Abstract
Radio observations of tidal disruption events (TDEs)—when a star is tidally disrupted by a supermassive black hole (SMBH)—provide a unique laboratory for studying outflows in the vicinity of SMBHs and their connection to accretion onto the supermassive black hole. Radio emission has been detected in only a handful of TDEs so far. Here we report the detection of delayed radio flares from an optically discovered TDE. Our prompt radio observations of the TDE ASASSN-15oi showed no radio emission until the detection of a flare six months later, followed by a second and brighter flare years later. We find that the standard scenario, in which an outflow is launched briefly after the stellar disruption, is unable to explain the combined temporal and spectral properties of the delayed flare. We suggest that the flare is due to the delayed ejection of an outflow, perhaps following a transition in accretion states. Our discovery motivates observations of TDEs at various timescales and highlights a need for new models.
Similar content being viewed by others
Data availability
The ASASSN-15oi radio data, presented in several figures, can be found in Supplementary Table 1. The raw VLA data are available via the NRAO archive at https://archive.nrao.edu/archive/advquery.jsp. The collection of radio data of other TDEs can be found in ref. 35. The ASASSN-15oi X-ray emission measurements can be found in ref. 25. Any additional data that support the findings of this study are available from the corresponding author upon reasonable request.
Code availability
Tools to analyse the VLA data can be found on the NRAO website at http://go.nature.com/2MEGye3.
References
van Velzen, S., Holoien, T. W. S., Onori, F., Hung, T. & Arcavi, I. Optical-ultraviolet tidal disruption events. Space Sci. Rev. 216, 124 (2020).
Rees, M. J. Tidal disruption of stars by black holes of 106–108 solar masses in nearby galaxies. Nature 333, 523–528 (1988).
Piran, T., Svirski, G., Krolik, J., Cheng, R. M. & Shiokawa, H. Disk formation versus disk accretion—what powers tidal disruption events? Astrophys. J. 806, 164 (2015).
Jiang, Y.-F., Guillochon, J. & Loeb, A. Prompt radiation and mass outflows from the stream-stream collisions of tidal disruption events. Astrophys. J. 830, 125 (2016).
Guillochon, J. & Ramirez-Ruiz, E. A dark year for tidal disruption events. Astrophys. J. 809, 166 (2015).
Bonnerot, C., Rossi, E. M., Lodato, G. & Price, D. J. Disc formation from tidal disruptions of stars on eccentric orbits by Schwarzschild black holes. Mon. Not. R. Astron. Soc. 455, 2253–2266 (2016).
Levan, A. J. et al. An extremely luminous panchromatic outburst from the nucleus of a distant galaxy. Science 333, 199–202 (2011).
Bloom, J. S. et al. A possible relativistic jetted outburst from a massive black hole fed by a tidally disrupted star. Science 333, 203–206 (2011).
Burrows, D. N. et al. Relativistic jet activity from the tidal disruption of a star by a massive black hole. Nature 476, 421–424 (2011).
Alexander, K. D., Berger, E., Guillochon, J., Zauderer, B. A. & Williams, P. K. G. Discovery of an outflow from radio observations of the tidal disruption event ASASSN-14li. Astrophys. J. 819, L25 (2016).
van Velzen, S. et al. A radio jet from the optical and X-ray bright stellar tidal disruption flare ASASSN-14li. Science 351, 62–65 (2016).
Holoien, T. W. S. et al. Six months of multiwavelength follow-up of the tidal disruption candidate ASASSN-14li and implied TDE rates from ASAS-SN. Mon. Not. R. Astron. Soc. 455, 2918–2935 (2016).
Krolik, J., Piran, T., Svirski, G. & Cheng, R. M. ASASSN-14li: a model tidal disruption event. Astrophys. J. 827, 127 (2016).
Yalinewich, A., Steinberg, E., Piran, T. & Krolik, J. H. Radio emission from the unbound debris of tidal disruption events. Mon. Not. R. Astron. Soc. 487, 4083–4092 (2019).
Zauderer, B. A. et al. Birth of a relativistic outflow in the unusual γ-ray transient Swift J164449.3+573451. Nature 476, 425–428 (2011).
Berger, E. et al. Radio monitoring of the tidal disruption event Swift J164449.3+573451. I. Jet energetics and the pristine parsec-scale environment of a supermassive black hole. Astrophys. J. 748, 36 (2012).
