The Next Steps for Primordial Black Hole Research

Authors: (1) Antonio Riotto, Département de Physique Theorique, Universite de Geneve, 24 quai Ansermet, CH-1211 Geneve 4, Switzerland and Gravitational Wave Science Center (GWSC), Universite de Geneve, CH-1211 Geneva, Switzerland; (2) Joe Silk, Institut d’Astrophysique, UMR 7095 CNRS, Sorbonne Universite, 98bis Bd Arago, 75014 Paris, France, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore MD 21218, USA, and Beecroft Institute of Particle Astrophysics and Cosmology, Department of Physics, University of Oxford, Oxford OX1 3RH, UK. Table of Links Abstract and 1 Introduction 2 Some open questions 2.1 What is the abundance of PBHs? 2.2 What is the effect of PBH clustering? 2.3 What fraction of the currently observed GW events can be ascribed to PBHs? 2.4 Are PBHs the Dark Matter? 3 The PBH Roadmap 3.1 High redshift mergers 3.2 Sub-solar PBHs 3.3 Plugging the pair instability gap with PBH? 3.4 PBH eccentricity, 3.5 PBH spin and 3.6 Future gamma-ray telescopes 4 Conclusions and References 4 Conclusions Support for the existence of PBHs hypothesis comes from a range of arguments spanning dark matter physics, inflationary models, astrophysics, gravitational microlensing and quantum cosmology. None are yet conclusive but the cumulative support for the existence of PBHs seems reasonably compelling. More to the point however is that there is a rich astrophysical agenda of open questions that contribute to a future road map for a plethora of research projects. Two of the most fundamental PBH probes that distinguish them from astrophysical counterparts are their redshift and mass distributions. This combination provides an armoury of smoking guns that will inevitably enrich the next generation of gravitational wave and gravitational microlensing experiments. Confirmation will require improved statistics as single events may not be conclusive. it is only too easy to come up with rare events that can masquerade as PBH candidates, for example by appealing to higher order generations of merging events or to non-Gaussianity. We have laid out a possible future road map for definitively assessing whether PBHs can present a viable candidate for dark matter, or possibly contribute to other astrophysical or even quantum cosmology anomalies. References [1] A. Ianniccari, A. J. Iovino, A. Kehagias, D. Perrone, and A. Riotto. The Primordial Black Hole Abundance: The Broader, the Better. 2 2024. [2] Albert Escriv`a, Cristiano Germani, and Ravi K. Sheth. Universal threshold for primordial black hole formation. Phys. Rev. D, 101(4):044022, 2020. [3] Valerio De Luca, Alex Kehagias, and Antonio Riotto. How well do we know the primordial black hole abundance: The crucial role of nonlinearities when approaching the horizon. Phys. Rev. D, 108(6):063531, 2023. [4] Gabriele Franciolini, Andrea Ianniccari, Alex Kehagias, Davide Perrone, and Antonio Riotto. Renormalized Primordial Black Holes. 11 2023. [5] Marcos M. Flores, Alexander Kusenko, and Misao Sasaki. Revisiting formation of primordial black holes in a supercooled first-order phase transition. 2 2024. [6] V. De Luca, V. Desjacques, G. Franciolini, A. Malhotra, and A. Riotto. The initial spin probability distribution of primordial black holes. JCAP, 05:018, 2019. [7] V. De Luca, G. Franciolini, P. Pani, and A. Riotto. Constraints on Primordial Black Holes: the Importance of Accretion. Phys. Rev. D, 102(4):043505, 2020. [8] Yacine Ali-Ha¨ımoud. Correlation function of high-threshold regions and application to the initial small-scale clustering of primordial black holes. Physical Review Letters, 121(8), aug 2018. [9] Vincent Desjacques and Antonio Riotto. Spatial clustering of primordial black holes. Phys. Rev. D, 98(12):123533, 2018. [10] Derek Inman and Yacine Ali-Ha¨ımoud. Early structure formation in primordial black hole cosmologies. Phys. Rev. D, 100(8):083528, 2019. [11] Bernard Carr and Joseph Silk. Primordial black holes as generators of cosmic structures. Monthly Notices