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ASASSN-15lh

October 15, 2023

ASASSN-15lh (supernova designation SN 2015L) is an extremely luminous astronomical transient event discovered by the All Sky Automated Survey for SuperNovae (ASAS-SN), with the appearance of a superluminous supernova event. It was first detected on June 14, 2015, located within a faint galaxy in the southern constellation Indus, and was the most luminous supernova-like object ever observed.[4] At its peak, ASASSN-15lh was 570 billion times brighter than the Sun, and 20 times brighter than the combined light emitted by the Milky Way Galaxy.[4] The emitted energy was exceeded by PS1-10adi.

ASASSN-15lh
A visual band light curve for ASASSN-15lh, plotted from data published by Godoy-Rivera et al. (2017).[1] The purple line shows the brightness of the host galaxy.
SLSNe (Type Ic), SNSLSN-I 
Right ascension22h 2m 15.45s[2]
Declination−61° 39′ 34.64″[2]
Distance1,171 megaparsecs
3.82 gigalight-years
Redshift0.2326 
HostAPMUKS(BJ) B215839.70−615403.9[3]
Peak apparent magnitude16.9
Other designationsSN 2015L
[edit on Wikidata]

The nature of ASASSN-15lh is disputed. The most popular explanations are that it is the most luminous type I supernova (hypernova) ever observed, or a tidal disruption event around a supermassive black hole. Other hypotheses include: gravitational lensing; a quark nova inside a Wolf–Rayet star; or a rapid magnetar spindown.

Discovery Edit

A possible supernova was first noticed during an observation in June 2015 by ASAS-SN's twin 14-cm telescopes in Chile; the team gave it the designation ASASSN-15lh.[5] It appeared as a transient dot of light on an image and was confirmed with additional observations from other telescopes.[5] The spectrum of ASASSN-15lh was provided by the 2.5-meter du Pont Telescope in Chile.[5] The Southern African Large Telescope was used to determine the redshift, and hence the distance and luminosity.[3] The Swift space telescope also contributed observations.[3] On July 24, the event formally received the supernova designation SN 2015L from the Central Bureau of Astronomical Telegrams.[6]

Later, other images were found to have been made of ASASSN-15lh as early as May 8, 2015. At this stage the visual magnitude was 17.4. From May 8 the possible supernova brightened until it reached a peak brightness of magnitude 16.9 on June 5. By September the brightness had dropped to magnitude 18.2.[3] There was an unusual "rebrightening" of up to 1.75 magnitudes at blue and ultraviolet wavelengths, starting about 90 days after the maximum. This coincided with a plateau in the bolometric luminosity that lasted for 120 days.[1]

Properties Edit

Based on its redshift and location projected on the nucleus of a large galaxy, the distance of ASASSN-15lh is calculated at 1,171 Mpc, in a large luminous galaxy.[3]

At its peak, the absolute magnitude of ASASSN-15lh in the AB magnitude system u band was −23.5. Its bolometric luminosity is twice that of the previous brightest type-I superluminous supernova, iPTF13ajg.[7] At its brightest, it was approximately 50 times more luminous than the whole Milky Way galaxy,[8] with an energy flux 570 billion times greater than the Sun.[9][10] The total energy radiated in the first 50 days exceeded 1.1×1045 joules.[3] According to Krzysztof Stanek of Ohio State University, one of the principal investigators at ASAS-SN, "If it was in our own galaxy, it would shine brighter than the full moon; there would be no night, and it would be easily seen during the day."[11]

The spectrum of ASASSN-15lh was relatively featureless, with no hydrogen or helium lines, but two very broad absorption bands. Ionised magnesium absorption doublets were detected and used to confirm the redshift at 0.2326.[3]

The temperature of ASASSN-15lh at the time of maximum luminosity was 20,000 K, although it was hotter earlier in the outburst. By 50 days after the peak, the temperature had declined to 11,000 K and then remained relatively constant. The radius of ASASSN-15lh at peak brightness was over 70,000 R☉.[3]

