Search

To self-consistently model galactic properties, reionization of the intergalactic medium, and the associated 21-cm signal, we have developed the algorithm polar by integrating the one-dimensional radiative transfer code grizzly with the semi-analytical galaxy formation code L-Galaxies 2020. Our proof-of-concept results are consistent with observations of the star formation rate history, UV luminosity function and the CMB Thomson scattering optical depth. We then investigate how different galaxy formation models affect UV luminosity functions and 21-cm power spectra, and find that while the former are most sensitive to the parameters describing the merger of halos, the latter have a stronger dependence on the supernovae feedback parameters, and both are affected by the escape fraction model., Comment: MNRAS accepted

The role of baryonic physics, star formation and stellar feedback, in shaping the galaxies and their host halos is an evolving topic. The dark matter aspects are illustrated in this work by showing distribution features in a Milky Way sized halo. We focus on the halo morphology, geometry, and profile as well as the phase space distribution using one dark matter only and five hydrodynamical cosmological high-resolution simulations of the same halo with different subgrid prescriptions for the baryonic physics (Kennicut versus multi-freefall star formation and delayed cooling versus mechanical supernovae feedback). If some general properties like the relative halo-galaxy orientation are similar, the modifications of the gravitational potential due to the presence of baryons are found to induce different dark matter distributions (rounder and more concentrated halo). The mass density profile as well as the velocity distribution are modified distinctively according to the specific resulting baryonic distribution highlighting the variability of those properties (e.g inner power index from 1.3 to 1.8, broader speed distribution). The uncertainties on those features are of paramount importance for dark matter phenomenology, particularly when dealing with dark matter dynamics or direct and indirect detection searches. As a consequence, dark matter properties and prospects using cosmological simulations require improvement on baryonic physics description. Modeling such processes is a key issue not only for galaxy formation but also for dark matter investigations.

Clusters of galaxies, being the largest collapsed structures in the universe, offer valuable insights into the nature of cosmic evolution. Precise calibration of the mass of clusters can be obtained by extracting their gravitational lensing signal on the Cosmic Microwave Background (CMB) fluctuations. We extend and test here the performance achieved on cluster scales by the parameter-free, maximum a posteriori (MAP) CMB lensing reconstruction method, which has been shown to be optimal in the broader context of CMB lensing mass map and power spectrum estimation. In the context of cluster lensing, the lensing signal of other large-scale structures acts as an additional source of noise. We show here that by delensing the CMB fluctuations around each and every cluster, this noise variance is reduced according to expectations. We also demonstrate that the well-known bias in the temperature quadratic estimator in this regime, sourced by the strong non-Gaussianity of the signal, is almost entirely mitigated without any scale cuts. Being statistically speaking an optimal and blind lensing mass map reconstruction, the MAP estimator is a promising tool for the calibration of the masses of clusters., 11 pages, 4 figures, prepared for PRD submission

We show that it is possible to directly measure the formation time of galaxies using large-scale structure. In particular, we show that the large-scale distribution of galaxies is sensitive to whether galaxies form over a narrow period of time before their observed times, or are formed over a time scale on the order of the age of the Universe. Along the way, we derive simple recursion relations for the perturbative terms of the most general bias expansion for the galaxy density, thus fully extending the famous dark-matter recursion relations to generic tracers., 6+2 pages, 1 figure, ancillary file included

Observations from the James Webb Space Telescope (JWST) have unveiled several galaxies with stellar mass $M_*\gtrsim10^{10} M_\odot$ at $7.4\lesssim z\lesssim 9.1$. These remarkable findings indicate an unexpectedly high stellar mass density, which contradicts the prediction of the $\Lambda \rm CDM$ model. We adopt the Chevallier--Polarski--Linder (CPL) parameterization, one of the dynamic dark energy models, to probe the role of dark energy on shaping the galaxy formation. By considering varying star formation efficiencies within this framework, our analysis demonstrates that an increased proportion of dark energy in the universe corresponds to the formation of more massive galaxies at higher redshifts, given a fixed perturbation amplitude observed today. Furthermore, through elaborately selecting CPL parameters, we successfully explain the JWST observations with star formation efficiencies $\epsilon\gtrsim0.05$ at a confidence level of $95\%$. These intriguing results indicate the promising prospect of revealing the nature of dark energy by analyzing the high-redshift massive galaxies., Comment: 7 pages, 3 figures

We provide a mean curvature flow method for numerical cosmology and test it on cases of inhomogenous inflation. The results show (in a proof of concept way) that the method can handle even large inhomogeneities that result from different regions exiting inflation at different times.

We perform the weak lensing mass mapping analysis to identify troughs, which are defined as local minima in the mass map. Since weak lensing probes projected matter along the line-of-sight, these troughs can be produced by single voids or multiple voids projected along the line-of-sight. To scrutinise the origins of the weak lensing troughs, we systematically investigate the line-of-sight structure of troughs selected from the latest Subaru Hyper Suprime-Cam (HSC) Year 3 weak lensing data covering $433.48 \, \mathrm{deg}^2$. From a curved sky mass map constructed with the HSC data, we identify 15 troughs with the signal-to-noise ratio higher than $5.7$ and address their line-of-sight density structure utilizing redshift distributions of two galaxy samples, photometric luminous red galaxies observed by HSC and spectroscopic galaxies detected by Baryon Oscillation Spectroscopic Survey. While most of weak lensing signals due to the troughs are explained by multiple voids aligned along the line-of-sight, we find that two of the 15 troughs potentially originate from single voids at redshift $\sim 0.3$. The single void interpretation appears to be consistent with our three-dimensional mass mapping analysis. We argue that single voids can indeed reproduce observed weak lensing signals at the troughs if these voids are not spherical but are highly elongated along the line-of-sight direction., 14 pages, 12 figures, submitted to MNRAS

