Papers
Topics
Authors
Recent
Gemini 2.5 Flash
Gemini 2.5 Flash
144 tokens/sec
GPT-4o
8 tokens/sec
Gemini 2.5 Pro Pro
46 tokens/sec
o3 Pro
4 tokens/sec
GPT-4.1 Pro
38 tokens/sec
DeepSeek R1 via Azure Pro
28 tokens/sec
2000 character limit reached

Probing The Early Universe Cosmology With NANOGrav: Possibilities and Limitations (2307.15123v2)

Published 27 Jul 2023 in astro-ph.CO, gr-qc, and hep-th

Abstract: A stochastic gravitational wave background is a prediction of a number of astrophysical and cosmological phenomena including early Universe Cosmology. Recently, the NANOGrav Collaboration reported conclusive evidence for a stochastic gravitational-wave background. We analyze the NANOGrav signal assuming it is of primordial origin including the reheating phase. We use the latest measurements from NANOGrav to constrain the Universe's reheating equation of state $w_{re}$ the reheating temperature, $T_{re}$, the tensor to scalar ratio $r$, and the tensor tilt $n_t$. Assuming the constant equation of state $w_{re}$ responsible for reheating phase, we find preference for instant reheating, $w_{re} = 0.36{+0.15}_{-0.28}$, and a very blue tilt $n_t = 1.94{+0.43}_{-0.88}$. We find a degeneracy between the tensor to scalar ratio $r$ and $T_{re}$ and suggest ways to break this degeneracy. In all cases where the reheating temperature is constrained, it is constrained to be very low with $T_{re}\leq 105 GeV$. We further find that a scale-invariant spectrum as suggested by inflation implies a stiff equation of state $w_{re}=19/3$. If extrapolated, the blue-tilted primordial spectrum that agrees with the NANOGrav signal at corresponding frequencies is incompatible with the LIGO bound. This incompatibility is another challenge for connecting NANOGrav with the primordial spectrum. We discuss a number of ways to circumvent this issue. We split the spectrum into a sum of astrophysical and primordial spectra and constrain the astrophysical and primordial components using NANOGrav data and the LIGO bound. In another attempt, we use the same data and constrain the running of the spectrum. Any of these or a combination of such methods can be used to reconcile the NANOGrav data and the LIGO bound with the primordial power spectrum.

Definition Search Book Streamline Icon: https://streamlinehq.com
References (101)
  1. Chiara Caprini and Daniel G. Figueroa, “Cosmological Backgrounds of Gravitational Waves,” Class. Quant. Grav. 35, 163001 (2018), arXiv:1801.04268 [astro-ph.CO] .
  2. Arianna I. Renzini, Boris Goncharov, Alexander C. Jenkins,  and Pat M. Meyers, “Stochastic Gravitational-Wave Backgrounds: Current Detection Efforts and Future Prospects,” Galaxies 10, 34 (2022), arXiv:2202.00178 [gr-qc] .
  3. George Hobbs and Shi Dai, “Gravitational wave research using pulsar timing arrays,” National Science Review 4, 707–717 (2017).
  4. Zaven Arzoumanian et al. (NANOGrav), “The NANOGrav 12.5 yr Data Set: Search for an Isotropic Stochastic Gravitational-wave Background,” Astrophys. J. Lett. 905, L34 (2020), arXiv:2009.04496 [astro-ph.HE] .
  5. Boris Goncharov et al., “On the Evidence for a Common-spectrum Process in the Search for the Nanohertz Gravitational-wave Background with the Parkes Pulsar Timing Array,” Astrophys. J. Lett. 917, L19 (2021), arXiv:2107.12112 [astro-ph.HE] .
  6. S. Chen et al., “Common-red-signal analysis with 24-yr high-precision timing of the European Pulsar Timing Array: inferences in the stochastic gravitational-wave background search,” Mon. Not. Roy. Astron. Soc. 508, 4970–4993 (2021), arXiv:2110.13184 [astro-ph.HE] .
  7. J. Antoniadis et al., “The International Pulsar Timing Array second data release: Search for an isotropic gravitational wave background,” Mon. Not. Roy. Astron. Soc. 510, 4873–4887 (2022), arXiv:2201.03980 [astro-ph.HE] .
