Swift/UVOT discovery of Swift J221951−484240: a UV luminous ambiguous nuclear transient

S. R. Oates; N. P.M. Kuin; M. Nicholl; F. Marshall; E. Ridley; K. Boutsia; A. A. Breeveld; D. A.H. Buckley; S. B. Cenko; M. De Pasquale; P. G. Edwards; M. Gromadzki; R. Gupta; S. Laha; N. Morrell; M. Orio; S. B. Pandey; M. J. Page; K. L. Page; T. Parsotan; A. Rau; P. Schady; J. Stevens; P. J. Brown; P. A. Evans; C. Gronwall; J. A. Kennea; N. J. Klingler; M. H. Siegel; A. Tohuvavohu; E. Ambrosi; S. D. Barthelmy; A. P. Beardmore; M. G. Bernardini; C. Bonnerot; S. Campana; R. Caputo; S. Ciroi; G. Cusumano; A. D. Aì; P. D. Avanzo; V. D. Elia; P. Giommi; D. H. Hartmann; H. A. Krimm; D. B. Malesani; A. Melandri; J. A. Nousek; P. T.O. Brien; J. P. Osborne; C. Pagani; D. M. Palmer; M. Perri; J. L. Racusin; T. Sakamoto; B. Sbarufatti; J. E. Schlieder; G. Tagliaferri; E. Troja; D. Xu

doi:10.1093/mnras/stae795

Swift/UVOT discovery of Swift J221951−484240: a UV luminous ambiguous nuclear transient

S. R. Oates, N. P.M. Kuin, M. Nicholl, F. Marshall, E. Ridley, K. Boutsia, A. A. Breeveld, D. A.H. Buckley, S. B. Cenko, M. De Pasquale, P. G. Edwards, M. Gromadzki, R. Gupta, S. Laha, N. Morrell, M. Orio, S. B. Pandey, M. J. Page, K. L. Page, T. ParsotanA. Rau, P. Schady, J. Stevens, P. J. Brown, P. A. Evans, C. Gronwall, J. A. Kennea, N. J. Klingler, M. H. Siegel, A. Tohuvavohu, E. Ambrosi, S. D. Barthelmy, A. P. Beardmore, M. G. Bernardini, C. Bonnerot, S. Campana, R. Caputo, S. Ciroi, G. Cusumano, A. D. Aì, P. D. Avanzo, V. D. Elia, P. Giommi, D. H. Hartmann, H. A. Krimm, D. B. Malesani, A. Melandri, J. A. Nousek, P. T.O. Brien, J. P. Osborne, C. Pagani, D. M. Palmer, M. Perri, J. L. Racusin, T. Sakamoto, B. Sbarufatti, J. E. Schlieder, G. Tagliaferri, E. Troja, D. Xu

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Abstract

We report the discovery of Swift J221951−484240 (hereafter: J221951), a luminous slow-evolving blue transient that was detected by the Neil Gehrels Swift Observatory Ultraviolet/Optical Telescope (Swift/UVOT) during the follow-up of gravitational wave alert S190930t, to which it is unrelated. Swift/UVOT photometry shows the UV spectral energy distribution of the transient to be well modelled by a slowly shrinking blackbody with an approximately constant temperature of T ∼ 2.5 × 10⁴ K. At a redshift z = 0.5205, J221951 had a peak absolute magnitude of M_u_,AB = −23 mag, peak bolometric luminosity L_max = 1.1 × 10⁴⁵ erg s⁻¹ and a total radiated energy of E > 2.6 × 10⁵² erg. The archival Wide-field Infrared Survey Explorer IR photometry shows a slow rise prior to a peak near the discovery date. Spectroscopic UV observations display broad absorption lines in N V and O VI, pointing towards an outflow at coronal temperatures. The lack of emission in the higher H α lines, N I and other neutral lines is consistent with a viewing angle close to the plane of the accretion or debris disc. The origin of J221951 cannot be determined with certainty but has properties consistent with a tidal disruption event and the turn-on of an active galactic nucleus.

Original language	English (US)
Pages (from-to)	1688-1710
Number of pages	23
Journal	Monthly Notices of the Royal Astronomical Society
Volume	530
Issue number	2
DOIs	https://doi.org/10.1093/mnras/stae795
State	Published - May 1 2024

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

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10.1093/mnras/stae795

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Oates, S. R., Kuin, N. P. M., Nicholl, M., Marshall, F., Ridley, E., Boutsia, K., Breeveld, A. A., Buckley, D. A. H., Cenko, S. B., De Pasquale, M., Edwards, P. G., Gromadzki, M., Gupta, R., Laha, S., Morrell, N., Orio, M., Pandey, S. B., Page, M. J., Page, K. L., ... Xu, D. (2024). Swift/UVOT discovery of Swift J221951−484240: a UV luminous ambiguous nuclear transient. Monthly Notices of the Royal Astronomical Society, 530(2), 1688-1710. https://doi.org/10.1093/mnras/stae795

