No abstract

We compute the number density of nonlinear seed fluctuations which have the right number density to be able to explain the presence of one supermassive black hole per galaxy, as a function of redshift. We find that there is an interesting range of symmetry breaking scales for which the density of seeds is larger that what is predicted in the standard cosmological model with Gaussian primordial fluctuations. Hence, global defects may help in light of the mounting tension between the standard cosmological model and observations of supermassive black hole candidates at high redshifts.

The observation of quasars at high redshifts presents a mystery in the theory of black hole formation. In order to source such objects, one often relies on the presence of heavy seeds (M ≈ 104 − 6 M⊙) in place at early times. Unfortunately, the formation of these heavy seeds are difficult to realize within the standard astrophysical context. Here, we investigate whether superconducting cosmic string loops can source sufficiently strong overdensities in the early universe to address this mystery. We review a set of direct collapse conditions under which a primordial gas cloud will undergo monolithic collapse into a massive black hole (forming with a mass of MBH ≈ 105 M⊙ at z ≈ 300 in our scenario), and systematically show how superconducting cosmic string loops can satisfy such conditions in regions of the Gμ − I parameter space.

We compute the energy spectrum of photons {and neutrinos} produced by the unwinding of a scaling distribution of cosmic textures, and discuss the implications for the spectrum of high energy cosmic rays, and for CMB spectral distortions. Textures lead to a contribution to the photon flux which scales as E3 F(E) ∼ E3/2. Hence, the tightest constraints on the texture model come from the highest energies from which primordial photons can reach us without being scattered by the CMB and other foregrounds. Textures lead to both μ type and y type distortions. While the constraints on the texture model coming from the current COBE bounds are weaker than the bounds from the angular power spectrum of the CMB, future surveys such as PIXIE can lead to stronger bounds. {The high energy neutrino flux is constrained by data from the Pierre Auger experiment and yields a bound on the energy scale of textures which is competitive with CMB bounds.}