The non-thermal nature of the stochastic gravitational-wave background of cosmological origin (CGWB) poses a challenge in defining the initial conditions for the graviton overdensity. Specifically, the adiabatic initial condition, which holds for Cosmic Microwave Background (CMB) photons, is not guaranteed a priori for the primordial GWs. In this letter, we compute the initial conditions for the cosmological background generated by quantum fluctuations of the metric during inflation. Our analysis reveals that adiabatic initial conditions are no longer valid. The violation of adiabaticity arises from the presence of independent tensor perturbations during inflation, which behave as two extra fields that affect the standard single-clock argument. Since the energy density of the CGWB is subdominant compared to ordinary matter, gravitational radiation plays a negligible role in Einstein's equations. Therefore, the only way to compute the initial conditions is to perturb the energy-momentum tensor defined in terms of the gravitational strain. A direct consequence of our finding is that the initial conditions from inflation enhance the total CGWB angular power-spectrum by an order of magnitude compared to the standard adiabatic case., 7 pages, 1 figure

Sodium iodide (NaI) based cryogenic scintillating calorimeters using quantum sensors for signal read out have shown promising first results towards a model-independent test of the annually modulating signal detected by the DAMA/LIBRA dark matter experiment. The COSINUS collaboration has previously reported on the first above-ground measurements using a dual channel readout of phonons and light based on transition edge sensors (TESs) that allows for particle discrimination on an event-by-event basis. In this letter, we outline the first underground measurement of a NaI cryogenic calorimeter read out via the novel remoTES scheme. A 3.67 g NaI absorber with an improved silicon light detector design was operated at the Laboratori Nazionali del Gran Sasso, Italy. A significant improvement in the discrimination power of $e^-$/$\gamma$-events to nuclear recoils was observed with a five-fold improvement in the nuclear recoil baseline resolution, achieving $\sigma$ = 441 eV. Furthermore, we present a limit on the spin-independent dark-matter nucleon elastic scattering cross-section achieving a sensitivity of $\mathcal{O}$(pb) with an exposure of only 11.6 g d., Comment: 11 pages, 14 figures

The Effective Field Theory of Large-Scale Structure (EFTofLSS) attempts to amend some of the shortcomings of the traditional perturbative methods used in cosmology. It models the evolution of long-wavelength perturbations above a cutoff scale without the need for a detailed description of the short-wavelength ones. Short-scale physics is encoded in the coefficients of a series of operators composed of the long-wavelength fields, and ordered in a systematic expansion. As applied in the literature, the EFTofLSS corrects a summary statistic (such as the power spectrum) calculated from standard perturbation theory by matching it to $N$-body simulations or observations. This `bottom-up' construction is remarkably successful in extending the range of validity of perturbation theory. In this work, we compare this framework to a `top-down' approach, which estimates the EFT coefficients from the stress tensor of an $N$-body simulation, and propagates the corrections to the summary statistic. We consider simple initial conditions, viz. two sinusoidal, plane-parallel density perturbations with substantially different frequencies and amplitudes. We find that the leading EFT correction to the power spectrum in the top-down model is in excellent agreement with that inferred from the bottom-up approach which, by construction, provides an exact match to the numerical data. This result is robust to changes in the wavelength separation between the two linear perturbations. However, in our setup, the leading EFT coefficient does not always grow linearly with the cosmic expansion factor as assumed in the literature based on perturbative considerations. Instead, it decreases after orbit crossing takes place., 31 pages, 16 figures; comments are welcome

The purpose of this work is to investigate the formation and evaporation of the primordial black holes in the inflationary scenarios. Thermodynamic parameters such as mass, temperature and entropy are expressed in terms of NANOGrav frequency. By numerical calculations we show that the constraint on the mass range $10^{-5}kg-10^{50}kg$ is well confirmed. We discuss the relation between the redshift and the probability for gravitational wave source populations. A new parameter associated with the frequency and Hubble rate is presented, by which for the spectral index $n_{s}\approx 0.996$ and the Hubble constant $H_{0}\approx 67.27km.s^{-1}.Mpc^{-1}$, the effective Hubble constant is calculated to be $H_{eff,0}\approx 73.24km.s^{-1}.Mpc^{-1} $ which is compatible with the observational data. We make a comparison between the Hubble tension and the primordial perturbations and the expression of the mass loss rate, chemical potential and central charge needed to describe the Hawking evaporation will be established.

We find the conditions under which scale-invariant Einstein-Cartan gravity with scalar matter fields leads to an approximate conformal invariance of the flat space particle theory up to energies of the order of the Planck mass. In the minimal setup, these models, in addition to the fields of the Standard Model and the graviton, contain only one extra particle -- a massless dilaton. Theories of this type can pave the way for a self-completion all the way up the Planck scale and lead to rather universal inflationary predictions, close to those of the simplest Higgs-inflation scenario in the metric theory of gravity., 38 pages, 2 figures

In the dark dimension scenario, which predicts an extra dimension of micron scale, dark gravitons (KK modes) are a natural dark matter candidate. In this paper, we study observable features of this model. In particular, their decay to standard matter fields can distort the CMB and impact other astrophysical signals. Using this we place bounds on the parameters of this model. In particular we find that the natural range of parameters in this scenario is consistent with these constraints and leads to the prediction that the mean mass of the dark matter today is less than a few hundred keV and the size of the extra dimension is greater than $\sim 10 \;\mu\mathrm{m}$., Comment: 20 pages, 5 figures

Within the framework of investigating the link between central super massive black holes in the core of galaxies and the galaxies themselves, we detected a variable X-ray source in the center of CGCG 077-102 NED02, member of the CGCG 077-102 galaxy pair within the Abell 2063 galaxy cluster. Our goal was then to combine X-ray and optical data to demonstrate that this object harbors an active super massive black hole in its core, and to relate this to the dynamical status of the galaxy pair within the Abell 2063 cluster. We used Chandra and XMM-Newton archival data to derive the X-ray spectral shape and variability. We also obtained optical spectroscopy to detect the expected emission lines that are typically found in Active Galactic Nuclei. And we finally used public ZTF imaging data to investigate the optical variability. There is no evidence of multiple X-ray sources or extended component within CGCG 077-102 NED02. Single X-ray spectral models fit well the source. Non-random significant X-ray flux inter-observation X-ray variabilities were detected, between ~4days for short term variations and up to ~700days for long term variations. Optical spectroscopy points toward a passive galaxy for CGCG 077-102 NED01 and a Seyfert for CGCG 077-102 NED02. We did not detect short-term variability in the optical ZTF light curves. However, we found a significant long-term stochastic variability in the g-band that can be well described by the damped random walk model. Finally, the CGCG 077-102 galaxy pair is deeply embedded within the Abell 2063 potential, and has underwent the cluster influence for a long time. Our observations point toward a moderatly massive black hole in the center of CGCG 077-102 NED02, of ~10^6 Msol. CGCG 077-102 NED02 is not heavily obscured, perhaps due to surrounding intra cluster medium ram pressure stripping., accepted in A&A