of the Royal Astronomical Society, 478(3):3756–3775, May 2018. [12] Joseph Silk, Mitchell Begelman, Colin Norman, Adi Nusser, and Rosemary Wyse. Which came first: supermassive black holes or galaxies? insights from jwst, 2024. [13] Gabriele Franciolini, Vishal Baibhav, Valerio De Luca, Ken K. Y. Ng, Kaze W. K. Wong, Emanuele Berti, Paolo Pani, Antonio Riotto, and Salvatore Vitale. Searching for a subpopulation of primordial black holes in LIGO-Virgo gravitational-wave data. Phys. Rev. D, 105(8):083526, 2022. [14] J. Iguaz, P.D. Serpico, and T. Siegert. Isotropic x-ray bound on primordial black hole dark matter. Physical Review D, 103(10), May 2021. [15] N. Bartolo, V. De Luca, G. Franciolini, M. Peloso, D. Racco, and A. Riotto. Testing primordial black holes as dark matter with LISA. Phys. Rev. D, 99(10):103521, 2019. [16] Chloe B. Richards, Thomas W. Baumgarte, and Stuart L. Shapiro. Accretion onto a small black hole at the center of a neutron star. Physical Review D, 103(10), May 2021. [17] Jason Dexter and Ryan M. O’Leary. The peculiar pulsar population of the central parsec. The Astrophysical Journal, 783(1):L7, February 2014. [18] Nicolas Esser, Sven De Rijcke, and Peter Tinyakov. The impact of primordial black holes on the stellar mass function of ultra-faint dwarf galaxies. 11 2023. [19] Jose A. de Freitas Pacheco, Elias Kiritsis, Matteo Lucca, and Joseph Silk. Quasiextremal primordial black holes are a viable dark matter candidate. Physical Review D, 107(12), June 2023. [20] Luis A. Anchordoqui, Ignatios Antoniadis, and Dieter L¨ust. Dark dimension, the swampland, and the dark matter fraction composed of primordial black holes. Phys. Rev. D, 106(8):086001, October 2022. [21] J. A. de Freitas Pacheco and Joseph Silk. Primordial Rotating Black Holes. Phys. Rev. D, 101(8):083022, 2020. [22] Ana Alexandre, Gia Dvali, and Emmanouil Koutsangelas. New Mass Window for Primordial Black Holes as Dark Matter from Memory Burden Effect. 2 2024. [23] Benjamin V. Lehmann, Christian Johnson, Stefano Profumo, and Thomas Schwemberger. Direct detection of primordial black hole relics as dark matter. Journal of Cosmology and Astroparticle Physics, 2019(10):046–046, October 2019. [24] Yang Bai and Nicholas Orlofsky. Primordial extremal black holes as dark matter. Physical Review D, 101(5), March 2020. [25] Guillem Dom`enech and Misao Sasaki. Probing primordial black hole scenarios with terrestrial gravitational wave detectors, 2024. [26] Seiji Kawamura et al. Current status of space gravitational wave antenna DECIGO and BDECIGO. PTEP, 2021(5):05A105, 2021. [27] Yungui Gong, Jun Luo, and Bin Wang. Concepts and status of chinese space gravitational wave detection projects. Nature Astronomy, 5(9):881–889, September 2021. [28] John Ellis, Malcolm Fairbairn, Juan Urrutia, and Ville Vaskonen. Probing supermassive black hole seed scenarios with gravitational wave measurements, 2023. [29] Joris van Heijningen et al. The payload of the Lunar Gravitational-wave Antenna. J. Appl. Phys., 133(24):244501, 2023. [30] John Ellis, Malcolm Fairbairn, Gabriele Franciolini, Gert H¨utsi, Antonio Iovino Jr. au2, Marek Lewicki, Martti Raidal, Juan Urrutia, Ville Vaskonen, and Hardi Veerm¨ae. What is the source of the pta gw signal?, 2023. [31] Yacine Ali-Ha¨ımoud, Ely D. Kovetz, and Marc Kamionkowski. Merger rate of primordial blackhole binaries. Phys. Rev. D, 96(12):123523, 2017. [32] Martti Raidal, Christian Spethmann, Ville Vaskonen, and Hardi Veerm¨ae. Formation and Evolution of Primordial Black Hole Binaries in the Early Universe. JCAP, 02:018, 2019. [33] V. De Luca, G. Franciolini, P. Pani, and A. Riotto. Primordial Black Holes Confront LIGO/Virgo data: Current situation. JCAP, 06:044, 2020. [34] Tomoya Kinugawa, Kohei Inayoshi, Kenta Hotokezaka, Daisuke Nakauchi, and Takashi Nakamura. Possible Indirect Confirmation of the Existence of Pop III Massive Stars by Gravitational Wave. Mon. Not. Roy. Astron. Soc., 442(4):2963–2992, 2014. [35] Tomoya Kinugawa, Akinobu Miyamoto, Nobuyuki Kanda, and