arXiv subjects

Yi-Zhong Fan

Publications and source records attributed to Yi-Zhong Fan.

At least 73 records · Page 4Linked to original sources

arXiv2024

JWST observations constrain the time evolution of fine structure constants and dark energy - electromagnetic coupling

It was hypothesized in the literature that some physical parameters may be time-evolving and the astrophysical data can serve as a probe. Recently, James Webb Space Telescope (JWST) have released its early observations. In this work, we select the JWST spectroscopic observations of the high redshift ($z>7.1$) galaxies with strong [OIII] ($λ=4959$ Å\,and $5007$ Å\,in the rest frame) emission lines to constraint the evolution of the fine structure constant ($α$). With the spectra from two galaxies at redshifts of $7.19$ and $8.47$, the deviation of $α$ to its fiducial value is found to be as small as $0.44^{+8.4+1.7}_{-8.3-1.7} \times 10^{-4}$ and $-10.0^{+18+1.5}_{-18-1.5} \times 10^{-4}$, respectively (the first error is statistical and the latter is systematic). The combination of our results with the previous data reveals that $\frac{1}α \frac{d α}{dt} = 0.30^{+4.5}_{-4.5} \times 10^{-17}~{\rm yr^{-1}}$. Clearly, there is no evidence for a cosmic evolution of $α$. The prospect of further constraining the time evolution of $α$ is also discussed. The scalar field of dark energy is hypothesized to drive the acceleration of the universe's expansion through an interaction with the electromagnetic field. By integrating the observational data of the fine-structure constant variation, $\frac{Δα}α(z)$, we have established a stringent upper limit on the coupling strength between dark energy and electromagnetism. Our analysis yields $ζ\leq 3.92 \times 10^{-7}$ at the 95\% confidence level, representing the most stringent bound to date.

astro-ph.CO↗

arXiv2024

Multi-spectral Sirens: Gravitational-wave Cosmology with (Multi-) Sub-populations of Binary Black Holes

The cosmic expansion rate can be directly measured with gravitational-wave (GW) data of the compact binary mergers by jointly constraining the mass function of the population and the cosmological model via the so-called spectral sirens. Such a method relies on the features in the mass functions, which may originate from some individual subpopulations, and hence become blurred/indistinct due to the superposition of different subpopulations. In this work we propose a novel approach to constrain the cosmic expansion rate with subpopulations of GW events, named multi-spectral sirens. The advantage of the multi-spectral sirens compared to the traditional spectral sirens is demonstrated by the simulation with the mock data. The application of this approach to the GWTC-3 data yields $H_0=73.3^{+29.9}_{-25.6}~{\rm Mpc}^{-1}~{\rm km}~{\rm s}^{-1}$ (median and symmetric 68.3\% credible interval), which is about 19\% tighter than the result inferred with the traditional spectral sirens utilizing a PowerLaw+Peak mass function. The incorporation of the bright standard siren GW170817 with a uniform prior in [10,200] (log-uniform prior in [20,140]) ${\rm Mpc}^{-1}~{\rm km}~{\rm s}^{-1}$ gives $H_0=71.1^{+15.0}_{-7.5}~(70.3^{+12.9}_{-7.1})~{\rm Mpc}^{-1}~{\rm km}~{\rm s}^{-1}$ (68.3\% confidence level), corresponding to an improvement of $\sim26\%$ (23\%) with respect to the measurement from sole GW170817.

astro-ph.CO↗

arXiv2024

Searching Accretion-Enhanced Dark Matter Annihilation Signals in the Galactic Centre

