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Junlin Qin

Publications and source records attributed to Junlin Qin.

6 recordsLinked to original sources
arXiv2026

A Catalog-Wide Study of Gravitational-Wave Residuals in GWTC-4 and GWTC-5

Improved sensitivity of the LIGO-Virgo-KAGRA detectors has enabled the accumulation of a large gravitational-wave event catalog, providing an opportunity for catalog-wide residual analyses to assess waveform-model performance. We study GWTC-4 and GWTC-5 events with signal-to-noise ratio $>12$ in at least one detector, applying three goodness-of-fit tests to the normalized Q-transform energies of whitened residuals obtained by subtracting the IMRPhenomXPHM and SEOBNRv5PHM waveform models. Across the catalog, the residuals are consistent with Gaussian noise, with no evidence of systematic deviations in either multi-detector events or valid single-detector events. For events exhibiting strong model dependence in parameter estimation, variations between waveform models likewise do not produce persistent residual structures. These results demonstrate that parameter-estimation biases associated with waveform modeling do not necessarily manifest as detectable features in the residuals. Residual analyses therefore provide a complementary diagnostic in data space for validating gravitational-wave waveform models within the detector sensitivity.

gr-qc↗
arXiv2026

Shadows and photon spheres of static black holes embedded in a Dehnen-(1,4,5/2)-type dark matter halo with a quintessential field

This paper investigates the appearance characteristics of static black holes embedded in Dehnen-(1,4,5/2)-type dark matter halos with a quintessential field, focusing on how the dark matter halo and dark energy affect the black hole images. We first derive the event horizon radius and the photon effective potential of the black hole, and then calculate critical quantities such as the critical photon sphere radius and critical impact parameter under different parameter sets. Trajectories of photons are subsequently plotted. The study reveals that as the parameters of the dark matter halo (the central density of the dark matter halo $ρ_s$ and the scale radius of the central halo $r_s$) and the quintessential field (the normalization factor $c$ and the equation of state parameter of dark energy $w_q$) increase, the aforementioned physical quantities generally exhibit an increasing trend. Based on the derived general expressions for the redshift factor and integrated intensity, we further explore the optical effects of the spherical accretion and the thin-disk accretion models. The results indicate that dark energy exerts an influence on the black hole shadow that is strongly dependent on the observer's position, whereas the influence exerted by dark matter exhibits no such conspicuous dependence. Furthermore, dark matter and dark energy have distinct effects on both the intensity and the radius of the black hole shadow. In particular, the intensity exhibits a greater sensitivity to dark energy, whereas the radius is more responsive to dark matter. This distinction offers a potential observational criterion for identifying, through black hole images, whether the dominant interacting component near the black hole is dark matter or dark energy, and provides an important basis for constraining the equation-of-state parameter $w_q$.

gr-qc↗
arXiv2026

Ensemble-Based Residual Tests of GW231123 across Waveform Models

GW231123 is an exceptional gravitational wave event for which different waveform models yield significantly different inferred source parameters. Residual tests provide a direct way to assess whether each waveform model gives an adequate description of the observed signal. In this work, we extend the conventional residual-test methods by subtracting the 100 highest likelihood waveforms, rather than only the maximum likelihood waveform for each model, thereby propagating waveform reconstruction uncertainty into the residual analysis. This ensemble-based approach turns the residual test from a single waveform diagnostic into a robustness test over the local high likelihood waveform manifold. We further perform injection tests to quantify the detectability of cross-model waveform discrepancies in realistic detector noise. The large-scale implementation of these analyses is made possible by the high speed and low computational cost of our residual testing framework, which is based on three goodness-of-fit tests: the Kolmogorov-Smirnov test, the Anderson-Darling test, and Pearson's chi-squared test.

gr-qc↗
arXiv2026

The shadows and photon rings of two minimal deformations of Schwarzschild black holes

This paper primarily investigates the optical characteristics of two minimal Schwarzschild black hole deformations, the Kazakov-Solodukhin and Ghosh-Kumar black holes, under different accretion models. The event horizon, photon sphere, and critical impact parameter of the former increase compared with the Schwarzschild black hole, but those of the latter decrease. The data from the Event Horizon Telescope Collaboration are used to constrain the parameter ranges of the two black holes. In the case of spherical accretion, the quantum correction of Kazakov-Solodukhin black hole leads to the increase of black hole shadow size and the decrease of integrated intensity, while the shadow size of magnetically charged Ghosh-Kumar black hole decreases and the integrated intensity increases. The shadow radius of the black hole is independent of the spherical accretion models. For an optically and geometrically thin accretion disk, the integrated intensity is mainly contributed by direct emission, and the contributions of photon rings and lensed rings are very small. In addition, the photon rings and lensed rings of Kazakov-Solodukhin black hole are narrower, while those of Ghosh-Kumar black hole are wider. Whereas the Kazakov-Solodukhin black hole exhibits higher brightness, the Ghosh-Kumar black hole shows lower brightness. Additionally, a disk closer to the black hole correlates with a smaller shadow radius. This paper proposes a method to distinguish different black holes in a specific thin disk model.

gr-qc↗
arXiv2025

Shadow and Optical Imaging in Einstein-Maxwell-Dilaton Black Hole

This paper investigates photon motion in black hole of Einstein-Maxwell-dilaton theory, exploring black hole shadows and observational characteristics under various accretion models. We first give the relation of the event horizon, photon sphere, and critical impact parameter in terms of the magnetic charge $q$. We then use the Event Horizon Telescope data to constrain $q$. For the two spherical accretion models, the infalling scenario yields a darker shadow due to the Doppler effect. However, the shadow radius remains unchanged for different models. In the case of an optically thin, geometrically thin disk accretion model, the observed brightness is predominantly determined by direct emission. The lensing ring provides a secondary contribution to the intensity, whereas the photon ring's emission is negligible. The widths of the lensing and photon rings exhibit a positive correlation with the magnetic charge $q$. Additionally, within the disk model framework, the black hole shadow radius is found to depend on the specific emission model.

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