Takashi Nakamura. The detection rate of inspiral and quasi-normal modes of Population III binary black holes which can confirm or refute the general relativity in the strong gravity region. Mon. Not. Roy. Astron. Soc., 456(1):1093– 1114, 2016. [36] Tilman Hartwig, Marta Volonteri, Volker Bromm, Ralf S. Klessen, Enrico Barausse, Mattis Magg, and Athena Stacy. Gravitational Waves from the Remnants of the First Stars. Mon. Not. Roy. Astron. Soc., 460(1):L74–L78, 2016. [37] K. Belczynski, T. Ryu, R. Perna, E. Berti, T. L. Tanaka, and T. Bulik. On the likelihood of detecting gravitational waves from Population III compact object binaries. Mon. Not. Roy. Astron. Soc., 471(4):4702–4721, 2017. [38] Kohei Inayoshi, Ryosuke Hirai, Tomoya Kinugawa, and Kenta Hotokezaka. Formation pathway of Population III coalescing binary black holes through stable mass transfer. Mon. Not. Roy. Astron. Soc., 468(4):5020–5032, 2017. [39] Boyuan Liu and Volker Bromm. The Population III origin of GW190521. Astrophys. J. Lett., 903(2):L40, 2020. [40] Boyuan Liu and Volker Bromm. Gravitational waves from Population III binary black holes formed by dynamical capture. Mon. Not. Roy. Astron. Soc., 495(2):2475–2495, 2020. [41] Tomoya Kinugawa, Takashi Nakamura, and Hiroyuki Nakano. Chirp Mass and Spin of Binary Black Holes from First Star Remnants. Mon. Not. Roy. Astron. Soc., 498(3):3946–3963, 2020. [42] Ataru Tanikawa, Hajime Susa, Takashi Yoshida, Alessandro A. Trani, and Tomoya Kinugawa. Merger rate density of Population III binary black holes below, above, and in the pair-instability mass gap. Astrophys. J., 910(1):30, 2021. [43] Neha Singh, Tomasz Bulik, Krzysztof Belczynski, and Abbas Askar. Exploring compact binary populations with the Einstein Telescope. Astron. Astrophys., 667:A2, 2022. [44] Savvas M. Koushiappas and Abraham Loeb. Maximum redshift of gravitational wave merger events. Phys. Rev. Lett., 119(22):221104, 2017. [45] V. De Luca, G. Franciolini, P. Pani, and A. Riotto. Bayesian Evidence for Both Astrophysical and Primordial Black Holes: Mapping the GWTC-2 Catalog to Third-Generation Detectors. JCAP, 05:003, 2021. [46] Ken K. Y. Ng, Shiqi Chen, Boris Goncharov, Ulyana Dupletsa, Ssohrab Borhanian, Marica Branchesi, Jan Harms, Michele Maggiore, B. S. Sathyaprakash, and Salvatore Vitale. On the Single-event-based Identification of Primordial Black Hole Mergers at Cosmological Distances. Astrophys. J. Lett., 931(1):L12, 2022. [47] Gabriele Franciolini, Roberto Cotesta, Nicholas Loutrel, Emanuele Berti, Paolo Pani, and Antonio Riotto. How to assess the primordial origin of single gravitational-wave events with mass, spin, eccentricity, and deformability measurements. Phys. Rev. D, 105(6):063510, 2022. [48] Matteo Martinelli, Francesca Scarcella, Natalie B. Hogg, Bradley J. Kavanagh, Daniele Gaggero, and Pierre Fleury. Dancing in the dark: detecting a population of distant primordial black holes. JCAP, 08(08):006, 2022. [49] Ken K. Y. Ng et al. Measuring properties of primordial black hole mergers at cosmological distances: Effect of higher order modes in gravitational waves. Phys. Rev. D, 107(2):024041, 2023. [50] Ken K. Y. Ng, Gabriele Franciolini, Emanuele Berti, Paolo Pani, Antonio Riotto, and Salvatore Vitale. Constraining High-redshift Stellar-mass Primordial Black Holes with Next-generation Ground-based Gravitational-wave Detectors. Astrophys. J. Lett., 933(2):L41, 2022. [51] Vitor Cardoso and Paolo Pani. Testing the nature of dark compact objects: a status report. Living Rev. Rel., 22(1):4, 2019. [52] Huai-Ke Guo, Kuver Sinha, and Chen Sun. Probing Boson Stars with Extreme Mass Ratio Inspirals. JCAP, 09:032, 2019. [53] Hiroko Niikura, Masahiro Takada, Shuichiro Yokoyama, Takahiro Sumi, and Shogo Masaki. Constraints on earth-mass primordial black holes from ogle 5-year microlensing events. Physical Review D, 99(8), April 2019. [54] Kaiki Taro Inoue and Takahiro Tanaka. Gravitational waves from sub-lunar-mass primordial black-hole binaries: A new probe of extra