arXiv subjects

Hong-Bo Jin

Publications and source records attributed to Hong-Bo Jin.

32 records · Page 2Linked to original sources

arXiv2024

Sky location of Massive Black Hole Binaries in the foreground of Galactic white dwarf binaries

For space-based gravitational wave (GW) detection, the main noise source for massive black hole binaries (MBHBs) is attributed to approximately $10^7$ double white dwarf binaries in the foreground. For a GW source, the amplitude of the detector response, recorded by a space-based gravitational wave detector, exhibits a modulation effect with a year period when observing the source from various orbital positions. Under the adverse conditions mentioned above, where there is a strong foreground noise and annual modulation in the signals, we employed the wavelet transform and the strong-amplitude relevant orbital position search methods, which allows the weak MBHB sources to achieve higher locating accuracy. In detail, for two MBHB sources of lower intensity, the precision of luminosity distance, represented by the ratio $ΔD_L / D_L$ at the 95$\%$ confidence level, is enhanced by factors of $\sim$ 2. And the angular resolutions, denoted by $ΔΩ_s$, are enhanced by a factor of $\sim$ 20. These improvements increase the number of detectable GW sources, facilitates multi-messenger follow-up observations and provides constraints on the cosmological constant.

astro-ph.HE↗

arXiv2024

Gravitational Wave Polarization Detection with Tetrahedron Constellation of Gravitational Wave Observatory

For the first time, we have introduced the Tetrahedron Constellation of Gravitational Wave Observatory (TEGO) composed of four identical spacecrafts (S/Cs). The laser telescopes and their pointing structures are mounted on the S/C platform and are evenly distributed at three locations 120 degrees apart. These structures form automatically a stable mass center for the platform. The time delay interferometry (TDI) are used to suppress the frequency noise of Gravitational Wave (GW) detector. The unequal arm Michelson TDI configuration and the Sagnac TDI configuration are equally effective at eliminating the laser frequency noise based on the TEGO configuration. Furthermore, comparing to the configurations of LISA, Taiji, and TianQin, the TEGO has more combinations of optical paths in its TDI system sensitive to GW signals. The six arms of TEGO are simultaneously sensitive to the six polarization modes of GWs. The sensitivity implies that GW modes beyond the predictions of general relativity (GR) can be detected directly. For instance, a scalar longitudinal mode of GWs, which is not predicted by GR, has been identified as a dominant polarization component. This mode is found to be evident in the response amplitudes of the TEGO arms, such as between S/C1 and S/C4, and S/C3 and S/C4, at certain orbital positions.

gr-qc↗

arXiv2024

Sky location of Galactic white dwarf binaries in space-based gravitational wave detection

Quickly localizing the identified white dwarf (WD) binaries is the basic requirement for the space-based gravitational wave (GW) detection. In fact, the amplitude of GW signals are modulated by the periodic motion of GW detectors on the solar orbit. The intensity of the observed signals is enhanced according to the observation time beyond a year to enhance a high signal to noise ratio (SNR). As data gap exists, the completeness of the data observed for a long time depends on filling gaps in the data. Actually, in a year period, the GW sources have a best observation orbit position of GW detectors, where the detector response intensity of GW is maximum. Thus, the best positions, where the direction of GW source is perpendicular to the detection arms, can be searched for the verified GW sources of the sky map to enhance SNR too. For the three arms response intensity of the GW signals changing more clearly with the location of the GW sources relative to the detector, the noises and the suppression of noise by time delay interferometer are ignored. In the four chosen sources, the two verification WD binaries: J0806 and V407 Vul are observed at the best orbit positions by TAIJI for the short time of 2 and 3 days respectively. The intensities of those GWs are above the values of the TAIJI sensitivity curve, significantly. Compared with a single detector, the network of two detectors does not significantly improve the accuracy of location of the verification binaries. These results imply that the searching of GW signals and parameter estimation of GW sources from the experimental data of the space-based mission do not ignore the orbit positions relevant to GW sources.