This study reanalyzes the detection prospects of dark matter (DM) annihilation signals in the Galactic Center, focusing on velocity-dependent dynamics within a spike density near the supermassive black hole (Sgr~A$^{\star}$). We investigate three annihilation processes -- $p$-wave, resonance, and forbidden annihilation -- under semi-relativistic velocities, leveraging gamma-ray data from Fermi and DAMPE telescopes. Our analysis integrates a fermionic DM model with an electroweak axion-like particle (ALP) portal, exploring annihilation into two or four photons. Employing a comprehensive six-dimensional integration, we precisely calculate DM-induced gamma-ray fluxes near Sgr~A$^{\star}$, incorporating velocity and positional dependencies in the annihilation cross-section and photon yield spectra. Our findings highlight scenarios of resonance and forbidden annihilation, where the larger ALP-DM-DM coupling constant $C_{aχχ}$ can affect spike density, potentially yielding detectable gamma-ray line spectra within Fermi and DAMPE energy resolution. We set upper limits for $C_{aχχ}$ across these scenarios, offering insights into the detectability and spectral characteristics of DM annihilation signals from the Galactic Center.

hep-ph↗

arXiv2024

Upper Limit of Sound Speed in Nuclear Matter: A Harmonious Interplay of Transport Calculation and Perturbative Quantum Chromodynamic Constraint

Very recently, it has been shown that there is an upper bound on the squared sound speed of nuclear matter from the transport, which reads $c_{\rm s}^2 \leq 0.781$. In this work, we demonstrate that this upper bound is corroborated by the reconstructed equation of state (EOS; modeled with a nonparametric method) for ultradense matter. The reconstruction integrates multimessenger observation for neutron stars, in particular, the latest radius measurements for PSR J0437-4715 ($11.36^{+0.95}_{-0.63}$ km), PSR J0030+0451 ($11.71^{+0.88}_{-0.83}$ km, in the ST+PDT model), and PSR J0740+6620 ($12.49^{+1.28}_{-0.88}$ km) by NICER have been adopted. The result shows in all cases, the $c_{\rm s}^2 \leq 0.781$ upper limit for EOS will naturally yield the properties of matter near the center of the massive neutron star consistent with the causality-driven constraint from pQCD, where, in practice, the density in implementing the pQCD likelihood ($n_{\rm L}$) is applied at $10n_s$ (where $n_s$ is the nuclear saturation density). We also note that there is a strong correlation for the maximum $c_s^2$ with $n_{\rm L}$, and $c_{\rm s}^2 \leq 0.781$ is somehow violated when $n_{\rm L} = n_{\rm c,TOV}$. The result indicates that a higher $n_{\rm L}$, even considering the uncertainties from statistics, is more natural. Moreover, the remarkable agreement between the outcomes derived from these two distinct and independent constraints (i.e., the transport calculation and pQCD boundary) lends strong support to their validity. In addition, the latest joint constraint for $R_{1.4}$, $R_{2.0}$, $R_{1.4}-R_{2.0}$, and $M_{\rm TOV}$ are $11.94_{-0.68}^{+0.77}$ km, $11.99_{-0.67}^{+0.88}$ km, $-0.1_{-0.27}^{+0.42}$ km, and $2.24_{-0.10}^{+0.13}M_\odot$ (at $90\%$ credible level), respectively.

astro-ph.HE↗

arXiv2024

The Detection Prospect of the Counter Jet Radiation in the Late Afterglow of GRB 170817A

The central engine of a Gamma-Ray Burst (GRB) is widely believed to launch a pair of oppositely moving jets, i.e. the forward jet moving towards us and the counter jet regressing away. The forward jet generates the radiation typically observed in GRBs, while the counter jet has not been detected yet due to its dimness. GRB 170817A, a short burst associated with a binary neutron star merger event, is a nearby event ($z=0.0097$) with an off-axis structured energetic forward jet and hence probably the most suitable target for searching the counter jet radiation. Assuming the same properties for the forward and counter jet components as well as the shock parameters, the fit to the multi-wavelength afterglow emission of GRB 170817A suggests a peak time $\sim {\rm quite~a~few}\times 10^{3}$ day of the counter jet radiation, but the detection prospect of this new component is not promising. Anyhow, if the shock parameters ($ε_{\rm e}$ and $ε_{\rm B}$) of the counter jet component are (a few times) higher than that of the forward shock e.g., the posterior results of the magnetic energy fraction of the forward shock and the counter jet are $\log_{10}ε_{\rm B}=-4.23^{+1.42}_{-0.69}$ and $\log_{10}ε_{\rm B, cj}=-3.65^{+3.06}_{-2.11}$, respectively), as still allowed by the current data, the counter jet afterglow emission will be enhanced and hence may be detected. A few hour exposure by JWST in F356W band will stringently test such a scenario.

