Event Horizon Telescope

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Event Horizon Telescope
Event Horizon Telescope.svg
Alternative namesEHT  OOjs UI icon edit-ltr-progressive.svg
Established2009;15 years ago (2009)
Website eventhorizontelescope.org OOjs UI icon edit-ltr-progressive.svg
Telescopes
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The Event Horizon Telescope (EHT) is a telescope array consisting of a global network of radio telescopes. The EHT project combines data from several very-long-baseline interferometry (VLBI) stations around Earth, which form a combined array with an angular resolution sufficient to observe objects the size of a supermassive black hole's event horizon. The project's observational targets include the two black holes with the largest angular diameter as observed from Earth: the black hole at the center of the supergiant elliptical galaxy Messier 87, and Sagittarius A*, at the center of the Milky Way. [1] [2]

Contents

The Event Horizon Telescope project is an international collaboration that was launched in 2009 [1] after a long period of theoretical and technical developments. On the theory side, work on the photon orbit [3] and first simulations of what a black hole would look like [4] progressed to predictions of VLBI imaging for the Galactic Center black hole, Sgr A*. [5] [6] Technical advances in radio observing moved from the first detection of Sgr A*, [7] through VLBI at progressively shorter wavelengths, ultimately leading to detection of horizon scale structure in both Sgr A* and M87. [8] [9] The collaboration now comprises over 300 [10] members, and 60 institutions, working in over 20 countries and regions. [11]

The first image of a black hole, at the center of galaxy Messier 87, was published by the EHT Collaboration on April 10, 2019, in a series of six scientific publications. [12] The array made this observation at a wavelength of 1.3 mm and with a theoretical diffraction-limited resolution of 25 microarcseconds . In March 2021, the Collaboration presented, for the first time, a polarized-based image of the black hole which may help better reveal the forces giving rise to quasars. [13] Future plans involve improving the array's resolution by adding new telescopes and by taking shorter-wavelength observations. [2] [14] On 12 May 2022, astronomers unveiled the first image of the supermassive black hole at the center of the Milky Way, Sagittarius A*. [15] Recently EHT Project has reported to have reached the resolution of 870 μm at 345 GHz, that is pair to 19 μas, the best angular resolution at astronomical facilities on Earth. [16]

Telescope array

A schematic diagram of the VLBI mechanism of EHT. Each antenna, spread out over vast distances, has an extremely precise atomic clock. Analogue signals collected by the antenna are converted to digital signals and stored on hard drives together with the time signals provided by the atomic clock. The hard drives are then shipped to a central location to be synchronized. An astronomical observation image is obtained by processing the data gathered from multiple locations. EHT-infography.png
A schematic diagram of the VLBI mechanism of EHT. Each antenna, spread out over vast distances, has an extremely precise atomic clock. Analogue signals collected by the antenna are converted to digital signals and stored on hard drives together with the time signals provided by the atomic clock. The hard drives are then shipped to a central location to be synchronized. An astronomical observation image is obtained by processing the data gathered from multiple locations.
EHT observations during its 2017 M87 multiwavelength campaign decomposed by instrument from lower (EHT/ALMA/SMA) to higher (VERITAS) frequency. (Fermi-LAT in continuous survey mode) (dates also in Modified Julian days) EHTobservations2017.jpg
EHT observations during its 2017 M87 multiwavelength campaign decomposed by instrument from lower (EHT/ALMA/SMA) to higher (VERITAS) frequency. (Fermi-LAT in continuous survey mode) (dates also in Modified Julian days)
Soft X-ray image of Sagittarius A* (center) and two light echoes from a recent explosion (circled) Sagittarius A*.jpg
Soft X-ray image of Sagittarius A* (center) and two light echoes from a recent explosion (circled)

The EHT is composed of many radio observatories or radio-telescope facilities around the world, working together to produce a high-sensitivity, high-angular-resolution telescope. Through the technique of very-long-baseline interferometry (VLBI), many independent radio antennas separated by hundreds or thousands of kilometres can act as a phased array, a virtual telescope which can be pointed electronically, with an effective aperture which is the diameter of the entire planet, substantially improving its angular resolution. [17] The effort includes development and deployment of submillimeter dual polarization receivers, highly stable frequency standards to enable very-long-baseline interferometry at 230–450 GHz, higher-bandwidth VLBI backends and recorders, as well as commissioning of new submillimeter VLBI sites. [18]