dimensions. Physical Review Letters, 91(2), July 2003. [55] The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, and R. Abbott et al. The population of merging compact binaries inferred using gravitational waves through gwtc-3, 2022. [56] Digvijay Wadekar, Javier Roulet, Tejaswi Venumadhav, Ajit Kumar Mehta, Barak Zackay, Jonathan Mushkin, Seth Olsen, and Matias Zaldarriaga. New black hole mergers in the ligovirgo o3 data from a gravitational wave search including higher-order harmonics, 2023. [57] Ilias Cholis, Ely D. Kovetz, Yacine Ali-Ha¨ımoud, Simeon Bird, Marc Kamionkowski, Julian B. Mu˜noz, and Alvise Raccanelli. Orbital eccentricities in primordial black hole binaries. Phys. Rev. D, 94(8):084013, 2016. [58] Yi-Fan Wang and Alexander H. Nitz. Prospects for detecting gravitational waves from eccentric subsolar mass compact binaries. Astrophys. J., 912(1):53, 2021. [59] Gabriele Franciolini and Paolo Pani. Searching for mass-spin correlations in the population of gravitational-wave events: The GWTC-3 case study. Phys. Rev. D, 105(12):123024, 2022. [60] Mrunal Korwar and Stefano Profumo. Updated constraints on primordial black hole evaporation. Journal of Cosmology and Astroparticle Physics, 2023(05):054, May 2023. [61] Henrike Fleischhack. Amego-x: Mev gamma-ray astronomy in the multimessenger era, 2021. [62] Manuela Mallamaci, A. De Angelis, V. Tatischeff, R. Rando, M. Tavani, U. Oberlack, R. Walter, G. Ambrosi, A. Argan, P. von Balmoos, D. Bastieri, E. Bernardini, S. Brandt, A. Bulgarelli, A. Bykov, V. Fioretti, I.A. Grenier, L. Hanlon, D. Hartmann, M. Hernanz, G. Kanbach, I. Kuvvetli, P. Laurent, M. Mariotti, M.N. Mazziotta, J. Mc Enery, S. Mereghetti, A. Morselli, K. Nakazawa, M. Pearce, E. Prandini, J. Rico, R. Curado da Silva, X. Wu, Andrzej Zdziarski, and A. Zoglauer. All-Sky-ASTROGAM: a MeV Companion for Multimessenger Astrophysics. PoS, ICRC2019:579, 2019. [63] Simeon Bird, Andrea Albert, Will Dawson, Yacine Ali-Ha¨ımoud, Adam Coogan, Alex DrlicaWagner, Qi Feng, Derek Inman, Keisuke Inomata, Ely Kovetz, Alexander Kusenko, Benjamin V. Lehmann, Julian B. Mu˜noz, Rajeev Singh, Volodymyr Takhistov, and Yu-Dai Tsai. Snowmass2021 cosmic frontier white paper: Primordial black hole dark matter. Physics of the Dark Universe, 41:101231, August 2023. [64] J´er´emy Auffinger. Primordial black hole constraints with hawking radiation—a review. Progress in Particle and Nuclear Physics, 131:104040, July 2023. [65] F. Hoyle and R. A. Lyttleton. On the accretion of interstellar matter by stars. Proceedings of the Cambridge Philosophical Society, 36(3):325, January 1940. [66] Xavier Boluna, Stefano Profumo, Juliette Bl´e, and Dana Hennings. Searching for exploding black holes, 2024. [67] Zhen Cao et al. Ultrahigh-energy photons up to 1.4 petaelectronvolts from 12 γ-ray Galactic sources. Nature, 594(7861):33–36, 2021. [68] J. Hinton and SWGO Collaboration. The Southern Wide-field Gamma-ray Observatory: Status and Prospects. In 37th International Cosmic Ray Conference, page 23, March 2022. [69] Keith Vanderlinde, Adrian Liu, Bryan Gaensler, Dick Bond, Gary Hinshaw, Cherry Ng, Cynthia Chiang, Ingrid Stairs, Jo-Anne Brown, Jonathan Sievers, Juan Mena, Kendrick Smith, Kevin Bandura, Kiyoshi Masui, Kristine Spekkens, Leo Belostotski, Matt Dobbs, Neil Turok, Patrick Boyle, Michael Rupen, Tom Landecker, Ue-Li Pen, and Victoria Kaspi. The canadian hydrogen observatory and radio-transient detector (chord). 