소용돌이치는 가스는 과학자들이 우리 은하의 초거대 블랙홀 질량을 확정하는 것을 돕습니다

밝은 전자기 복사 섬광은 궁수자리 A*를 측정하는 척도 역할을 합니다.

 

 

2022년 5월 12일 사건지평선망원경에 의해 밝혀진 거대한 '궁수자리 A*'라는 이름을 가진 우리 은하 중심의 초거대 블랙홀의 이미지. (이미지 크레딧: 사건지평선망원경 공동작업)

우리 은하의 중심에는 궁수자리 A*라는 이름의 초거대 블랙홀인 어두운 수수께끼가 있습니다. 천문학자들은 한동안 Sgr A*의 존재에 대해 알고 있었고, 심지어 2022년에 그것의 장관을 이뤘지만, 그것의 크기와 활동에 대한 정확한 측정을 하는 것은 어려운 것으로 증명되었습니다.

이제 막스 플랑크 외계 물리학 연구소(MPE)의 새로운 발견에 따르면, 한 무리의 천문학자들이 높은 정확도로 Sgr A*의 질량과 반지름을 결정했습니다. 

구체적으로, Sgr A*는 금성이 태양 주위를 도는 궤도의 반지름보다 작은 반경으로 429만 7천 태양질량으로 아주 큰 것으로 밝혀졌습니다. 그 팀은 이 거대한 공극의 궤도에서 발견되는 발광 가스를 연구함으로써 이 정보를 추론했습니다.

 

At the center of our galaxy sits a dark enigma, a supermassive black hole named Sagittarius A*. Astronomers have known about the existence of Sgr A* for some time, and even snagged a spectacular image of it in 2022, but getting exact measurements of its size and activity has proven difficult.

Now, according to new findings from the Max Planck Institute for Extraterrestrial Physics (MPE), a group of astronomers has determined, with high accuracy, the mass and radius of Sgr A*. 

Specifically, Sgr A* was found to come in at a whooping 4.297 million solar masses — with a radius smaller than that of Venus' orbit around the sun. The team deduced this information by studying the luminous gas found in this enormous void's orbit. 

 

기본적으로, 연구자들은 블랙홀 주위에서 소용돌이치는 가스의 전자기 방출을 추적하기 위해 유럽 남방 천문대의 초거대 망원경 간섭계(VLTI)의 근적외선 간섭계의 데이터를 사용했습니다. 그들은 하루에 한두 번 일어날 수 있는 전자기 방사선의 밝은 섬광인 플레어를 찾고 있었습니다. 간단히 말해서, 이 플레어들은 천문학자들이 Sgr A*를 둘러싼 가스의 움직임을 추적할 수 있도록 해주었습니다. 

관련: 지구에서 두 번째로 가까운 괴물 블랙홀을 위해 이웃 은하계에서 사냥이 진행되고 있습니다.

 

Basically, the researchers used data from the near-infrared interferometer at the European Southern Observatory's Very Large Telescope Interferometer (VLTI) to track electromagnetic emissions of gas swirling around the black hole. They were on the lookout for flares — bright flashes of electromagnetic radiation that might happen once or twice a day. These flares, in short, allowed the astronomers to trace the motion of gas surrounding Sgr A*. 

Related: The hunt is on in neighboring galaxy for 2nd closest monster black hole to Earth

 

 

이 팀은 2018년, 2021년 및 2022년에 관찰된 플레어를 분석했습니다. 그들은 이 결합된 데이터를 통해 연구원들이 높은 수준의 정확도로 블랙홀의 질량을 추정할 수 있었으며, 이는 블랙홀의 질량에 대한 새롭고 독립적인 측정을 제공하기 때문에 중요하다고 말합니다. 감사하게도, 결과는 이전의 추정치에 부합했습니다. 

이러한 이전 측정은 Sgr. A* 주변의 별들의 궤도 궤적을 기반으로 했지만 문제는 이러한 별들이 새로 측정된 플레어보다 훨씬 더 멀리 떨어져 있다는 사실이었습니다. 따라서 이러한 이전 결과는 기술적으로 신뢰성이 떨어졌습니다. 

연구자들은 그들이 어떻게 Sgr. A*의 질량을 계산했는지를 논의할 때 "중력 반지름"이라고 알려진 것을 언급합니다. 물체의 중력 반지름 값은 물체의 반지름 거리와 관련이 있습니다; 그것은 물체의 질량에 비례해야 합니다. Sgr. A*의 경우, 반지름은 블랙홀의 중심에서 사건의 지평선까지의 거리를 나타냅니다. 사건의 지평선 너머에서는 빛조차 블랙홀의 엄청난 중력에 의해 추월됩니다. 

