arXiv subjects

Bing-Yu Su

Publications and source records attributed to Bing-Yu Su.

13 recordsLinked to original sources

arXiv2026

Searching for Solar-Basin Axionlike-Particle Decay with XMM-Newton Blank-Sky Observations

Axion-like particles (ALPs) bound in the solar gravitational field form the so-called ALP solar-basin. Since the two-photon decay of non-relativistic particles is approximately isotropic, this population can be searched for using observations in the anti-solar direction. In this work, we propose a search strategy for narrow decay-line signals from the ALP solar basin using \textit{XMM-Newton} blank-sky observations (XMM-BSOs) stacked spectra data taken in directions opposite to the Sun. By jointly fitting the signal and background model, we obtain limits on $g_{a\gamma\gamma}^{95}$ in the mass range $m_a=1.4\text{--}16~{\rm keV}$, with typical sensitivities of $g_{a\gamma\gamma}\sim10^{-10}\text{--}10^{-11}~{\rm GeV}^{-1}$. We have implemented the first anti-solar search for the solar basin, demonstrating that this strategy can exploit the stacked exposure of a large number of X-ray observations and provide a scalable analysis framework for future searches.

hep-ph↗

arXiv2026

Synchrotron self-Compton process for constraining sub-GeV dark matter in Omega Centauri via SKA

The search for the particle identity of dark matter (DM) continues to be a primary objective in modern physics. In this field, the sub-GeV mass range of DM detection remains a crucial yet challenging window. We investigate synchrotron self-Compton (SSC) emission from electrons and positrons produced by MeV-scale DM annihilation as a novel indirect detection channel. Focusing on the globular cluster Omega Centauri and the sensitivity of the Square Kilometre Array, we derive constraints on the annihilation cross section reaching $\langle\sigma v\rangle \sim 10^{-29}\,\rm{cm}^{3}\,\rm{s}^{-1}$ in the tens-of-MeV range. Furthermore, constraints can reach below $\langle\sigma v\rangle \sim 10^{-30}\,\rm{cm}^{3}\,\rm{s}^{-1}$ under favorable parameter choices. Although the derived limits depend on the uncertain propagation parameters, the SSC channel remains competitive with existing indirect constraints over a representative range of astrophysical assumptions, establishing SSC emission as a promising probe of sub-GeV DM.

astro-ph.CO↗

arXiv2025

New Constraints on Cosmic-ray boosted Sub-GeV Dark Matter via Light Mediators

Traditional direct detection experiments lack the sensitivity to probe the sub-GeV dark matter (DM), primarily due to the low energy of the expected nuclear recoils. In this work, we investigate cosmic-ray (CR) upscattering as a mechanism to accelerate DM particles to detectable velocities in underground experiments. By analyzing four models of DM-nucleon interactions -- namely scalar, vector, pseudoscalar, and axial-vector mediators -- we derive constraints on the coupling parameters using data from the LZ, XENON, and Borexino experiments, covering mediator mass from $10^{-6}$ to $1$ GeV. As the mediator mass varies, the shift in dominance between momentum transfer and mediator mass leads to a turnover in the constraints around $10^{-2}$--$10^{-3}~\mathrm{GeV}$. Our results extend the reach of direct detection into the sub-GeV window and clarify the critical role of momentum dependence in light-mediator scenarios.

astro-ph.HE↗

arXiv2025

Exploring sub-GeV Dark Matter Physics with Cosmic Ray and Future Telescopes

If sub-GeV Dark matter(DM) annihilates to the charged particles such as $e^+ e^-$, $\mu^+ \mu^-$, or $\pi^+ \pi^-$, it generates an additional source of electrons and positrons in the cosmic ray (CR) population within our Milky Way. During propagation, these secondary electrons and positrons undergo reacceleration processes, boosting their energies to the GeV scale. Observatories like AMS-02 can detect these high-energy particles, enabling constraints on the properties of sub-GeV DM. By analyzing AMS-02 electron and positron data, the 95\% upper limits on the DM annihilation cross-section have been established in the range of $10^{-28}$ to $10^{-27}$ cm$^3\,$s$^{-1}$, corresponding to DM masses ranging from 100 MeV to 1 GeV. Meanwhile, MeV telescopes will provide complementary constraints on DM properties by detecting photon emissions from such annihilation processes. Notably, the sensitivity of future MeV gamma-ray observatories is projected to approach or match the constraints derived from CR data.

astro-ph.HE↗

arXiv2025

Primordial black holes from the ultraslow-roll phase in the inflaton--curvaton mixed field inflation