astro-ph.HE↗

arXiv2024

The AMS-02 cosmic ray deuteron flux is consistent with a secondary origin

The recent measurements of cosmic ray deuteron fluxes by AMS-02 show that the rigidity dependence of deuterons is similar with that of protons but flatter than $^3$He, which has been attributed to the existence of primary deuterons with abundance much higher than that from the Big Bang nucleosynthesis. The requirement of highly deuteron-abundant sources imposes a serious challenge on the modern astrophysics since there is no known process to produce a large amount of deuterons without violating other constraints \citep{1976Natur.263..198E}. In this work we demonstrate that the fragmentation of heavy nuclei up to nickel plays a crucial role in shaping/enhancing the spectrum/flux of the cosmic ray deuterons. Based on the latest cosmic ray data, the predicted secondary fluxes of deuterons and $^3$He are found to be reasonably consistent with the AMS-02 measurements and a primary deuteron component is not needed. The observed differences between the spectra of D and $^3$He, as well as those between the D/$^4$He (D/p) and $^3$He/$^4$He ($^3$He/p) flux ratios, measured in the rigidity space, is probably due to the kinetic-energy-to-rigidity conversion and the solar modulation, given different charge-to-mass ratios of D and $^3$He. More precise measurements of the fragmentation cross sections of various nuclei to produce deuterons, tritons, and $^3$He in a wide energy range will be very helpful in further testing the secondary origin of cosmic ray deuterons.

astro-ph.HE↗

arXiv2024

Digging into the ultraviolet luminosity functions of galaxies at high redshifts: galaxies evolution, reionization, and cosmological parameters

Thanks to the successful performance of the James Webb Space Telescope, our understanding of the epoch of reionization of the Universe has been advanced. The ultraviolet luminosity functions (UV LFs) of galaxies span a wide range of redshift, not only revealing the connection between galaxies and dark matter (DM) halos but also providing the information during reionization. In this work, we develop a model connecting galaxy counts and apparent magnitude based on UV LFs, which incorporates redshift-dependent star formation efficiency (SFE) and corrections for dust attenuation. By synthesizing some observations across the redshift range $4\le z \le 10$ from various galaxy surveys, we discern the evolving SFE with increasing redshift and DM halo mass through model fitting. Subsequent analyses indicate that the Thomson scattering optical depth was $τ_{\rm e} = 0.054^{+0.001}_{-0.003}$ and the epoch of reionization started (ended) at $z=18.8^{+7.2}_{-6.0}$ ($z=5.3^{+0.8}_{-1.0}$) which is insensitive to the choice of the truncated magnitude of the UV LFs. Incorporating additional dataset and some reasonable constraints, the amplitude of matter perturbation is found to be $σ_8=0.80\pm0.05$, which is consistent with the standard $Λ$CDM model. Future galaxy surveys and the dynamical simulations of galaxy evolution will break the degeneracy between SFE and cosmological parameters, improving the accuracy and the precision of the UV LF model further.

astro-ph.CO↗

arXiv2024

The Spatial Distribution of $\rm CH_4$ and $\rm CO_2$ Ice around Protostars IRAS 16253-2429 and IRAS 23385+6053