2019. This paper is available on arxiv under CC BY 4.0 DEED license. Authors: (1) Antonio Riotto, Département de Physique Theorique, Universite de Geneve, 24 quai Ansermet, CH-1211 Geneve 4, Switzerland and Gravitational Wave Science Center (GWSC), Universite de Geneve, CH-1211 Geneva, Switzerland; (2) Joe Silk, Institut d’Astrophysique, UMR 7095 CNRS, Sorbonne Universite, 98bis Bd Arago, 75014 Paris, France, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore MD 21218, USA, and Beecroft Institute of Particle Astrophysics and Cosmology, Department of Physics, University of Oxford, Oxford OX1 3RH, UK. Authors: Authors: (1) Antonio Riotto, Département de Physique Theorique, Universite de Geneve, 24 quai Ansermet, CH-1211 Geneve 4, Switzerland and Gravitational Wave Science Center (GWSC), Universite de Geneve, CH-1211 Geneva, Switzerland; (2) Joe Silk, Institut d’Astrophysique, UMR 7095 CNRS, Sorbonne Universite, 98bis Bd Arago, 75014 Paris, France, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore MD 21218, USA, and Beecroft Institute of Particle Astrophysics and Cosmology, Department of Physics, University of Oxford, Oxford OX1 3RH, UK. Table of Links Abstract and 1 Introduction Abstract and 1 Introduction 2 Some open questions 2 Some open questions 2.1 What is the abundance of PBHs? 2.1 What is the abundance of PBHs? 2.2 What is the effect of PBH clustering? 2.2 What is the effect of PBH clustering? 2.3 What fraction of the currently observed GW events can be ascribed to PBHs? 2.3 What fraction of the currently observed GW events can be ascribed to PBHs? 2.4 Are PBHs the Dark Matter? 2.4 Are PBHs the Dark Matter? 3 The PBH Roadmap 3 The PBH Roadmap 3.1 High redshift mergers 3.1 High redshift mergers 3.2 Sub-solar PBHs 3.2 Sub-solar PBHs 3.3 Plugging the pair instability gap with PBH? 3.3 Plugging the pair instability gap with PBH? 3.4 PBH eccentricity, 3.5 PBH spin and 3.6 Future gamma-ray telescopes 3.4 PBH eccentricity, 3.5 PBH spin and 3.6 Future gamma-ray telescopes 4 Conclusions and References 4 Conclusions and References 4 Conclusions Support for the existence of PBHs hypothesis comes from a range of arguments spanning dark matter physics, inflationary models, astrophysics, gravitational microlensing and quantum cosmology. None are yet conclusive but the cumulative support for the existence of PBHs seems reasonably compelling. More to the point however is that there is a rich astrophysical agenda of open questions that contribute to a future road map for a plethora of research projects. Two of the most fundamental PBH probes that distinguish them from astrophysical counterparts are their redshift and mass distributions. This combination provides an armoury of smoking guns that will inevitably enrich the next generation of gravitational wave and gravitational microlensing experiments. Confirmation will require improved statistics as single events may not be conclusive. it is only too easy to come up with rare events that can masquerade as PBH candidates, for example by appealing to higher order generations of merging events or to non-Gaussianity. We have laid out a possible future road map for definitively assessing whether PBHs can present a viable candidate for dark matter, or possibly contribute to other astrophysical or even quantum cosmology anomalies. References [1] A. Ianniccari, A. J. Iovino, A. Kehagias, D. Perrone, and A. Riotto. The Primordial Black Hole Abundance: The Broader, the Better. 2 2024. [2] Albert Escriv`a, Cristiano Germani, and Ravi K. Sheth. Universal threshold for primordial black hole formation. Phys. Rev. D, 101(4):044022, 2020. [3] Valerio De Luca, Alex Kehagias, and Antonio Riotto. How well do we know the primordial black hole abundance: The crucial role of nonlinearities when approaching the horizon. Phys. Rev. D, 108(6):063531, 2023. [4] Gabriele Franciolini, Andrea Ianniccari, Alex Kehagias, Davide Perrone, and Antonio Riotto. Renormalized Primordial Black Holes. 11 2023. [5] Marcos M. Flores, Alexander Kusenko, and Misao Sasaki. Revisiting formation of primordial black holes in a supercooled first-order phase transition. 