Mattila, S. et al. A dust-enshrouded tidal disruption event with a resolved radio jet in a galaxy merger. Science 361, 482–485 (2018).
Anderson, M. M. et al. Caltech-NRAO Stripe 82 Survey (CNSS). III. The first radio-discovered tidal disruption event, CNSS J0019+00. Astrophys. J. 903, 116 (2020).
Stein, R. et al. A tidal disruption event coincident with a high-energy neutrino. Nat. Astron. https://doi.org/10.1038/s41550-020-01295-8 (2020).
Kochanek, C. S. et al. The All-Sky Automated Survey for Supernovae (ASAS-SN) light curve server v1.0. Publ. Astron. Soc. Pac. 129, 104502 (2017).
Holoien, T. W. S. et al. ASASSN-15oi: a rapidly evolving, luminous tidal disruption event at 216 Mpc. Mon. Not. R. Astron. Soc. 463, 3813–3828 (2016).
Smartt, S. J. et al. PESSTO: survey description and products from the first data release by the Public ESO Spectroscopic Survey of Transient Objects. Astron. Astrophys. 579, A40 (2015).
Prentice, S. et al. PESSTO spectroscopic classification of optical transients. Astron. Telegr. 7936 (2015).
Arcavi, I. et al. Swift observations of the TDE ASASSN-15oi. Astron. Telegr. 7945 (2015).
Gezari, S., Cenko, S. B. & Arcavi, I. X-ray brightening and UV fading of tidal disruption event ASASSN-15oi. Astrophys. J. 851, L47 (2017).
Holoien, T. W. S. et al. The unusual late-time evolution of the tidal disruption event ASASSN-15oi. Mon. Not. R. Astron. Soc. 480, 5689–5703 (2018).
Shiokawa, H., Krolik, J. H., Cheng, R. M., Piran, T. & Noble, S. C. General relativistic hydrodynamic simulation of accretion flow from a stellar tidal disruption. Astrophys. J. 804, 85 (2015).
Dai, L., McKinney, J. C. & Miller, M. C. Soft X-ray temperature tidal disruption events from stars on deep plunging orbits. Astrophys. J. 812, L39 (2015).
Lacy, M. et al. The Karl G. Jansky Very Large Array Sky Survey (VLASS). Science case and survey design. Publ. Astron. Soc. Pac. 132, 035001 (2020).
O’Dea, C. P. et al. Multifrequency VLA observations of GHz-peaked-spectrum radio cores. Astron. Astrophys. Supp. 84, 549–562 (1990).
Giannios, D. & Metzger, B. D. Radio transients from stellar tidal disruption by massive black holes. Mon. Not. R. Astron. Soc. 416, 2102–2107 (2011).
Metzger, B. D., Giannios, D. & Mimica, P. Afterglow model for the radio emission from the jetted tidal disruption candidate Swift J1644+57. Mon. Not. R. Astron. Soc. 420, 3528–3537 (2012).
Chevalier, R. A. Synchrotron self-absorption in radio supernovae. Astrophys. J. 499, 810–819 (1998).
Generozov, A. et al. The influence of circumnuclear environment on the radio emission from TDE jets. Mon. Not. R. Astron. Soc. 464, 2481–2498 (2017).
Alexander, K. D., van Velzen, S., Horesh, A. & Zauderer, B. A. Radio properties of tidal disruption events. Space Sci. Rev. 216, 81 (2020).
van Eerten, H., van der Horst, A. & MacFadyen, A. Gamma-ray burst afterglow broadband fitting based directly on hydrodynamics simulations. Astrophys. J. 749, 44 (2012).
Mimica, P., Giannios, D., Metzger, B. D. & Aloy, M. A. The radio afterglow of Swift J1644+57 reveals a powerful jet with fast core and slow sheath. Mon. Not. R. Astron. Soc. 450, 2824–2841 (2015).
Granot, J. & van der Horst, A. J. Gamma-ray burst jets and their radio observations. Publ. Astron. Soc. Aust. 31, e008 (2014).
Harris, C. E., Nugent, P. E. & Kasen, D. N. Against the wind: radio light curves of type Ia supernovae interacting with low-density circumstellar shells. Astrophys. J. 823, 100 (2016).
