# Linking gravitational waves and X-ray phenomena with joint LISA and Athena observations

## Abstract

The evolution of cosmic structures, the formation and growth of the first black holes and the connection to their baryonic environment are key unsolved problems in astrophysics. The X-ray Athena mission and the gravitational-wave Laser Interferometer Space Antenna (LISA) offer independent and complementary angles on these problems. We show that up to about 10 black hole binaries in the mass range of approximately 105 to 108 solar masses discovered by LISA at redshift below about 3.5 could be detected by Athena in an exposure time up to 100 ks, if prompt X-ray emission of 1–10% of the Eddington luminosity is present. Likewise, if any LISA-detected extreme-mass-ratio inspirals occur in accretion disks, Athena can detect associated electromagnetic emission out to a redshift of about 1. Finally, warned by LISA, Athena can point in advance and stare at stellar-mass binary black hole mergers at redshift less than about 0.1. These science opportunities emphasize the vast discovery space of simultaneous observations from the two observatories, which would be missed if they were operated in different epochs.

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The source data used in the figures are available on request from the corresponding author.

## References

1. 1.

Abbott, B. P. et al. GW170817: observation of gravitational waves from a binary neutron star inspiral. Phys. Rev. Lett. 119, 161101 (2017).

2. 2.

Abbott, B. P. et al. Gravitational waves and gamma-rays from a binary neutron star merger: GW170817 and GRB 170817A. Astrophys. J. Lett. 848, L13 (2017).

3. 3.

Coulter, D. A. et al. Swope Supernova Survey 2017a (SSS17a), the optical counterpart to a gravitational wave source. Science 358, 1556–1558 (2017).

4. 4.

Abbott, B. P. et al. Multi-messenger observations of a binary neutron star merger. Astrophys. J. Lett. 848, L12 (2017).

5. 5.

Abbott, B. P. et al. A gravitational-wave standard siren measurement of the Hubble constant. Nature 551, 85–88 (2017).

6. 6.

Mooley, K. P. et al. Superluminal motion of a relativistic jet in the neutron-star merger GW170817. Nature 561, 355–359 (2018).

7. 7.

Ghirlanda, G. et al. Compact radio emission indicates a structured jet was produced by a binary neutron star merger. Science 363, 968–971 (2019).

8. 8.

Amaro-Seoane, P. et al. Laser Interferometer Space Antenna. Preprint at https://arxiv.org/abs/1702.00786 (2017).

9. 9.

Klein, A. et al. Science with the space-based interferometer eLISA: supermassive black hole binaries. Phys. Rev. D. 93, 024003 (2016).

10. 10.

Aird, J. et al. The hot and energetic Universe: the formation and growth of the earliest supermassive black holes. Preprint at https://arxiv.org/abs/1306.2325 (2013).

11. 11.

Nandra, K. et al. The hot and energetic Universe: a White Paper presenting the science theme motivating the Athena+ mission. Preprint at https://arxiv.org/abs/1306.2307 (2013).

12. 12.

LSST Science Collaboration et al. LSST Science Book, Version 2.0. Preprint at https://arxiv.org/abs/0912.0201 (2009).

13. 13.

Dewdney, P. E., Hall, P. J., Schilizzi, R. T. & Lazio, T. J. L. W. The Square Kilometre Array. Proc. IEEE 97, 1482–1496 (2009).

14. 14.

Volonteri, M., Haardt, F. & Madau, P. The assembly and merging history of supermassive black holes in hierarchical models of galaxy formation. Astrophys. J. 582, 559–573 (2003).

15. 15.

Sesana, A., Haardt, F., Madau, P. & Volonteri, M. Low-frequency gravitational radiation from coalescing massive black hole binaries in hierarchical cosmologies. Astrophys. J. 611, 623–632 (2004).

16. 16.

Barack, L. & Cutler, C. LISA capture sources: approximate waveforms, signal-to-noise ratios, and parameter estimation accuracy. Phys. Rev. D. 69, 082005 (2004).

