distant Galaxy Candidate YetNicolás Lira et al. — 7 April 2022
- 6journalA Search for H-Dropout Lyman Break Galaxies at z ~ 12–16Harikane, Yuichi — 2 February 2022
- 8journalAre the newly-discovered z ~ 13 drop-out sources starburst galaxies or quasars?Pacucci, Fabio — 7 April 2022
- 9newsAstronomers discover the most distant galaxy yet - Unusually bright in ultraviolet light, HD1 may also set another cosmic record.Caitlyn Buongiorno — 7 April 2022
- 11newsMeet HD1, The New Most Distant Galaxy Found 13.5 Billion Years Back In Time And Close To The 'Big Bang'Jamie Carter — 7 April 2022
- 13newsAstronomers spot oldest and most distant galaxy, new study claimsBBC News Staff — 10 April 2022