@article{a2245c7a55d64ff7880e6d1680ce9eba,

title = "Swift/UVOT discovery of Swift J221951−484240: a UV luminous ambiguous nuclear transient",

abstract = "We report the discovery of Swift J221951−484240 (hereafter: J221951), a luminous slow-evolving blue transient that was detected by the Neil Gehrels Swift Observatory Ultraviolet/Optical Telescope (Swift/UVOT) during the follow-up of gravitational wave alert S190930t, to which it is unrelated. Swift/UVOT photometry shows the UV spectral energy distribution of the transient to be well modelled by a slowly shrinking blackbody with an approximately constant temperature of T ∼ 2.5 × 104 K. At a redshift z = 0.5205, J221951 had a peak absolute magnitude of Mu,AB = −23 mag, peak bolometric luminosity Lmax = 1.1 × 1045 erg s−1 and a total radiated energy of E > 2.6 × 1052 erg. The archival Wide-field Infrared Survey Explorer IR photometry shows a slow rise prior to a peak near the discovery date. Spectroscopic UV observations display broad absorption lines in N V and O VI, pointing towards an outflow at coronal temperatures. The lack of emission in the higher H α lines, N I and other neutral lines is consistent with a viewing angle close to the plane of the accretion or debris disc. The origin of J221951 cannot be determined with certainty but has properties consistent with a tidal disruption event and the turn-on of an active galactic nucleus.",

author = "Oates, {S. R.} and Kuin, {N. P.M.} and M. Nicholl and F. Marshall and E. Ridley and K. Boutsia and Breeveld, {A. A.} and Buckley, {D. A.H.} and Cenko, {S. B.} and {De Pasquale}, M. and Edwards, {P. G.} and M. Gromadzki and R. Gupta and S. Laha and N. Morrell and M. Orio and Pandey, {S. B.} and Page, {M. J.} and Page, {K. L.} and T. Parsotan and A. Rau and P. Schady and J. Stevens and Brown, {P. J.} and Evans, {P. A.} and C. Gronwall and Kennea, {J. A.} and Klingler, {N. J.} and Siegel, {M. H.} and A. Tohuvavohu and E. Ambrosi and Barthelmy, {S. D.} and Beardmore, {A. P.} and Bernardini, {M. G.} and C. Bonnerot and S. Campana and R. Caputo and S. Ciroi and G. Cusumano and A{\`i}, {A. D.} and Avanzo, {P. D.} and Elia, {V. D.} and P. Giommi and Hartmann, {D. H.} and Krimm, {H. A.} and Malesani, {D. B.} and A. Melandri and Nousek, {J. A.} and Brien, {P. T.O.} and Osborne, {J. P.} and C. Pagani and Palmer, {D. M.} and M. Perri and Racusin, {J. L.} and T. Sakamoto and B. Sbarufatti and Schlieder, {J. E.} and G. Tagliaferri and E. Troja and D. Xu",

note = "Publisher Copyright: {\textcopyright} 2024 The Author(s).",

year = "2024",

month = may,

day = "1",

doi = "10.1093/mnras/stae795",

language = "English (US)",

volume = "530",

pages = "1688--1710",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

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Oates, SR, Kuin, NPM, Nicholl, M, Marshall, F, Ridley, E, Boutsia, K, Breeveld, AA, Buckley, DAH, Cenko, SB, De Pasquale, M, Edwards, PG, Gromadzki, M, Gupta, R, Laha, S, Morrell, N, Orio, M, Pandey, SB, Page, MJ, Page, KL, Parsotan, T, Rau, A, Schady, P, Stevens, J, Brown, PJ, Evans, PA, Gronwall, C , Kennea, JA, Klingler, NJ, Siegel, MH, Tohuvavohu, A, Ambrosi, E, Barthelmy, SD, Beardmore, AP, Bernardini, MG, Bonnerot, C, Campana, S, Caputo, R, Ciroi, S, Cusumano, G, Aì, AD, Avanzo, PD, Elia, VD, Giommi, P, Hartmann, DH, Krimm, HA, Malesani, DB, Melandri, A, Nousek, JA, Brien, PTO, Osborne, JP, Pagani, C, Palmer, DM, Perri, M, Racusin, JL, Sakamoto, T, Sbarufatti, B, Schlieder, JE, Tagliaferri, G, Troja, E & Xu, D 2024, 'Swift/UVOT discovery of Swift J221951−484240: a UV luminous ambiguous nuclear transient', Monthly Notices of the Royal Astronomical Society, vol. 530, no. 2, pp. 1688-1710. https://doi.org/10.1093/mnras/stae795

TY - JOUR

T1 - Swift/UVOT discovery of Swift J221951−484240

T2 - a UV luminous ambiguous nuclear transient

AU - Oates, S. R.