Sgr A*의 중력 반지름은 대략 0.1 천문단위, 즉 지구에서 태양까지의 거리의 10분의 1에 해당하는 것으로 밝혀졌습니다. 이것은 작게 들릴지 모르지만, 태양의 중력 반지름이 약 3킬로미터(1.9마일)와 같기 때문에 실제로는 비교적 큽니다. 이것은 또한 태양이 블랙홀로 붕괴되기 전까지 압축되어야 하는 크기입니다. 

맥스 플랑크 외계 물리학 연구소에서 이 연구의 이론적 모델링을 담당한 디오고 리베이로는 성명에서 "우리가 지금 유도한 질량은 수천 개의 중력 반경에서 별들의 궤도들로부터 측정된 값과 일치한다"고 말했습니다. 

"이것은 우리 은하의 중심에 있는 하나의 블랙홀에 대한 사례를 강화시킵니다," 라고 그가 덧붙였습니다.

 

The team analyzed flares observed in 2018, 2021 and 2022. This combined data allowed the researchers to estimate the mass of the black hole with a high level of accuracy, they say, which is important because it provides a new, independent measurement of the black hole's mass. Thankfully, the results sat in accordance with previous estimates. 

Those prior measurements were based on the orbital trajectories of stars around Sgr. A*, but the issue was the fact that those stars are much further away than the newly measured flares appear to be. Thus, those previous results were technically less reliable. 

The researchers refer to what's known as  "gravitational radii" when discussing how they calculated the mass of Sgr. A*. The gravitational radii value of an object has to do with the radial distance of the object; it also must be proportional to that object's mass. For Sgr. A*, the radii represents the distance from the center of the black hole to the event horizon, which is the barrier between our universe and whatever's inside the black hole. Beyond the event horizon, even light gets overtaken by the black hole's immense gravitational strength. 

The gravitational radii of Sgr A* turned out to be equal to roughly 0.1 astronomical units, or one tenth the distance from the Earth to the sun. While this might sound small, it's actually relatively large, as the sun's gravitational radii value is equal to approximately 3 kilometers (1.9 miles). This is also the size the sun would need to be compressed to before it can collapse into a black hole. 

''The mass we derived now from the flares at just a few gravitational radii is compatible with the value measured from the orbits of stars at several thousand gravitational radii,'' Diogo Ribeiro, who was responsible for the study's theoretical modeling at the Max Planck Institute for Extraterrestrial Physics, said in a statement. 

"This strengthens the case for a single black hole at the center of the Milky Way," he adds.

 

연구원들은 또한 이러한 측정치들이 은하 중심부의 구조물들의 형성과 관련하여 어떤 보물들을 포함하고 있을지에 대해 흥분하고 있습니다. 연구 측정에 또한 참여했던 Antonia Drescher에 따르면, 플레어들의 궤도들의 방향은 블랙홀로부터 훨씬 멀리 떨어져 있는 항성 원반과의 물리적인 연관성을 암시한다고 합니다. 

"플레어의 반복적이고 유사한 행동을 보는 것은 멋진 일입니다," 라고 드레셔가 성명서에서 말했습니다. "모두 하늘에서 시계 방향으로 고리를 그리며 움직이는 것을 보여줍니다. 모두 반경이 비슷하고 궤도 주기가 비슷합니다. 보기에 정말 아름답습니다."

연구팀은 플레어로부터 수집된 데이터가 결국 과학계에 블랙홀의 회전에 대한 정보를 제공할 수 있기를 바라고 있는데, 이는 미스터리로 남아 있습니다. 

이러한 연구 결과에 대한 연구는 9월에 Astronomy & Astrophysics 저널에 발표되었습니다. 

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Researchers are also excited about what treasures these measurements might contain regarding the formation of structures in the Galactic Center. According to Antonia Drescher, who was also involved in the study measurements, the orientation of the flares' orbits hint at a physical connection with a stellar disk sitting much further away from the black hole. 

''It is great to see the repeated, similar behavior of the flares,'' Drescher said in the statement. ''All of them show a clockwise looped motion on the sky; all have a similar radius and a similar orbital period. This is really beautiful to see."

The team hopes data collected from the flares may eventually provide the scientific community with information on the spin of the black hole too, something that remains a mystery. 

A study on these findings was published in September in the journal Astronomy & Astrophysics. 

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