Each year since its first data capture in 2006, the EHT array has moved to add more observatories to its global network of radio telescopes. The first image of the Milky Way's supermassive black hole, Sagittarius A*, was expected to be produced from data taken in April 2017, [19] [20] but because there are no flights in or out of the South Pole during austral winter (April to October), the full data set could not be processed until December 2017, when the shipment of data from the South Pole Telescope arrived. [21]

Data collected on hard drives are transported by commercial freight airplanes [22] (a so-called sneakernet) from the various telescopes to the MIT Haystack Observatory and the Max Planck Institute for Radio Astronomy, where the data are cross-correlated and analyzed on a grid computer made from about 800 CPUs all connected through a 40 Gbit/s network. [23]

Because of the COVID-19 pandemic, weather patterns, and celestial mechanics, the 2020 observational campaign was postponed to March 2021. [24]

Published images

Messier 87*

A series of images descriptive of the level of magnification achieved by the EHT (akin to seeing, from the Earth's surface, an object the size of a tennis ball on the Moon); starts at top-left image and moves counter-clockwise to finish at top-right corner Event Horizon Telescope and Apollo 16.png
A series of images descriptive of the level of magnification achieved by the EHT (akin to seeing, from the Earth's surface, an object the size of a tennis ball on the Moon); starts at top-left image and moves counter−clockwise to finish at top-right corner
Image of M87* generated from data gathered by the Event Horizon Telescope Black hole - Messier 87 crop max res.jpg
Image of M87* generated from data gathered by the Event Horizon Telescope
A view of M87* black hole in polarised light A view of the M87 supermassive black hole in polarised light.tif
A view of M87* black hole in polarised light

The Event Horizon Telescope Collaboration announced its first results in six simultaneous press conferences worldwide on April 10, 2019. [25] [26] [27] The announcement featured the first direct image of a black hole, which showed the supermassive black hole at the center of Messier 87, designated M87*. [2] [28] [29] The scientific results were presented in a series of six papers published in The Astrophysical Journal Letters . [30] A clockwise rotating black hole was observed in the 6σ region. [31]

The image provided a test for Albert Einstein's general theory of relativity under extreme conditions. [17] [20] Studies have previously tested general relativity by looking at the motions of stars and gas clouds near the edge of a black hole. However, an image of a black hole brings observations even closer to the event horizon. [32] Relativity predicts a dark shadow-like region, caused by gravitational bending and capture of light, [5] [6] which matches the observed image. The published paper states: "Overall, the observed image is consistent with expectations for the shadow of a spinning Kerr black hole as predicted by general relativity." [33] Paul T.P. Ho, EHT Board member, said: "Once we were sure we had imaged the shadow, we could compare our observations to extensive computer models that include the physics of warped space, superheated matter, and strong magnetic fields. Many of the features of the observed image match our theoretical understanding surprisingly well." [30]

The image also provided new measurements for the mass and diameter of M87*. EHT measured the black hole's mass to be 6.5±0.7 billion solar masses and measured the diameter of its event horizon to be approximately 40 billion kilometres (270 AU; 0.0013 pc; 0.0042 ly), roughly 2.5 times smaller than the shadow that it casts, seen at the center of the image. [30] [32] Previous observations of M87 showed that the large-scale jet is inclined at an angle of 17° relative to the observer's line of sight and oriented on the plane of the sky at a position angle of −72°. [2] [34] From the enhanced brightness of the southern part of the ring due to relativistic beaming of approaching funnel wall jet emission, EHT concluded the black hole, which anchors the jet, spins clockwise, as seen from Earth. [2] [14] EHT simulations allow for both prograde and retrograde inner disk rotation with respect to the black hole, while excluding zero black hole spin using a conservative minimum jet power of 1042 erg/s via the Blandford–Znajek process. [2] [35]

Producing an image from data from an array of radio telescopes requires much mathematical work. Four independent teams created images to assess the reliability of the results. [36] These methods included both an established algorithm in radio astronomy for image reconstruction known as CLEAN, invented by Jan Högbom, [37] as well as self-calibrating image processing methods [38] for astronomy such as the CHIRP algorithm created by Katherine Bouman and others. [36] [39] The algorithms that were ultimately used were a regularized maximum likelihood (RML) [40] algorithm and the CLEAN algorithm. [36]