Host galaxy Edit

The host galaxy for ASASSN-15lh is APMUKS(BJ) B215839.70−615403.9, much larger and more luminous than the Milky Way. The host galaxy has visual magnitude 18.5 and is red in color with a low rate of star formation. It maintained a steady brightness until the supernova lit up. The strongest parts of the galaxy's spectrum have wavelengths around 1 μm in the near infrared.[3]

Suggested mechanisms Edit

The precise mechanism underlying the very large ASASSN-15lh explosion is still unknown, with speculation ranging from the presence of very large quantities of decaying nickel-56 to the amplifying effects of a magnetar. Its unusual location in a relatively quiescent galaxy may offer clues for scientists to discover and observe similar events.[12]

Superluminous supernova Edit

The initial hypothesis was that ASASSN-15lh was the most extreme superluminous supernova (SLSN) so far seen, but it was recognized as being unusual in several respects. The spectrum did not closely match other type I SLSNe and previous SLSNe have been discovered in relatively small active star-producing galaxies, not in the central regions of large galaxies.[12] The double-peaked light curve is not expected from a SLSN and the total energy output approaches theoretical limits.[3]

The lack of hydrogen and helium features in the spectrum suggest an explosion originating in an object lacking both hydrogen and helium, which would imply a highly stripped star such as a massive Wolf–Rayet star. The energetics of the explosion would require a massive star.

Magnetar Edit

One model for unusually luminous supernovae involves the conversion of rotational energy from a rapidly-spinning neutron star into polar jets that heat surrounding material. Again, the energy produced by ASASSN-15lh strains the theoretical limits of this type of explosion and the detailed properties are difficult to reproduce with a magnetar model.[3]

Quark nova Edit

One unusual explanation for ASASSN-15lh is a quark-nova within the supernova explosion from a WO-type Wolf-Rayet star. The quark nova is produced by the neutron star remnant of the supernova and occurs a few days after the core collapse of the Wolf-Rayet star. This can reproduce many of the unusual features of the observed event but is somewhat speculative and not widely accepted.[13]

Tidal disruption event (TDE) Edit

One known method for producing extremely large amounts of energy is the tidal disruption of objects such as stars by a supermassive black hole. ASASSN-15lh occurred in the nucleus of a large passive galaxy where a supermassive black hole is likely. A black hole of the mass expected in the host galaxy of ASASSN-15lh would normally swallow stars without a visible flare. The conditions for the production of a highly luminous flare from a TDE around a black hole of the expected mass are unusual, but a rapidly-spinning Kerr black hole might be able to disrupt a star with a mass similar to the sun outside the event horizon and produce a hot accretion disc and luminous transient. It could also account for the temperature changes, rebrightening, and unusual spectral evolution.[14] However, lack of hydrogen and/or helium lines in the spectra of ASASSN-15lh poses a major problem for the TDE scenario.

Gravitational lensing Edit

Unexpectedly bright visible objects can be produced by gravitational lensing of very distant objects by extremely massive objects closer to Earth. However, this usually occurs with objects much more distant than ASASSN-15lh, and there are no observations indicating the presence of a galaxy cluster suitable to produce a lensing effect.[3]