gr-qc↗

arXiv2023

Taiji Data Challenge for Exploring Gravitational Wave Universe

The direct observation of gravitational waves (GWs) opens a new window for exploring new physics from quanta to cosmos and provides a new tool for probing the evolution of universe. GWs detection in space covers a broad spectrum ranging over more than four orders of magnitude and enables us to study rich physical and astronomical phenomena. Taiji is a proposed space-based GW detection mission that will be launched in the 2030s. Taiji will be exposed to numerous overlapping and persistent GW signals buried in the foreground and background, posing various data analysis challenges. In order to empower potential scientific discoveries, the Mock LISA Data Challenge and the LISA Data Challenge (LDC) were developed. While LDC provides a baseline framework, the first LDC needs to be updated with more realistic simulations and adjusted detector responses for Taiji's constellation. In this paper, we review the scientific objectives and the roadmap for Taiji, as well as the technical difficulties in data analysis and the data generation strategy, and present the associated data challenges. In contrast to LDC, we utilize second-order Keplerian orbit and second-generation time delay interferometry techniques. Additionally, we employ a new model for the extreme-mass-ratio inspiral waveform and stochastic GW background spectrum, which enables us to test general relativity and measure the non-Gaussianity of curvature perturbations. Furthermore, we present a comprehensive showcase of parameter estimation using a toy dataset. This showcase not only demonstrates the scientific potential of the Taiji Data Challenge but also serves to validate the effectiveness of the pipeline. As the first data challenge for Taiji, we aim to build an open ground for data analysis related to Taiji sources and sciences. More details can be found on the official website at http://taiji-tdc.ictp-ap.org.

gr-qc↗

arXiv2022

The estimation of far-field wavefront error of tilt-to-length distortion coupling in space-based gravitational wave detection

In space-based gravitational wave detection, the estimation of far-field wavefront error of the distorted beam is the precondition for the noise reduction. Zernike polynomials is used to describe the wavefront error of the transmitted distorted beam. The propagation of a laser beam between two telescope apertures is calculated numerically. Far-field wavefront error is estimated with the absolute height of the peak-to-valley phase deviation between distorted Gaussian beam and a reference distortion-free Gaussian beam. The results show the pointing jitter is strongly related to the wavefront error. Furthermore, when jitter decreases 10 times from 100 to 10 nrad, wavefront error reduces for more than an order of magnitude. In the analysis of multi-parameter minimization, the minimum of wavefront error tends to Z[5,3] Zernike in some parameter ranges. Some Zernikes have a strong correlation with wavefront error of the received beam. When the aperture diameter increases at Z[5,3] Zernike, wavefront error is not monotonic and has oscillation. Nevertheless, wavefront error almost remains constant with the arm length increasing from 10$^{-1}$ Mkm to 10$^3$ Mkm. When the arm length decreases for three orders of magnitude from 10$^{-1}$ Mkm to 10$^{-4}$ Mkm, wavefront error has only an order of magnitude increasing. In the range of 10$^{-4}$ Mkm to 10$^3$ Mkm, the lowest limit of the wavefront error is from 0.5 fm to 0.015 fm, at Z[5,3] Zernike and 10 nrad jitter.

astro-ph.IM↗

arXiv2022

Spot size estimation of flat-top beams in space-based gravitational wave detectors

Motivated by the necessity of a high-quality stray light control in the detection of the gravitational waves in space, the spot size of a flat top beam generated by the clipping of the Gaussian beam (GB) is studied. By adopting the mode expansion method (MEM) approach to simulating the beam, a slight variant of the definition of the mean square deviation (MSD) spot size for the MEM beam is proposed. This enables us to quickly estimate the spot size for arbitrary propagation distances. Given that the degree of clipping is dependent on the power ratio within the surface of an optical element, the power ratio within the MSD spot range is used as a measure of spot size. The definition is then validated in the cases of simple astigmatic Gaussian beam and nearly-Gaussian beam profiles. As a representative example, the MSD spot size for a top-hat beam in a science interferometer in the detection of gravitational waves in space is then simulated. As in traditional MSD spot size analysis, the spot size is divergent when diffraction is taken into account. A careful error analysis is carried out on the divergence and in the present context, it is argued that this error will have little effect on our estimation. Using the results of our study allows an optimal design of optical systems with top-hat or other types of non-Gaussian beams. Furthermore, it allows testing the interferometry of space-based gravitational wave detectors for beam clipping in optical simulations. The present work will serve as a useful guide in the future system design of the optical bench and the sizes of the optical components.

astro-ph.IM↗

arXiv2018

Cosmic ray $e^{+} e^{-}$ spectrum excess and peak feature observed by the DAMPE experiment from dark matter