We report the discovery of Mothra, an extremely magnified monster star, likely a binary system of two supergiant stars, in one of the strongly lensed galaxies behind the galaxy cluster MACS0416. The star is in a galaxy with spectroscopic redshift $z=2.091$ in a portion of the galaxy that is parsecs away from the cluster caustic. The binary star is observed only on the side of the critical curve with negative parity but has been detectable for at least eight years, implying the presence of a small lensing perturber. Microlenses alone cannot explain the earlier observations of this object made with the Hubble Space Telescope. A larger perturber with a mass of at least $10^4$\,\Msun\ offers a more satisfactory explanation. Based on the lack of perturbation on other nearby sources in the same arc, the maximum mass of the perturber is $M< 2.5\times10^6$\,\Msun, making it the smallest substructure constrained by lensing above redshift 0.3. The existence of this millilens is fully consistent with the expectations from the standard cold dark matter model. On the other hand, the existence of such small substructure in a cluster environment has implications for other dark matter models. In particular, warm dark matter models with particle masses below 8.7\,keV are excluded by our observations. Similarly, axion dark matter models are consistent with the observations only if the axion mass is in the range $0.5\times10^{-22}\, {\rm eV} < m_a < 5\times10^{-22}\, {\rm eV}$., 26 pages and 27 figures

We introduce GWDALI, a new Fisher-matrix, python based software that computes likelihood gradients to forecast parameter-estimation precision of arbitrary network of terrestrial gravitational wave detectors observing compact binary coalescences. The main new feature with respect to analogous software is to assess parameter uncertainties beyond Fisher-matrix approximation, using the derivative approximation for Likelihood (DALI). The software makes optional use of the LSC algorithm library LAL and the stochastic sampling algorithm Bilby, which can be used to perform Monte-Carlo sampling of exact or approximate likelihood functions. As an example we show comparison of estimated precision measurement of selected astrophysical parameters for both the actual likelihood, and for a variety of its derivative approximations, which turn out particularly useful when the Fisher matrix is not invertible., 18 pages, 11 figures

Self-interacting dark radiations (SIdr) can have significant implications in the evolution of the universe, affecting the cosmic microwave background (CMB) and the clustering of large-scale structures. In this work, we analyze the implications of SIdr on the CMB power spectrum and explore its potential in resolving the Hubble tension. SIdr exhibits two distinct behaviors based on the interacting strength: strongly self-coupled and medium self-coupled. These behaviors are evident in the analysis of CMB data. According to Planck data, the dark radiation component consists of both free-streaming neutrinos and possible SIdr. The total contribution from these components yields relativistic species with $N_{\rm eff}=3.046$. In the framework of universal coupling between dark radiations, a consistent value of $N_{\rm eff}=3.27_{-0.31}^{+0.23}$ is obtained. Additionally, this coupling results in an increase in the Hubble constant ($H_0$) to $70.1_{-1.6}^{+1.3}, \text{km/s/Mpc}$. However, when considering the number of free-streaming neutrinos as a parameter, the existence of SIdr is not supported. This makes its fraction in radiation to be $R_x=0.047^{+0.025}_{-0.053}$. Although the Hubble constant is still enhanced, it comes at the expense of a higher $N_{\rm eff}=3.52\pm0.25$. Our findings reveal that the ACT and SPT data provide support for the presence of SIdr, particularly when considering a variable number of free-streaming species. In this case, SIdr accounts for approximately 12.7\% of the total radiation content. However, it is important to note that relying solely on SIdr is insufficient to completely resolve the Hubble tension. Finally, we investigate the constraints on SIdr imposed by future experiments, which improve the limits on scaled interacting strength $\log_{10}\tilde G_{\rm eff}$ by a factor of 4.5 compared to the current constraints., 23 pages, 8 figures, 4 tables

Galaxy clusters enable unique opportunities to study cosmology, dark matter, galaxy evolution, and strongly-lensed transients. We here present a new cluster-finding algorithm, CluMPR (Clusters from Masses and Photometric Redshifts), that exploits photometric redshifts (photo-z's) as well as photometric stellar mass measurements. CluMPR uses a 2-dimensional binary search tree to search for overdensities of massive galaxies with similar redshifts on the sky and then probabilistically assigns cluster membership by accounting for photo-z uncertainties. We leverage the deep DESI Legacy Surveys grzW1W2 imaging over one-third of the sky to create a catalogue of ~ 300,000 galaxy cluster candidates out to z = 1, including tabulations of member galaxies and estimates of each cluster's total stellar mass. Compared to other methods, CluMPR is particularly effective at identifying clusters at the high end of the redshift range considered (z = 0.75-1), with minimal contamination from low-mass groups. These characteristics make it ideal for identifying strongly lensed high-redshift supernovae and quasars that are powerful probes of cosmology, dark matter, and stellar astrophysics. As an example application of this cluster catalogue, we present a catalogue of candidate wide-angle strongly-lensed quasars in Appendix C. The five best candidates identified from this sample include two known lensed quasar systems and a possible changing-look lensed QSO with SDSS spectroscopy. All code and catalogues produced in this work are publicly available (see Data Availability)., 20 pages, 26 figures, to be submitted to MNRAS