References Edit

  1. ^ a b Godoy-Rivera, D.; Stanek, K. Z.; Kochanek, C. S.; Chen, Ping; Dong, Subo; Prieto, J. L.; Shappee, B. J.; Jha, S. W.; Foley, R. J.; Pan, Y.-C.; Holoien, T. W.-S.; Thompson, Todd. A.; Grupe, D.; Beacom, J. F. (2017). "The unexpected, long-lasting, UV rebrightening of the superluminous supernova ASASSN-15lh". Monthly Notices of the Royal Astronomical Society. 466 (2): 1428. arXiv:1605.00645. Bibcode:2017MNRAS.466.1428G. doi:10.1093/mnras/stw3237. S2CID 119253925.
  2. ^ a b Young, Monica (July 12, 2015). "The Most Luminous Supernova". Sky & Telescope. Retrieved January 16, 2016.
  3. ^ a b c d e f g h i j k l Dong, S.; Shappee, B. J.; Prieto, J. L.; Jha, S. W.; Stanek, K. Z.; Holoien, T. W.- S.; Kochanek, C. S.; Thompson, T. A.; Morrell, N.; et al. (January 15, 2016). "ASASSN-15lh: A highly super-luminous supernova". Science. 351 (6270): 257–260. arXiv:1507.03010. Bibcode:2016Sci...351..257D. doi:10.1126/science.aac9613. PMID 26816375. S2CID 31444274.
  4. ^ a b Jessica Orwig (January 14, 2016). "Astronomers are baffled by a newly discovered cosmic explosion that shines 570 billion times brighter than the sun". Business Insider. Retrieved March 22, 2016.
  5. ^ a b c Billings, Lee (January 14, 2016). "Found: The Most Powerful Supernova Ever Seen". Scientific American. Retrieved January 16, 2016.
  6. ^ S. Dong; B.J. Shappee; J.L. Prieto; S.W. Jha; K.Z. Stanek; T.W.-S. Holoien; C.S. Kochanek; T.A. Thompson; N. Morrell; I.B. Thompson; U. Basu; J.F. Beacom; D. Bersier; J. Brimacombe; J.S. Brown; P. Chen; E. Conseil; A.B. Danilet; E. Falco; D. Grupe; S. Kiyota; G. Masi; B. Nicholls; F. Olivares; G. Pignata; G. Pojmanski; G.V. Simonian; D.M. Szczygiel; P.R. Wozniak (July 24, 2015). Daniel W. E. Green (ed.). "SN 2015L". Central Bureau Electronic Telegrams. Central Bureau for Astronomical Telegrams. 4120: 1. Bibcode:2015CBET.4120....1D.
  7. ^ Young, Monica (January 15, 2016). "Brightest Supernova Baffles Astronomers". Sky & Telescope. Retrieved January 16, 2016.
  8. ^ Carnegie Institution for Science (January 14, 2016). "Most-luminous supernova ever discovered". phys.org. Retrieved January 15, 2016.
  9. ^ Cowen, Ron (January 14, 2016). "Brightest-ever supernova still baffles astronomers". Nature. doi:10.1038/nature.2016.19176. S2CID 182077393.
  10. ^ Bhanoo, Sindya N. (January 15, 2016). "Supernova Has Energy of Hundreds of Billions of Suns". The New York Times. Retrieved January 16, 2016.
  11. ^ Boyle, Rebecca (January 14, 2016). "We've found the brightest ever supernova but can't explain it". New Scientist. Retrieved January 15, 2016.
  12. ^ a b Thomson, Jason (January 14, 2016). "Astronomers spot brightest supernova in history". The Christian Science Monitor. Retrieved January 15, 2016.
  13. ^ Ouyed, Rachid; Leahy, Denis; Welbanks, Luis; Koning, Nico (2016). "The Superluminous (Type I) Supernova ASASSN-15lh : A case for a Quark-Nova inside an Oxygen-type Wolf-Rayet supernova remnant". arXiv:1611.03657 [astro-ph.HE].
  14. ^ Leloudas, G.; Fraser, M.; Stone, N. C.; Van Velzen, S.; Jonker, P. G.; Arcavi, I.; Fremling, C.; Maund, J. R.; Smartt, S. J.; et al. (2016). "The superluminous transient ASASSN-15lh as a tidal disruption event from a Kerr black hole". Nature Astronomy. 1: 0002. arXiv:1609.02927. Bibcode:2016NatAs...1E...2L. doi:10.1038/s41550-016-0002. S2CID 73645264.

Further reading Edit

  • Gilkis, Avishai; Soker, Noam; Papish, Oded (November 4, 2015). "Explaining the most luminous supernovae with an inefficient jet-feedback mechanism". The Astrophysical Journal. 826 (2): 178. arXiv:1511.01471. Bibcode:2016ApJ...826..178G. doi:10.3847/0004-637X/826/2/178. S2CID 119159928.

