Charged planckian interacting dark matter

The James Webb Space Telescope (JWST) will revolutionize our understanding of early galaxy formation, and could potentially set stringent constraints on the nature of dark matter. We use a semi-empirical model of galaxy formation to investigate the extent to which uncertainties in the implementation of baryonic physics may be degenerate with the predictions of two different models of dark matter – cold dark matter (CDM) and a 7 keV sterile neutrino, which behaves as warm dark matter (WDM). Our models are calibrated to the observed UV luminosity function at z = 4 using two separate dust attenuation prescriptions, which manifest as high and low star formation efficiency in low-mass haloes. These efficiencies capture the net effect of processes that regulate star formation. We find that while at fixed star formation efficiency, ε, there are marked differences in the abundance of faint galaxies in the two dark matter models at high-z; these differences are mimicked easily by varying ε in the same dark matter model. We find that a high ε WDM and a low ε CDM model – which provide equally good fits to the z = 4 UV luminosity function – exhibit nearly identical evolution in the cosmic stellar mass and star formation rate densities. We show that differences in the star formation rate at fixed stellar mass are larger for variations in ε in a given dark matter model than they are between dark matter models; however, the scatter in star formation rates is larger between the two models than they are when varying ε. Our results suggest that JWST will likely be more informative in constraining baryonic processes operating in high-z galaxies than it will be in constraining the nature of dark matter.

view Abstract Citations (15) References (13) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Are SP 91 and COBE Inconsistent with Cold Dark Matter? Bunn, Emory ; White, Martin ; Srednicki, Mark ; Scott, Douglas Abstract We present results on the consistency of standard cold dark matter (CDM) models with both the COBE normalization and the data from the 4th channel of the 9-point South Pole scan. We find that CDM models are consistent with both experiments, a conclusion which is at odds with some other analyses. This is partly due to our careful treatment of the temperature autocorrelation function, but also derives from a realization that the statistical conclusions depend strongly on assumptions about the prior distribution for the normalization $Q$. Publication: The Astrophysical Journal Pub Date: July 1994 DOI: 10.1086/174296 arXiv: arXiv:astro-ph/9308021 Bibcode: 1994ApJ...429....1B Keywords: Astronomical Models; Cosmology; Dark Matter; Infrared Radiation; Microwave Emission; Sky Surveys (Astronomy); Bayes Theorem; Cosmic Background Explorer Satellite; Cosmic Noise; Distribution Functions; Fluctuation Theory; Astrophysics; COSMOLOGY: COSMIC MICROWAVE BACKGROUND; COSMOLOGY: DARK MATTER; COSMOLOGY: THEORY; Astrophysics; High Energy Physics - Phenomenology E-Print: 8 pages in Plain TeX plus 2 PS figures full text sources arXiv | ADS |

Many models of dark matter place their dark matter candidate inside a broader dark sector with other particles and fields for theoretical and phenomenological reasons. The cosmological evolution of these dark sectors can differ significantly from standard scenarios, in particular due to their interplay with the Standard Model of particle physics. In this thesis, we study various dark sector cosmologies, including their evolution and resulting constraints. In view of ever more stringent limits from direct and indirect searches on dark matter as a thermal relic from the primordial plasma encompassing the SM particles, scenarios of a dark sector decoupled from the Standard Model receive increasing interest. Interestingly, the corresponding dark matter production mechanism of thermal freeze-out can also occur entirely in a decoupled dark sector. Still, certain modifications to the standard treatment need to be taken into account. We study these changes and find significant deviations of the annihilation cross-section required to obtain the observed dark matter abundance, in particular if the dark matter particle and its annihilation product are similar in mass. After the first gravitational waves were observed by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), interest in primordial black holes as a candidate for dark matter has been renewed. As gravitational waves can be produced in primordial black hole binary mergers, this setup can be considered a dark sector with purely gravitational interactions. Large initial primordial black hole clustering has been suggested to circumvent the strong limits on this scenario. We show that instead, gravitational wave constraints are enhanced by large clustering such that highly clustered primordial black holes with the masses corresponding to the LIGO events cannot account for all of the dark matter in the Universe. A major part of this thesis studies Big Bang Nucleosynthesis (BBN) as a probe for MeVscale dark sectors. Due to the remarkable agreement of predictions for the primordial light element abundances from BBN with observations, alterations are generally strongly constrained. Dark sectors can change the predictions for the primordial light element abundances by the influence of their cosmological evolution during BBN itself and subsequent disintegration processes, e.g. photodisintegration. The former proceed via alterations of the Hubble rate, neutrino decoupling, the time-temperature relation, and the best-fit value for the baryon-to-photon ratio. The latter are due to late-time high-energy electromagnetic injections into the Standard Model plasma, which induce an electromagnetic cascade producing an abundance of non-thermal photons that can disintegrate light nuclei. We derive these constraints for annihilations of MeV-scale dark matter, electromagnetic decays of MeV-scale dark sector particles, and axion-like particles coupled to photons.