Gravitational-wave observations by the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo have provided us a new tool to explore the universe on all scales from nuclear physics to the cosmos and have the massive potential to further impact fundamental physics, astrophysics, and cosmology for decades to come. In this paper we have studied the science capabilities of a network of LIGO detectors when they reach their best possible sensitivity, called A#, and a new generation of observatories that are factor of 10 to 100 times more sensitive (depending on the frequency), in particular a pair of L-shaped Cosmic Explorer observatories (one 40 km and one 20 km arm length) in the US and the triangular Einstein Telescope with 10 km arms in Europe. We use a set of science metrics derived from the top priorities of several funding agencies to characterize the science capabilities of different networks. The presence of one or two A# observatories in a network containing two or one next generation observatories, respectively, will provide good localization capabilities for facilitating multimessenger astronomy and precision measurement of the Hubble parameter. A network of two Cosmic Explorer observatories and the Einstein Telescope is critical for accomplishing all the identified science metrics including the nuclear equation of state, cosmological parameters, growth of black holes through cosmic history, and make new discoveries such as the presence of dark matter within or around neutron stars and black holes, continuous gravitational waves from rotating neutron stars, transient signals from supernovae, and the production of stellar-mass black holes in the early universe. For most metrics the triple network of next generation terrestrial observatories are a factor 100 better than what can be accomplished by a network of three A# observatories., 45 pages, 20 figures

Field-level inference provides a means to optimally extract information from upcoming cosmological surveys, but requires efficient sampling of a high-dimensional parameter space. This work applies Microcanonical Langevin Monte Carlo (MCLMC) to sample the initial conditions of the Universe, as well as the cosmological parameters $\sigma_8$ and $\Omega_m$, from simulations of cosmic structure. MCLMC is shown to be over an order of magnitude more efficient than traditional Hamiltonian Monte Carlo (HMC) for a $\sim 2.6 \times 10^5$ dimensional problem. Moreover, the efficiency of MCLMC compared to HMC greatly increases as the dimensionality increases, suggesting gains of many orders of magnitude for the dimensionalities required by upcoming cosmological surveys., Comment: Accepted at the ICML 2023 Workshop on Machine Learning for Astrophysics. 4 pages, 4 figures

Ultralight bosonic fields (ULBFs) are predicted by various theories beyond the standard model of particle physics and are viable candidates of cold dark matter. There have been increasing interests to search for the ULBFs in physical and astronomical experiments. In this paper, we investigate the sensitivity of several planned space-based gravitational-wave interferometers to ultralight scalar and vector fields. Using time-delay interferometry (TDI) to suppress the overwhelming laser frequency noise, we derive the averaged transfer functions of different TDI combinations to scalar and vector fields, and estimate the impacts of bosonic field's velocities. We obtain the sensitivity curves for LISA, Taiji and TianQin, and explore their projected constraints on the couplings between ULBFs and standard model particles, illustrating with the ULBFs as dark matter., 33 pages,8 figures

Recently, hybrid bias expansions have emerged as a powerful approach to modelling the way in which galaxies are distributed in the Universe. Similarly, field-level emulators have recently become possible thanks to advances in machine learning and $N$-body simulations. In this paper we explore whether both techniques can be combined to provide a field-level model for the clustering of galaxies in real and redshift space. Specifically, here we will demonstrate that field-level emulators are able to accurately predict all the operators of a $2^{\rm nd}$-order hybrid bias expansion. The precision achieved in real and redshift space is similar to that obtained for the nonlinear matter power spectrum. This translates to roughly 1-2\% precision for the power spectrum of a BOSS and a Euclid-like galaxy sample up to $k\sim 0.6 h^{-1}$Mpc. Remarkably, this combined approach also delivers precise predictions for field-level galaxy statistics. Despite all these promising results, we detect several areas where further improvements are required. Therefore, this work serves as a road-map for the developments required for a more complete exploitation of upcoming large-scale structure surveys., 13 pages, 9 figures

We present a forecast analysis on the feasibility of measuring the cosmological parameters with a large number of galaxy-galaxy scale strong gravitational lensing systems. Future wide area surveys are expected to discover and measure the properties of more than 10 000 strong lensing systems. We develop a hierarchical model that can simultaneously constrain the lens population and cosmological parameters by combining Einstein radius measurements with stellar dynamical mass estimates for every lens. Marginalizing over the lens density profiles and stellar orbital anisotropies, we find that $w$ can be constrained to a precision of $0.11$ with 10 000 galaxy-galaxy lens systems, which would be better than any existing single-probe constraint. We test our method on 161 existing lenses, finding $w=-0.96\pm0.46$. We also show how to mitigate against the potential systematic of redshift evolution in the mean lens density profile of the population.

We implement and explore high-dimensional generalized dark matter (HDGDM) with an arbitrary equation of state as a function of redshift as an extension to {\Lambda}CDM.. Exposing this model to CMB, BAO, and supernova data, we demonstrate that the use of marginalized posterior distributions can easily lead to misleading conclusions on the viability of a high-dimensional model such as this one. We discuss such pitfalls and corresponding mitigation strategies, which can be used to search for an observationally favored region of the parameter space. We further show that the HDGDM model in particular does show promise in terms of its ability to ease the Hubble tension once such techniques are employed, and we find interesting features in the best-fitting equation of state that can serve as an inspiration for future model building.