Primordial black holes (PBHs) are a promising candidate for dark matter, as they can form in the very early universe without invoking new particle physics. This work explores PBH formation within a curvaton scenario featuring an ultraslow-roll (USR) phase. An inflaton--curvaton mixed field model is presented, where the inflaton drives early inflation and then transits into the USR phase, amplifying the small-scale curvature perturbation. During inflation, the curvaton generates entropy perturbation, which later converts into curvature perturbation after the curvaton decays in the radiation-dominated era. Using the $\delta N$ formalism, we compute the power spectrum of the total primordial curvature perturbation and analyze the relevant non-Gaussianity. Our results show that adding a curvaton field not only has a significant impact on primordial non-Gaussianity, but also introduces more complex inflationary dynamics, even saving the inflaton potentials that generate too low scalar spectral indices. Our model can produce PBHs with mass around $10^{-14}\,M_\odot$ that account for all dark matter, while remaining consistent with current observational constraints.

astro-ph.CO↗

arXiv2024

Constraining primordial black holes as dark matter using AMS-02 data

Primordial black holes (PBHs) are the plausible candidates for the cosmological dark matter. Theoretically, PBHs with masses $M_{\rm PBH}$ in the range of $4\times10^{14}\sim 10^{17}\,{\rm g}$ can emit sub-GeV electrons and positrons through Hawking radiation. Some of these particles could undergo diffusive reacceleration during propagation in the Milky Way, potentially reaching energies up to the GeV level observed by AMS-02. In this work, we utilize AMS-02 data to constrain the PBH abundance $f_{\rm PBH}$ by employing the reacceleration mechanism. Under the assumption of a monochromatic PBH mass distribution, our findings reveal that the limit is stricter than that derived from Voyager 1 data. This difference is particularly pronounced when $M_{\rm PBH}\lesssim10^{15}\,{\rm g}$, exceeding an order of magnitude. The constraints are even more robust in a more realistic scenario involving a log-normal mass distribution of PBHs. Moreover, we explore the impact of varying propagation parameters and solar modulation potential within reasonable ranges, and find that such variations have minimal effects on the final results.

astro-ph.HE↗

arXiv2023

Exploring the Dark Energy Equation of State with JWST

Observations from the James Webb Space Telescope (JWST) have unveiled several galaxies with stellar masses $M_*\gtrsim10^{10} M_\odot$ at redshifts $7.4\lesssim z\lesssim 9.1$. These remarkable findings indicate an unexpectedly high stellar mass density, which contradicts the prediction of the $\Lambda \rm CDM$ model. Our study utilizes the Chevallier--Polarski--Linder (CPL) parameterization, one of the dynamic dark energy models, to probe the role of dark energy on shaping galaxy formation. By considering varying star formation efficiencies within this framework, our analysis demonstrates that in a universe with a higher proportion of dark energy, more massive galaxies are formed at high redshifts, given a fixed perturbation amplitude observed today. These intriguing results highlight the promising prospect of revealing the nature of dark energy by analyzing the high-redshift massive galaxies.

astro-ph.CO↗

arXiv2023

The Joule--Thomson and Joule--Thomson-like effects of the black holes in a cavity

When a black hole is enclosed in a cavity in asymptotically flat space, an effective volume can be introduced, and an effective pressure can be further defined as its conjugate variable. By this means, an extended phase space is constructed in a cavity, which resembles that in the anti-de Sitter (AdS) space in many aspects. However, there are still some notable dissimilarities simultaneously. In this work, the Joule--Thomson (JT) effect of the black holes, widely discussed in the AdS space as an isenthalpic (constant-mass) process, is shown to only have cooling region in a cavity. On the contrary, in a constant-thermal-energy process (the JT-like effect), there is only heating region in a cavity. Altogether, different from the AdS case, there is no inversion temperature or inversion curve in a cavity. Our work reveals the subtle discrepancy between the two different extended phase spaces that is sensitive to the specific boundary conditions.

gr-qc↗

arXiv2023

An inflation model for massive primordial black holes to interpret the JWST observations