We investigate the effects of warm dark matter (WDM) on the cosmic 21-cm signal. If dark matter exists as WDM instead of cold dark matter (CDM), its non-negligible velocities can inhibit the formation of low-mass halos that normally form first in CDM models, therefore delaying star-formation. The absence of early sources delays the build-up of UV and X-ray backgrounds that affect the 21-cm radiation signal produced by neutral hydrogen. With use of the 21CMFAST, code, we demonstrate that the pre-reionization 21-cm signal can be changed significantly in WDM models with a free-streaming length equivalent to that of a thermal relic with mass mx of up to ~10-20 keV. In such a WDM cosmology, the 21-cm signal traces the growth of more massive halos, resulting in a delay of the 21-cm absorption signature and followed by accelerated X-ray heating. CDM models where astrophysical sources have a suppressed photon-production efficiency can delay the 21-cm signal as well, although its subsequent evolution is not as rapid as compared to WDM. This motivates using the gradient of the global 21-cm signal to differentiate between some CDM and WDM models. Finally, we show that the degeneracy between the astrophysics and mx can be broken with the 21-cm power spectrum, as WDM models should have a bias-induced excess of power on large scales. This boost in power should be detectable with current interferometers for models with mx < 3 keV, while next generation instruments will easily be able to measure this difference for all relevant WDM models.

Spatially resolved spectroscopic data from the CIRPASS integral field unit (IFU) on Gemini are used to measure the gravitational lensing of the four-image quasar Q2237+0305 on different size scales. A method for measuring the substructure present in the lens using observations at multiple wavelengths is demonstrated to be very effective and independent of many of the degeneracies inherent in previous methods. The magnification ratios of the QSO's narrow-line region (NLR) and broad-line region (BLR) are measured and found to disagree with each other and with the published radio and mid-infrared magnification ratios. The disagreement between the BLR ratios and the radio/mid-infrared ratios is interpreted as the result of microlensing by stars in the lens galaxy of the BLR. This implies that the mid-infrared emission region is larger than the BLR and that the BLR is 0.1 pc in size. We find a small difference between the shape of the Hβ line in image A and that in the other images. We consider this difference too small and symmetric to be strong evidence for rotation or large-scale infall in the Hβ emission region. The disagreement between the radio/mid-infrared ratios and the NLR ratios is interpreted as a signature of substructure on a larger scale, possibly the missing small-scale structure predicted by the standard cold dark matter (CDM) model. Extensive lensing simulations are performed to obtain a lower limit on the amount of substructure that is required to cause this discrepancy as a function of its mass and the radial profile of the host lens. The substructure surface density is degenerate with the radial profile of the host lens, but if the expectations of the CDM model are taken into account, certain radial profiles and substructure surface densities can be ruled out. A substructure mass scale as large as 108 M☉ is strongly disfavored, while 104 M☉ is too small if the radio and mid-infrared emission regions have the expected sizes of ~10 pc. The standard elliptical isothermal lens mass profile is not compatible with a substructure surface density of Σsub < 280 M☉ pc-2, at the 95% confidence level. This is 4%-7% of the galaxy's surface density (depending on which image position is used to evaluate this). The required substructure surface density at the required mass scale is high in comparison with the present expectations within the CDM model. Lens mass profiles that are flatter than isothermal—where the surface density in dark matter is higher at the image positions—are compatible with smaller quantities of substructure.

The Cold Dark Matter (CDM) model has an elegant simplicitly which makes it very predictive, but when its parameters are fixed at their ‘canonical’ values its predictions are in conflict with observational data. There is, however, much leeway in the initial conditions within the CDM framework. We advocate a re-examination of the CDM model, taking into account modest variation of parameters from their canonical values. We find that CDM models with n = 0.8–0.9 and h = 0.45–0.50 can fit the available data. Our ‘best fitting’ CDM model has n = 0.9, h = 0.45 and |$C_{2}^{\text T}/C_{2}^{\text S}=0.7$|⁠. We discuss the current state of observations which could definitely rule out this model.