17. 17.

Amaro-Seoane, P. et al. Topical Review: Intermediate and extreme mass-ratio inspirals: astrophysics, science applications and detection using LISA. Class. Quantum Gravity 24, R113–R169 (2007).

18. 18.

Sesana, A. Prospects for multiband gravitational-wave astronomy after GW150914. Phys. Rev. Lett. 116, 231102 (2016).

19. 19.

Armitage, P. J. & Natarajan, P. Accretion during the merger of supermassive black holes. Astrophys. J. Lett. 567, L9–L12 (2002).

20. 20.

Milosavljević, M. & Phinney, E. S. The afterglow of massive black hole coalescence. Astrophys. J. Lett. 622, L93–L96 (2005).

21. 21.

Chang, P., Strubbe, L. E., Menou, K. & Quataert, E. Fossil gas and the electromagnetic precursor of supermassive binary black hole mergers. Mon. Not. R. Astron. Soc. 407, 2007–2016 (2010).

22. 22.

Palenzuela, C., Lehner, L. & Liebling, S. L. Dual jets from binary black holes. Science 329, 927–930 (2010).

23. 23.

Bode, T., Haas, R., Bogdanović, T., Laguna, P. & Shoemaker, D. Relativistic mergers of supermassive black holes and their electromagnetic signatures. Astrophys. J. 715, 1117–1131 (2010).

24. 24.

Gold, R. et al. Accretion disks around binary black holes of unequal mass: general relativistic MHD simulations of postdecoupling and merger. Phys. Rev. D. 90, 104030 (2014).

25. 25.

Cerioli, A., Lodato, G. & Price, D. J. Gas squeezing during the merger of a supermassive black hole binary. Mon. Not. R. Astron. Soc. 457, 939–948 (2016).

26. 26.

Tang, Y., Haiman, Z. & MacFadyen, A. The late inspiral of supermassive black hole binaries with circumbinary gas discs in the LISA band. Mon. Not. R. Astron. Soc. 476, 2249–2257 (2018).

27. 27.

d’Ascoli, S. et al. Electromagnetic emission from supermassive binary black holes approaching merger. Astrophys. J. 865, 140 (2018).

28. 28.

Rau, A. et al. The hot and energetic Universe: the Wide Field Imager (WFI) for Athena+. Preprint at https://arxiv.org/abs/1308.6785 (2013).

29. 29.

Barausse, E. The evolution of massive black holes and their spins in their galactic hosts. Mon. Not. R. Astron. Soc. 423, 2533–2557 (2012).

30. 30.

Santamaría, L. et al. Matching post-Newtonian and numerical relativity waveforms: systematic errors and a new phenomenological model for nonprecessing black hole binaries. Phys. Rev. D. 82, 064016 (2010).

31. 31.

Reeves, J. N. & Turner, M. J. L. X-ray spectra of a large sample of quasars with ASCA. Mon. Not. R. Astron. Soc. 316, 234–248 (2000).

32. 32.

Lusso, E. et al. Bolometric luminosities and Eddington ratios of X-ray selected active galactic nuclei in the XMM-COSMOS survey. Mon. Not. R. Astron. Soc. 425, 623–640 (2012).

33. 33.

Barnes, J. E. & Hernquist, L. Transformations of galaxies. II. Gasdynamics in merging disk galaxies. Astrophys. J. 471, 115 (1996).

34. 34.

Hopkins, P. F., Hernquist, L., Cox, T. J. & Kereš, D. A cosmological framework for the co-evolution of quasars, supermassive black holes, and elliptical galaxies. I. Galaxy mergers and quasar activity. Astrophys. J. Suppl. 175, 356–389 (2008).

35. 35.

Shankar, F., Weinberg, D. H. & Miralda-Escudé, J. Accretion-driven evolution of black holes: Eddington ratios, duty cycles and active galaxy fractions. Mon. Not. R. Astron. Soc. 428, 421–446 (2013).