Guillochon, J. & Ramirez-Ruiz, E. Hydrodynamical simulations to determine the feeding rate of black holes by the tidal disruption of stars: the importance of the impact parameter and stellar structure. Astrophys. J. 767, 25 (2013).
Campana, S. et al. Multiple tidal disruption flares in the active galaxy IC 3599. Astron. Astrophys. 581, A17 (2015).
Coughlin, E. R., Armitage, P. J., Nixon, C. & Begelman, M. C. Tidal disruption events from supermassive black hole binaries. Mon. Not. R. Astron. Soc. 465, 3840–3864 (2017).
Dunn, R. J. H., Fender, R. P., Körding, E. G., Belloni, T. & Cabanac, C. A global spectral study of black hole X-ray binaries. Mon. Not. R. Astron. Soc. 403, 61–82 (2010).
Maccarone, T. J. Do X-ray binary spectral state transition luminosities vary? Astron. Astrophys. 409, 697–706 (2003).
Tetarenko, B. E., Sivakoff, G. R., Heinke, C. O. & Gladstone, J. C. WATCHDOG: a comprehensive all-sky database of galactic black hole X-ray binaries. Astrophys. J. Supp. 222, 15 (2016).
Fender, R. P., Belloni, T. M. & Gallo, E. Towards a unified model for black hole X-ray binary jets. Mon. Not. R. Astron. Soc. 355, 1105–1118 (2004).
King, A. L. et al. Discrete knot ejection from the jet in a nearby low-luminosity active galactic nucleus, M81*. Nat. Phys. 12, 772–777 (2016).
Fromm, C. M. et al. Catching the radio flare in CTA 102. I. Light curve analysis. Astron. Astrophys. 531, A95 (2011).
Marscher, A. P. & Gear, W. K. Models for high-frequency radio outbursts in extragalactic sources, with application to the early 1983 millimeter-to-infrared flare of 3C 273. Astrophys. J. 298, 114–127 (1985).
Falcke, H., Körding, E. & Markoff, S. A scheme to unify low-power accreting black holes. Jet-dominated accretion flows and the radio/X-ray correlation. Astron. Astrophys. 414, 895–903 (2004).
Bright, J. S. et al. An extremely powerful long-lived superluminal ejection from the black hole MAXI J1820+070. Nat. Astron. 4, 697–703 (2020).
McMullin, J. P., Waters, B., Schiebel, D., Young, W. & Golap, K. in Astronomical Data Analysis Software and Systems XVI (eds Shaw, R. A. et al.) 127–130 (ASP, 2007).
Weiler, K. W., Panagia, N., Montes, M. J. & Sramek, R. A. Radio emission from supernovae and gamma-ray bursters. Annu. Rev. Astron. Astrophys. 40, 387–438 (2002).
Barniol Duran, R., Nakar, E. & Piran, T. Radius constraints and minimal equipartition energy of relativistically moving synchrotron sources. Astrophys. J. 772, 78 (2013).
Björnsson, C. I. & Keshavarzi, S. T. Inhomogeneities and the modeling of radio supernovae. Astrophys. J. 841, 12 (2017).
Chandra, P. et al. Type Ib supernova master OT J120451.50+265946.6: radio-emitting shock with inhomogeneities crossing through a dense shell. Astrophys. J. 877, 79 (2019).
O’Dea, C. P. The compact steep-spectrum and gigahertz peaked-spectrum radio sources. Publ. Astron. Soc. Pac. 110, 493–532 (1998).
Chevalier, R. A. & Fransson, C. Circumstellar emission from type Ib and Ic supernovae. Astrophys. J. 651, 381 (2006).
Granot, J., De Colle, F. & Ramirez-Ruiz, E. Off-axis afterglow light curves and images from 2D hydrodynamic simulations of double-sided GRB jets in a stratified external medium. Mon. Not. R. Astron. Soc. 481, 2711–2720 (2018).
Alexander, K. D., Wieringa, M. H., Berger, E., Saxton, R. D. & Komossa, S. Radio observations of the tidal disruption event XMMSL1 J0740-85. Astrophys. J. 837, 153 (2017).
Irwin, J. A. et al. CHANG-ES V: nuclear outflow in a Virgo Cluster spiral after a tidal disruption event. Astrophys. J. 809, 172 (2015).
