Sun-like star’s orbit reveals the closest black hole ever found

(ORDO NEWS) — In 1916, Karl Schwarzschild proposed that black holes exist as a solution to Einstein’s field equations for his general theory of relativity.

By the middle of the 20th century, astronomers first began to detect black holes. time using indirect methods, which consisted in observing their impact on surrounding objects and space.

Since the 1980s, scientists have been studying supermassive black holes (SMBHs), which are at the center of the most massive galaxies in the universe. . And by April 2019, the Event Horizon Telescope (EHT) collaboration published the first-ever image of a supermassive black hole.

These observations provide an opportunity to test the laws of physics under the most extreme conditions and provide insight into the forces that have shaped the universe.

According to a recent study, an international research team relied on data from ESA’s Gaia Observatory to observe a sun-like star with strange orbital characteristics. Due to the nature of its orbit, the team concluded that it must be part of a binary black hole system.

This makes it the closest black hole to our solar system and suggests the existence of a significant population of black holes. dormant black holes in our galaxy.

The study was led by Karim El-Badri, Fellow of the Harvard Society, astrophysicist at the Harvard-Smithsonian Center for Astrophysics (CfA) and the Max Planck Institute for Astronomy (MPIA). .

He was joined by researchers from CfA, MPIA, Caltech, UC Berkeley, Flatiron Institute Center for Computational Astrophysics (CCA), Weizmann Institute of Science, Paris Observatory, MIT’s Kavli Institute for Astrophysics. and space research, as well as at several universities.

A paper describing their results will be published in the Monthly Notices of the Royal Astronomical Society .

As El Badri explained to Universe Today via email, these sightings were part of a larger campaign to identify b. ordinary stars in the Milky Way galaxy do not have companion holes.

“For the past four years, I have been searching for dormant black holes using a wide range of datasets and methods,” he said.

“My previous attempts have uncovered a diverse menagerie of binary systems that masquerade as black holes, but this was the first time the search has come to fruition.”

For this study, El-Badri and his colleagues relied on data obtained by the Gaia Observatory of the European Space Agency (ESA). This mission has spent nearly a decade measuring the positions, distances and proper motions of nearly 1 billion astronomical objects such as stars, planets, comets, asteroids and galaxies.

By tracking the movement of objects as they orbit the center of the Milky Way (a technique known as astrometry), the Gaia mission aims to create the most accurate 3D space catalog ever created.

For their purposes, El-Badri and colleagues studied all 168,065 stars in the Gaia 3 data release (GDR3) that appear to have two-body orbits.

Their analysis found a particularly promising candidate, a G-type (yellow star) designated Gaia DR3 4373465352415301632 – because of their goals, the team designated it Gaia BH1. Based on the observed orbital solution, El-Badri and his colleagues determined that this star must have a binary companion black hole.

El-Badri said: “The Gaia data limits the movement of the star across the sky, tracking the ellipse as it orbits the black hole. The size of the orbit and its period give us a limit on the mass of the invisible companion – about 10 solar masses.

“To confirm that the Gaia solution is correct and rules out alternatives other than black holes, we observed the star spectroscopically with several other telescopes. This tightened our limits on the mass of the companion and proved that it is indeed “dark”.

To confirm their observations, the team analyzed Gaia BH1’s radial velocity measurements from multiple telescopes.

>This included the WM Keck Observatory High Resolution Echelle Spectrometer (HIRES), the MPG/ESO Extended Range Optical Spectrograph (FEROS), the Very Large Telescope (VLT) X-Shooter Spectrograph, Multi-Object Gemini. Spectrographs (GMOS), Magellan Echellette Spectrograph (MagE), and the Large Sky Multi-Object Fiber Optic Telescope (LAMOST).

Similar to the technique used to search for exoplanets (Doppler spectroscopy), the spectra of these instruments allowed the team to observe and measure the gravitational forces affecting its orbit. These subsequent observations confirmed the orbital solution of Gaia BH1 and that a satellite of about 10 solar masses is in the same orbit as it.

As an El Badri indica, these findings may therefore represent the first black hole in the Milky Way that has not been observed based on its X-ray emission or other energetic releases:

“Models predict that the Milky Way contains about 100 million black holes. . But we only observed about 20 of them. All of the previous ones we’ve seen are “X-ray doubles”: a black hole engulfs a companion star and glows brightly in X-rays as the material’s gravitational potential energy is converted into light.

“But this is just the tip of the iceberg: there could be a much larger population hidden in more distant binary systems. The discovery of Gaia BH1 sheds light on this population.”

If confirmed, these results could mean that there is a large population of dormant black holes in the Milky Way. This refers to black holes that are not visible from bright disks, bursts of radiation, or ultra-velocity jets emanating from their poles (as is often the case with quasars).

If these objects are ubiquitous in our galaxy, the implications for stellar and galactic evolution could be profound. However, it is possible that this particular dormant black hole is an outlier and does not indicate a large population.

To confirm their findings, El-Badri and colleagues are looking forward to the release of the Gaia 4 (GDR) data. 4), whose date is yet to be determined and which will include all data collected during the five-year nominal mission (GDR 4).

This release will include the latest astrometric, photometric, and radial velocity catalogs for all observed stars, binary systems, galaxies, and exoplanets.

The fifth and final release (GDR 5) will include nominal and extended mission data (full 10 years).

“Based on the frequency of BH companions predicted by Gaia BH1, we estimate that the next release of Gaia data will detect dozens of such systems,” El-Badri said.

“It’s hard to tell from one object exactly what it says about the population (it may just be an oddity, an accident). We are excited about the population demographic studies that we will be able to do with larger samples.”

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