micrOMEGAs5.0 : Freeze-in

We investigate non-linear structure formation in the context of the fuzzy dark matter (FDM) model and compare it to the cold dark matter (CDM) model from a weak lensing perspective. Employing Eulerian perturbation theory (PT) up to fourth order, we calculate the tree-level matter trispectra and the one-loop matter spectra and bispectra from consistently chosen initial conditions. Furthermore, we conduct N-body simulations with CDM and FDM initial conditions to predict the non-linear matter power spectra. Subsequently, we derive the respective lensing spectra, bispectra, and trispectra for CDM and FDM within the framework of a Euclid-like weak lensing survey. In our analysis, we compute attainable cumulative signal-to-noise ratios and estimate χ2-functionals, aimed at distinguishing FDM from CDM at particle masses of m = 10−21 eV, m = 10−22 eV, and m = 10−23 eV. Our results indicate that PT predictions are insufficient for distinguishing between the CDM and FDM models within the context of our simulated weak lensing survey for the considered particle masses. Assuming that N-body simulations overestimate late-time small-scale power in the FDM model, future weak lensing surveys may provide the means to discriminate between FDM and CDM up to a mass of m = 10−23 eV. However, for stronger constraints on the FDM mass, observations of the local high-z universe may be more suitable.

Observations of the high redshift universe provide a promising avenue for constraining the nature of the dark matter (DM). This will be even more true with the advent of the James Webb Space Telescope (JWST). We run cosmological simulations of galaxy formation as part of the Effective Theory of Structure Formation (ETHOS) project to compare high redshift galaxies in cold dark matter (CDM) and alternative DM models which have varying relativistic coupling and self-interaction strengths. The interacting DM scenarios produce a cutoff in the linear power spectrum on small-scales, followed by a series of ‘dark acoustic oscillations’. We find that DM interactions suppress the abundance of galaxies below $M_\star \sim 10^8\, {\rm M}_\odot$ for the models considered. The cutoff in the power spectrum delays structure formation relative to CDM. Objects in ETHOS that end up at the same final masses as their CDM counterparts are characterized by a more vigorous phase of early star formation. While galaxies with $M_\star \lesssim 10^6\, {\rm M_\odot }$ make up more than 60 per cent of star formation in CDM at z ≈ 10, they contribute only about half the star formation density in ETHOS. These differences diminish with decreasing redshift. We find that the effects of DM self-interactions are negligible compared to effects of relativistic coupling (i.e. the effective initial conditions for galaxy formation) in all properties of the galaxy population we examine. Finally, we show that the clustering strength of galaxies at high redshifts depends sensitively on DM physics, although these differences are manifest on scales that may be too small to be measurable by JWST.

We introduce the AIDA-TNG project, a suite of cosmological magnetohydrodynamic simulations that simultaneously model galaxy formation and different variations in the underlying dark matter model. We consider the standard cold dark matter model and five variations, including three warm dark matter scenarios and two self-interacting models with a constant or velocity-dependent cross-section. In each model, we simulated two cosmological boxes of 51.7 and 110.7 Mpc on a side with the same initial conditions as TNG50 and TNG100, and we combined the variations in the physics of dark matter with the fiducial IllustrisTNG galaxy formation model. The AIDA-TNG runs are thus ideal for studying the simultaneous effects of baryons and alternative dark matter models on observable properties of galaxies and large-scale structures. We resolved haloes in the range between 108 and 4×1014 M⊙ and scales down to the nominal resolution of 570 pc in the highest-resolution runs. This work presents the first results on statistical quantities such as the halo mass function and the matter power spectrum. We quantified the modification in the number of haloes and the power on scales smaller than 1 Mpc due to the combination of baryonic and dark matter physics. Despite being calibrated on cold dark matter, we find that the TNG galaxy formation model can produce a realistic galaxy population in all scenarios. The stellar and gas mass fraction, stellar mass function, black hole mass as a function of stellar mass, and star formation rate density are very similar in all dark matter models, with some deviations only in the most extreme warm dark matter model. Finally, we also quantify changes in halo structure due to warm and self-interacting dark matter, which appear in the density profiles, concentration-mass relation, and galaxy sizes.