  8. Gabriella Agazie et al. (NANOGrav), “The NANOGrav 15 yr Data Set: Evidence for a Gravitational-wave Background,” Astrophys. J. Lett. 951, L8 (2023a), arXiv:2306.16213 [astro-ph.HE] .
  9. J. Antoniadis et al., “The second data release from the European Pulsar Timing Array III. Search for gravitational wave signals,” .  (2023a), arXiv:2306.16214 [astro-ph.HE] .
  10. Daniel J. Reardon et al., “Search for an Isotropic Gravitational-wave Background with the Parkes Pulsar Timing Array,” Astrophys. J. Lett. 951, L6 (2023a), arXiv:2306.16215 [astro-ph.HE] .
  11. Heng Xu et al., “Searching for the Nano-Hertz Stochastic Gravitational Wave Background with the Chinese Pulsar Timing Array Data Release I,” Res. Astron. Astrophys. 23, 075024 (2023), arXiv:2306.16216 [astro-ph.HE] .
  12. Gabriella Agazie et al. (NANOGrav), “The NANOGrav 15 yr Data Set: Observations and Timing of 68 Millisecond Pulsars,” Astrophys. J. Lett. 951, L9 (2023b), arXiv:2306.16217 [astro-ph.HE] .
  13. Gabriella Agazie, Akash Anumarlapudi, Anne M Archibald, Paul T Baker, Bence Bécsy, Laura Blecha, Alexander Bonilla, Adam Brazier, Paul R Brook, Sarah Burke-Spolaor, et al., “The nanograv 15-year data set: Constraints on supermassive black hole binaries from the gravitational wave background,” arXiv preprint arXiv:2306.16220  (2023c).
  14. Gabriella Agazie et al. (NANOGrav), “The NANOGrav 15-year Data Set: Search for Anisotropy in the Gravitational-Wave Background,” .  (2023d), arXiv:2306.16221 [astro-ph.HE] .
  15. Adeela Afzal et al. (NANOGrav), “The NANOGrav 15 yr Data Set: Search for Signals from New Physics,” Astrophys. J. Lett. 951, L11 (2023), arXiv:2306.16219 [astro-ph.HE] .
  16. Gabriella Agazie et al. (NANOGrav), “The NANOGrav 15 yr Data Set: Detector Characterization and Noise Budget,” Astrophys. J. Lett. 951, L10 (2023e), arXiv:2306.16218 [astro-ph.HE] .
  17. Aaron D Johnson, Patrick M Meyers, Paul T Baker, Neil J Cornish, Jeffrey S Hazboun, Tyson B Littenberg, Joseph D Romano, Stephen R Taylor, Michele Vallisneri, Sarah J Vigeland, et al., “The nanograv 15-year gravitational-wave background analysis pipeline,” arXiv preprint arXiv:2306.16223  (2023).
  18. Gabriella Agazie et al. (NANOGrav), “The NANOGrav 15 yr Data Set: Bayesian Limits on Gravitational Waves from Individual Supermassive Black Hole Binaries,” Astrophys. J. Lett. 951, L50 (2023f), arXiv:2306.16222 [astro-ph.HE] .
  19. J. Antoniadis et al., “The second data release from the European Pulsar Timing Array II. Customised pulsar noise models for spatially correlated gravitational waves,” .  (2023b), arXiv:2306.16225 [astro-ph.HE] .
  20. J. Antoniadis et al., “The second data release from the European Pulsar Timing Array IV. Search for continuous gravitational wave signals,” .  (2023c), arXiv:2306.16226 [astro-ph.HE] .
  21. J. Antoniadis et al., “The second data release from the European Pulsar Timing Array: V. Implications for massive black holes, dark matter and the early Universe,” arXiv preprint arXiv:2306.16227  (2023d), arXiv:2306.16227 [astro-ph.CO] .
  22. Clemente Smarra et al. (European Pulsar Timing Array), “The second data release from the European Pulsar Timing Array: VI. Challenging the ultralight dark matter paradigm,” .  (2023), arXiv:2306.16228 [astro-ph.HE] .
