Alexandre Arbey, Jérémy Auffinger, Pearl Sandick, Barmak Shams Es Haghi, Kuver Sinha
We present precision calculations of dark radiation in the form of gravitons coming from Hawking evaporation of spinning primordial black holes (PBHs) in the early Universe. Our calculation incorporates a careful treatment of extended spin distributions of a population of PBHs, the PBH reheating temperature, and the number of relativistic degrees of freedom. We compare our precision results with those existing in the literature, and show constraints on PBHs from current bounds on dark radiation from BBN and the CMB, as well as the projected sensitivity of CMB Stage 4 experiments. As an application, we consider the case of PBHs formed during an early matter-dominated era (EMDE). We calculate graviton production from various PBH spin distributions pertinent to EMDEs, and find that PBHs in the entire mass range up to $10^9\,$g will be constrained by measurements from CMB Stage 4 experiments, assuming PBHs come to dominate the Universe prior to Hawking evaporation. We also find that for PBHs with monochromatic spins $a^*>0.81$, all PBH masses in the range $10^{-1}\,{\rm g} < M_{\rm BH} <10^9\,$g will be probed by CMB Stage 4 experiments.
Jérémy Auffinger, Alexandre Arbey
We present the public code \texttt{BlackHawk}, a powerful tool to compute the evaporation of any distribution of Schwarzschild and Kerr Black Holes and the emission spectra of Hawking radiation.
Alexandre Arbey, Jérémy Auffinger, Joseph Silk
Dec 29, 2020·astro-ph.CO·PDF Primordial Black Holes (PBHs) are appealing candidates for dark matter in the universe but are severely constrained by theoretical and observational constraints. We will focus on the Hawking evaporation limits extended to Kerr black holes. In particular, we will discuss the possibility to distinguish between black holes of primordial and of stellar origins based on the Thorne limit on their spin. We will also review the isotropic extragalactic gamma ray background constraints and show that the ``window'' in which PBHs can constitute all of the dark matter depends strongly on the PBH spin. Finally, we will consider the possibility that the so-called Planet 9 is a primordial black hole.
Alexandre Arbey, Jérémy Auffinger
Concordant evidence points towards the existence of a ninth planet in the Solar System at more than $400\,$AU from the Sun. In particular, trans-Neptunian object orbits are perturbed by the presence of a putative gravitational source. Since this planet has not yet been observationally found with conventional telescope research, it has been argued that it could be a dark compact object, namely a black hole of probably primordial origin. Within this assumption, we discuss the possibility of detecting Planet 9 via a sub-relativistic spacecraft fly-by and the measure of its Hawking radiation in the radio band and conclude that it is too faint compared to the CMB. We thus present other perspectives with rather a satellite mission and conclude that smaller black holes would give much more interesting signals. We emphasize the importance of the study of such Hawking radiation laboratories in the Solar System.
Jérémy Auffinger, Isabella Masina, Giorgio Orlando
We consider light dark matter candidates originated from the evaporation of Schwarzschild primordial black holes, with masses in the range $10^{-5}-10^9$ g. These candidates are beyond Standard Model particles with negligible couplings to the other particles, so that they interact only gravitationally. Belonging to the category of warm dark matter, they nevertheless spoil structure formation, with a softer impact for increasing values of the candidate spin. Requiring such candidates to fully account for the observed dark matter, we find that the scenario of black hole domination is ruled out for all spin values up to 2. For the scenario of radiation domination, we derive upper limits on the parameter $β$ (the primordial black hole energy density at formation over the radiation one), which are less stringent the higher the candidate spin is.
Jérémy Auffinger, Alexandre Arbey
We present the new version of BlackHawk v2.0. BlackHawk is a public code designed to compute the Hawking radiation spectra of (primordial) black holes. In the version 2.0, we have added several non-standard BH metrics: charged, higher dimensional and polymerized black holes, in addition to the usual rotating (Kerr) BHs. BlackHawk also embeds some additional scripts and numerical tables that can prove useful in e.g. dark matter studies. We describe these new features and provide some examples of the capabilities of the code. A tutorial for BlackHawk is available on the TOOLS2021 website: https://indico.cern.ch/event/1076291/contributions/4609967/
Jérémy Auffinger
Primordial black holes (PBHs) are convenient candidates to explain the elusive dark matter (DM). However, years of constraints from various astronomical observations have constrained their abundance over a wide range of masses, leaving only a narrow window open at $10^{17}\,{\rm g} \lesssim M \lesssim 10^{22}\,$g for all DM in the form of PBHs. We reexamine this disputed window with a critical eye, interrogating the general hypotheses underlying the direct photon constraints. We review 4 levels of assumptions: i) instrument characteristics, ii) prediction of the (extra)galactic photon flux, iii) statistical method of signal-to-data comparison and iv) computation of the Hawking radiation rate. Thanks to Isatis, a new tool designed for the public Hawking radiation code BlackHawk, we first revisit the existing and prospective constraints on the PBH abundance and investigate the impact of assumptions i)-iv). We show that the constraints can vary by several orders of magnitude, advocating the necessity of a reduction of the theoretical sources of uncertainties. Second, we consider an "ideal" instrument and we demonstrate that the PBH DM scenario can only be constrained by the direct photon Hawking radiation phenomenon below $M_{\rm max} \sim 10^{20}\,$g. The upper part of the mass window should therefore be closed by other means.