2 2024. [6] V. De Luca, V. Desjacques, G. Franciolini, A. Malhotra, and A. Riotto. The initial spin probability distribution of primordial black holes. JCAP, 05:018, 2019. [7] V. De Luca, G. Franciolini, P. Pani, and A. Riotto. Constraints on Primordial Black Holes: the Importance of Accretion. Phys. Rev. D, 102(4):043505, 2020. [8] Yacine Ali-Ha¨ımoud. Correlation function of high-threshold regions and application to the initial small-scale clustering of primordial black holes. Physical Review Letters, 121(8), aug 2018. [9] Vincent Desjacques and Antonio Riotto. Spatial clustering of primordial black holes. Phys. Rev. D, 98(12):123533, 2018. [10] Derek Inman and Yacine Ali-Ha¨ımoud. Early structure formation in primordial black hole cosmologies. Phys. Rev. D, 100(8):083528, 2019. [11] Bernard Carr and Joseph Silk. Primordial black holes as generators of cosmic structures. Monthly Notices of the Royal Astronomical Society, 478(3):3756–3775, May 2018. [12] Joseph Silk, Mitchell Begelman, Colin Norman, Adi Nusser, and Rosemary Wyse. Which came first: supermassive black holes or galaxies? insights from jwst, 2024. [13] Gabriele Franciolini, Vishal Baibhav, Valerio De Luca, Ken K. Y. Ng, Kaze W. K. Wong, Emanuele Berti, Paolo Pani, Antonio Riotto, and Salvatore Vitale. Searching for a subpopulation of primordial black holes in LIGO-Virgo gravitational-wave data. Phys. Rev. D, 105(8):083526, 2022. [14] J. Iguaz, P.D. Serpico, and T. Siegert. Isotropic x-ray bound on primordial black hole dark matter. Physical Review D, 103(10), May 2021. [15] N. Bartolo, V. De Luca, G. Franciolini, M. Peloso, D. Racco, and A. Riotto. Testing primordial black holes as dark matter with LISA. Phys. Rev. D, 99(10):103521, 2019. [16] Chloe B. Richards, Thomas W. Baumgarte, and Stuart L. Shapiro. Accretion onto a small black hole at the center of a neutron star. Physical Review D, 103(10), May 2021. [17] Jason Dexter and Ryan M. O’Leary. The peculiar pulsar population of the central parsec. The Astrophysical Journal, 783(1):L7, February 2014. [18] Nicolas Esser, Sven De Rijcke, and Peter Tinyakov. The impact of primordial black holes on the stellar mass function of ultra-faint dwarf galaxies. 11 2023. [19] Jose A. de Freitas Pacheco, Elias Kiritsis, Matteo Lucca, and Joseph Silk. Quasiextremal primordial black holes are a viable dark matter candidate. Physical Review D, 107(12), June 2023. [20] Luis A. Anchordoqui, Ignatios Antoniadis, and Dieter L¨ust. Dark dimension, the swampland, and the dark matter fraction composed of primordial black holes. Phys. Rev. D, 106(8):086001, October 2022. [21] J. A. de Freitas Pacheco and Joseph Silk. Primordial Rotating Black Holes. Phys. Rev. D, 101(8):083022, 2020. [22] Ana Alexandre, Gia Dvali, and Emmanouil Koutsangelas. New Mass Window for Primordial Black Holes as Dark Matter from Memory Burden Effect. 2 2024. [23] Benjamin V. Lehmann, Christian Johnson, Stefano Profumo, and Thomas Schwemberger. Direct detection of primordial black hole relics as dark matter. Journal of Cosmology and Astroparticle Physics, 2019(10):046–046, October 2019. [24] Yang Bai and Nicholas Orlofsky. Primordial extremal black holes as dark matter. Physical Review D, 101(5), March 2020. [25] Guillem Dom`enech and Misao Sasaki. Probing primordial black hole scenarios with terrestrial gravitational wave detectors, 2024. [26] Seiji Kawamura et al. Current status of space gravitational wave antenna DECIGO and BDECIGO. PTEP, 2021(5):05A105, 2021. [27] Yungui Gong, Jun Luo, and Bin Wang. Concepts and status of chinese space gravitational wave detection projects. Nature Astronomy, 5(9):881–889, September 2021. [28] John Ellis, Malcolm Fairbairn, Juan Urrutia, and Ville Vaskonen. Probing supermassive black hole seed scenarios with gravitational wave measurements, 2023. [29] Joris van Heijningen et al. The payload of the Lunar Gravitational-wave Antenna. J. Appl. Phys., 133(24):244501, 2023. [30] John Ellis, Malcolm Fairbairn, Gabriele Franciolini, Gert H¨utsi, Antonio Iovino Jr. au2, Marek Lewicki, Martti Raidal, Juan Urrutia, Ville Vaskonen, and Hardi Veerm¨ae. What is the source of the pta gw signal?, 2023. [31] Yacine Ali-Ha¨ımoud, Ely D. Kovetz, and Marc Kamionkowski. Merger rate of primordial blackhole binaries. Phys. Rev. D, 96(12):123523, 2017. [32] Martti Raidal, Christian Spethmann, Ville Vaskonen, and Hardi Veerm¨ae. Formation and Evolution of Primordial Black Hole Binaries in the Early Universe. JCAP, 02:018, 2019. [33] V. De