External links Edit

  • Brightest supernova ever seen pushes theoretical models to the edge Astronomy
  • 'Brightest Supernova Ever' Was Actually Monster Black Hole's Violent Star Slashing Space.com
  • Kerr Black Hole Eating Sun-like Star Explains Superluminous Explosion ASASSN-15lh Breaking Science News | Sci-News.com
  • Superluminous Supernova Is The Brightest Ever Seen Forbes

October 15, 2023
asassn, 15lh, supernova, designation, 2015l, extremely, luminous, astronomical, transient, event, discovered, automated, survey, supernovae, asas, with, appearance, superluminous, supernova, event, first, detected, june, 2015, located, within, faint, galaxy, s. ASASSN 15lh supernova designation SN 2015L is an extremely luminous astronomical transient event discovered by the All Sky Automated Survey for SuperNovae ASAS SN with the appearance of a superluminous supernova event It was first detected on June 14 2015 located within a faint galaxy in the southern constellation Indus and was the most luminous supernova like object ever observed 4 At its peak ASASSN 15lh was 570 billion times brighter than the Sun and 20 times brighter than the combined light emitted by the Milky Way Galaxy 4 The emitted energy was exceeded by PS1 10adi ASASSN 15lhA visual band light curve for ASASSN 15lh plotted from data published by Godoy Rivera et al 2017 1 The purple line shows the brightness of the host galaxy SLSNe Type Ic SNSLSN I Right ascension22h 2m 15 45s 2 Declination 61 39 34 64 2 Distance1 171 megaparsecs3 82 gigalight yearsRedshift0 2326 HostAPMUKS BJ B215839 70 615403 9 3 Peak apparent magnitude16 9Other designationsSN 2015L edit on Wikidata The nature of ASASSN 15lh is disputed The most popular explanations are that it is the most luminous type I supernova hypernova ever observed or a tidal disruption event around a supermassive black hole Other hypotheses include gravitational lensing a quark nova inside a Wolf Rayet star or a rapid magnetar spindown Contents 1 Discovery 2 Properties 3 Host galaxy 4 Suggested mechanisms 4 1 Superluminous supernova 4 2 Magnetar 4 3 Quark nova 4 4 Tidal disruption event TDE 4 5 Gravitational lensing 5 References 6 Further reading 7 External linksDiscovery EditA possible supernova was first noticed during an observation in June 2015 by ASAS SN s twin 14 cm telescopes in Chile the team gave it the designation ASASSN 15lh 5 It appeared as a transient dot of light on an image and was confirmed with additional observations from other telescopes 5 The spectrum of ASASSN 15lh was provided by the 2 5 meter du Pont Telescope in Chile 5 The Southern African Large Telescope was used to determine the redshift and hence the distance and luminosity 3 The Swift space telescope also contributed observations 3 On July 24 the event formally received the supernova designation SN 2015L from the Central Bureau of Astronomical Telegrams 6 Later other images were found to have been made of ASASSN 15lh as early as May 8 2015 At this stage the visual magnitude was 17 4 From May 8 the possible supernova brightened until it reached a peak brightness of magnitude 16 9 on June 5 By September the brightness had dropped to magnitude 18 2 3 There was an unusual rebrightening of up to 1 75 magnitudes at blue and ultraviolet wavelengths starting about 90 days after the maximum This coincided with a plateau in the bolometric luminosity that lasted for 120 days 1 Properties EditBased on its redshift and location projected on the nucleus of a large galaxy the distance of ASASSN 15lh is calculated at 1 171 Mpc in a large luminous galaxy 3 At its peak the absolute magnitude of ASASSN 15lh in the AB magnitude system u band was 23 5 Its bolometric luminosity is twice that of the previous brightest type I superluminous supernova iPTF13ajg 7 At its brightest it was approximately 50 times more luminous than the whole Milky Way galaxy 8 with an energy flux 570 billion times greater than the Sun 9 10 The total energy radiated in the first 50 days exceeded 1 1 1045 joules 3 