Cai Yong, Zhu Mian, Piao Yun-Song
Institute for Astrophysics, School of Physics, <a href="https://ror.org/04ypx8c21">Zhengzhou University</a>, Zhengzhou 450001, China.
Faculty of Physics, Astronomy and Applied Computer Science, <a href="https://ror.org/03bqmcz70">Jagiellonian University</a>, 30-348 Krakow, Poland.
Phys Rev Lett. 2024 Jul 12;133(2):021001. doi: 10.1103/PhysRevLett.133.021001.
Primordial black holes (PBHs) and the violation of the null energy condition (NEC) have significant implications for our understanding of the very early Universe. We present a novel approach to generate PBHs via the NEC violation in a single-field inflationary scenario. In our scenario, the Universe transitions from a first slow-roll inflation stage with a Hubble parameter H=H_{inf1} to a second slow-roll inflation stage with H=H_{inf2}≫H_{inf1}, passing through an intermediate stage of NEC violation. The NEC violation naturally enhances the primordial scalar power spectrum at a certain wavelength, leading to the production of PBHs with masses and abundances of observational interest. We also investigate the phenomenological signatures of scalar-induced gravitational waves resulting from the enhanced density perturbations. Our work highlights the potential of utilizing a combination of PBHs, scalar-induced gravitational waves, and primordial gravitational waves as a valuable probe for studying NEC violation during inflation, opening up new avenues for exploring the early Universe.
原初黑洞（PBHs）以及零能量条件（NEC）的违反对于我们理解极早期宇宙具有重要意义。我们提出了一种新颖的方法，通过单场暴胀情景中的NEC违反来产生PBHs。在我们的情景中，宇宙从具有哈勃参数(H = H_{inf1})的第一个慢滚暴胀阶段过渡到具有(H = H_{inf2} \gg H_{inf1})的第二个慢滚暴胀阶段，经历一个NEC违反的中间阶段。NEC的违反自然地在特定波长处增强了原初标量功率谱，从而导致产生具有观测意义的质量和丰度的PBHs。我们还研究了由增强的密度扰动产生的标量诱导引力波的现象学特征。我们的工作突出了利用PBHs、标量诱导引力波和原初引力波的组合作为研究暴胀期间NEC违反的有价值探针的潜力，为探索早期宇宙开辟了新途径。