The origin and evolution of organic molecules represent a pivotal issue in the fields of astrobiology and astrochemistry, potentially shedding light on the origins of life. The James Webb Space Telescope (JWST), with its exceptional sensitivity and spectral resolution, is well suitable to observe molecules such as methane ($\rm CH_4$). Our analysis focused on the distribution of $\rm CH_4$, $\rm CO_2$, $\rm H_2O$, $\rm{CH_3OH+NH_4^+}$ ice and silicate absorption dips at approximately 7.7, 15.0, 6.0, 6.7 and 10.0 micrometres in two protostars: IRAS 16253-2429 and IRAS 23385+6053. We extract the $\rm CH_4$, $\rm CO_2$, $\rm H_2O$, $\rm{CH_3OH+NH_4^+}$ ice equivalent width (EW) maps and silicate extinction maps of the two sources. Our results reveal that the spatial distribution of $\rm CH_4$ in the protostellar system IRAS 16253-2429 closely mirrors that of its $\rm CO_2$ ice, forming a surrounded distribution that encircles the central protostar. This alignment suggests a common formation mechanism and subsequent trapping within the protostellar envelope, which is consistent with the "Classical" dark-cloud chemistry with ion-molecule reaction. In contrast, the spatial distributions of various molecules in the system IRAS 23385+6053 exhibit low similarities, which may be attributed to the dynamic influences of outflows or accretion processes. These discrepancies highlight the complex interplay between physical processes and chemical evolution in protostellar environments.

astro-ph.GA↗

arXiv2024

Weak Lensing Constraints on Dark Matter-Baryon Interactions with $N$-Body Simulations and Machine Learning

We investigate the elastic scattering cross section between dark matter and protons using the DES Year 3 weak lensing data. This scattering induces a dark acoustic oscillation structure in the matter power spectra. To address non-linear effects at low redshift, we utilize principal component analysis alongside a limited set of $N$-body simulations, improving the reliability of our matter power spectrum prediction. We further perform a robust Markov Chain Monte Carlo analysis to derive the upper bounds on the DM-proton elastic scattering cross-section, assuming different velocity dependencies. Our results, presented as the first Frequentist upper limits, are compared with the ones obtained by Bayesian approach. Compared with the upper limits derived from the Planck cosmic microwave background data, our findings from DES Year 3 data exhibit improvements of up to a factor of five. In addition, we forecast the future sensitivities of the China Space Station Telescope, the upcoming capabilities of this telescope could improve the current limits by approximately one order of magnitude.

astro-ph.CO↗

arXiv2024

Resolving the Stellar-Collapse and Hierarchical-Merger origins of the Coalescing Black Holes

Spin and mass properties provide essential clues in distinguishing the origins of coalescing black holes (BHs). With a dedicated semiparametric population model for the coalescing binary black holes (BBHs), we identify two distinct categories of BHs among the GWTC-3 events, which is {favored over the one population scenario by} a logarithmic Bayes factor ($\ln\mathcal{B}$) of 7.5. One category, with a mass ranging from $\sim 25M_\odot$ to $\sim 80M_\odot$, is distinguished by the high spin magnitudes ($\sim0.75$) and consistent with the hierarchical merger origin. The other category, characterized by low spins, has a sharp mass cutoff at $\sim 40M_\odot$, which is natural for the stellar-collapse origin and in particular the pair-instability explosion of massive stars. We infer the local hierarchical merger rate density as $0.46^{+0.61}_{-0.24}~{\rm Gpc^{-3}yr^{-1}}$. Additionally, we find that a fraction of the BBHs has a cosine-spin-tilt-angle distribution concentrated preferentially around $1$, and the fully isotropic distribution for spin orientation is disfavored by a $\ln\mathcal{B}$ of -6.3, suggesting that the isolated field evolution channels are contributing to the total population.

astro-ph.HE↗

arXiv2024

Multi-frequency test of dark matter annihilation into long-lived particles in Sirius

New long-lived particles produced at the colliders may escape from conventional particle detectors. Using satellites or ground telescopes, we can detect the photons generated from the annihilation of the star-captured dark matter into a pair of long-lived particles. When the propagation length of these long-lived particles surpasses the interplanetary distance between the Sun and Jupiter, it becomes unfeasible to detect such dark matter signals originating from the Sun or Jupiter on Earth. Our analysis of the dark matter-induced photons produced by prompt radiation, inverse Compton scattering, and synchrotron radiation mechanisms reveals that a decay length of about $10^{-3}$ pc for long-lived particles is required for maximum detectability. We investigate the parameters that allow the long-lived particle's lifetime to be consistent with Big Bang nucleosynthesis while also allowing it to escape the confines of our solar system. The Sirius system is proposed as a promising target for the indirect detection of such long-lived particles. Utilizing the prompt, inverse Compton scattering, and synchrotron radiation, upper limits on the dark matter-proton spin-independent and spin-dependent cross section are estimated with the Fermi-LAT null-signal observation and the capabilities of the upcoming Square Kilometre Array radio telescope.