According to Krzysztof Stanek of Ohio State University one of the principal investigators at ASAS SN If it was in our own galaxy it would shine brighter than the full moon there would be no night and it would be easily seen during the day 11 The spectrum of ASASSN 15lh was relatively featureless with no hydrogen or helium lines but two very broad absorption bands Ionised magnesium absorption doublets were detected and used to confirm the redshift at 0 2326 3 The temperature of ASASSN 15lh at the time of maximum luminosity was 20 000 K although it was hotter earlier in the outburst By 50 days after the peak the temperature had declined to 11 000 K and then remained relatively constant The radius of ASASSN 15lh at peak brightness was over 70 000 R 3 Host galaxy EditThe host galaxy for ASASSN 15lh is APMUKS BJ B215839 70 615403 9 much larger and more luminous than the Milky Way The host galaxy has visual magnitude 18 5 and is red in color with a low rate of star formation It maintained a steady brightness until the supernova lit up The strongest parts of the galaxy s spectrum have wavelengths around 1 mm in the near infrared 3 Suggested mechanisms EditThe precise mechanism underlying the very large ASASSN 15lh explosion is still unknown with speculation ranging from the presence of very large quantities of decaying nickel 56 to the amplifying effects of a magnetar Its unusual location in a relatively quiescent galaxy may offer clues for scientists to discover and observe similar events 12 Superluminous supernova Edit The initial hypothesis was that ASASSN 15lh was the most extreme superluminous supernova SLSN so far seen but it was recognized as being unusual in several respects The spectrum did not closely match other type I SLSNe and previous SLSNe have been discovered in relatively small active star producing galaxies not in the central regions of large galaxies 12 The double peaked light curve is not expected from a SLSN and the total energy output approaches theoretical limits 3 The lack of hydrogen and helium features in the spectrum suggest an explosion originating in an object lacking both hydrogen and helium which would imply a highly stripped star such as a massive Wolf Rayet star The energetics of the explosion would require a massive star Magnetar Edit One model for unusually luminous supernovae involves the conversion of rotational energy from a rapidly spinning neutron star into polar jets that heat surrounding material Again the energy produced by ASASSN 15lh strains the theoretical limits of this type of explosion and the detailed properties are difficult to reproduce with a magnetar model 3 Quark nova Edit One unusual explanation for ASASSN 15lh is a quark nova within the supernova explosion from a WO type Wolf Rayet star The quark nova is produced by the neutron star remnant of the supernova and occurs a few days after the core collapse of the Wolf Rayet star This can reproduce many of the unusual features of the observed event but is somewhat speculative and not widely accepted 13 Tidal disruption event TDE Edit One known method for producing extremely large amounts of energy is the tidal disruption of objects such as stars by a supermassive black hole ASASSN 15lh occurred in the nucleus of a large passive galaxy where a supermassive black hole is likely A black hole of the mass expected in the host galaxy of ASASSN 15lh would normally swallow stars without a visible flare The conditions for the production of a highly luminous flare from a TDE around a black hole of the expected mass are unusual but a rapidly spinning Kerr black hole might be able to disrupt a star with a mass similar to the sun outside the event horizon and produce a hot accretion disc and luminous transient It could also account for the temperature changes rebrightening and unusual spectral evolution 14 However lack of hydrogen and or helium lines in the spectra of ASASSN 15lh poses a major problem for the TDE scenario Gravitational lensing Edit Unexpectedly bright visible