The first observations of the James Webb Space Telescope (JWST) have identified six massive galaxy candidates with the stellar masses $M_\ast\gtrsim 10^{10}\,M_\odot$ at high redshifts $7.4\lesssim z\lesssim 9.1$, with two most massive high-$z$ objects having the cumulative comoving number densities $n_{\rm G}$ up to $1.6\times 10^{-5}\, {\rm Mpc}^{-3}$. The presence of such massive sources in the early universe challenges the standard $Λ$CDM model since the needed star formation efficiency is unrealistically high. This tension can be alleviated via the accretion of massive primordial black holes (PBHs). In this work, with the updated data from the first JWST observations, we find that the PBHs with mass $10^8\,M_\odot\lesssim M_{\rm PBH}\lesssim 10^{11}\,M_\odot$ can act as the seeds of extremely massive galaxies even with a low abundance $10^{-7}\lesssim f_{\rm PBH}\lesssim 10^{-3}$. We construct an ultraslow-roll inflation model and investigate its possibility of producing the required PBHs. We explore the model in two cases, depending on whether there is a perfect plateau on the inflaton potential. If the plateau is allowed to incline slightly, our model can produce the PBHs that cover the required PBH mass and abundance range to explain the JWST data.

astro-ph.CO↗

arXiv2022

On the dual relation in the Hawking--Page phase transition of the black holes in a cavity

The Hawking--Page phase transitions of the $d$-dimensional Schwarzschild and charged black holes are explored in a cavity. The phase transition temperature $T_{\rm HP}$, the minimum black hole temperature $T_0$, and the Gibbs free energy $G$ are systematically calculated. A dual relation for the Schwarzschild black holes in the anti-de Sitter space, $T_{\rm HP}(d)=T_0(d+1)$, is found to be also approximately valid in the cavity case to a high precision, and this relation can be further generalized to the charged black holes in a suitable form. Our work reveals the universal properties of the black holes in different extended phase spaces and motivates further studies on their thermodynamic behaviors that are sensitive to specific boundary conditions, like the terminal points in the $G$--$T$ curves.

gr-qc↗

arXiv2021

Primordial black holes from the perturbations in the inflaton potential in peak theory

The primordial black hole (PBH) is an effective candidate for dark matter. In this work, the PBH abundance $f$ is calculated in peak theory, with one or two perturbations in the inflaton potential. We construct an antisymmetric perturbation that can create a perfect plateau in the inflaton potential, leading inflation to the ultra-slow-roll stage. During this stage, the power spectrum of primordial curvature perturbation is remarkably enhanced on small scales, generating abundant PBHs. The PBH abundance $f\sim 0.1$ can be achieved in one or two typical mass windows at $10^{-17}M_\odot$, $10^{-13}M_\odot$, and $30M_\odot$, without spoiling the nearly scale-invariant power spectrum on large scales. For comparison, $f$ is calculated in two approximate methods of peak theory (with different spectral moments) and also in the Press--Schechter theory. It is found that the Press--Schechter theory systematically underestimates $f$ by two or three orders of magnitude compared with peak theory.

astro-ph.CO↗

arXiv2021

Hawking--Page phase transitions in four-dimensional Einstein--Gauss--Bonnet gravity

The Hawking-Page (HP) phase transitions of the anti-de Sitter black holes in the extended phase space are studied in a novel four-dimensional Einstein-Gauss-Bonnet (4EGB) gravity, which is proposed by rescaling the Gauss--Bonnet (GB) coupling constant $α\toα/(d-4)$ in $d$ dimensions and redefining the four-dimensional gravity in the limit $d \to 4$. The GB term shows nontrivial contributions to both black hole mass and entropy simultaneously, and decreases the HP phase transition temperature $T_{\rm HP}$. Moreover, the HP phase transitions can happen only within a range of pressure in the 4EGB gravity. For the charged black holes, $T_{\rm HP}$ also decreases with the electric potential in the grand canonical ensemble. A general discussion of the HP phase transitions in the Einstein, GB, and 4EGB gravities is also presented.

gr-qc↗

arXiv2020

The Hawking-Page phase transitions in the extended phase space in the Gauss-Bonnet gravity

In this paper, the Hawking-Page phase transitions between the black holes and thermal anti-de Sitter (AdS) space are studied with the Gauss-Bonnet term in the extended phase space, in which the varying cosmological constant plays the role of an effective thermodynamic pressure. The Gauss-Bonnet term exhibits its effects via introducing the corrections to the black hole entropy and Gibbs free energy. The global phase structures, especially the phase transition temperature $T_{\rm HP}$ and the Gibbs free energy $G$, are systematically investigated, first for the Schwarzschild-AdS black holes and then for the charged and rotating AdS black holes in the grand canonical ensembles, with both analytical and numerical methods. It is found that there are terminal points in the coexistence lines, and $T_{\rm HP}$ decreases at large electric potentials and angular velocities and also decreases with the Gauss-Bonnet coupling constant $α$.

gr-qc↗