TON 618

TON 618 is a very distant and extremely luminous quasar—technically a hyperluminous, broad-absorption-line, radio-loud quasar—located near the border of the constellations Canes Venatici and Coma Berenices. It possesses one of the most massive black holes ever found, with a mass of 66 billion M☉.[2]

TON 618
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TON 618, imaged by the Sloan Digital Sky Survey Data Release 9 (DR9). The quasar appears as the bright, bluish-white dot at the center.
Observation data (Epoch )
ConstellationCanes Venatici
Right ascension12h 28m 24.9s[1]
Declination+31° 28′ 38″[1]
Redshift2.219[1]
Distance3.18 Gpc (10.4 Gly)[1]
TypeQuasar[1]
Apparent magnitude (V)15.9[1]
Notable featuresHyperluminous quasar
Other designations
FBQS J122824.9+312837, B2 1225+31, B2 1225+317, 7C 1225+3145[1]
See also: Quasar, List of quasars

Observational history

Because quasars were not recognized until 1963,[3] the nature of this object was unknown when it was first noted in a 1957 survey of faint blue stars (mainly white dwarfs) that lie away from the plane of the Milky Way. On photographic plates taken with the 0.7 m Schmidt telescope at the Tonantzintla Observatory in Mexico, it appeared "decidedly violet" and was listed as number 618 in the Tonantzintla Catalogue.[4]

In 1970, a radio survey at Bologna discovered radio emission from TON 618, indicating that it was a quasar.[5] Marie-Helene Ulrich then obtained optical spectra of TON 618 at the McDonald Observatory which showed emission lines typical of a quasar. From the redshift of the lines Ulrich deduced that TON 618 was very distant, and hence was one of the most luminous quasars known.[6]

Supermassive black hole

As a quasar, TON 618 is believed to be an accretion disc of intensely hot gas swirling around a giant black hole in the center of a galaxy. The light originating from the quasar is estimated to be 10.4 billion years old. The surrounding galaxy is not visible from Earth, because the quasar itself outshines it. With an absolute magnitude of −30.7, it shines with a luminosity of 4×1040 watts, or as brilliantly as 140 trillion Suns, making it one of the brightest objects in the known Universe.[1]

Like other quasars, TON 618 has a spectrum containing emission lines from cooler gas much further out than the accretion disc, in the broad-line region. The size of the broad-line region can be calculated from the brightness of the quasar radiation that is lighting it up.[7] Shemmer et al utilized the use of both NV and CIV emission lines in order to calculate the widths of the Hβ spectral line of at least 29 QSO's, including TON 618, as a direct measurement of their accretion rates and hence the mass of the central black hole.[2] The emission lines in the spectrum of TON 618 are unusually wide,[6] indicating that the gas is travelling very fast; the full width half maxima of TON 618 has been the largest of the 29 QSO's, with indications of 7,000 km/s speeds of infalling material by a direct measure of the Hβ line, indication of a very strong gravitational force.[2] From this measure, the mass of the central black hole of TON 618 is at least 66 billion solar masses.[2] This is considered one of the highest masses ever recorded for such an object; higher than the mass of all stars in the Milky Way galaxy combined, which is 64 billion solar masses,[8] and 15,300 times more massive than Sagittarius A*, our galaxy's central black hole. With a mass this high, TON 618 falls into the new classification of ultramassive black holes.[9][10] A black hole of this mass has a Schwarzschild radius of 1,300 AU (about 390 billion km in diameter, more than 40 times the size of Neptune's orbit).

See also

References
  1. "NED results for object TON 618". NASA/IPAC EXTRAGALACTIC DATABASE.
  2. Shemmer, O.; Netzer, H.; Maiolino, R.; Oliva, E.; Croom, S.; Corbett, E.; di Fabrizio, L. (2004). "Near-infrared spectroscopy of high-redshift active galactic nuclei: I. A metallicity-accretion rate relationship". The Astrophysical Journal. 614 (2): 547–557. arXiv:astro-ph/0406559. Bibcode:2004ApJ...614..547S. doi:10.1086/423607.
  3. "1963: Maarten Schmidt Discovers Quasars". Observatories of the Carnegie Institution for Science. Retrieved 21 October 2017.
  4. Iriarte, Braulio; Chavira, Enrique (1957). "Blue stars in the North Galactic Cap" (PDF). Boletín de los Observatorios de Tonantzintla y Tacubaya. 2 (16): 3–36. Retrieved 21 October 2017.
  5. Colla, G.; Fanti, C.; Ficarra, A.; Formiggini, L.; Gandolfi, E.; Grueff, G.; Lari, C.; Padrielli, L.; Roffi, G.; Tomasi, P; Vigotti, M. (1970). "A catalogue of 3235 radio sources at 408 MHz". Astronomy & Astrophysics Supplement Series. 1 (3): 281. Bibcode:1970A&AS....1..281C.
  6. Ulrich, Marie-Helene (1976). "Optical spectrum and redshifts of a quasar of extremely high intrinsice luminosity: B2 1225+31". The Astrophysical Journal. 207: L73–L74. Bibcode:1976ApJ...207L..73U. doi:10.1086/182182.
  7. Kaspi, Shai; Smith, Paul S.; Netzer, Hagai; Maos, Dan; Jannuzi, Buell T.; Giveon, Uriel (2000). "Reverberation measurements for 17 quasars and the size-mass-luminosity relations in active galactic nuclei". The Astrophysical Journal. 533 (2): 631–649. arXiv:astro-ph/9911476. Bibcode:2000ApJ...533..631K. doi:10.1086/308704.
  8. McMillan, P. J. (July 2011). "Mass models of the Milky Way". Monthly Notices of the Royal Astronomical Society. 414 (3): 2446–2457. arXiv:1102.4340. Bibcode:2011MNRAS.414.2446M. doi:10.1111/j.1365-2966.2011.18564.x. S2CID 119100616.
  9. Irving, Michael (21 February 2018). ""Ultramassive" black holes may be the biggest ever found – and they're growing fast". New Atlas.
  10. "From Super to Ultra: Just How Big Can Black Holes Get?". NASA – Chandra X-Ray Observatory. 18 December 2012.
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