36. 36.

Rossi, E. M., Lodato, G., Armitage, P. J., Pringle, J. E. & King, A. R. Black hole mergers: the first light. Mon. Not. R. Astron. Soc. 401, 2021–2035 (2010).

37. 37.

Blandford, R. D. & Znajek, R. L. Electromagnetic extraction of energy from Kerr black holes. Mon. Not. R. Astron. Soc. 179, 433–456 (1977).

38. 38.

Babak, S. et al. Science with the space-based interferometer LISA. V. Extreme mass-ratio inspirals. Phys. Rev. D. 95, 103012 (2017).

39. 39.

Gair, J. R., Tang, C. & Volonteri, M. LISA extreme-mass-ratio inspiral events as probes of the black hole mass function. Phys. Rev. D. 81, 104014 (2010).

40. 40.

Levin, Y. Starbursts near supermassive black holes: young stars in the Galactic Centre, and gravitational waves in LISA band. Mon. Not. R. Astron. Soc. 374, 515–524 (2007).

41. 41.

Yunes, N., Kocsis, B., Loeb, A. & Haiman, Z. Imprint of accretion disk-induced migration on gravitational waves from extreme mass ratio inspirals. Phys. Rev. Lett. 107, 171103 (2011).

42. 42.

Barausse, E., Cardoso, V. & Pani, P. Can environmental effects spoil precision gravitational-wave astrophysics? Phys. Rev. D. 89, 104059 (2014).

43. 43.

McKernan, B., Ford, K. E. S., Kocsis, B. & Haiman, Z. Ripple effects and oscillations in the broad Fe Kα line as a probe of massive black hole mergers. Mon. Not. R. Astron. Soc. 432, 1468–1482 (2013).

44. 44.

Reines, A. E., Greene, J. E. & Geha, M. Dwarf galaxies with optical signatures of active massive black holes. Astrophys. J. 775, 116 (2013).

45. 45.

Del Pozzo, W., Sesana, A. & Klein, A. Stellar binary black holes in the LISA band: a new class of standard sirens. Mon. Not. R. Astron. Soc. 475, 3485–3492 (2018).

46. 46.

Punturo, M. et al. The Einstein Telescope: a third-generation gravitational wave observatory. Class. Quantum Gravity 27, 194002 (2010).

47. 47.

Abbott, B. P. et al. Exploring the sensitivity of next generation gravitational wave detectors. Class. Quantum Gravity 34, 044001 (2017).

48. 48.

Kawai, N. et al. X-ray upper limits of GW150914 with MAXI. Publ. Astron. Soc. Jpn 69, 84 (2017).

49. 49.

Michaely, E. & Perets, H. B. Supernova and prompt gravitational-wave precursors to LIGO gravitational-wave sources and short GRBs. Astrophys. J. Lett. 855, L12 (2018).

50. 50.

Perna, R., Lazzati, D. & Giacomazzo, B. Short gamma-ray bursts from the merger of two black holes. Astrophys. J. Lett. 821, L18 (2016).

51. 51.

de Mink, S. E. & King, A. Electromagnetic signals following stellar-mass black hole mergers. Astrophys. J. Lett. 839, L7 (2017).

## Acknowledgements

S.McG. acknowledges the support of the UK Science and Technology Facilities Council (STFC); A.S. is supported by a University Research Fellowship of the Royal Society; A.V. acknowledges support from STFC, UK Space Agency, the Royal Society and the Wolfson Foundation. We thank E. Barausse for providing the MBHB population models discussed in the text.

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Correspondence to Sean McGee.

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McGee, S., Sesana, A. & Vecchio, A. Linking gravitational waves and X-ray phenomena with joint LISA and Athena observations. Nat Astron 4, 26–31 (2020). https://doi.org/10.1038/s41550-019-0969-7

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