astro-ph.HE↗

arXiv2024

Constraints on Einstein-dilation-Gauss-Bonnet gravity and electric charge of compact binary systems from GW230529

In this work, we study the implications of GW230529 on gravity theories and the charge of black holes. The GW230529, which was initially released in O4a, is most likely neutron star-black hole (NSBH) mergers. We reanalyze the data from the GW230529 event to obtain bounds on the Einstein-dilation-Gauss-Bonnet (EdGB) gravity parameter $\sqrt{α_{\rm EdGB}}$ and the electric charge of compact binary systems. The event places a $90\%$ credible upper bounds on $\sqrt{α_{\rm EdGB}}$ of $\lesssim 0.298$ km. After including high order corrections of EdGB gravity, the bounds improve to $\sqrt{α_{\rm EdGB}} \lesssim 0.260$ km. Analyses of GW230529 also yield a $90\%$ credible upper bounds on the combination of charge-to-mass ratio of the binary components $ζ\lesssim 0.024$. The constraints are more stringent than those derived from previously observed single gravitational wave merger event.

gr-qc↗

arXiv2024

Mirror QCD phase transition as the origin of the nanohertz Stochastic Gravitational-Wave Background

Several Pulsar Timing Array (PTA) collaborations have recently provided strong evidence for a nHz Stochastic Gravitational-Wave Background (SGWB). Here we investigate the implications of a first-order phase transition occurring within the early universe's dark quantum chromodynamics (dQCD) epoch, specifically within the framework of the mirror twin Higgs dark sector model. Our analysis indicates a distinguishable SGWB signal originating from this phase transition, which can explain the measurements obtained by PTAs. Remarkably, a significant portion of the parameter space for the SGWB signal also effectively resolves the existing tensions in both the $H_0$ and $S_8$ measurements in Cosmology. This intriguing correlation suggests a possible common origin of these three phenomena for $0.2 < ΔN_{\rm eff} < 0.5$, where the mirror dark matter component constitutes about $30\%$ of the total dark matter abundance. Next generation CMB experiment such as CMB-S4 is able to test this parameter region.

astro-ph.HE↗

arXiv2024

SKA sensitivity for possible radio emission from dark matter in Omega Centauri

Omega Centauri, the largest known globular cluster in the Milky Way, is believed to be the remains of a dwarf galaxy's core. Giving its potential abundance of dark matter (DM), it is an attractive target for investigating the nature of this elusive substance in our local environment. Our study demonstrates that by observing Omega Centauri with the SKA for 1000 hours, we can detect synchrotron radio or Inverse Compton (IC) emissions from the DM annihilation products. It enables us to constrain the cross-section of DM annihilation down to $\sim {\rm 10^{-30}~cm^3~s^{-1}}$ for DM mass from several $\rm{GeV}$ to $\rm{100~GeV}$, which is much stronger compared with other observations. Additionally, we explore the axion, another well-motivated DM candidate, and provide stimulated decay calculations. It turns out that the sensitivity can reach $g_{\rm{aγγ}} \sim 10^{-10} ~\rm{GeV^{-1}}$ for $2\times 10^{-7} ~\rm{eV} < m_a < 2\times 10^{-4} ~\rm{eV}$.

astro-ph.HE↗

arXiv2024

Rapidly growing primordial black holes as seeds of the massive high-redshift JWST Galaxies