  23. Daniel J. Reardon et al., “The Gravitational-wave Background Null Hypothesis: Characterizing Noise in Millisecond Pulsar Arrival Times with the Parkes Pulsar Timing Array,” Astrophys. J. Lett. 951, L7 (2023b), arXiv:2306.16229 [astro-ph.HE] .
  24. Andrew Zic et al., “The Parkes Pulsar Timing Array Third Data Release,” .  (2023), arXiv:2306.16230 [astro-ph.HE] .
  25. Sunny Vagnozzi, “Implications of the NANOGrav results for inflation,” Monthly Notices of the Royal Astronomical Society: Letters 502, L11–L15 (2020), https://academic.oup.com/mnrasl/article-pdf/502/1/L11/35873635/slaa203.pdf .
  26. Sunny Vagnozzi, “Inflationary interpretation of the stochastic gravitational wave background signal detected by pulsar timing array experiments,” .  (2023), arXiv:2306.16912 [astro-ph.CO] .
  27. Satyabrata Datta, “Inflationary gravitational waves, pulsar timing data and low-scale-leptogenesis,” .  (2023), arXiv:2307.00646 [hep-ph] .
  28. George Lazarides, Rinku Maji,  and Qaisar Shafi, “Superheavy quasi-stable strings and walls bounded by strings in the light of NANOGrav 15 year data,” .  (2023), arXiv:2306.17788 [hep-ph] .
  29. Zhi-Chao Zhao, Qing-Hua Zhu, Sai Wang,  and Xin Zhang, “Exploring the Equation of State of the Early Universe: Insights from BBN, CMB, and PTA Observations,” .  (2023), arXiv:2307.13574 [astro-ph.CO] .
  30. Barnali Das, Nur Jaman,  and M. Sami, “Gravitational Waves Background (NANOGrav) from Quintessential Inflation,” .  (2023), arXiv:2307.12913 [gr-qc] .
  31. Mohammad Ali Gorji, Misao Sasaki,  and Teruaki Suyama, “Extra-tensor-induced origin for the PTA signal: No primordial black hole production,” .  (2023), arXiv:2307.13109 [astro-ph.CO] .
  32. Moslem Ahmadvand, Ligong Bian,  and Soroush Shakeri, “A Heavy QCD Axion model in Light of Pulsar Timing Arrays,” .  (2023), arXiv:2307.12385 [hep-ph] .
  33. Zhao Zhang, Chengfeng Cai, Yu-Hang Su, Shiyu Wang, Zhao-Huan Yu,  and Hong-Hao Zhang, “Nano-Hertz gravitational waves from collapsing domain walls associated with freeze-in dark matter in light of pulsar timing array observations,” .  (2023), arXiv:2307.11495 [hep-ph] .
  34. M. Bousder, A. Riadsolh, A. El Fatimy, M. El Belkacemi,  and H. Ez-Zahraouy, “Implications of the NANOGrav results for primordial black holes and Hubble tension,” .  (2023), arXiv:2307.10940 [gr-qc] .
  35. Lorenzo Valbusa Dall’Armi, Alina Mierna, Sabino Matarrese,  and Angelo Ricciardone, “Adiabatic or Non-Adiabatic? Unraveling the Nature of Initial Conditions in the Cosmological Gravitational Wave Background,” .  (2023), arXiv:2307.11043 [astro-ph.CO] .
  36. Yanou Cui, Soubhik Kumar, Raman Sundrum,  and Yuhsin Tsai, “Unraveling Cosmological Anisotropies within Stochastic Gravitational Wave Backgrounds,” .  (2023), arXiv:2307.10360 [astro-ph.CO] .
  37. Spyros Basilakos, Dimitri V. Nanopoulos, Theodoros Papanikolaou, Emmanuel N. Saridakis,  and Charalampos Tzerefos, “Gravitational wave signatures of no-scale Supergravity in NANOGrav and beyond,” .  (2023), arXiv:2307.08601 [hep-th] .