The Chinese satellite Wukong, also known as the DArk Matter Particle Explorer (DAMPE), has released its observation data of the cosmic ray (CR) electrons and positrons. The data shows an excess in the energy spectrum up to TeV energy, and possibly a peak-like fine structure at $\sim 1.4 \TeV$. We investigate the scenario that the source of the excess comes from dark matter annihilation or decay. We find that the annihilation or decay of diffuse dark matter particles in the Galactic halo can give excellent ($W^+W^-$ channel) or at least good (double $τ^+τ^-$ channel) fits to the broad excess. However, the annihilation cross-section is $10^{-23}\cm^3s^{-1}$, larger than required for getting the correct relic abundance. We then study whether the narrow peak at $\sim 1.4\TeV$ could be explained by a nearby subhalo, which thanks to the smaller distance, could supply $e^+e^-$ within a narrow energy range. We find that in order to produce a peak width less than the energy bin width (0.2 TeV), the source must be located within $r\lsim 0.53~\kpc$. Our global fit models do not produce the peak-like feature, instead at 1.4 TeV the spectrum show either a slope or a cliff-like feature. However, if less than optimal fit is allowed, the peak-like feature could be generated. Furthermore, an excellent fit with peak could be obtained with model B if the background is rescaled. If the dark matter decay and annihilation rates are determined using the broad excess, the required subhalo mass $\sim10^{5}~M_\odot$ for decay model, or $\sim10^{4.5}\Msun$ for annihilation model and a shallower density profile slope $α=1.2$, or $\sim10^{2.5}\Msun$ for the steep density profile $α=1.7$. However, the probability for the existence of a such nearby subhalo as massive as given above is very low.

astro-ph.HE↗

arXiv2018

Astrophysical background and dark matter implication based on latest AMS-02 data

The cosmic ray(CR) positrons and antiprotons are often regarded as the collision products of CR nucleons with the interstellar medium. However this conclusion is challenged by recent experimental data. In this work, we choose the latest AMS-02 data to analyze the astrophysical background of CR positrons and antiprotons with the GALPROP code for CR propagation and the QGSJET-II-04 model for the hadronic interactions. The results show that in low energies the predicted fluxes of CR antiprotons and positrons are consistent with AMS-02 data in the diffusion model combining the re-acceleration and convection terms (DCR model). Thus, the excess of CR antiprotons in the low energy are not justified. In that model, the predicted flux of CR protons is consistent with AMS-02 data whose hardening feature above 330 GeV is also matched. Based on that model, the total fluxes of CR electrons and positrons from AMS-02 are also used to analyzed the interpretation of dark matter annihilation about the positron excess. The predicted best-fit masses of dark matter are from 400 GeV to 4 TeV. The DCR model does not give the unusual interpretation of the positron excess.

hep-ph↗

arXiv2015

Spectra of cosmic ray electrons and diffuse gamma rays with the constraints of AMS-02 and HESS data

Recently, AMS-02 reported their observed results of cosmic rays(CRs). In addition to the AMS-02 data, we add HESS data to estimate the spectra of CR electrons and the diffuse gamma rays above TeV. In the conventional diffusion model, a global analysis is performed on the spectral features of CR electrons and the diffuse gamma rays by GALRPOP package. The results show that the spectrum structure of the primary component of CR electrons can not be fully reproduced by a simple power law and the relevant break is around hundred GeV. At 99\% C.L., the injection indices above the break decrease from 2.54 to 2.35, but the ones below the break are only in the range 2.746 - 2.751. The spectrum of CR electrons does not need to add TeV cutoff to match the features of HESS data too. Based on the difference between the fluxes of CR electrons and the primary component of them, the predicted excess of CR positrons is consistent with the interpretations as pulsar or dark matter. In the analysis of the Galactic diffuse gamma rays with the indirect constraint of AMS-02 and HESS data, it is found that the fluxes of Galactic diffuse gamma rays are consistent with GeV data of Fermi-LAT in the high latitude regions. The results indicate that the inverse Compton scattering(IC) is the dominant component in the range of the hundred GeV to tens of TeV respectively from the high latitude regions to the low ones, and in the all regions of Galaxy the flux of diffuse gamma rays is less than CR electrons at the energy scale of 20 TeV.

astro-ph.HE↗

arXiv2015

Implications of the first AMS-02 antiproton data for dark matter

The implications of the first AMS-02 $\bar p/p$ data for the propagation of cosmic rays and the properties of dark matter (DM) are discussed. Using various diffusive re-acceleration (DR) propagation models, one can derive very conservative upper limits on the DM annihilation cross sections. The limits turned out to be compatible with that from the Ferm-LAT gamma-ray data on the dwarf spheroidal satellite galaxies. The flattening of the $\bar p/p$ spectrum above $\sim 100$~GeV in the current data still leaves some room for TeV scale DM particles. More antiproton data at high kinetic energies are needed to constrain the properties of the DM particles.

hep-ph↗

arXiv2015

Upper limits on DM annihilation cross sections from the first AMS-02 antiproton data

The first measurement on the antiproton to proton ratio made by the AMS-02 collaboration agrees with the expection from conventional cosmic-ray secondaries in the kinetic energy range $\sim 10-100$ GeV, which can be turned into stringent upper limits on the dark matter (DM) annihilation cross sections above $\sim 300$ GeV. Using the GALPROP code, we derive the upper limits in various propagation models and DM profiles. We show that in the "conventional" propagation model, for the $q\bar q$, $b\bar b$, and $WW$ final states, the constraints can be more stringent than that derived from the recent Ferm-LAT gamma-ray data on the dwarf spheroidal satellite galaxies. Making use of the typical minimal, median and maximal models obtained from a previous global fit, we show that the variation of the upper limits is around a factor of five. The possibility of DM contribution to the high energy $\bar p/p$ data is discussed.

