Astronomers using the International Gemini Observatory have discovered the closest known black hole to Earth. It is also the first definitive detection of a dormant stellar-mass black hole in the Milky Way. Its proximity to Earth, just 1600 light-years away, offers an intriguing study target to advance our understanding of the evolution of binary systems. Credit: International Gemini Observatory/NOIRLab/NSF/AURA/J. da Silva/Space Engine/M. the time
Gemini North telescope in Hawaii reveals first dormant stellar mass[{” attribute=””>black hole in our cosmic backyard.
Using the International Gemini Observatory, astronomers have discovered the closest-known black hole to Earth. This is the first unambiguous detection of a dormant stellar-mass black hole in the Milky Way. Located a mere 1600 light-years away, its close proximity to Earth offers an intriguing target of study to advance our understanding of the evolution of binary systems.
“Take the Solar System, put a black hole where the Sun is, and the Sun where the Earth is, and you get this system.” — Kareem El-Badry
Black holes are the most extreme objects in the Universe. It is believed that supermassive versions of these unimaginably dense objects reside at the centers of all large galaxies. Stellar-mass black holes — which weigh approximately five to 100 times the mass of the Sun — are much more common. In fact, there are an estimated 100 million stellar-mass black holes in the Milky Way alone. However, only a handful have been confirmed to date, and nearly all of these are ‘active’. This means that they shine brightly in X-rays as they consume material from a nearby stellar companion, unlike dormant black holes which do not.
Astronomers have now discovered the closest black hole to Earth, which the researchers have dubbed Gaia BH1. To find it, they used the Gemini North telescope in Hawai‘i, one of the twin telescopes of the International Gemini Observatory, operated by NSF’s NOIRLab.
Gaia BH1 is a dormant black hole that is about 10 times more massive than the Sun and is located about 1600 light-years away in the constellation Ophiuchus. This means it is three times closer to Earth than the previous record holder, an X-ray binary in the constellation of Monoceros. The new discovery was made possible by making exquisite observations of the motion of the black hole’s companion, a Sun-like star that orbits the black hole at about the same distance as the Earth orbits the Sun.
This animation shows a Sun-like star orbiting Gaia BH1, the closest black hole to Earth, located about 1600 light-years away. Observations made by Gemini North, one of the twin telescopes of the International Gemini Observatory, operated by NSF’s NOIRLab, were crucial to limiting the orbital motion and thus the masses of the two components in the binary system, allowing the team to identify the central body as one. A black hole about 10 times larger than our sun. Credits: T. Müller (MPIA), PanSTARRS DR1 (KC Chambers et al. 2016), ESA/Gaia/DPAC
“Take the Solar System, put a black hole where the Sun is, and put the Sun where the Earth is, and you have this system,” explained Kareem El-Badry, an astrophysicist at the Center for Astrophysics | Harvard & Smithsonian and Max Planck Institute for Astronomy and lead author of the paper describing this discovery, published Nov. Monthly Notices of the Royal Astronomical Society.
“While many such system detections have been claimed, almost all of these discoveries were later rejected. This is the first definitive detection of a Sun-like star in a large orbit around a stellar-mass black hole in our Galaxy.”
Although there are possibly millions of stellar-mass black holes circulating in the Milky Way Galaxy, a few of those detected were revealed by their energetic interactions with a companion star. As material from a nearby star spirals into the black hole, it overheats and produces powerful X-rays and jets of material. If a black hole is not actively feeding (i.e. dormant), it simply blends in with its surroundings.
“For the past four years I’ve been looking for dormant black holes using a wide variety of datasets and methods,” El-Badry said. “My previous attempts have – among others – uncovered a collection of binary systems that look like black holes, but this search has borne fruit for the first time.”