  38. Graciela B. Gelmini and Jonah Hyman, “Catastrogenesis with unstable ALPs as the origin of the NANOGrav 15 yr gravitational wave signal,” .  (2023), arXiv:2307.07665 [hep-ph] .
  39. Masaki Yamada and Kazuya Yonekura, “Dark baryon from pure Yang-Mills theory and its GW signature from cosmic strings,” JHEP 09, 197 (2023), arXiv:2307.06586 [hep-ph] .
  40. E. Babichev, D. Gorbunov, S. Ramazanov, R. Samanta,  and A. Vikman, “NANOGrav spectral index γ=3𝛾3\gamma=3italic_γ = 3 from melting domain walls,” .  (2023), arXiv:2307.04582 [hep-ph] .
  41. Wilfried Buchmuller, Valerie Domcke,  and Kai Schmitz, “Metastable cosmic strings,” .  (2023), arXiv:2307.04691 [hep-ph] .
  42. Zhi-Qiang You, Zhu Yi,  and You Wu, “Constraints on primordial curvature power spectrum with pulsar timing arrays,” .  (2023), arXiv:2307.04419 [gr-qc] .
  43. Alberto Salvio, “Supercooling in Radiative Symmetry Breaking: Theory Extensions, Gravitational Wave Detection and Primordial Black Holes,” .  (2023), arXiv:2307.04694 [hep-ph] .
  44. Yann Gouttenoire, “First-order Phase Transition interpretation of PTA signal produces solar-mass Black Holes,” .  (2023), arXiv:2307.04239 [hep-ph] .
  45. Michael Geller, Subhajit Ghosh, Sida Lu,  and Yuhsin Tsai, “Challenges in Interpreting the NANOGrav 15-Year Data Set as Early Universe Gravitational Waves Produced by ALP Induced Instability,” .  (2023), arXiv:2307.03724 [hep-ph] .
  46. Xiao Kang Du, Ming Xia Huang, Fei Wang,  and Ying Kai Zhang, “Did the nHZ Gravitational Waves Signatures Observed By NANOGrav Indicate Multiple Sector SUSY Breaking?” .  (2023), arXiv:2307.02938 [hep-ph] .
  47. Géraldine Servant and Peera Simakachorn, “Constraining Post-Inflationary Axions with Pulsar Timing Arrays,” .  (2023), arXiv:2307.03121 [hep-ph] .
  48. Xiu-Fei Li, “Probing the high temperature symmetry breaking with gravitational waves from domain walls,” .  (2023), arXiv:2307.03163 [hep-ph] .
  49. Lang Liu, Zu-Cheng Chen,  and Qing-Guo Huang, “Probing the equation of state of the early Universe with pulsar timing arrays,” .  (2023a), arXiv:2307.14911 [astro-ph.CO] .
  50. Lang Liu, Zu-Cheng Chen,  and Qing-Guo Huang, “Implications for the non-Gaussianity of curvature perturbation from pulsar timing arrays,” .  (2023b), arXiv:2307.01102 [astro-ph.CO] .
  51. V. K. Oikonomou, “Flat energy spectrum of primordial gravitational waves versus peaks and the NANOGrav 2023 observation,” Phys. Rev. D 108, 043516 (2023), arXiv:2306.17351 [astro-ph.CO] .
  52. Daniel G. Figueroa, Mauro Pieroni, Angelo Ricciardone,  and Peera Simakachorn, “Cosmological Background Interpretation of Pulsar Timing Array Data,” .  (2023), arXiv:2307.02399 [astro-ph.CO] .
  53. Caner Unal, Alexandros Papageorgiou,  and Ippei Obata, “Axion-Gauge Dynamics During Inflation as the Origin of Pulsar Timing Array Signals and Primordial Black Holes,” .  (2023), arXiv:2307.02322 [astro-ph.CO] .
  54. Xuce Niu and Moinul Hossain Rahat, ‘‘NANOGrav signal from axion inflation,” .  (2023), arXiv:2307.01192 [hep-ph] .
  55. Yi-Fu Cai, Xin-Chen He, Xiaohan Ma, Sheng-Feng Yan,  and Guan-Wen Yuan, “Limits on scalar-induced gravitational waves from the stochastic background by pulsar timing array observations,” .  (2023), arXiv:2306.17822 [gr-qc] .