In the primordial plasma, at temperatures above the scale of electroweak symmetry breaking, the presence of chiral asymmetries is expected to induce the development of helical hypermagnetic fields through the phenomenon of chiral plasma instability. It results in magnetohydrodynamic turbulence due to the high conductivity and low viscosity and sources gravitational waves that survive in the universe today as a stochastic polarized gravitational wave background. In this article, we show that this scenario only relies on Standard Model physics, and therefore the observable signatures, namely the relic magnetic field and gravitational background, are linked to a single parameter controlling the initial chiral asymmetry. We estimate the magnetic field and gravitational wave spectra, and validate these estimates with 3D numerical simulations., 8 pages, 4 figures, 1 table

Massive neutrinos are expected to affect the large-scale structure formation, including the major component of solid substances, dark matter halos. How halos are influenced by neutrinos is vital and interesting, and angular momentum (AM) as a significant feature provides a statistical perspective for this issue. Exploring halos from TianNu N-body cosmological simulation with the co-evolving neutrino particles, we obtain some concrete conclusions. First, by comparing the same halos with and without neutrinos, in contrast to the neutrino-free case, over 89.71\% of halos have smaller halo moduli, over 71.06\% have smaller particle-mass-reduced (PMR) AM moduli, and over 95.44\% change their orientations of less than $0.65^\circ$. Moreover, the relative variation of PMR modulus is more visible for low-mass halos. Second, to explore the PMR moduli of halos in dense or sparse areas, we divide the whole box into big cubes, and search for halos within a small spherical cell in a single cube. From the two-level divisions, we discover that in denser cubes, the variation of PMR moduli with massive neutrinos decreases more significantly. This distinction suggests that neutrinos exert heavier influence on halos' moduli in compact regions. With massive neutrinos, most halos (86.60\%) have lower masses than without neutrinos., 12 pages(without ref.), 12 figures. The statistical research of the angular momentum moduli of dark halos in TianNu N-body simulation. Second update only corrects the author name on the arXiv page

We demonstrate that enhanced early galaxy formation can generically arise in axion-like particle (ALP) dark matter (DM) theories with the kinetic misalignment mechanism, potentially addressing the excess recently observed by the James Webb Space Telescope (JWST), while being consistent with existing constraints. We identify viable parameter regions with the ALP mass in the range of $10^{-22}~{\rm eV}, Comment: 6 pages, 5 figures

The intracluster medium (ICM) is the low-density diffuse magnetized plasma in galaxy clusters, which reaches virial temperatures of up to 10^8 K. Under these conditions, the plasma is weakly collisional and therefore has an anisotropic pressure tensor with respect to the local direction of the magnetic field. This triggers very fast, Larmor-scale, pressure-anisotropy-driven kinetic instabilities that alter magnetic field amplification. We study magnetic field amplification through a turbulent small-scale dynamo, including the effects of the kinetic instabilities, during the evolution of a typical massive galaxy cluster. A specific aim of this work is to establish a redshift limit from which a dynamo has to start to amplify the magnetic field up to equipartition with the turbulent velocity field at redshift z=0. We implemented 1D radial profiles for various plasma quantities for merger trees generated with the Modified GALFORM algorithm. We assume that turbulence is driven by successive mergers of dark matter halos and construct effective models for the Reynolds number Re_eff dependence on the magnetic field in three different magnetization regimes, including the effects of kinetic instabilities. The magnetic field growth rate is calculated for the different Re_eff models. The model results in a higher magnetic field growth rate at higher redshift. For all scenarios considered, to reach equipartition at z=0, the amplification of the magnetic field has to start at redshift z_start=1.5 and above. The time to reach equipartition can be significantly shorter, in cases with systematically smaller turbulent forcing scales, and for the highest Re_eff models. Merger trees are useful tools for studying the evolution of magnetic fields in weakly collisional plasmas, and could also be used to constrain the different stages of the dynamo that potentially could be observed by future radio telescopes., 15 pages, 9 figures

The stochastic signal detected by pulsar timing arrays (PTAs) has raised great interest in understanding its physical origin. Assuming the signal is a cosmological gravitational-wave background produced by overly large primordial density perturbations, we investigate the sound speed resonance effect with an oscillatory behavior using the combined PTA data from NANOGrav 15-yr data set, PPTA DR3, and EPTA DR2. We find that the stochastic signal can be explained by the induced gravitational waves sourced by the sound speed resonance mechanism, with the oscillation frequency $f_* \in [1.52, 4.67] \times 10^{-7}$Hz and the start time of oscillation $|\tau_0| \in [2.17, 95.7] \times 10^7$s., Comment: 16 pages, 2 figures, 1 table

We show that, whenever the perturbations of some field are excited during inflation by a physical process on sub-horizon scales, they unavoidably generate, even through gravitational interactions alone, a significant resonant IR cascade of power down to scales that are of the order of the horizon at that time (we denote these scales as near IR). We provide general analytic one-loop results for the enhancement of the IR power of the curvature perturbation generated by this effect, highlighting the role played by the resonance. We then study a number of examples in which the excited state is: (i) an isocurvature field, (ii) the curvature perturbation itself, (iii) a mixture of curvature and isocurvature fluctuations driven to an excited state by their coupled dynamics. In the cases shown, the cascade significantly modifies the near IR part of the power spectrum of the curvature perturbation with respect to the linear theory, indicating that this effect can impact the phenomenology associated with a variety of mechanisms considered in the literature, notably concerning primordial black holes and gravitational waves., 37 pages, 5 figures

This thesis treats the topic of CMB Spectral Distortions (SDs), which represent any deviation from a pure black body shape of the CMB energy spectrum. As such, they can be used to probe the inflationary, expansion and thermal evolution of the universe both within $\Lambda$CDM and beyond it. The currently missing observation of this rich probe of the universe makes of it an ideal target for future observational campaigns. In fact, while the $\Lambda$CDM signal guarantees a discovery, the sensitivity to a wide variety of new physics opens the door to an enormous uncharted territory. In light of these considerations, the thesis opens by reviewing the topic of CMB SDs in a pedagogical and illustrative fashion, aimed at waking the interest of the broader community. This introductory premise sets the stage for the first main contribution of the thesis to the field of SDs: their implementation in the Boltzmann solver CLASS and the parameter inference code MontePython. The CLASS+MontePython pipeline is publicly available, fast, it includes all sources of SDs within $\Lambda$CDM and many others beyond that, and allows to consistently account for any observational setup. By means of these numerical tools, the second main contribution of the thesis consists in showcasing the versatility and competitiveness of SDs for several cosmological models as well as for a number of different mission designs. Among others, the results cover features in the primordial power spectrum, primordial gravitational waves, non-standard dark matter properties, primordial black holes, primordial magnetic fields and Hubble tension. Finally, the manuscript is disseminated with (20) follow-up ideas that naturally extend the work carried out so far, highlighting how rich of unexplored possibilities the field of CMB SDs still is. The hope is that these suggestions will become a propeller for further interesting developments., Comment: PhD thesis. Pedagogical review of theory, experimental status and numerical tools (CLASS+MontePython) with broad overview of applications. Includes 20 original follow-up ideas

