NAOC Open IR
https://ir.bao.ac.cn:443
中国科学院国家天文台Sun, 02 Apr 2023 13:06:40 GMT2023-04-02T13:06:40ZExtend Bekenstein’s theorem to Einstein–Maxwell-scalar theories with a scalar potential
https://ir.bao.ac.cn:443/handle/114a11/87922
Title: Extend Bekenstein’s theorem to Einstein–Maxwell-scalar theories with a scalar potential
Authors: Jianhui Qiu; Changjun Gao
Description: The Bekenstein’s theorem allows us to generate an Einstein-conformal scalar solution from a single Einstein-ordinary scalar solution. In this article, we extend this theorem to the Einstein–Maxwell-scalar (EMS) theory with a non-minimal coupling between the scalar and Maxwell field when a scalar potential is also included. As applications of this extended theorem, the well-known static dilaton solution and rotating solution with a specific coupling between dilaton and Maxwell field are considered, and new conformal dilaton black hole solutions are found. The Noether charges, such as mass, electric charge, and angular momentum, are compared between the old and new black hole solutions connected by conformal transformations, and they are found conformally invariant. We speculate that the theorem may be useful in the computations of metric perturbations and spontaneous scalarization of black holes in the Einstein–Maxwell-conformal-scalar theory since they can be mapped to the corresponding EMS theories, which have been investigated in detail.Mon, 19 Sep 2022 06:14:48 GMThttps://ir.bao.ac.cn:443/handle/114a11/879222022-09-19T06:14:48ZConstraining Mass of M31 Combing Kinematics of Stars, Planetary Nebulae and Globular clusters
https://ir.bao.ac.cn:443/handle/114a11/87916
Title: Constraining Mass of M31 Combing Kinematics of Stars, Planetary Nebulae and Globular clusters
Authors: Yuan, Sunshun; Zhu, Ling; Liu, Cheng; Qu, Han; Fan, Zhou
Description: We construct a multiple-population discrete axisymmetric Jeans model for the Andromeda (M31) galaxy, considering three populations of kinematic tracers: 48 supergiants and 721 planetary nebulae (PNe) in the bulge and disk regions, 554 globular clusters extending to similar to 30 kpc, and halo stars extending to similar to 150 kpc of the galaxy. The three populations of tracers are organized in the same gravitational potential, while each population is allowed to have its own spatial distribution, rotation, and internal velocity anisotropy. The gravitational potential is a combination of stellar mass and a generalized NFW dark matter halo. We created two sets of models, one with a cusped dark matter halo and one with a cored dark matter halo. Both the cusped and cored model fit kinematics of all the three populations well, but the cored model is not preferred due to a too high concentration compared to that predicted from cosmological simulations. With a cusped dark matter halo, we obtained total stellar mass of 1.0 +/- 0.1 x 10(11) M (circle dot), dark matter halo virial mass of M (200) = 7.0 +/- 0.9 x 10(11) M (circle dot), virial radius of r (200) = 184 +/- 4 kpc, and concentration of c = 20 +/- 4. The mass of M31 we obtained is at the lower side of the allowed ranges in the literature and consistent with the previous results obtained from the H i rotation curve and PNe kinematics. Velocity dispersion profile of the outer stellar halo is important in constraining the total mass while it is still largely uncertain. Further proper motion of bright sources from Gaia or the Chinese Space Station Telescope might help on improving the data and lead to stronger constraints on the total mass of M31.Mon, 19 Sep 2022 06:14:47 GMThttps://ir.bao.ac.cn:443/handle/114a11/879162022-09-19T06:14:47ZMulti-Category Segmentation of Sentinel-2 Images Based on the Swin UNet Method
https://ir.bao.ac.cn:443/handle/114a11/87919
Title: Multi-Category Segmentation of Sentinel-2 Images Based on the Swin UNet Method
Authors: Yao, Junyuan; Jin, Shuanggen