  56. Ido Ben-Dayan, “Gravitational Waves in Bouncing Cosmologies from Gauge Field Production,” JCAP 09, 017 (2016), arXiv:1604.07899 [astro-ph.CO] .
  57. Ido Ben-Dayan and Judy Kupferman, “Sourced scalar fluctuations in bouncing cosmology,” JCAP 07, 050 (2019), [Erratum: JCAP 12, E01 (2020)], arXiv:1812.06970 [gr-qc] .
  58. Jerome Martin, Christophe Ringeval,  and Vincent Vennin, “Observing Inflationary Reheating,” Phys. Rev. Lett. 114, 081303 (2015), arXiv:1410.7958 [astro-ph.CO] .
  59. Liang Dai, Marc Kamionkowski,  and Junpu Wang, “Reheating constraints to inflationary models,” Phys. Rev. Lett. 113, 041302 (2014), arXiv:1404.6704 [astro-ph.CO] .
  60. Kaloian D. Lozanov, “Lectures on Reheating after Inflation,” .  (2019), arXiv:1907.04402 [astro-ph.CO] .
  61. Latham A. Boyle and Alessandra Buonanno, “Relating gravitational wave constraints from primordial nucleosynthesis, pulsar timing, laser interferometers, and the CMB: Implications for the early Universe,” Phys. Rev. D 78, 043531 (2008), arXiv:0708.2279 [astro-ph] .
  62. D. Battefeld and Patrick Peter, “A Critical Review of Classical Bouncing Cosmologies,” Phys. Rept. 571, 1–66 (2015), arXiv:1406.2790 [astro-ph.CO] .
  63. Justin Khoury, Burt A. Ovrut, Paul J. Steinhardt,  and Neil Turok, “The Ekpyrotic universe: Colliding branes and the origin of the hot big bang,” Phys. Rev. D 64, 123522 (2001), arXiv:hep-th/0103239 .
  64. Tsutomu Kobayashi, Masahide Yamaguchi,  and Jun’ichi Yokoyama, “G-inflation: Inflation driven by the Galileon field,” Phys. Rev. Lett. 105, 231302 (2010), arXiv:1008.0603 [hep-th] .
  65. Hiroaki W. H. Tahara and Tsutomu Kobayashi, “Nanohertz gravitational waves from a null-energy-condition violation in the early universe,” Phys. Rev. D 102, 123533 (2020), arXiv:2011.01605 [gr-qc] .
  66. Yun-Song Piao and Yuan-Zhong Zhang, “Phantom inflation and primordial perturbation spectrum,” Phys. Rev. D 70, 063513 (2004), arXiv:astro-ph/0401231 .
  67. Andrei Gruzinov, “Elastic inflation,” Phys. Rev. D 70, 063518 (2004), arXiv:astro-ph/0404548 .
  68. Masaki Satoh and Jiro Soda, “Higher Curvature Corrections to Primordial Fluctuations in Slow-roll Inflation,” JCAP 09, 019 (2008), arXiv:0806.4594 [astro-ph] .
  69. Yosuke Mishima and Tsutomu Kobayashi, “Revisiting slow-roll dynamics and the tensor tilt in general single-field inflation,” Phys. Rev. D 101, 043536 (2020), arXiv:1911.02143 [gr-qc] .
  70. Yi-Fu Cai, Jinn-Ouk Gong, Shi Pi, Emmanuel N. Saridakis,  and Shang-Yu Wu, “On the possibility of blue tensor spectrum within single field inflation,” Nucl. Phys. B 900, 517–532 (2015), arXiv:1412.7241 [hep-th] .
  71. Jinn-Ouk Gong, “Blue running of the primordial tensor spectrum,” JCAP 07, 022 (2014), arXiv:1403.5163 [astro-ph.CO] .
  72. Xingang Chen, Hassan Firouzjahi, Mohammad Hossein Namjoo,  and Misao Sasaki, “A Single Field Inflation Model with Large Local Non-Gaussianity,” EPL 102, 59001 (2013), arXiv:1301.5699 [hep-th] .