Luca, G. Franciolini, P. Pani, and A. Riotto. Primordial Black Holes Confront LIGO/Virgo data: Current situation. JCAP, 06:044, 2020. [34] Tomoya Kinugawa, Kohei Inayoshi, Kenta Hotokezaka, Daisuke Nakauchi, and Takashi Nakamura. Possible Indirect Confirmation of the Existence of Pop III Massive Stars by Gravitational Wave. Mon. Not. Roy. Astron. Soc., 442(4):2963–2992, 2014. [35] Tomoya Kinugawa, Akinobu Miyamoto, Nobuyuki Kanda, and Takashi Nakamura. The detection rate of inspiral and quasi-normal modes of Population III binary black holes which can confirm or refute the general relativity in the strong gravity region. Mon. Not. Roy. Astron. Soc., 456(1):1093– 1114, 2016. [36] Tilman Hartwig, Marta Volonteri, Volker Bromm, Ralf S. Klessen, Enrico Barausse, Mattis Magg, and Athena Stacy. Gravitational Waves from the Remnants of the First Stars. Mon. Not. Roy. Astron. Soc., 460(1):L74–L78, 2016. [37] K. Belczynski, T. Ryu, R. Perna, E. Berti, T. L. Tanaka, and T. Bulik. On the likelihood of detecting gravitational waves from Population III compact object binaries. Mon. Not. Roy. Astron. Soc., 471(4):4702–4721, 2017. [38] Kohei Inayoshi, Ryosuke Hirai, Tomoya Kinugawa, and Kenta Hotokezaka. Formation pathway of Population III coalescing binary black holes through stable mass transfer. Mon. Not. Roy. Astron. Soc., 468(4):5020–5032, 2017. [39] Boyuan Liu and Volker Bromm. The Population III origin of GW190521. Astrophys. J. Lett., 903(2):L40, 2020. [40] Boyuan Liu and Volker Bromm. Gravitational waves from Population III binary black holes formed by dynamical capture. Mon. Not. Roy. Astron. Soc., 495(2):2475–2495, 2020. [41] Tomoya Kinugawa, Takashi Nakamura, and Hiroyuki Nakano. Chirp Mass and Spin of Binary Black Holes from First Star Remnants. Mon. Not. Roy. Astron. Soc., 498(3):3946–3963, 2020. [42] Ataru Tanikawa, Hajime Susa, Takashi Yoshida, Alessandro A. Trani, and Tomoya Kinugawa. Merger rate density of Population III binary black holes below, above, and in the pair-instability mass gap. Astrophys. J., 910(1):30, 2021. [43] Neha Singh, Tomasz Bulik, Krzysztof Belczynski, and Abbas Askar. Exploring compact binary populations with the Einstein Telescope. Astron. Astrophys., 667:A2, 2022. [44] Savvas M. Koushiappas and Abraham Loeb. Maximum redshift of gravitational wave merger events. Phys. Rev. Lett., 119(22):221104, 2017. [45] V. De Luca, G. Franciolini, P. Pani, and A. Riotto. Bayesian Evidence for Both Astrophysical and Primordial Black Holes: Mapping the GWTC-2 Catalog to Third-Generation Detectors. JCAP, 05:003, 2021. [46] Ken K. Y. Ng, Shiqi Chen, Boris Goncharov, Ulyana Dupletsa, Ssohrab Borhanian, Marica Branchesi, Jan Harms, Michele Maggiore, B. S. Sathyaprakash, and Salvatore Vitale. On the Single-event-based Identification of Primordial Black Hole Mergers at Cosmological Distances. Astrophys. J. Lett., 931(1):L12, 2022. [47] Gabriele Franciolini, Roberto Cotesta, Nicholas Loutrel, Emanuele Berti, Paolo Pani, and Antonio Riotto. How to assess the primordial origin of single gravitational-wave events with mass, spin, eccentricity, and deformability measurements. Phys. Rev. D, 105(6):063510, 2022. [48] Matteo Martinelli, Francesca Scarcella, Natalie B. Hogg, Bradley J. Kavanagh, Daniele Gaggero, and Pierre Fleury. Dancing in the dark: detecting a population of distant primordial black holes. JCAP, 08(08):006, 2022. [49] Ken K. Y. Ng et al. Measuring properties of primordial black hole mergers at cosmological distances: Effect of higher order modes in gravitational waves. Phys. Rev. D, 107(2):024041, 2023. [50] Ken K. Y. Ng, Gabriele Franciolini, Emanuele Berti, Paolo Pani, Antonio Riotto, and Salvatore Vitale. Constraining High-redshift Stellar-mass Primordial Black Holes with Next-generation Ground-based Gravitational-wave Detectors. Astrophys. J. Lett., 933(2):L41, 2022. [51] Vitor Cardoso and Paolo Pani. Testing the nature of dark compact objects: a status report. Living Rev. Rel., 22(1):4, 2019. [52] Huai-Ke Guo, Kuver Sinha, and Chen Sun. Probing