In March 2020, astronomers proposed an improved way of seeing more of the rings in the first black hole image. [41] [42] In March 2021, a new photo was revealed, showing how the M87 black hole looks in polarised light. This is the first time astronomers have been able to measure polarisation so close to the edge of a black hole. The lines on the photo mark the orientation of polarisation, which is related to the magnetic field around the shadow of the black hole. [43]

In August 2022, a team led by University of Waterloo researcher Avery Broderick released a "remaster[ed]" version of original image generated from the data collected by the EHT. This image "resolve[d] a fundamental signature of gravity around a black hole," with it showing a displaying photon ring around M87* [44] [45] .The claim has been subsequently disputed. [46]

In 2023, EHT released new, sharper images of the M87 black hole, reconstructed from the same 2017 data but created using the PRIMO algorithm. [47]

3C 279

EHT image of the archetypal blazar 3C 279 showing a relativistic jet down to the AGN core surrounding the supermassive black hole. EHT3C279PressReleaseImage.png
EHT image of the archetypal blazar 3C 279 showing a relativistic jet down to the AGN core surrounding the supermassive black hole.

In April 2020, the EHT released the first 20 microarcsecond resolution images of the archetypal blazar 3C 279 it observed in April 2017. [48] These images, generated from observations over 4 nights in April 2017, reveal bright components of a jet whose projection on the observer plane exhibit apparent superluminal motions with speeds up to 20 c. [49] Such apparent superluminal motion from relativistic emitters such as an approaching jet is explained by emission originating closer to the observer (downstream along the jet) catching up with emission originating further from the observer (at the jet base) as the jet propagates close to the speed of light at small angles to the line of sight.

Centaurus A

Image of Centaurus A showing its black hole jet at different scales EHTcentaurusA2021.jpg
Image of Centaurus A showing its black hole jet at different scales

In July 2021, high resolution images of the jet produced by the supermassive black hole sitting at the center of Centaurus A were released. With a mass around 5.5×107  M☉, the black hole is not large enough for its photon sphere to be observed, as in EHT images of Messier M87*, but its jet extends even beyond its host galaxy while staying as a highly collimated beam which is a point of study. Edge-brightening of the jet was also observed which would exclude models of particle acceleration that are unable to reproduce this effect. The image was 16 times sharper than previous observations and utilized a 1.3 mm wavelength. [50] [51] [52]

Sagittarius A*

EHT Saggitarius A black hole.tif
Sagittarius A*, first image released in 2022
Sagittarius Astar in polarised light.tif
Sagittarius A* in polarised light, image released in 2024

On May 12, 2022, the EHT Collaboration revealed an image of Sagittarius A*, the supermassive black hole at the center of the Milky Way galaxy. The black hole is 27,000 light-years away from Earth; it is thousands of times smaller than M87*. Sera Markoff, Co-Chair of the EHT Science Council, said: "We have two completely different types of galaxies and two very different black hole masses, but close to the edge of these black holes they look amazingly similar. This tells us that General Relativity governs these objects up close, and any differences we see further away must be due to differences in the material that surrounds the black holes." [53]

On March 22, 2024, the EHT Collaboration released an image of Sagittarius A* in polarized light. [54]

J1924-2914

A multifrequency view of the bent jet in Blazar J1924-2914. EHTj1924-2914.png
A multifrequency view of the bent jet in Blazar J1924-2914.

In August 2022, the EHT together with Global Millimeter VLBI Array and the Very Long Baseline Array imaged the distant blazar J1924-2914. They operated at 230 GHz, 86 GHz and 2.3+8.7 GHz, respectively, the highest angular resolution images of polarized emission from a quasar ever obtained. Observations reveal a helically bent jet and the polarization of its emission suggest a toroidal magnetic field structure. The object is used as calibrator for Sagittarius A* sharing strong optical variability and polarization with it. [55] [56]

NRAO 530

NRAO 530 by EHT. The total intensity is shown in grayscale with black contours indicating 10%, 25%, 50%, and 75% of the peak LP intensity. Black dotted contours indicate 25%, 50%, and 75% of the peak polarized intensity. NRAO 530 by EHT 01.jpg
NRAO 530 by EHT. The total intensity is shown in grayscale with black contours indicating 10%, 25%, 50%, and 75% of the peak LP intensity. Black dotted contours indicate 25%, 50%, and 75% of the peak polarized intensity.
Schematic of the total-intensity and LP components in the EHT fiducial image of NRAO 530; white contours show the total intensity levels; color scale and cyan contours represent the polarized intensity of the method-averaged image. NRAO 530 by EHT 02.jpg
Schematic of the total-intensity and LP components in the EHT fiducial image of NRAO 530; white contours show the total intensity levels; color scale and cyan contours represent the polarized intensity of the method-averaged image.