  73. Chunshan Lin, “Massive Graviton on a Spatial Condensate,” Phys. Lett. B 738, 386–390 (2014), arXiv:1307.2574 [hep-th] .
  74. A. Emir Gumrukcuoglu, Sachiko Kuroyanagi, Chunshan Lin, Shinji Mukohyama,  and Norihiro Tanahashi, “Gravitational wave signal from massive gravity,” Class. Quant. Grav. 29, 235026 (2012), arXiv:1208.5975 [hep-th] .
  75. Neil Barnaby, Enrico Pajer,  and Marco Peloso, “Gauge Field Production in Axion Inflation: Consequences for Monodromy, non-Gaussianity in the CMB, and Gravitational Waves at Interferometers,” Phys. Rev. D 85, 023525 (2012), arXiv:1110.3327 [astro-ph.CO] .
  76. Yi Wang and Wei Xue, “Inflation and Alternatives with Blue Tensor Spectra,” JCAP 10, 075 (2014), arXiv:1403.5817 [astro-ph.CO] .
  77. Chiara Caprini and Lorenzo Sorbo, ‘‘Adding helicity to inflationary magnetogenesis,” JCAP 10, 056 (2014), arXiv:1407.2809 [astro-ph.CO] .
  78. Shinji Mukohyama, Ryo Namba, Marco Peloso,  and Gary Shiu, “Blue Tensor Spectrum from Particle Production during Inflation,” JCAP 08, 036 (2014), arXiv:1405.0346 [astro-ph.CO] .
  79. Mar Bastero-Gil, Arjun Berera, Rudnei O. Ramos,  and João G. Rosa, “Observational implications of mattergenesis during inflation,” JCAP 10, 053 (2014), arXiv:1404.4976 [astro-ph.CO] .
  80. Jessica L. Cook and Lorenzo Sorbo, “Particle production during inflation and gravitational waves detectable by ground-based interferometers,” Phys. Rev. D 85, 023534 (2012), [Erratum: Phys.Rev.D 86, 069901 (2012)], arXiv:1109.0022 [astro-ph.CO] .
  81. Daniel Carney, Willy Fischler, Ely D. Kovetz, Dustin Lorshbough,  and Sonia Paban, “Rapid field excursions and the inflationary tensor spectrum,” JHEP 11, 042 (2012), arXiv:1209.3848 [hep-th] .
  82. Leonardo Senatore, Eva Silverstein,  and Matias Zaldarriaga, “New Sources of Gravitational Waves during Inflation,” JCAP 08, 016 (2014), arXiv:1109.0542 [hep-th] .
  83. Sabino Matarrese, Silvia Mollerach,  and Marco Bruni, “Second order perturbations of the Einstein-de Sitter universe,” Phys. Rev. D 58, 043504 (1998), arXiv:astro-ph/9707278 .
  84. Matteo Biagetti, Matteo Fasiello,  and Antonio Riotto, “Enhancing Inflationary Tensor Modes through Spectator Fields,” Phys. Rev. D 88, 103518 (2013), arXiv:1305.7241 [astro-ph.CO] .
  85. N. Aghanim et al. (Planck), “Planck 2018 results. VI. Cosmological parameters,” Astron. Astrophys. 641, A6 (2020), [Erratum: Astron.Astrophys. 652, C4 (2021)], arXiv:1807.06209 [astro-ph.CO] .
  86. Sachiko Kuroyanagi, Tomo Takahashi,  and Shuichiro Yokoyama, “Blue-tilted Tensor Spectrum and Thermal History of the Universe,” JCAP 02, 003 (2015), arXiv:1407.4785 [astro-ph.CO] .
  87. Ido Ben-Dayan, Brian Keating, David Leon,  and Ira Wolfson, “Constraints on scalar and tensor spectra from Ne⁢f⁢fsubscript𝑁𝑒𝑓𝑓N_{eff}italic_N start_POSTSUBSCRIPT italic_e italic_f italic_f end_POSTSUBSCRIPT,” JCAP 06, 007 (2019), arXiv:1903.11843 [astro-ph.CO] .