AU - Kuin, N. P.M.

AU - Nicholl, M.

AU - Marshall, F.

AU - Ridley, E.

AU - Boutsia, K.

AU - Breeveld, A. A.

AU - Buckley, D. A.H.

AU - Cenko, S. B.

AU - De Pasquale, M.

AU - Edwards, P. G.

AU - Gromadzki, M.

AU - Gupta, R.

AU - Laha, S.

AU - Morrell, N.

AU - Orio, M.

AU - Pandey, S. B.

AU - Page, M. J.

AU - Page, K. L.

AU - Parsotan, T.

AU - Rau, A.

AU - Schady, P.

AU - Stevens, J.

AU - Brown, P. J.

AU - Evans, P. A.

AU - Gronwall, C.

AU - Kennea, J. A.

AU - Klingler, N. J.

AU - Siegel, M. H.

AU - Tohuvavohu, A.

AU - Ambrosi, E.

AU - Barthelmy, S. D.

AU - Beardmore, A. P.

AU - Bernardini, M. G.

AU - Bonnerot, C.

AU - Campana, S.

AU - Caputo, R.

AU - Ciroi, S.

AU - Cusumano, G.

AU - Aì, A. D.

AU - Avanzo, P. D.

AU - Elia, V. D.

AU - Giommi, P.

AU - Hartmann, D. H.

AU - Krimm, H. A.

AU - Malesani, D. B.

AU - Melandri, A.

AU - Nousek, J. A.

AU - Brien, P. T.O.

AU - Osborne, J. P.

AU - Pagani, C.

AU - Palmer, D. M.

AU - Perri, M.

AU - Racusin, J. L.

AU - Sakamoto, T.

AU - Sbarufatti, B.

AU - Schlieder, J. E.

AU - Tagliaferri, G.

AU - Troja, E.

AU - Xu, D.

PY - 2024/5/1

Y1 - 2024/5/1

N2 - We report the discovery of Swift J221951−484240 (hereafter: J221951), a luminous slow-evolving blue transient that was detected by the Neil Gehrels Swift Observatory Ultraviolet/Optical Telescope (Swift/UVOT) during the follow-up of gravitational wave alert S190930t, to which it is unrelated. Swift/UVOT photometry shows the UV spectral energy distribution of the transient to be well modelled by a slowly shrinking blackbody with an approximately constant temperature of T ∼ 2.5 × 104 K. At a redshift z = 0.5205, J221951 had a peak absolute magnitude of Mu,AB = −23 mag, peak bolometric luminosity Lmax = 1.1 × 1045 erg s−1 and a total radiated energy of E > 2.6 × 1052 erg. The archival Wide-field Infrared Survey Explorer IR photometry shows a slow rise prior to a peak near the discovery date. Spectroscopic UV observations display broad absorption lines in N V and O VI, pointing towards an outflow at coronal temperatures. The lack of emission in the higher H α lines, N I and other neutral lines is consistent with a viewing angle close to the plane of the accretion or debris disc. The origin of J221951 cannot be determined with certainty but has properties consistent with a tidal disruption event and the turn-on of an active galactic nucleus.

AB - We report the discovery of Swift J221951−484240 (hereafter: J221951), a luminous slow-evolving blue transient that was detected by the Neil Gehrels Swift Observatory Ultraviolet/Optical Telescope (Swift/UVOT) during the follow-up of gravitational wave alert S190930t, to which it is unrelated. Swift/UVOT photometry shows the UV spectral energy distribution of the transient to be well modelled by a slowly shrinking blackbody with an approximately constant temperature of T ∼ 2.5 × 104 K. At a redshift z = 0.5205, J221951 had a peak absolute magnitude of Mu,AB = −23 mag, peak bolometric luminosity Lmax = 1.1 × 1045 erg s−1 and a total radiated energy of E > 2.6 × 1052 erg. The archival Wide-field Infrared Survey Explorer IR photometry shows a slow rise prior to a peak near the discovery date. Spectroscopic UV observations display broad absorption lines in N V and O VI, pointing towards an outflow at coronal temperatures. The lack of emission in the higher H α lines, N I and other neutral lines is consistent with a viewing angle close to the plane of the accretion or debris disc. The origin of J221951 cannot be determined with certainty but has properties consistent with a tidal disruption event and the turn-on of an active galactic nucleus.

UR - http://www.scopus.com/inward/record.url?scp=85191195877&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85191195877&partnerID=8YFLogxK

U2 - 10.1093/mnras/stae795

DO - 10.1093/mnras/stae795

M3 - Article

AN - SCOPUS:85191195877

SN - 0035-8711

VL - 530

SP - 1688

EP - 1710

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 2

ER -

Swift/UVOT discovery of Swift J221951−484240: a UV luminous ambiguous nuclear transient

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