arXiv subjects

Xiu-Hui Tan

Publications and source records attributed to Xiu-Hui Tan.

5 recordsLinked to original sources

arXiv2026

Neutrino Constraints on memory-burdened Primordial Black Holes from Dwarf Spheroidal Galaxies

Dwarf spheroidal galaxies (dSphs) represent prime targets for indirect dark matter (DM) searches due to their substantial DM content and low astrophysical backgrounds. In this work, we conduct a comprehensive search for neutrino signals originating from memory-burdened primordial black holes (PBHs) as DM candidates, utilizing 10 years of publicly available muon-track data from the IceCube Neutrino Observatory. We systematically compile $\mathcal{D}$-factor measurements from four independent literature sources, resulting in a robust sample of 14 dSphs with well-characterized DM distributions. For each dSph, we perform an unbinned maximum-likelihood analysis to evaluate the significance of potential PBH neutrino emission, incorporating $\mathcal{D}$-factor uncertainties through a profile likelihood framework. No significant excess over the background-only hypothesis is detected. Building upon these null results, we derive upper limits on the PBH abundance fraction, assuming a monochromatic mass distribution. Our analysis demonstrates that constraints obtained in the $k=1$ case exhibit significant improvement compared to previous studies, while the $k=2$ case yields less restrictive limits due to limited sensitivity of IceCube in the relevant energy range. Furthermore, our combined analysis of 14 dSphs achieves substantially enhanced sensitivity, as the independent error treatment effectively reduces statistical uncertainties.

astro-ph.CO↗

arXiv2024

Axion effects on gamma-ray spectral irregularities. II: Implications of EBL absorption

The extragalactic background light (EBL) plays a crucial role in the propagation of high-energy particles throughout the Universe. In this work, we explore the impact of the EBL absorption effect on photon to axionlike particle (ALP) conversions from the very-high-energy gamma-ray spectral irregularities. For our purpose, we select four BL Lac blazars: Markarian 501, 1ES 0229+200, PKS 0301-243, and PKS 0447-439 for analysis. Their redshifts range from approximately 0.03 to 0.34. We first discuss the EBL absorption effect on the gamma-ray spectral energy distributions (SEDs) using three common EBL spectral models: Finke-10, Franceschini-17, and Saldana-Lopez-21. Then we consider the photon-ALP conversions in astrophysical magnetic fields. The best-fit chi-square distributions of these EBL models under the ALP assumption in the ALP parameter $\{m_a, g_{a\gamma}\}$ plane are provided, showing similar distributions. For comparison, we define a new delta chi-square, $\chi_d^2$, to quantify the difference in chi-square values. The distributions of $\chi_d^2$ and the gamma-ray SEDs corresponding to the maximum delta chi-square, $\chi^2_{d, \rm max}$, are also presented for comparison. Our results indicate that the influence of these different EBL models is non-dominant at the low-redshift gamma-ray axionscope. In these cases, choosing the latest model, Saldana-Lopez-21, is sufficient. However, as the redshift of the sources increases, this influence becomes more significant.

hep-ph↗

arXiv2024

Constraints on Primordial Magnetic Fields from High Redshift Stellar Mass Density

Primordial magnetic fields (PMFs) play a pivotal role in influencing small-scale fluctuations within the primordial density field, thereby enhancing the matter power spectrum within the context of the $\Lambda$CDM model at small scales. These amplified fluctuations accelerate the early formation of galactic halos and stars, which can be observed through advanced high-redshift observational techniques. Therefore, Stellar Mass Density (SMD) observations, which provide significant opportunities for detailed studies of galaxies at small scales and high redshifts, offer a novel perspective on small-scale cosmic phenomena and constrain the characteristics of PMFs. In this study, we compile 14 SMD data points at redshifts $z > 6$ and derive stringent constraints on the parameters of PMFs, which include the amplitude of the magnetic field at a characteristic scale of $\lambda=1\,{\rm Mpc}$, denoted as $B_0$, and the spectral index of the magnetic field power spectrum, $n_{\rm B}$. At 95\% confidence level, we establish upper limits of $B_0 < 4.44$ nG and $n_{\rm B} < -2.24$, along with a star formation efficiency of approximately $f_*^0 \sim 0.1$. If we fix $n_{\rm B}$ at specific values, such as $-2.85$, $-2.9$, and $-2.95$, the 95\% upper limits for the amplitude of the magnetic field can be constrained to 1.33 nG, 2.21 nG, and 3.90 nG, respectively. Finally, we attempt to interpret recent early observations provided by James Webb Space Telescope (JWST) using the theory of PMFs, and find that by selecting appropriate PMF parameters, it is possible to explain these results without significantly increasing the star formation efficiency.

astro-ph.CO↗

arXiv2022

Searching for Signal of Primordial Black Hole from CMB Lensing and $γ$-ray Emissions

In this $\textit{Letter}$, we search for the signal of the primordial black holes (PBHs) by correlating the $γ$-ray emissions in the MeV energy band produced by the Hawking evaporation and the lensing effect of the cosmic microwave background (CMB). We use the conservative case of the astrophysical model as much as possible in the calculations, since the potential astrophysical origins dominate the observed emission in the MeV energy band. By carefully discussing the appropriate energy bands corresponding to different PBHs masses, it is worth expecting a tight constraint on the fraction of the Schwarzschild PBHs in the mass range of $10^{16} - 5\times10^{17}\,{\rm g}$, by simulations of the sensitivity of the future CMB-S4 project and the $γ$-ray telescope e-ASTROGAM. Furthermore, we also consider the PBHs model with spins, and find that the constraining ability of the PBHs fraction from the correlation between CMB lensing and $γ$-ray emissions can be improved by another order of magnitude, which could importantly fill the gaps with PBHs fraction limits in the mass range of $5\times 10^{17} - 2\times 10^{18}\,{\rm g}$.

astro-ph.CO↗

arXiv2020

Searching for Integrated Sachs-Wolfe Effect from Fermi-LAT Diffuse $γ$-ray Map

In this paper, we estimate the cross-correlation power spectra between the Planck 2018 cosmic microwave background (CMB) temperature anisotropy map and the unresolved $γ$-ray background (UGRB) from the 9-years Fermi-Large Area Telescope (LAT) data. In this analysis, we use up to nine energy bins over a wide energy range of [0.631, 1000] GeV from the Fermi-LAT UGRB data. Firstly, we find that the Fermi data with the energy ranges [1.202, 2.290] GeV and [17.38, 36.31] GeV show the positive evidence for the Integrated Sachs-Wolfe (ISW) effect at $1.8σ$ confidence level, and the significance would be increased to $2.7σ$ when using these two energy bins together. Secondly, we apply the single power-law model to normalize the amplitude and use all the nine Fermi energy bins to measure the significance of the ISW effect, we obtained ${\rm A_{amp}}=0.95 \pm 0.53$ ($68\%$ C.L.). For the robustness test, we implement a null hypothesis by randomizing the Fermi mock maps of nine energy bins and obtain the non-detection of ISW effect, which confirms that the ISW signal comes from the Fermi-LAT diffuse $γ$-ray data and is consistent with the standard $Λ$CDM model prediction essentially. We use a cross-correlation coefficient to show the relation between different energy bins. Furthermore, we vary the cut ranges $|b|$ of galactic plane on the mask of Fermi map and carefully check the consequent influence on the ISW signal detection.

astro-ph.CO↗