A group of massive galaxies at redshifts of $z\gtrsim 7$ have been recently detected by the James Webb Space Telescope (JWST), which were unexpected to form so early within the framework of standard Big Bang cosmology. In this work, we propose that this puzzle can be explained by the presence of some primordial black holes (PBHs) with a mass of $\sim 1000 M_\odot$. These PBHs, clothed in dark matter halo and undergoing super-Eddington accretion, serve as seeds for the early galaxy formation with masses of $\sim 10^{8}-10^{10}~M_\odot$ at high redshift, thus accounting for the JWST observations. Using a hierarchical Bayesian inference framework to constrain the PBH mass distribution models, we find that the Lognormal model with $M_{\rm c}\sim 750M_\odot$ is preferred over other hypotheses. These rapidly growing BHs are expected to emit strong radiation and may appear as high-redshift compact objects, similar to those recently discovered by JWST. Although we focuse on PBHs in this work, the bound on the initial mass of the seed black holes remains robust even if they were formed through astrophysical channels.

astro-ph.CO↗

arXiv2024

The Heavier the Faster: A Sub-population of Heavy, Rapidly Spinning and Quickly Evolving Binary Black Holes

The spins of binary black holes (BBHs) measured from gravitational waves carry notable information of the formation pathways. Here we propose a quantity "dimensionless net spin" ($χ_{\rm N}$), which is related to the sum of angular momentum of component black holes in the system, to provide a novel perspective to study the origin(s) of BBHs. By performing hierarchical Bayesian inference on $χ_{\rm N}$, we find strong evidence that the marginal distribution of this quantity can be better fitted by two Gaussian components rather than one: there is a narrow peak at $χ_{\rm N} \sim 0.15$ and another extended peak at $χ_{\rm N} \sim 0.47$. We also find that the rapidly spinning systems likely dominate the high-mass end of the population and they evolve with redshift much quicker. These findings bring new challenges to the field binary scenario, and suggest that dynamical process should plays a key role in forming high total mass BBHs.

astro-ph.HE↗

arXiv2024

An optical-ultraviolet flare with absolute AB magnitude of -39.4 detected in GRB 220101A

Hyperluminous optical-ultraviolet fares have been detected in gamma-ray bursts and the luminosity record was held by naked-eye event GRB 080319B. Such fares are widely attributed to internal shock or external reverse shock radiation. Here, with a new method developed to derive reliable photometry from saturated sources of Swift/UVOT, we carry out time-resolved analysis of the initial white-band 150s exposure of GRB 220101A, a burst at a redshift of 4.618, and report a rapidly evolving optical-ultraviolet fare with a high absolute AB magnitude of -39.4$\pm$0.2. In contrast to GRB 080319B, the temporal behaviour of this new fare does not trace the gamma-ray activity. Instead of either internal shocks or reverse shock, this extremely energetic optical-ultraviolet fare is most likely to originate from the refreshed shocks induced by the late-ejected extremely energetic material catching up with the earlier-launched decelerating outflow. This finding reveals the diverse origins of the extremely energetic optical-ultraviolet fares and demonstrates the necessity of high-time-resolution observations at early times.

astro-ph.HE↗

arXiv2024

A delayed 400 GeV photon from GRB 221009A and implication on the intergalactic magnetic field

Large High Altitude Air Shower Observatory has detected $0.2-13$ TeV emission of GRB 221009A within 2000 s since the trigger. Here we report the detection of a 400 GeV photon, without accompanying prominent low-energy emission, by Fermi Large Area Telescope in this direction with a 0.4 days' delay. Given an intergalactic magnetic field strength of about $4 \times 10^{-17}$ G, which is comparable to limits from TeV blazars, the delayed 400 GeV photon can be explained as the cascade emission of about 10 TeV gamma rays. We estimate the probabilities of the cascade emission that can result in one detectable photon beyond 100 GeV by Fermi Large Area Telescope within $0.3-1$ days is about 2$\%$ whereas it is about 20.5$\%$ within $0.3-250$ days. Our results show that Synchrotron Self-Compton explanation is less favored with probabilities lower by a factor of about $3-30$ than the cascade scenario.

astro-ph.HE↗