Invertible disformal transformations serve as a useful tool to explore ghost-free scalar-tensor theories. In this paper, we construct a generalization of invertible disformal transformations that involves arbitrary higher-order covariant derivatives of the scalar field. As a result, we obtain a more general class of ghost-free scalar-tensor theories than ever. Notably, our generalization is such that matter fields can be consistently coupled to these theories without introducing an unwanted extra degree of freedom in the unitary gauge., 9 pages

With the emersion of precise cosmology and the emergence of cosmic tensions, we are faced with the question of whether the simple model of cold dark matter needs to be extended and whether doing so can alleviate the tensions and improve our understanding of the properties of dark matter. In this study, we investigate one of the generalized models of dark matter so that the behavior of this dark matter changes according to the scale of $k$. In large scales (small $k$'s), the dark matter is cold, while it becomes warm for small scales (large $k$'s). This behavior is modeled phenomenologically for two different scenarios. We show that the $S_8$ tension can be alleviated, but the $H_0$ tension becomes milder while not too much., 8 pages, 6 figures. comments are welcome

Recently it has been shown that the cosmological dynamics of covariant $f(Q)$ gravity depend on different affine connections. In this paper, two specific $f(Q)$ models are investigated with SNe+CC+BAO+QSO observational data, and the spatial curvature of the universe is studied in covariant $f(Q)$ gravity. It is found that the parameter $\mathcal{X}$ characterizing affine connections significantly affects the behavior of the effective equation of state $w_Q$ and may drive it across the phantom divide line. A flat universe could be favored in covariant $f(Q)$ gravity rather than the $\Lambda$CDM model. These results imply some inertial effects of the universe change the cosmic dynamics and renew our cognition of the geometric structure of the universe., Comment: 14 pages, 6 figures, 3 tables

We study a new source of stochastic gravitational wave background (SGWB) from the final collapse of a string-wall network. In the context of $N_{\rm DW}=1$ axionic string-wall network, the final collapse of walls bounded by strings can release gravitational waves (GWs). This source is typically considered negligible due to its subdominance compared to GW emissions throughout the long-term evolution in the scaling regime. However, in some cases, a network can be driven outside of horizon by inflation and later re-enter horizon. Then, the network's final collapse after re-entering horzion becomes the dominant GW source and therefore cannot be neglected. Our caculation of the corresponding GW spectrum suggests it could potentially explain the nano-Hertz SGWB signal possibly detected by various Pulsar Timing Array experiments. In addition, with different parameter choices, the resultant GWs could be probed by various GW interferometry experiments., 5 pages, 3 figures

In addition to the Standard Model, the introduction of a singlet complex scalar field that acquires vacuum expectation value may give rise to a cosmologically stable pseudo-Nambu-Goldstone boson (pNGB), a suitable dark matter (DM) candidate. This work extends this scenario by including a second cosmological stable particle: a fermion singlet. The pNGB and the new fermion can be regarded as DM candidates simultaneously, both interacting with the Standard Model through Higgs portals via two non-degenerate Higgs bosons. We explore the thermal freeze-out of this scenario, with particular emphasis on the increasing yield of the pNGB before it completely decouples (recently called \textit{Bouncing DM}). We test the model under collider, relic abundance, and direct detection, and we explore the consequences of the yield bouncing on indirect detection observables today.

Dark Matter (DM) particles with sufficiently large cross sections may scatter as they travel through Earth's bulk. The corresponding changes in the DM flux give rise to a characteristic daily modulation signal in detectors sensitive to DM-electron interactions. Here, we report results obtained from the first underground operation of the DAMIC-M prototype detector searching for such a signal from DM with MeV-scale mass. A model-independent analysis finds no modulation in the rate of 1$e^-$ events with periods in the range 1-48 h. We then use these data to place exclusion limits on DM in the mass range [0.53, 2.7] MeV/c$^2$ interacting with electrons via a dark photon mediator. Taking advantage of the time-dependent signal we improve by $\sim$2 orders of magnitude on our previous limit obtained from the total rate of 1$e^-$ events, using the same data set. This daily modulation search represents the current strongest limit on DM-electron scattering via ultralight mediators for DM masses around 1 MeV/c$^2$.

We present the possibility that the seesaw mechanism and nonthermal leptogenesis can be probed via primordial non-Gaussianities in the context of a majoron curvaton model. Originating as a massless Nambu-Goldstone boson from the spontaneous breaking of the global baryon ($B$) minus lepton ($L$) number symmetry at a scale $v_{B-L}$, majoron becomes massive when it couples to a new confining sector through anomaly. Acting as a curvaton, majoron produces the observed red-tilted curvature power spectrum without relying on any inflaton contribution, and its decay in the post-inflationary era gives rise to a nonthermal population of right-handed neutrinos that participate in leptogenesis. A distinctive feature of the mechanism is the generation of observable non-Gaussianity, nontrivially linked to the scale of seesaw and leptogenesis. Identifying the viable parameter space, we show that the non-Gaussianity parameter $f_{\rm NL} \gtrsim \mathcal{O} (0.1)$ is produced for high-scale seesaw ($v_{B-L}$ at $\mathcal{O}(10^{14-17})$ GeV) and leptogenesis ($M_1 \gtrsim \mathcal{O}(10^6)$ GeV) where the latter represents the lightest right-handed neutrino mass. While the current bounds on local non-Gaussianity excludes some part of parameter space, the rest can be fully probed by future experiments like CMB-S4, LSST, and 21 cm tomography., 19 pages + references, 7 figures