Acknowledgements
We thank T. Piran, E. Nakar and R. Fender for useful discussions. A.H. was suported by grants from the I-CORE Program of the Planning and Budgeting Committee and the Israel Science Foundation (ISF), and from the US–Israel Binational Science Foundation (BSF). I.A. is a CIFAR Azrieli Global Scholar in the Gravity and the Extreme Universe Program and acknowledges support from that program, from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement number 852097), from the Israel Science Foundation (grant number 2752/19), from the United States – Israel Binational Science Foundation (BSF), and from the Israeli Council for Higher Education Alon Fellowship. We thank the NRAO staff for approving and scheduling the VLA observations. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. We thank the Swift TOO team. This research has made use of data and/or software provided by the High Energy Astrophysics Science Archive Research Center (HEASARC), which is a service of the Astrophysics Science Division at NASA/GSFC. This research has made use of the CIRADA cutout service at http://cutouts.cirada.ca/, operated by the Canadian Initiative for Radio Astronomy Data Analysis (CIRADA). CIRADA is funded by a grant from the Canada Foundation for Innovation 2017 Innovation Fund (Project 35999), as well as by the Provinces of Ontario, British Columbia, Alberta, Manitoba and Quebec, in collaboration with the National Research Council of Canada, the US National Radio Astronomy Observatory and Australia’s Commonwealth Scientific and Industrial Research Organisation.
Author information
Authors and Affiliations
Contributions
A.H. led the radio observing campaign, the data analysis and modelling, the interpretation and the manuscript preparation. S.B.C and I.A. contributed to the interpretation of the results and to the manuscript preparation.
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing interests.
Additional information
Peer review information Nature Astronomy thanks Miguel Perez Torres, Elad Steinberg and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Extended data
Extended Data Fig. 1 VLA K-band images of the position of the optical TDE candidate ASASSN-15oi, before and after radio detection.
The left panel (a) presents the third VLA image we obtained of this field 3 months after optical discovery on 2015 Nov 12, still showing a null-detection. The right panel (b) presents the image from our forth VLA observation on 2016 Feb 12 which reveals a delayed radio flare, 6 months after optical discovery. The synthesized beam size is shown as a white ellipse at the bottom left corner of the images. The flux density scale is identical in both images.
Extended Data Fig. 2 The full observed broadband spectral evolution of the delayed radio flare from ASASSN-15oi.
Each of the radio broadband spectra is from a different observing epoch, starting from the initial detection of the delayed flare on 182 days and up to 576 days after optical discovery. Data from each epoch is represented by a different marker shape and color as noted in the legend (a dashed line connecting the data has been added for convenience). The error bars represent the image noise and flux calibration error added in quadrature (see Supplementary Table 1).
Extended Data Fig. 3 Best fit single-epoch spectral models of the radio flare.
Observing epochs at Δt=182, 190, 197 days are represented in purple, yellow and red, respectively. The broadband spectrum in each single epoch was fitted independently, thus not including any modeling of the temporal evolution. The errors of the data modeled here include the flux density calibration error and image noise added in quadrature. The left panel (a) presents the best-fit homogeneous SSA model33. The middle panel (b) shows the best-fit models of the radio flare spectra using the internal free-free absorption model53. The right panel (c) is the best-fit models using the inhomogeneous SSA model55. Out of the three models that we try here, the latter model is the best match to the spectral data presented in this figure (see details in Methods).
Extended Data Fig. 4 Comparison of the temporal evolution of the observed optically thin radio emission with different rising and declining power-law functions.
The presented radio emission is at a frequency of 15 GHz (black solid line and markers). The various power-law functions for both the rise of the emission (since the last non-detection) and its decline are presented as dashed curves (representing various predictions, see details in Methods). The black triangle represents a 3σ non-detection limit (based on the average between the 22 GHz and 6 GHz limits).
Supplementary information
Supplementary Information
Supplementary Table 1.
Rights and permissions
About this article
Cite this article
Horesh, A., Cenko, S.B. & Arcavi, I. Delayed radio flares from a tidal disruption event. Nat Astron 5, 491–497 (2021). https://doi.org/10.1038/s41550-021-01300-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/s41550-021-01300-8
- Springer Nature Limited