In February 2023, the EHT reported on the observations of the quasar NRAO 530. NRAO 530 (1730−130, J1733−1304) is a flat-spectrum radio quasar (FSRQ) that belongs to the class of bright γ-ray blazars and shows significant variability across the entire electromagnetic spectrum. The source was monitored by the University of Michigan Radio Observatory at 4.8, 8.4, and 14.5 GHz for several decades until 2012. The quasar underwent a dramatic radio outburst in 1997, during which its flux density at 14.5 GHz exceeded 10 Jy, while the average value is ~2 Jy. Since 2002, NRAO 530 has been monitored by the Submillimeter Array (SMA; Maunakea, Hawaii) at 1.3 mm and 870 μm. NRAO 530 has a redshift of z = 0.902 (Junkkarinen 1984), for which 100 μas corresponds to a linear distance of 0.803 pc. The source contains a supermassive black hole, the mass of which is currently uncertain, with estimates ranging from 3×108 M☉ to 2×109 M☉. [57]

It was observed with the Event Horizon Telescope on 2017 April 5−7, when NRAO 530 was used as a calibrator for the EHT observations of Sagittarius A*. The observations were performed with the full EHT 2017 array of eight telescopes located at six geographical sites. At z = 0.902, this is the most distant object imaged by the EHT so far. The team reconstructed the first images of the source at 230 GHz, at an angular resolution of ~20 μas, both in total intensity and in linear polarization (LP). Source variability was not detected, that allowed to represent the whole data set with static images. The images reveal a bright feature located on the southern end of the jet, which was associated with the core. The feature is linearly polarized, with a fractional polarization of ~5%–8%, and it has a substructure consisting of two components. Their observed brightness temperature suggests that the energy density of the jet is dominated by the magnetic field. The jet extends over 60 μas along a position angle ~ −28°. It includes two features with orthogonal directions of polarization (electric vector position angle), parallel and perpendicular to the jet axis, consistent with a helical structure of the magnetic field in the jet. The outermost feature has a particularly high degree of LP, suggestive of a nearly uniform magnetic field. [57]

Collaborating institutes

The EHT Collaboration consists of 13 stakeholder institutes: [58]

Locations of the telescopes that make up the EHT array. A global map showing the radio observatories that form the Event Horizon Telescope (EHT) network used to image the Milky Way's central black hole, Sagittarius A*. The telescopes highlighted in yellow were part of the EHT network during the observations of Sagittarius A* in 2017. These include the Atacama Large Millimeter/submillimeter Array (ALMA), the Atacama Pathfinder EXperiment (APEX), IRAM 30-meter telescope (30-M), James Clark Maxwell Telescope (JCMT), Large Millimeter Telescope (LMT), Submillimeter Array (SMA), Submillimetere Telescope (SMT) and South Pole Telescope (SPT). Highlighted in blue are the three telescopes added to the EHT Collaboration after 2018: the Greenland Telescope (GLT), the NOrthern Extended Millimeter Array (NOEMA) in France, and the UArizona ARO 12-meter Telescope at (Kitt Peak}. Locations of the telescopes that make up the EHT array (eso2208-eht-mwi).tiff
Locations of the telescopes that make up the EHT array. A global map showing the radio observatories that form the Event Horizon Telescope (EHT) network used to image the Milky Way’s central black hole, Sagittarius A*. The telescopes highlighted in yellow were part of the EHT network during the observations of Sagittarius A* in 2017. These include the Atacama Large Millimeter/submillimeter Array (ALMA), the Atacama Pathfinder EXperiment (APEX), IRAM 30-meter telescope (30-M), James Clark Maxwell Telescope (JCMT), Large Millimeter Telescope (LMT), Submillimeter Array (SMA), Submillimetere Telescope (SMT) and South Pole Telescope (SPT). Highlighted in blue are the three telescopes added to the EHT Collaboration after 2018: the Greenland Telescope (GLT), the NOrthern Extended Millimeter Array (NOEMA) in France, and the UArizona ARO 12-meter Telescope at (Kitt Peak}.