  88. Sunny Vagnozzi and Abraham Loeb, “The Challenge of Ruling Out Inflation via the Primordial Graviton Background,” Astrophys. J. Lett. 939, L22 (2022), arXiv:2208.14088 [astro-ph.CO] .
  89. William Giarè, Matteo Forconi, Eleonora Di Valentino,  and Alessandro Melchiorri, “Towards a reliable calculation of relic radiation from primordial gravitational waves,” Mon. Not. Roy. Astron. Soc. 520, 2 (2023), arXiv:2210.14159 [astro-ph.CO] .
  90. Jesus Torrado and Antony Lewis, “Cobaya: Code for Bayesian Analysis of hierarchical physical models,” JCAP 05, 057 (2021), arXiv:2005.05290 [astro-ph.IM] .
  91. P. A. R. Ade et al. (BICEP, Keck), “Improved Constraints on Primordial Gravitational Waves using Planck, WMAP, and BICEP/Keck Observations through the 2018 Observing Season,” Phys. Rev. Lett. 127, 151301 (2021), arXiv:2110.00483 [astro-ph.CO] .
  92. Giovanni Cabass, Luca Pagano, Laura Salvati, Martina Gerbino, Elena Giusarma,  and Alessandro Melchiorri, “Updated Constraints and Forecasts on Primordial Tensor Modes,” Phys. Rev. D 93, 063508 (2016), arXiv:1511.05146 [astro-ph.CO] .
  93. R. Abbott et al. (KAGRA, Virgo, LIGO Scientific), “Upper limits on the isotropic gravitational-wave background from Advanced LIGO and Advanced Virgo’s third observing run,” Phys. Rev. D 104, 022004 (2021), arXiv:2101.12130 [gr-qc] .
  94. Bruce Allen and Ram Brustein, “Detecting relic gravitational radiation from string cosmology with LIGO,” Phys. Rev. D 55, 3260–3264 (1997), arXiv:gr-qc/9609013 .
  95. Sai Wang, Zhi-Chao Zhao, Jun-Peng Li,  and Qing-Hua Zhu, “Exploring the Implications of 2023 Pulsar Timing Array Datasets for Scalar-Induced Gravitational Waves and Primordial Black Holes,” .  (2023), arXiv:2307.00572 [astro-ph.CO] .
  96. Micol Benetti, Leila Lobato Graef,  and Sunny Vagnozzi, “Primordial gravitational waves from NANOGrav: A broken power-law approach,” Phys. Rev. D 105, 043520 (2022), arXiv:2111.04758 [astro-ph.CO] .
  97. Seyed Ali Hosseini Mansoori, Fereshteh Felegray, Alireza Talebian,  and Mohammad Sami, “PBHs and GWs from 𝕋2superscript𝕋2\mathbb{T}^{2}blackboard_T start_POSTSUPERSCRIPT 2 end_POSTSUPERSCRIPT-inflation and NANOGrav 15-year data,” .  (2023), arXiv:2307.06757 [astro-ph.CO] .
  98. Kingman Cheung, C. J. Ouseph,  and Po-Yan Tseng, “NANOGrav Signal and PBH from the Modified Higgs Inflation,” .  (2023), arXiv:2307.08046 [hep-ph] .
  99. Sayantan Choudhury, “Single field inflation in the light of NANOGrav 15-year Data: Quintessential interpretation of blue tilted tensor spectrum through Non-Bunch Davies initial condition,” .  (2023), arXiv:2307.03249 [astro-ph.CO] .
  100. Michał Artymowski, Ido Ben-Dayan,  and Udaykrishna Thattarampilly, “Sourced fluctuations in generic slow contraction,” JCAP 06, 010 (2021), arXiv:2011.00626 [gr-qc] .
  101. Ido Ben-Dayan and Udaykrishna Thattarampilly, “Requiem to ”Proof of Inflation” or Sourced Fluctuations in a Non-Singular Bounce,” .  (2023), arXiv:2308.00256 [astro-ph.CO] .
Citations (19)
View on Semantic Scholar

Summary

We haven't generated a summary for this paper yet.

Ai Sparkles Streamline Icon: https://streamlinehq.com Summarize Now