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       What's next for the Event Horizon Telescope? Twelve possible new
       targets
        
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       Image of a black hole event horizon. Credit: EHT
        
       Both the Milky Way and a galaxy known as M87 have supermassive black
       holes at their core. These are the two largest black holes we know
       about and the Event Horizon Telescope has just captured stunning
       images of their event horizons. A new paper looks at what we might
       expect from a next generation EHT and highlights twelve targets that
       should be top of the list.
        
       The Event Horizon Telescope (EHT) is an international collaboration
       that uses a global network of radio telescopes. Connecting multiple
       telescopes together in a technique known as interferometry enables
       them all to work together, forming one massive virtual telescope the
       size of the distance between them. In April 2019, the EHT achieved a
       historic milestone by capturing the first-ever image of a black hole,
       located at the center of the galaxy M87.
        
       Black holes like that in M87 are most definitely the target of the
       EHT. They are regions in space with such strong gravitational forces
       that nothing, not even light, can escape. They are formed from the
       remnants of massive stars that collapse under their own gravity,
       creating an object known as a singularity which has infinite density.
       Surrounding the singularity is the event horizon, beyond which no
       information or matter can return and it is this which is of particular
       interest to EHT.
        
       Several extensions to the array are planned to enhance the quality of
       images. Doing so will improve its resolution, allowing for a larger
       number of black holes to be studied. Theoretical studies of EHT images
       of both Sgr A at the center of our galaxy and the black hole at the
       center of M87 favor models with dynamically significant magnetic
       fields.
        
       Magnetically arrested disk (MAD) models, which power jet mechanisms,
       have important implications for the relationship between supermassive
       black holes and the evolution of its host galaxy. The extensions
       require new dishes to be added to the infrastructure and many existing
       telescopes require upgrades. On completion, simultaneous observations
       in the frequency range 86-230-345 GHz will be possible, facilitating
       new studies.
        
       In the paper authored by Xinyue Alice Zhang from the Center for
       Astrophysics at the Harvard & Smithsonian, the team reports on their
       attempt to study the 12 most promising supermassive black hole targets
       for the EHT. The study is available on the _arXiv_ preprint server.
        
       The targets were selected following an exhaustive analysis that
       started off with the ETHER database, a list of 3.8 million sources.
       This was then narrowed down to those with a flux density (signal
       strength) that allowed mass measurements to be taken optically. A fair
       chunk of this was done by hand. Further sources with large angular
       sizes are being constantly added to the database so the number of
       possible targets will rise in time.
        
       The target galaxies identified to date include; IC1459,
       NGC45elliptical94, NGC3998, NGC4261, NGC2663, NGC3894, M84, NGC4552,
       3C 317, NGC315, NGC1218 and NGC5077. These are all suitable for future
       EHT targets but they all exhibit some similarities. For example, many
       of them are elliptical galaxies but a few are classed as lenticular
       galaxies.
        
       **More information:** Xinyue Alice Zhang et al, Accessing a New
       Population of Supermassive Black Holes with Extensions to the Event
       Horizon Telescope, _arXiv_ (2024). DOI: 10.48550/arxiv.2406.17754
        
       **Journal information:** arXiv
        
       **Citation** : What's next for the Event Horizon Telescope? Twelve
       possible new targets (2024, July 1) retrieved 3 July 2024 from
       https://phys.org/news/2024-07-event-horizon-telescope-twelve.html
        
       This document is subject to copyright. Apart from any fair dealing for
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       without the written permission. The content is provided for
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