Funding

The EHT Collaboration receives funding from numerous sources including: [59]

Additionally, Western Digital and Xilinx are industry donors. [60]

Related Research Articles

<span class="mw-page-title-main">Quasar</span> Active galactic nucleus containing a supermassive black hole

A quasar is an extremely luminous active galactic nucleus (AGN). It is sometimes known as a quasi-stellar object, abbreviated QSO. The emission from an AGN is powered by a supermassive black hole with a mass ranging from millions to tens of billions of solar masses, surrounded by a gaseous accretion disc. Gas in the disc falling towards the black hole heats up and releases energy in the form of electromagnetic radiation. The radiant energy of quasars is enormous; the most powerful quasars have luminosities thousands of times greater than that of a galaxy such as the Milky Way. Quasars are usually categorized as a subclass of the more general category of AGN. The redshifts of quasars are of cosmological origin.

<span class="mw-page-title-main">Messier 87</span> Elliptical galaxy in the Virgo Galaxy Cluster

Messier 87 is a supergiant elliptical galaxy in the constellation Virgo that contains several trillion stars. One of the largest and most massive galaxies in the local universe, it has a large population of globular clusters—about 15,000 compared with the 150–200 orbiting the Milky Way—and a jet of energetic plasma that originates at the core and extends at least 1,500 parsecs, traveling at a relativistic speed. It is one of the brightest radio sources in the sky and a popular target for both amateur and professional astronomers.

<span class="mw-page-title-main">Very-long-baseline interferometry</span> Comparing widely separated telescope wavefronts

Very-long-baseline interferometry (VLBI) is a type of astronomical interferometry used in radio astronomy. In VLBI a signal from an astronomical radio source, such as a quasar, is collected at multiple radio telescopes on Earth or in space. The distance between the radio telescopes is then calculated using the time difference between the arrivals of the radio signal at different telescopes. This allows observations of an object that are made simultaneously by many radio telescopes to be combined, emulating a telescope with a size equal to the maximum separation between the telescopes.

<span class="mw-page-title-main">Supermassive black hole</span> Largest type of black hole

A supermassive black hole is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions, of times the mass of the Sun (M☉). Black holes are a class of astronomical objects that have undergone gravitational collapse, leaving behind spheroidal regions of space from which nothing can escape, including light. Observational evidence indicates that almost every large galaxy has a supermassive black hole at its center. For example, the Milky Way galaxy has a supermassive black hole at its center, corresponding to the radio source Sagittarius A*. Accretion of interstellar gas onto supermassive black holes is the process responsible for powering active galactic nuclei (AGNs) and quasars.

<span class="mw-page-title-main">3C 279</span> Optically violent variable quasar in the constellation Virgo

3C 279 is an optically violent variable quasar (OVV), which is known in the astronomical community for its variations in the visible, radio and x-ray bands. The quasar was observed to have undergone a period of extreme activity from 1987 until 1991. The Rosemary Hill Observatory (RHO) started observing 3C 279 in 1971, the object was further observed by the Compton Gamma Ray Observatory in 1991, when it was unexpectedly discovered to be one of the brightest gamma ray objects in the sky. It is also one of the brightest and most variable sources in the gamma ray sky monitored by the Fermi Gamma-ray Space Telescope. It was used as a calibrator source for Event Horizon Telescope observations of M87* that resulted in the first image of a black hole.

<span class="mw-page-title-main">Sagittarius A*</span> Supermassive black hole at the center of the Milky Way

Sagittarius A*, abbreviated as Sgr A*, is the supermassive black hole at the Galactic Center of the Milky Way. Viewed from Earth, it is located near the border of the constellations Sagittarius and Scorpius, about 5.6° south of the ecliptic, visually close to the Butterfly Cluster (M6) and Lambda Scorpii.

<span class="mw-page-title-main">Paolo Padovani</span> Italian astronomer

Paolo Padovani is an Italian astronomer working at the European Southern Observatory, specializing in the study of Active galactic nuclei including the study of quasars and blazars, evolution and multifrequency studies and extragalactic backgrounds. In 2004 he and several other astronomers discovered 30 supermassive blackholes at the European Astrophysical Virtual Observatory using pioneering techniques.