Alexandre Arbey, Jérémy Auffinger, Joseph Silk
Jun 11, 2019·astro-ph.CO·PDF Primordial black holes can represent all or most of the dark matter in the window $10^{17}-10^{22}\,$g. Here we present an extension of the constraints on PBHs of masses $10^{13}-10^{18}\,$g arising from the isotropic diffuse gamma ray background. Primordial black holes evaporate by emitting Hawking radiation that should not exceed the observed background. Generalizing from monochromatic distributions of Schwarzschild black holes to extended mass functions of Kerr rotating black holes, we show that the lower part of this mass window can be closed for near-extremal black holes.
Alexandre Arbey, Jérémy Auffinger, Joseph Silk
We evaluate abundance anomalies generated in patches of the universe where the baryon-to-photon ratio was locally enhanced by possibly many orders of magnitude in the range $η= 10^{-10} - 10^{-1}$. Our study is motivated by the possible survival of rare dense regions in the early universe, the most extreme of which, above a critical threshold, collapsed to form primordial black holes. If this occurred, one may expect there to also be a significant population of early-forming stars that formed in similar but subthreshold patches. We derive a range of element abundance signatures by performing BBN simulations at high values of the baryon-to-photon ratio that may be detectable in any surviving first generation stars of around a solar mass. Our predictions apply to metal-poor galactic halo stars, to old globular star clusters and to dwarf galaxies, and we compare with observations in each of these cases.
Alexandre Arbey, Jérémy Auffinger
We describe BlackHawk, a public C program for calculating the Hawking evaporation spectra of any black hole distribution. This program allows the users to compute the primary and secondary spectra of stable or long-lived particles generated by Hawking radiation of the distribution of black holes, and to study their evolution in time. The physics of Hawking radiation is presented, and the capabilities, features and usage of BlackHawk are described here under the form of a manual. This is the BlackHawk v2.0 manual, which is available on the BlackHawk webpage http://blackhawk.hepforge.org/. A brief release note summarizing the new aspects of BlackHawk v2.0 as well as illustrating examples can be found in https://arxiv.org/abs/2108.02737.
Jérémy Auffinger, Alexandre Arbey, Pearl Sandick, Barmak Shams Es Haghi, Kuver Sinha
Jan 13, 2022·astro-ph.CO·PDF Light black holes could have formed in the very early universe through the collapse of large primordial density fluctuations. These primordial black holes (PBHs), if light enough, would have evaporated by now because of the emission of Hawking radiation; thus they could not represent a sizable fraction of dark matter today. However, they could have left imprints in the early cosmological epochs. We will discuss the impact of massless graviton emission by (rotating) PBHs before the onset of big bang nucleosynthesis (BBN) and conclude that this contribution to dark radiation is constrained by the cosmic microwave background (CMB) (with the future CMB Stage 4) and BBN in the lighter portion of the PBH mass range, under the hypothesis that they dominated the energy density of the universe.
Jérémy Auffinger
Primordial black holes are under intense scrutiny since the detection of gravitational waves from mergers of solar-mass black holes in 2015. More recently, the development of numerical tools and the precision observational data have rekindled the effort to constrain the black hole abundance in the lower mass range, that is $M < 10^{23}$g. In particular, primordial black holes of asteroid mass $M \sim 10^{17}-10^{23}\,$g may represent 100\% of dark matter. While the microlensing and stellar disruption constraints on their abundance have been relieved, Hawking radiation of these black holes seems to be the only detection (and constraining) mean. Hawking radiation constraints on primordial black holes date back to the first papers by Hawking. Black holes evaporating in the early universe may have generated the baryon asymmetry, modified big bang nucleosynthesis, distorted the cosmic microwave background, or produced cosmological backgrounds of stable particles such as photons and neutrinos. At the end of their lifetime, exploding primordial black holes would produce high energy cosmic rays that would provide invaluable access to the physics at energies up to the Planck scale. In this review, we describe the main principles of Hawking radiation, which lie at the border of general relativity, quantum mechanics and statistical physics. We then present an up-to-date status of the different constraints on primordial black holes that rely on the evaporation phenomenon, and give, where relevant, prospects for future work. In particular, non-standard black holes and emission of beyond the Standard Model degrees of freedom is currently a hot subject.