The Standard Model of particle physics is governed by Poincaré symmetry, while all other symmetries, exact or approximate, are essentially dictated by theoretical consistency with the particle spectrum. On the other hand, many models of dark matter exist that rely upon the addition of new added global symmetries in order to stabilize the dark matter particle and/or achieve the correct abundance. In this work we begin a systematic exploration into truly natural models of dark matter, organized by only relativity and quantum mechanics, without the appeal to any additional global symmetries, no fine-tuning, and no small parameters. We begin by reviewing how singlet dark sectors based on spin 0 or spin frac{1}{2} should readily decay, while pure strongly coupled spin 1 models have an overabun-dance problem. This inevitably leads us to construct chiral models with spin frac{1}{2} particles charged under confining spin 1 particles. This leads to stable dark matter candidates that are analogs of baryons, with a confinement scale that can be naturally \U0001d4aa(100)TeV. This leads to the right freeze-out abundance by annihilating into massless unconfined dark fermions. The minimal model involves a dark copy of SU(3) × SU(2) with 1 generation of chiral dark quarks and leptons. The presence of massless dark leptons can potentially give rise to a somewhat large value of ∆Neff during BBN. In order to not upset BBN one may either appeal to a large number of heavy degrees of freedom beyond the Standard Model, or to assume the dark sector has a lower reheat temperature than the visible sector, which is also natural in this framework. This reasoning provides a robust set of dark matter models that are entirely natural. Some are concrete realizations of the nightmare scenario in which dark matter may be very difficult to detect, which may impact future search techniques.

This article questions the common assumption of cold dark matter (DM) by exploring the possibility of a nonzero equation of state (EOS) without relying on any parametric approach. In standard cosmological analyses, DM is typically modeled as pressureless dust with w DM = 0 , an assumption that aligns with large-scale structure formation, supports the empirical success of the Λ -cold dark matter model, and simplifies cosmological modeling. However, there is no fundamental reason to exclude a nonzero w DM from the cosmological framework. In this work, we explore this possibility through nonparametric and parametric reconstructions based on Gaussian process regression. The reconstructions use Hubble parameter measurements from cosmic chronometers, the Pantheon + sample of Type Ia supernovae, and baryon acoustic oscillation (BAO) data from DESI DR1 and DR2. Our findings suggest that a dynamical EOS for DM, although only mildly supported statistically, cannot be conclusively ruled out. Notably, we observe a mild tendency ( ∼ 1 σ ) toward a negative w DM at the present epoch, which is most likely due to inconsistencies between the BAO data from DESI and other datasets.

We investigate the process of reionisation in a model in which the dark matter is a warm elementary particle such as a sterile neutrino. We focus on models that are consistent with the dark matter decay interpretation of the recently detected line at 3.5 keV in the X-ray spectra of galaxies and clusters. In warm dark matter models the primordial spectrum of density perturbations has a cut-off on the scale of dwarf galaxies. Structure formation therefore begins later than in the standard cold dark matter (CDM) model and very few objects form below the cut-off mass scale. To calculate the number of ionising photons, we use the Durham semi-analytic model of galaxy formation, GALFORM. We find that even the most extreme 7 keV sterile neutrino we consider is able to reionise the Universe early enough to be compatible with the bounds on the epoch of reionisation from Planck. This, perhaps surprising, result arises from the rapid build-up of high redshift galaxies in the sterile neutrino models which is also reflected in a faster evolution of their far-UV luminosity function between 10 &gt; z &gt; 7 than in CDM. The dominant sources of ionising photons are systematically more massive in the sterile neutrino models than in CDM. As a consistency check on the models, we calculate the present-day luminosity function of satellites of Milky Way-like galaxies. When the satellites recently discovered in the DES survey are taken into account, strong constraints are placed on viable sterile neutrino models.

Cosmological observations have revealed the existence of a dark matter sector, which is commonly assumed to be made up of one particle species only. However, this sector might be more complicated than we currently believe: there might be more than one dark matter species (for example two components of cold dark matter or a mixture of hot and cold dark matter) and there may be new interactions between these particles. In this paper we study the possibility of multiple dark matter species and interactions mediated by a dark energy field. We study both the background and the perturbation evolution in these scenarios. We find that the background evolution of a system of multiple dark matter particles (with constant couplings) mimics a single fluid with a time-varying coupling parameter. However, this is no longer true on the perturbative level. We study the case of attractive and repulsive forces as well as a mixture of cold and hot dark matter particles.

We consider dark matter physics in a model for the dark sector with extra dark U(1)$_X$ gauge symmetry. The dark sector is composed of exotic fermions that are charged under both dark U(1)$_X$ and the standard model SU(3)$_C \times$U(1)$_Y$ gauge groups, as well as standard model singlet complex scalars $\Phi$ and $X$ with nonzero U(1)$_X$ charge. In this model, there are two dark matter candidates$-$a scalar and a fermion$-$both of which are stabilized by accidental $Z_2$ symmetry. Their thermal relic density, and direct and indirect detection constraints are discussed in detail and we search for the parameter space of the model accommodating dark matter observations. We also discuss constraints from diphoton resonance searches associated with the scalar field which breaks the dark U(1)$_X$, in a way consistent with dark matter physics. In addition, implications for collider physics are discussed, focusing on the production cross section of the scalar boson.