Earth-wide telescope confirms black hole’s shadow is ‘real’
- February 13, 2024
- Posted by: OptimizeIAS Team
- Category: DPN Topics
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Earth-wide telescope confirms black hole’s shadow is ‘real’
Subject: Science and tech
Section: Space tech
Imaging the black hole:
- Scientists have made significant advancements in our understanding of black holes, particularly one located 53 million light-years away, which was first imaged in 2017 by the Event Horizon Telescope (EHT). This imaging feat was groundbreaking as it provided the first visual confirmation of black holes’ existence, supporting a key aspect of general relativity.
Detailed analysis of Black hole’s image:
- Recent enhancements in the EHT’s capabilities have allowed researchers to observe finer details near the black hole’s event horizon, the point beyond which light cannot escape. These observations revealed a distinct ring formation around the event horizon.
- The initial EHT observations had identified the black hole’s “shadow” – an area shaped by the gravitational effects of the event horizon and a critical indicator of the black hole’s presence.
- This evidence was not only a source of amazement but also served to validate the mass, size, and shape of the black hole against predictions made by general relativity.
- The latest findings, resulting from improved telescope resolution and coverage, have reaffirmed the dimensions and characteristics of the black hole’s shadow.
- This outcome helps to assure scientists that their observations are not skewed by biases, further enhancing our comprehension of these mysterious cosmic entities.
Event Horizon Telescope (EHT):
- The Event Horizon Telescope (EHT) is a global network of 8 radio telescopes that collaborate to observe celestial bodies, utilizing a method known as very-long baseline interferometry. The 8 radio telescopes are:
- Atacama Large Millimetre/sub-millimetre Array,
- Atacama Pathfinder Experiment,
- IRAM 30-metre telescope,
- James Clerk Maxwell telescope,
- Large Millimetre Telescope Alfonso Serrano,
- Submillimetre Array,
- UArizona Submillimetre Telescope and
- South Pole Telescope.
- This technique involves synchronizing the data collected from various telescopes using highly accurate clocks to study specific objects in space.
- The resolution of the network is determined by the maximum distance between these telescopes.
- In 2017, the EHT made a significant discovery, detecting a bright, asymmetric ring of light that aligns with the expected characteristics of a supermassive black hole, a finding further corroborated by independent analyses of EHT data.
- Following these observations, efforts were made to enhance the EHT’s capabilities. These improvements included increasing the rate at which data is recorded, enhancing the ability to capture spatial information, and incorporating the Greenland Telescope into the array.
- The addition of the Greenland Telescope notably enhanced the EHT’s resolution in the north-south direction.
Piecing the data together:
- In a recent observational campaign, the Event Horizon Telescope (EHT) involved nine stations to collect data over six days in April 2018, utilizing four different frequencies.
- To delve deeper into the phenomena observed, the research team employed general relativistic magnetohydrodynamic (GRMHD) simulations to model the M87 black hole, taking into account the influence of the black hole’s gravity on the surrounding spacetime, in line with Einstein’s theory of general relativity.
Gravitational lensing:
- The recent findings from the Event Horizon Telescope (EHT) have confirmed the presence of an asymmetric ring structure around a black hole, measuring approximately 42 microarc seconds across.
- Observations made in 2017 and 2018 showed that the diameter of this ring remained relatively constant, demonstrating that the black hole’s gravity consistently bends light over time, forming the observed ring.
- This behaviour is a direct manifestation of gravitational lensing, a phenomenon predicted by the general theory of relativity, where massive objects cause spacetime to bend, affecting the path of light passing near them.
Significance of observations made by EHT:
- The EHT observations revealed that the southwest portion of the ring appears brighter, which is attributed to the black hole’s rotation affecting the distribution of light due to spacetime being dragged along its rotation direction.
- These observations align with the characteristics expected of a Kerr (rotating) black hole, with a mass about 6.5 billion times that of the Sun.
- Additionally, the study noted a shift in the orientation or position of the black hole’s accretion disk and the jet of high-energy particles it emits by approximately 30 degrees between 2017 and 2018.
- This change is speculated to be related to the black hole’s spin and has implications for understanding the complex dynamics between the accretion disk, the jet, and the surrounding magnetic fields.
- The EHT’s efforts have consistently validated the ring formation process and the black hole’s physical traits across different observations and frequencies.
- The project has also demonstrated improvements in observational techniques, narrowing the gap between image-based studies and direct modelling methods.
- Looking ahead, the EHT team plans a “movie project” in 2026 to observe changes in the black hole’s brightness over a period, offering further insights into the dynamics of black holes and the physics governing their surrounding environments.
Source: TH