“While this potentially heralds future discoveries of the predicted dormant black hole population in our Galaxy, the observations also leave a mystery to be solved – why is the companion star in this binary so normal, despite a shared history with its exotic neighbor?” – Aunt Martin
The team initially determined that the system potentially hosts a black hole by analyzing its data. of the European Space Agency. Gaia spacecraft. Gaia caught the tiny irregularities in the star’s motion caused by the gravity of a massive unseen body. To study the system in more detail, El-Badry and his team turned to the Gemini Multi-Object Spectrograph instrument on Gemini North, which measures the speed of the black hole-orbiting companion star and provides precise measurement of its orbital period. The Gemini tracking observations were crucial to limiting the orbital motion and thus the masses of the two components in the binary system, allowing the team to identify the central body as a black hole about 10 times larger than our Sun.
“Our Gemini tracking observations confirmed beyond reasonable doubt that the binary system contains a normal star and at least one dormant black hole,” said El-Badry. “We couldn’t find a plausible astrophysical scenario that could explain the observed trajectory of the system that does not contain at least one black hole.”
The team relied not only on Gemini North’s excellent observation capabilities, but also on Gemini’s ability to provide data on a tight deadline, as the team only had a short window to conduct follow-up observations.
“When we got the first indications that the system contained a black hole, we only had a week before the two objects came into closest orbit in their orbits. “Measurements at this point are crucial for making accurate mass estimates in a binary system,” said El-Badry. The ability to provide observations on a short time scale was crucial to the success of the project. If we had missed that narrow window, we would have had to wait another year.”
Current astronomers’ models of binary systems evolution struggle to explain how the peculiar configuration of the Gaia BH1 system might have arisen. Specifically, the progenitor star that later turned into the newly detected black hole would have been at least 20 times larger than our Sun. This means that it can only live for a few million years. Had both stars formed at the same time, this massive star would rapidly evolve into a supergiant, inflating the other star and engulfing it before becoming a viable, hydrogen-burning, main-sequence star like our Sun.
It’s not clear how the solar-mass star escaped this episode, ending up as a seemingly normal star, as the black hole binary observations show. All of the theoretical models that allow for survival predict that the solar-mass star must be in a much narrower orbit than actually observed.
This may indicate significant gaps in our understanding of how black holes form and evolve in binary systems, and also suggests the existence of an as yet undiscovered population of dormant black holes in binary systems.
“It’s interesting that this system doesn’t fit easily with standard binary evolution models,” El-Badry said. “It raises a lot of questions about how this binary system formed and how many of these dormant black holes there are.”
As part of a network of space and ground-based observatories, Gemini North not only provided strong evidence for the closest black hole to date, but also the first undisturbed black hole system with the usual hot gas interacting with the black hole. ”said Martin Still, Program Officer at NSF Gemini. “While this potentially heralds future discoveries of the predicted dormant black hole population in our Galaxy, the observations also leave a mystery to be solved – why is the companion star in this binary so normal, despite a shared history with its exotic neighbor?”
Reference: “Sun-like star orbiting a black hole” by Kareem El-Badry, Hans-Walter Rix, Eliot Quataert, Andrew W Howard, Howard Isaacson, Jim Fuller, Keith Hawkins, Katelyn Breivik, Kaze WK Wong, Antonio C Rodriguez, Charlie Conroy, Sahar Shahaf, Tsevi Mazeh, Frédéric Arenou, Kevin B Burge, Dolev Bashi, Simchon Faigler, Daniel R Weisz, Rhys Seeburger, Silvia Almada Monter and Jennifer Wojno, 2 November 2022 Monthly Notices of the Royal Astronomical Society.
DOI: 10.1093/mnras/stac3140
Gemini North observations were made as part of a director’s optional time schedule (program ID: GN-2022B-DD-202).
The International Gemini Observatory is operated in partnership with six countries, including the United States through the National Science Foundation, Canada through the National Research Council of Canada, Chile through Agencia Nacional de Investigación y Desarrollo, Ministério da Ciência, Brazil through Tecnologia. e Inovações, Argentina, through the Ministerio de Ciencia, Tecnología e Innovación, and Korea, through the Korean Institute of Astronomy and Space Sciences. These Participants and the University of Hawaii with regular access to Gemini each have a “National Gemini Office” to support their local users.
