Primordial Black Hole Archaeology with Gravitational Waves from Cosmic Strings. (arXiv:2304.04793v1 [hep-ph])
<a href="http://arxiv.org/find/hep-ph/1/au:+Ghoshal_A/0/1/0/all/0/1">Anish Ghoshal</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Gouttenoire_Y/0/1/0/all/0/1">Yann Gouttenoire</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Heurtier_L/0/1/0/all/0/1">Lucien Heurtier</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Simakachorn_P/0/1/0/all/0/1">Peera Simakachorn</a>
Light primordial black holes (PBHs) with masses smaller than $10^9$ g
($10^{-24} M_odot$) evaporate before the onset of Big-Bang nucleosynthesis,
rendering their detection rather challenging. If efficiently produced, they may
have dominated the universe energy density. We study how such an early
matter-dominated era can be probed successfully using gravitational waves (GW)
emitted by local and global cosmic strings. While previous studies showed that
a matter era generates a single-step suppression of the GW spectrum, we instead
find a “double-step” suppression for local-string GW whose spectral shape
provides information on the duration of the matter era. The presence of the two
steps in the GW spectrum originates from GW being produced through two events
separated in time: loop formation and loop decay, taking place either before or
after the matter era. The second step – called the “knee” – is a novel feature
which is universal to any early matter-dominated era and is not only specific
to PBHs. Detecting GWs from cosmic strings with LISA, ET, or BBO would set
constraints on PBHs with masses between $10^6$ and $10^9$ g for local strings
with tension $Gmu = 10^{-11}$, and PBHs masses between $10^4$ and $10^9$ g for
global strings with symmetry-breaking scale $eta = 10^{15}~mathrm{GeV}$.
Effects from the spin of PBHs are discussed.
Light primordial black holes (PBHs) with masses smaller than $10^9$ g
($10^{-24} M_odot$) evaporate before the onset of Big-Bang nucleosynthesis,
rendering their detection rather challenging. If efficiently produced, they may
have dominated the universe energy density. We study how such an early
matter-dominated era can be probed successfully using gravitational waves (GW)
emitted by local and global cosmic strings. While previous studies showed that
a matter era generates a single-step suppression of the GW spectrum, we instead
find a “double-step” suppression for local-string GW whose spectral shape
provides information on the duration of the matter era. The presence of the two
steps in the GW spectrum originates from GW being produced through two events
separated in time: loop formation and loop decay, taking place either before or
after the matter era. The second step – called the “knee” – is a novel feature
which is universal to any early matter-dominated era and is not only specific
to PBHs. Detecting GWs from cosmic strings with LISA, ET, or BBO would set
constraints on PBHs with masses between $10^6$ and $10^9$ g for local strings
with tension $Gmu = 10^{-11}$, and PBHs masses between $10^4$ and $10^9$ g for
global strings with symmetry-breaking scale $eta = 10^{15}~mathrm{GeV}$.
Effects from the spin of PBHs are discussed.
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