We present a comprehensive study of Parker-type bounds on magnetic monopoles with arbitrary magnetic charge, including minicharged monopoles and magnetic black holes. We derive the bounds based on the survival of galactic magnetic fields, seed magnetic fields, as well as primordial magnetic fields. We find that monopoles with different magnetic charges are best constrained by different astrophysical systems: while monopoles with a Dirac charge are tightly constrained by seed galactic magnetic fields, minicharged monopoles are strongly constrained by primordial magnetic fields, and magnetic black holes by the density of dark matter. We also assess the viability of the various types of monopoles as dark matter, by studying whether they can cluster with galaxies hosting magnetic fields., 33 pages, 6 figures

We obtain a new sample of 1192 Type I quasars with the UV-optical, radio and X-ray wavebands coverage by combining \citet{Huang2022} and other matching data of SDSS-DR16 with FIRST, XMM-Newton, and Chandra Source Catalog, and a sample of 407 flat-spectrum radio-loud quasars (FSRLQs) of blazars from the Roma-BZCAT, which can be used to investigate their multi-band luminosity correlations and measure the luminosity distances of these Type I radio-loud quasars (RLQs) samples. We check the correlation between X-ray, UV-optical, and radio luminosity for various groupings of radio-quiet quasars (RQQs) and RLQs by parameterizing X-ray luminosity as a sole function of UV-optical or radio luminosity and as a joint function of UV-optical radio luminosity, which also can be employed to determine these cosmological distances. By Bayesian information criterion (BIC), the data suggest that the X-ray luminosity of RQQs is indirectly correlative with radio luminosity because of the connection between UV-optical and radio luminosity. But for RLQs, the X-Ray luminosity is directly related to radio luminosity, and the correlations between X-ray, optical/UV, and radio luminosity increase with the ratio of monochromatic luminosities logR. Meanwhile, we compare the results from RLQs with different UV-optical power law index ${\Gamma _{UV}}$, the goodness of fit for RLQs with ${\Gamma _{UV}}\le 1.6$ seems to be better. Finally, we apply a combination of Type I RLQs and SN Ia Pantheon to verify the nature of dark energy concerning whether or not its density deviates from the constant, and give the statistical results., Comment: arXiv admin note: text overlap with arXiv:2207.08390

Dark matter induced event rate in an Earth-based detector is predicted to show an annual modulation as a result of the Earth's orbital motion around the Sun. We searched for this modulation signature using the ionization signal of the DarkSide-50 liquid argon time projection chamber. No significant signature compatible with dark matter is observed in the electron recoil equivalent energy range above $40~{\rm eV_{ee}}$, the lowest threshold ever achieved in such a search., 8 pages, 4 figures

Majoron-like bosons would emerge from a supernova (SN) core by neutrino coalescence of the form $\nu\nu\to\phi$ and $\bar\nu\bar\nu\to\phi$ with 100 MeV-range energies. Subsequent decays to (anti)neutrinos of all flavors provide a flux component with energies much larger than the usual flux from the "neutrino sphere." The absence of 100 MeV-range events in the Kamiokande-II and Irvine-Michigan-Brookhaven signal of SN 1987A implies that less than 1% of the total energy was thus emitted and provides the strongest constraint on the Majoron-neutrino coupling of $g\lesssim 10^{-9}\,{\rm MeV}/m_\phi$ for $100~{\rm eV}\lesssim m_\phi\lesssim 100~{\rm MeV}$. It is straightforward to extend our new argument to other hypothetical feebly interacting particles., Comment: 5+8 pages, 2+6 figures. Matches published version

In this paper, we propose a novel mechanism in $\mathbb{T}^2$-inflation to enhance the power spectrum large enough to seed primordial black holes (PBHs) formation. To accomplish this, we consider the coupling function between the inflaton field and $\mathbb{T}^2= T_{\mu \nu}T^{\mu \nu}$ term. PBHs formed within this scenario can contribute partially or entirely to dark matter (DM) abundance. Furthermore, the amplification in the scalar power spectrum will concurrently produce significant scalar-induced gravitational waves (SIGWs) as a second-order effect. In addition, the energy spectrum associated with SIGWs can be compatible with the recent NANOGrav 15-year stochastic gravitational wave detection and fall into the sensitivity range of other forthcoming GW observatories., Comment: 8 pages, 7 figures, and one table

We provide a pedagogical approach to gravitational waves in cosmology with focus on gravitational wave signals related to primordial black holes. These lectures notes contain more details than one is able to present in the two two-hour lectures they are meant to and, as such, they should be thought as a complementary material. The main aim of these lectures is that, by the end, one obtains a certain degree of intuition on gravitational waves in cosmology and understands the basic features of scalar induced gravitational waves. We also highlight must-check properties of induced gravitational waves as well as current issues regarding secondary gravitational waves in cosmology. Throughout the lecture we provide exercises, supplementary information and activities with public codes to be ready to derive your own results., Lectures notes prepared for the ICCUB School 2023 on Primordial Black holes in the University of Barcelona. Comments and corrections are welcome

The Square Kilometre Array (SKA) will have the sensitivity to take the 3D light-cones of the 21 cm signal from the epoch of reionization. This signal, however, is highly non-Gaussian and can not be fully interpreted by the traditional statistic using power spectrum. In this work, we introduce the 3D ScatterNet that combines the normalizing flows with solid harmonic wavelet scattering transform, a 3D CNN featurizer with inductive bias, to perform implicit likelihood inference (ILI) from 21 cm light-cones. We show that 3D ScatterNet outperforms the ILI with a fine-tuned 3D CNN in the literature. It also reaches better performance than ILI with the power spectrum for varied light-cone effects and varied signal contaminations., 9 pages, 4 figures, 2 tables. Accepted to ICML 2023 Machine Learning for Astrophysics workshop. Comments and suggestions are welcome