Alexandre Arbey, Jérémy Auffinger, Marc Geiller, Etera R. Livine, Francesco Sartini
In the context of the dynamics and stability of black holes in modified theories of gravity, we derive the Teukolsky equations for massless fields of all spins in general spherically-symmetric and static metrics. We then compute the short-ranged potentials associated with the radial dynamics of spin 1 and spin 1/2 fields, thereby completing the existing literature on spin 0 and 2. These potentials are crucial for the computation of Hawking radiation and quasi-normal modes emitted by black holes. In addition to the Schwarzschild metric, we apply these results and give the explicit formulas for the radial potentials in the case of charged (Reissner--Nordström) black holes, higher-dimensional black holes, and polymerized black holes arising from loop quantum gravity. These results are in particular relevant and applicable to a large class of regular black hole metrics. The phenomenological applications of these formulas will be the subject of a companion paper.
Alexandre Arbey, Jérémy Auffinger
We present the new version v2.0 of the public code BlackHawk designed to compute the Hawking radiation of black holes, with both primary and hadronized spectra. This new version aims at opening an avenue toward physics beyond the Standard Model (BSM) in Hawking radiation. Several major additions have been made since version v1.0: dark matter/dark radiation emission, spin $3/2$ greybody factors, scripts for cosmological studies, BSM black hole metrics with their associated greybody factors and a careful treatment of the low energy showering of secondary particles; as well as bug corrections. We present, in each case, examples of the new capabilities of BlackHawk.
Jérémy Auffinger, Guillaume Laibe
Sep 25, 2017·astro-ph.EP·PDF Streaming instability is a powerful mechanism which concentrates dust grains in pro- toplanetary discs, eventually up to the stage where they collapse gravitationally and form planetesimals. Previous studies inferred that it should be ineffective in viscous discs, too efficient in inviscid discs, and may not operate in local pressure maxima where solids accumulate. From a linear analysis of stability, we show that streaming instability behaves differently inside local pressure maxima. Under the action of the strong differential advection imposed by the bump, a novel unstable mode develops and grows even when gas viscosity is large. Hence, pressure bumps are found to be the only places where streaming instability occurs in viscous discs. This offers a promising way to conciliate models of planet formation with recent observations of young discs.
Alexandre Arbey, Jérémy Auffinger, Joseph Silk
Jun 10, 2019·astro-ph.CO·PDF Near extremal Kerr black holes are subject to the Thorne limit $a<a^*_{\rm lim}=0.998$ in the case of thin disc accretion, or some generalized version of this in other disc geometries. However any limit that differs from the thermodynamics limit $a^* < 1$ can in principle be evaded in other astrophysical configurations, and in particular if the near extremal black holes are primordial and subject to evaporation by Hawking radiation only. We derive the lower mass limit above which Hawking radiation is slow enough so that a primordial black hole with a spin initially above some generalized Thorne limit can still be above this limit today. Thus, we point out that the observation of Kerr black holes with extremely high spin should be a hint of either exotic astrophysical mechanisms or primordial origin.
Alexandre Arbey, Jérémy Auffinger, Marc Geiller, Etera R. Livine, Francesco Sartini
In the companion paper [Phys. Rev. D 103 (2021) 10, [2101.02951]] we have derived the short-ranged potentials for the Teukolsky equations for massless spins $(0,1/2,1,2)$ in general spherically-symmetric and static metrics. Here we apply these results to numerically compute the Hawking radiation spectra of such particles emitted by black holes (BHs) in three different ansatz: charged BHs, higher-dimensional BHs, and polymerized BHs arising from models of quantum gravity. In order to ensure the robustness of our numerical procedure, we show that it agrees with newly derived analytic formulas for the cross-sections in the high and low energy limits. We show how the short-ranged potentials and precise Hawking radiation rates can be used inside the code $\texttt{BlackHawk}$ to predict future primordial BH evaporation signals for a very wide class of BH solutions, including the promising regular BH solutions derived from loop quantum gravity. In particular, we derive the first Hawking radiation constraints on polymerized BHs from AMEGO. We prove that the mass window $10^{16}-10^{18}\,$g for all dark matter into primordial BHs can be reopened with high values of the polymerization parameter, which encodes the typical scale and strength of quantum gravity corrections.
A. Arbey, J. Auffinger, K. P. Hickerson, E. S. Jenssen
Jun 28, 2018·astro-ph.CO·PDF We present the version 2 of AlterBBN, an open public code for the calculation of the abundance of the elements from Big-Bang nucleosynthesis. It does not rely on any closed external library or program, aims at being user-friendly and allowing easy modifications, and provides a fast and reliable calculation of the Big-Bang nucleosynthesis constraints in the standard and alternative cosmologies.