Boson Stars with Extreme Mass Ratio Inspirals. JCAP, 09:032, 2019. [53] Hiroko Niikura, Masahiro Takada, Shuichiro Yokoyama, Takahiro Sumi, and Shogo Masaki. Constraints on earth-mass primordial black holes from ogle 5-year microlensing events. Physical Review D, 99(8), April 2019. [54] Kaiki Taro Inoue and Takahiro Tanaka. Gravitational waves from sub-lunar-mass primordial black-hole binaries: A new probe of extra dimensions. Physical Review Letters, 91(2), July 2003. [55] The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, and R. Abbott et al. The population of merging compact binaries inferred using gravitational waves through gwtc-3, 2022. [56] Digvijay Wadekar, Javier Roulet, Tejaswi Venumadhav, Ajit Kumar Mehta, Barak Zackay, Jonathan Mushkin, Seth Olsen, and Matias Zaldarriaga. New black hole mergers in the ligovirgo o3 data from a gravitational wave search including higher-order harmonics, 2023. [57] Ilias Cholis, Ely D. Kovetz, Yacine Ali-Ha¨ımoud, Simeon Bird, Marc Kamionkowski, Julian B. Mu˜noz, and Alvise Raccanelli. Orbital eccentricities in primordial black hole binaries. Phys. Rev. D, 94(8):084013, 2016. [58] Yi-Fan Wang and Alexander H. Nitz. Prospects for detecting gravitational waves from eccentric subsolar mass compact binaries. Astrophys. J., 912(1):53, 2021. [59] Gabriele Franciolini and Paolo Pani. Searching for mass-spin correlations in the population of gravitational-wave events: The GWTC-3 case study. Phys. Rev. D, 105(12):123024, 2022. [60] Mrunal Korwar and Stefano Profumo. Updated constraints on primordial black hole evaporation. Journal of Cosmology and Astroparticle Physics, 2023(05):054, May 2023. [61] Henrike Fleischhack. Amego-x: Mev gamma-ray astronomy in the multimessenger era, 2021. [62] Manuela Mallamaci, A. De Angelis, V. Tatischeff, R. Rando, M. Tavani, U. Oberlack, R. Walter, G. Ambrosi, A. Argan, P. von Balmoos, D. Bastieri, E. Bernardini, S. Brandt, A. Bulgarelli, A. Bykov, V. Fioretti, I.A. Grenier, L. Hanlon, D. Hartmann, M. Hernanz, G. Kanbach, I. Kuvvetli, P. Laurent, M. Mariotti, M.N. Mazziotta, J. Mc Enery, S. Mereghetti, A. Morselli, K. Nakazawa, M. Pearce, E. Prandini, J. Rico, R. Curado da Silva, X. Wu, Andrzej Zdziarski, and A. Zoglauer. All-Sky-ASTROGAM: a MeV Companion for Multimessenger Astrophysics. PoS, ICRC2019:579, 2019. [63] Simeon Bird, Andrea Albert, Will Dawson, Yacine Ali-Ha¨ımoud, Adam Coogan, Alex DrlicaWagner, Qi Feng, Derek Inman, Keisuke Inomata, Ely Kovetz, Alexander Kusenko, Benjamin V. Lehmann, Julian B. Mu˜noz, Rajeev Singh, Volodymyr Takhistov, and Yu-Dai Tsai. Snowmass2021 cosmic frontier white paper: Primordial black hole dark matter. Physics of the Dark Universe, 41:101231, August 2023. [64] J´er´emy Auffinger. Primordial black hole constraints with hawking radiation—a review. Progress in Particle and Nuclear Physics, 131:104040, July 2023. [65] F. Hoyle and R. A. Lyttleton. On the accretion of interstellar matter by stars. Proceedings of the Cambridge Philosophical Society, 36(3):325, January 1940. [66] Xavier Boluna, Stefano Profumo, Juliette Bl´e, and Dana Hennings. Searching for exploding black holes, 2024. [67] Zhen Cao et al. Ultrahigh-energy photons up to 1.4 petaelectronvolts from 12 γ-ray Galactic sources. Nature, 594(7861):33–36, 2021. [68] J. Hinton and SWGO Collaboration. The Southern Wide-field Gamma-ray Observatory: Status and Prospects. In 37th International Cosmic Ray Conference, page 23, March 2022. [69] Keith Vanderlinde, Adrian Liu, Bryan Gaensler, Dick Bond, Gary Hinshaw, Cherry Ng, Cynthia Chiang, Ingrid Stairs, Jo-Anne Brown, Jonathan Sievers, Juan Mena, Kendrick Smith, Kevin Bandura, Kiyoshi Masui, Kristine Spekkens, Leo Belostotski, Matt Dobbs, Neil Turok, Patrick Boyle, Michael Rupen, Tom Landecker, Ue-Li Pen, and Victoria Kaspi. The canadian hydrogen observatory and radio-transient detector (chord). 2019. This paper is available on arxiv under CC BY 4.0 DEED license. This paper is available on arxiv under CC BY 4.0 DEED license. available on arxiv