The inner slope gammaDM of the dark matter (DM) density profile of cosmological halos carries information about the properties of DM and/or baryonic processes affecting the halo gravitational potential. Cold DM cosmological simulations predict steep inner slopes, gammaDM>~1. We test this prediction on the MACS J1206.2-0847 cluster at redshift z=0.44, whose DM density profile was claimed to be cored at the center. We determine the cluster DM density profile from 2 kpc from the cluster center to the virial radius (~2 Mpc), using the velocity distribution of ~500 cluster galaxies and the velocity dispersion profile of the Brightest Cluster Galaxy (BCG), obtained from VIMOS@VLT and MUSE@VLT data. We solve the Jeans equation of dynamical equilibrium using an upgraded version of the MAMPOSSt method. The total mass profile is modeled as a sum of a generalized-NFW profile that describes the DM component, allowing for a free inner slope of the density profile, a Jaffe profile that describes the BCG stellar mass component, and a non-parametric baryonic profile that describes the sum of the remaining galaxy stellar mass and of the hot intra-cluster gas mass. Our total mass profile is in remarkable agreement with independent determinations based on X-ray observations and strong lensing. We find gammaDM=0.7 -0.1 +0.2 (68% confidence levels), consistent with predictions from recent LambdaCDM cosmological numerical simulations., Submitted to ApJ on June, 1st 2023. 14 pages, 9 figures

Generative adversarial networks (GANs) are frequently utilized in astronomy to construct an emulator of numerical simulations. Nevertheless, training GANs can prove to be a precarious task, as they are prone to instability and often lead to mode collapse problems. Conversely, the diffusion model also has the ability to generate high-quality data without adversarial training. It has shown superiority over GANs with regard to several natural image datasets. In this study, we undertake a quantitative comparison between the denoising diffusion probabilistic model (DDPM) and StyleGAN2 (one of the most robust types of GANs) via a set of robust summary statistics from scattering transform. In particular, we utilize both models to generate the images of 21 cm brightness temperature mapping, as a case study, conditionally based on astrophysical parameters that govern the process of cosmic reionization. Using our new Fr\'echet Scattering Distance (FSD) as the evaluation metric to quantitatively compare the sample distribution between generative models and simulations, we demonstrate that DDPM outperforms StyleGAN2 on varied sizes of training sets. Through Fisher forecasts, we demonstrate that on our datasets, StyleGAN2 exhibits mode collapses in varied ways, while DDPM yields a more robust generation. We also explore the role of classifier-free guidance in DDPM and show the preference for a non-zero guidance scale only when the training data is limited. Our findings indicate that the diffusion model presents a promising alternative to GANs in the generation of accurate images. These images can subsequently provide reliable parameter constraints, particularly in the realm of astrophysics., Comment: 13 pages, 10 figures, 1 table. Submitted to MNRAS. Comments welcome

The Laser Interferometer Space Antenna (LISA) will detect gravitational waves (GWs) emitted by massive black hole binaries (MBHBs) in the low-frequency ($\sim$mHz) band. Low-mass lenses, such as dark-matter (DM) subhalos, have sizes comparable to the wavelength of these GWs. Encounters with these lenses produce wave-optics (WO) effects that alter waveform phase and amplitude. Thus, a single event with observable WO effects can be used to probe the lens properties. In this paper, we first compute the probability of observing WO effects in a model-agnostic way. We perform parameter estimation over approximately 1000 MBHBs with total mass, mass ratio, and redshift spanning the ranges relevant to LISA. We then calculate lensing rates using three semi-analytical models of MBHB populations. In both cases, we use a waveform model that includes merger, ringdown, and higher-order modes. We use two lens population models: the theory-based Press-Schechter halo mass function and an observation-based model derived from Sloan Digital Sky Survey, called the measured velocity function. We find that the probability of detecting WO effects can be as large as $\sim 3\%$, $\sim1.5\%$, and $\sim 1 \%$ at $1\sigma$, $3\sigma$, and $5\sigma$ confidence levels, respectively. The most optimistic MBHB population model yields $\sim 8$, $\sim 4$, and $\sim 3$ events at the same confidence levels, while the rates drop to $\sim 0.01$ in the more pessimistic scenarios. The most likely lens masses probed by LISA are in the range $(10^3, 10^8)\, M_{\odot}$, and the most probable redshifts are in the range $(0.3, 1.7)$. Therefore, LISA observations of WO effects can probe DM subhalos, complementing strong lensing and other observations., Comment: 24 pages, 15 figures. Comments are welcome

The density of relic neutrinos is expected to be enhanced due to clustering in our local neighbourhood at Earth. We introduce a novel analytical technique to calculate the neutrino overdensity, based on kinetic field theory. Kinetic field theory is a particle-based theory for cosmic structure formation and in this work we apply it for the first time to massive neutrinos. The gravitational interaction is expanded in a perturbation series and we take into account the first-order contribution to the local density of relic neutrinos. For neutrino masses that are consistent with cosmological neutrino mass bounds, our results are in excellent agreement with state-of-the-art calculations., Comment: 7 pages, 1 figure

Powerful radio sources associated with super-massive black holes are among the most luminous objects in the Universe, and are frequently recognized both as cosmological probes and active constituents in the evolution of galaxies. We present alignments between radio jets and cold molecular gas in the environment of distant radio galaxies, and show that the brightness of the radio synchrotron source can be enhanced by its interplay with the molecular gas. Our work is based on CO J>1 observations with the Atacama Large Millimeter/submillimeter Array (ALMA) of three radio galaxies with redshifts in the range 1.4 < z < 2.1, namely MRC 0114-211 (z = 1.41), MRC 0156-252 (z = 2.02), and MRC 2048-272 (z = 2.05). These ALMA observations support previous work that found molecular gas out to 50 kpc in the circumgalactic environment, based on a CO(1-0) survey performed with the Australia Telescope Compact Array (ATCA). The CO emission is found along the radio axes but beyond the main radio lobes. When compared to a large sample of high-z radio galaxies from the literature, we find that the presence of this cold molecular medium correlates with an increased flux-density ratio of the main vs. counter lobe. This suggest that the radio lobe brightens when encountering cold molecular gas in the environment. While part of the molecular gas is likely related to the interstellar medium (ISM) from either the host or a companion galaxy, a significant fraction of the molecular gas in these systems shows very low excitation, with r$_{2-1/1-0}$ and r$_{3-2/1-0}$ values $\lesssim$0.2. This could be part of the circumgalactic medium (CGM)., Accepted for publication in ApJ (19 pages, 6 figures)