Ultra-low frequency gravitational waves: distinguishing cosmological backgrounds from astrophysical foregrounds. (arXiv:2104.15130v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Moore_C/0/1/0/all/0/1">Christopher J. Moore</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vecchio_A/0/1/0/all/0/1">Alberto Vecchio</a>
The gravitational wave (GW) spectrum at frequencies below $sim
100,mathrm{nHz}$ may contain overlapping contributions from processes in the
early Universe and black hole binaries with masses $sim
10^{6}-10^{9},M_odot$ at low redshifts. Pulsar timing arrays are measuring
the GW background at $sim 1-100,mathrm{nHz}$, but are currently unable to
distinguish an astrophysical foreground from a cosmological background due to,
say, a first order phase transition at a temperature $sim 1-100,mathrm{MeV}$
in a weakly-interacting dark sector. Our analysis reveals the extent to which
including integrated bounds on the ultra-low frequency GW spectrum from cosmic
microwave background, big bang nucleosynethesis or astrometric observations can
break this degeneracy.
The gravitational wave (GW) spectrum at frequencies below $sim
100,mathrm{nHz}$ may contain overlapping contributions from processes in the
early Universe and black hole binaries with masses $sim
10^{6}-10^{9},M_odot$ at low redshifts. Pulsar timing arrays are measuring
the GW background at $sim 1-100,mathrm{nHz}$, but are currently unable to
distinguish an astrophysical foreground from a cosmological background due to,
say, a first order phase transition at a temperature $sim 1-100,mathrm{MeV}$
in a weakly-interacting dark sector. Our analysis reveals the extent to which
including integrated bounds on the ultra-low frequency GW spectrum from cosmic
microwave background, big bang nucleosynethesis or astrometric observations can
break this degeneracy.
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