objects can be produced by gravitational lensing of very distant objects by extremely massive objects closer to Earth However this usually occurs with objects much more distant than ASASSN 15lh and there are no observations indicating the presence of a galaxy cluster suitable to produce a lensing effect 3 References Edit a b Godoy Rivera D Stanek K Z Kochanek C S Chen Ping Dong Subo Prieto J L Shappee B J Jha S W Foley R J Pan Y C Holoien T W S Thompson Todd A Grupe D Beacom J F 2017 The unexpected long lasting UV rebrightening of the superluminous supernova ASASSN 15lh Monthly Notices of the Royal Astronomical Society 466 2 1428 arXiv 1605 00645 Bibcode 2017MNRAS 466 1428G doi 10 1093 mnras stw3237 S2CID 119253925 a b Young Monica July 12 2015 The Most Luminous Supernova Sky amp Telescope Retrieved January 16 2016 a b c d e f g h i j k l Dong S Shappee B J Prieto J L Jha S W Stanek K Z Holoien T W S Kochanek C S Thompson T A Morrell N et al January 15 2016 ASASSN 15lh A highly super luminous supernova Science 351 6270 257 260 arXiv 1507 03010 Bibcode 2016Sci 351 257D doi 10 1126 science aac9613 PMID 26816375 S2CID 31444274 a b Jessica Orwig January 14 2016 Astronomers are baffled by a newly discovered cosmic explosion that shines 570 billion times brighter than the sun Business Insider Retrieved March 22 2016 a b c Billings Lee January 14 2016 Found The Most Powerful Supernova Ever Seen Scientific American Retrieved January 16 2016 S Dong B J Shappee J L Prieto S W Jha K Z Stanek T W S Holoien C S Kochanek T A Thompson N Morrell I B Thompson U Basu J F Beacom D Bersier J Brimacombe J S Brown P Chen E Conseil A B Danilet E Falco D Grupe S Kiyota G Masi B Nicholls F Olivares G Pignata G Pojmanski G V Simonian D M Szczygiel P R Wozniak July 24 2015 Daniel W E Green ed SN 2015L Central Bureau Electronic Telegrams Central Bureau for Astronomical Telegrams 4120 1 Bibcode 2015CBET 4120 1D Young Monica January 15 2016 Brightest Supernova Baffles Astronomers Sky amp Telescope Retrieved January 16 2016 Carnegie Institution for Science January 14 2016 Most luminous supernova ever discovered phys org Retrieved January 15 2016 Cowen Ron January 14 2016 Brightest ever supernova still baffles astronomers Nature doi 10 1038 nature 2016 19176 S2CID 182077393 Bhanoo Sindya N January 15 2016 Supernova Has Energy of Hundreds of Billions of Suns The New York Times Retrieved January 16 2016 Boyle Rebecca January 14 2016 We ve found the brightest ever supernova but can t explain it New Scientist Retrieved January 15 2016 a b Thomson Jason January 14 2016 Astronomers spot brightest supernova in history The Christian Science Monitor Retrieved January 15 2016 Ouyed Rachid Leahy Denis Welbanks Luis Koning Nico 2016 The Superluminous Type I Supernova ASASSN 15lh A case for a Quark Nova inside an Oxygen type Wolf Rayet supernova remnant arXiv 1611 03657 astro ph HE Leloudas G Fraser M Stone N C Van Velzen S Jonker P G Arcavi I Fremling C Maund J R Smartt S J et al 2016 The superluminous transient ASASSN 15lh as a tidal disruption event from a Kerr black hole Nature Astronomy 1 0002 arXiv 1609 02927 Bibcode 2016NatAs 1E 2L doi 10 1038 s41550 016 0002 S2CID 73645264 Further reading EditGilkis Avishai Soker Noam Papish Oded November 4 2015 Explaining the most luminous supernovae with an inefficient jet feedback mechanism The Astrophysical Journal 826 2 178 arXiv 1511 01471 Bibcode 2016ApJ 826 178G doi 10 3847 0004 637X 826 2 178 S2CID 119159928 External links EditBrightest supernova ever seen pushes theoretical models to the edge Astronomy Brightest Supernova Ever Was Actually Monster Black Hole s Violent Star Slashing Space com Kerr Black Hole Eating Sun like Star Explains Superluminous Explosion ASASSN 15lh Breaking Science News Sci News com Superluminous Supernova Is The Brightest Ever Seen Forbes Retrieved from https en wikipedia org w index php title ASASSN 15lh amp oldid 1174823361, wikipedia, wiki, book, books, library,

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