<span class="mw-page-title-main">IRAM 30m telescope</span> Radio telescope in Spain

The IRAM 30m telescope is a radio telescope, located in the Sierra Nevada Mountain Range, Spain. It is operated by the Institute for Radio Astronomy in the Millimetre Range (IRAM) for observing astronomical objects in the millimetre range of the electromagnetic spectrum. With its large surface and wide-angle camera, the telescope is capable of exploring vast cosmic objects. It is one of the largest and most sensitive millimetre wavelength telescopes in the world, serving over 200 astronomers annually. The telescope is primarily used to study interstellar clouds, star nurseries, galaxies, and black hole jets.

The CLEAN algorithm is a computational algorithm to perform a deconvolution on images created in radio astronomy. It was published by Jan Högbom in 1974 and several variations have been proposed since then.

<span class="mw-page-title-main">Heino Falcke</span> German professor of radio astronomy and astroparticle physics

Heino Falcke is a German professor of radio astronomy and astroparticle physics at the Radboud University Nijmegen (Netherlands). His main field of study is black holes, and he is the originator of the concept of the 'black hole shadow'. In 2019, Falcke announced the first Event Horizon Telescope results at the EHT Press Conference in Brussels.

<span class="mw-page-title-main">Greenland Telescope</span> Radio Telescope

The Greenland Telescope is a radio telescope situated at the Thule Air Base in north-western Greenland. It will later be deployed at the Summit Station research camp, located at the highest point of the Greenland ice sheet at an altitude of 3,210 meters.

<span class="mw-page-title-main">CHIRP (algorithm)</span> Algorithm used for image processing

CHIRP is a Bayesian algorithm used to perform a deconvolution on images created in radio astronomy. The acronym was coined by lead author Katherine L. Bouman in 2016.

Jan Arvid Högbom is a Swedish radio astronomer and astrophysicist.

Sheperd "Shep" S. Doeleman is an American astrophysicist. His research focuses on super massive black holes with sufficient resolution to directly observe the event horizon. He is a senior research fellow at the Center for Astrophysics | Harvard & Smithsonian and the Founding Director of the Event Horizon Telescope (EHT) project. He led the international team of researchers that produced the first directly observed image of a black hole.

<span class="mw-page-title-main">Anton Zensus</span> German radio astronomer (born 1958)

Johann Anton Zensus is a German radio astronomer. He is director at the Max Planck Institute for Radio Astronomy (MPIfR) and honorary professor at the University of Cologne. He is chairman of the collaboration board of the Event Horizon Telescope (EHT). The collaboration announced the first image of a black hole in April 2019.

<span class="mw-page-title-main">Ramesh Narayan (astrophysicist)</span> Indian-American theoretical astrophysicist

Ramesh Narayan is an Indian-American theoretical astrophysicist, currently the Thomas Dudley Cabot Professor of the Natural Sciences in the Department of Astronomy at Harvard University. Full member of the National Academy of Sciences, Ramesh Narayan is widely known for his contributions on the theory of black hole accretion processes. He is involved in the Event Horizon Telescope project, which led in 2019 to the first image of the event horizon of a black hole.

<span class="mw-page-title-main">PKS 2131-021</span> Quasar in the constellation Aquarius

PKS 2131-021 is a quasar and a BL Lacerate object, producing an astrophysical jet. lt is located in the constellation Aquarius and classified as a blazar, a type of active galactic nucleus whose relativistic jet points in the direction towards Earth.

Monika Mościbrodzka is a Polish astrophysicist who is a professor at Radboud University Nijmegen. She is an expert in general relativistic plasma dynamics and numerical astrophysics. She was part of the Event Horizon Telescope team who contributed to the first direct image of a black hole, supermassive black hole M87*. She was awarded the 2022 Dutch Research Council Athena Prize and the 2023 Eddington Medal of the Royal Astronomical Society.

<span class="mw-page-title-main">4C +71.07</span> Quasar in the constellation Ursa Major

4C +71.07 known as S5 0836+71, is a quasar located in the constellation Ursa Major. Based on its high redshift, the object is located 10.7 billion light-years away from Earth and such, classified as a blazar with a flat-spectrum radio source and features a radio jet.

<span class="mw-page-title-main">PKS 2215+020</span> Quasar in the constellation Aquarius

PKS 2215+020, known as PMN J2217+0220, is a quasar located in the Aquarius constellation. Its redshift is 3.570000, meaning the object is located 11.6 billion light-years away from Earth. It is classified as a flat spectrum radio source quasar.

References

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