hep-ph↗

arXiv2015

Cosmic ray propagation and dark matter in light of the latest AMS-02 data

The AMS-02 experiment is measuring the high energy charged cosmic rays with unprecedented accuracy. We explore the possibility of determining the cosmic-ray propagation models using the AMS-02 data $alone$. A global Bayesian analysis of the constraints on the cosmic-ray propagation models from the latest AMS-02 data on the Boron to Carbon nuclei flux ratio and proton flux is performed, with the assumption that the primary nucleon source is a broken power law in rigidity. The ratio of the diffusion coefficient $D_{0}$ to the diffusive halo height $Z_{h}$ is found to be determined with high accuracy $D_{0}/Z_{h}\simeq 2.00\pm0.07\text{cm}^{2}\text{s}^{-1}\text{kpc}^{-1}$. The best-fit value of the halo width is $Z_{h}\simeq 3.3$ kpc with uncertainty less than $50\$. As a consequence, the typical uncertainties in the positron fraction is within a factor of two, and that in the antiproton flux is within an order of magnitude. Both of them are significantly smaller than that from the analyses prior to AMS-02. Taking into account all the uncertainties and correlations in the propagation parameters we derive conservative upper limits on the cross sections for DM annihilating into various standard model final states from the current PAMELA antiproton data. We also investigate the reconstruction capability of the future AMS-02 antiproton data on the DM properties. The result shows that for DM particles lighter than 100 GeV and with typical thermal annihilation cross section, the cross section can be well reconstructed with uncertainties about a factor of two for the AMS-02 three-year data taking.

hep-ph↗

arXiv2013

Implications of the first AMS-02 measurement for dark matter annihilation and decay

In light of the first measurement of the positron fraction by the AMS-02 experiment, we perform a detailed global analysis on the interpretation of the latest data of PAMELA, Fermi-LAT, and AMS-02 in terms of dark matter (DM) annihilation and decay in various propagation models. The allowed regions for the DM particle mass and annihilation cross section or decay life-time are obtained for channels with leptonic final states: $2e$, $2μ$, $2τ$, $4e$, $4μ$ and $4τ$. We show that for the conventional astrophysical background the AMS-02 positron fraction data alone favour a DM particle mass $\sim 500 \ (800)$ GeV if DM particles annihilate dominantly into $2μ\ (4μ)$ final states, which is significantly lower than that favoured by the Fermi-LAT data of the total flux of electrons and positrons. The allowed regions by the two experiments do not overlap at a high confidence level ($99.99999\%$C.L.). We consider a number of propagation models with different halo height $Z_{h}$, diffusion parameters $D_{0}$ and $δ_{1/2}$, and power indices of primary nucleon sources $γ_{p1/p2}$. The normalization and the slope of the electron background are also allowed to vary. We find that the tension between the two experiments can be only slightly reduced in the propagation model with large $Z_{h}$ and $D_{0}$. The consistency of fit is improved for annihilation channels with $2τ$ and $4τ$ final states which favour TeV scale DM particle with large cross sections above $\sim 10^{-23} \text{cm}^3\text{s}^{-1}$. In all the considered leptonic channels, the current data favour the scenario of DM annihilation over DM decay. In the decay scenario, the charge asymmetric DM decay is slightly favoured.

hep-ph↗

arXiv2013

Implications of the latest XENON100 and cosmic ray antiproton data for isospin violating dark matter

In the scenario of isospin-violating dark matter (IVDM), the dark matter (DM) spin-independent couplings to protons and to neutrons are allowed to be different, which has been considered to relax the tensions between the results of DAMA, CoGeNT and XENON experiments. We explore the allowed values of DM-nucleon couplings favored and excluded by the current experiments under the assumption of IVDM. We find that the recently updated XENON100 result excludes the main part of the overlapping signal region between DAMA and CoGeNT. The mass of the IVDM is restricted to a narrow range near 7.5-8 GeV. We also show that the possible tensions between some experiments such as that between DAMA and SIMPLE are unlikely to be affected by isospin violating interactions. In an effective operator approach, we investigate conservative upper bounds on the DM-quark couplings required by the IVDM scenario from the cosmic ray antiproton fluxes measured recently by BESS-Polar II and PAMELA, and that from the relic density. The results show that the relatively large couplings favored by DAMA and CoGeNT are tightly constrained, if the operators contribute to velocity-independent annihilation cross sections. For thermal relic DM, the upper bounds from the relic density can also be stringent.

hep-ph↗