Description: Medium-resolution remote sensing satellites have provided a large amount of long time series and full coverage data for Earth surface monitoring. However, the different objects may have similar spectral values and the same objects may have different spectral values, which makes it difficult to improve the classification accuracy. Semantic segmentation of remote sensing images is greatly facilitated via deep learning methods. For medium-resolution remote sensing images, the convolutional neural network-based model does not achieve good results due to its limited field of perception. The fast-emerging vision transformer method with self-attentively capturing global features well provides a new solution for medium-resolution remote sensing image segmentation. In this paper, a new multi-class segmentation method is proposed for medium-resolution remote sensing images based on the improved Swin UNet model as a pure transformer model and a new pre-processing, and the image enhancement method and spectral selection module are designed to achieve better accuracy. Finally, 10-categories segmentation is conducted with 10-m resolution Sentinel-2 MSI (Multi-Spectral Imager) images, which is compared with other traditional convolutional neural network-based models (DeepLabV3+ and U-Net with different backbone networks, including VGG, ResNet50, MobileNet, and Xception) with the same sample data, and results show higher Mean Intersection Over Union (MIOU) (72.06%) and better accuracy (89.77%) performance. The vision transformer method has great potential for medium-resolution remote sensing image segmentation tasks.Mon, 19 Sep 2022 06:14:47 GMThttps://ir.bao.ac.cn:443/handle/114a11/879192022-09-19T06:14:47ZExtend Bekenstein's theorem to Einstein-Maxwell-scalar theories with a scalar potential
https://ir.bao.ac.cn:443/handle/114a11/87911
Title: Extend Bekenstein's theorem to Einstein-Maxwell-scalar theories with a scalar potential
Authors: Qiu, Jianhui; Gao, Changjun
Description: The Bekenstein's theorem allows us to generate an Einstein-conformal scalar solution from a single Einstein-ordinary scalar solution. In this article, we extend this theorem to the Einstein-Maxwell-scalar (EMS) theory with a non-minimal coupling between the scalar and Maxwell field when a scalar potential is also included. As applications of this extended theorem, the well-known static dilaton solution and rotating solution with a specific coupling between dilaton and Maxwell field are considered, and new conformal dilaton black hole solutions are found. The Noether charges, such as mass, electric charge, and angular momentum, are compared between the old and new black hole solutions connected by conformal transformations, and they are found conformally invariant. We speculate that the theorem may be useful in the computations of metric perturbations and spontaneous scalarization of black holes in the Einstein-Maxwell-conformal-scalar theory since they can be mapped to the corresponding EMS theories, which have been investigated in detail.Mon, 19 Sep 2022 06:14:46 GMThttps://ir.bao.ac.cn:443/handle/114a11/879112022-09-19T06:14:46ZChina Manned Space Project[CMS-CSST-2021-B03]
https://ir.bao.ac.cn:443/handle/114a11/87912
Title: China Manned Space Project[CMS-CSST-2021-B03]Mon, 19 Sep 2022 06:14:46 GMThttps://ir.bao.ac.cn:443/handle/114a11/879122022-09-19T06:14:46ZChina Manned Space Project[12033003]
https://ir.bao.ac.cn:443/handle/114a11/87913
Title: China Manned Space Project[12033003]Mon, 19 Sep 2022 06:14:46 GMThttps://ir.bao.ac.cn:443/handle/114a11/879132022-09-19T06:14:46ZPredicting Supermassive Black Hole Mass with Machine Learning Methods
https://ir.bao.ac.cn:443/handle/114a11/87908
Title: Predicting Supermassive Black Hole Mass with Machine Learning Methods
Authors: He, Yi; Guo, Qi; Shao, Shi
Description: It is crucial to measure the mass of supermassive black holes (SMBHs) in understanding the co-evolution between the SMBHs and their host galaxies. Previous methods usually require spectral data which are expensive to obtain. We use the AGN catalog from the Sloan Digital Sky Survey project Data Release 7 (DR7) to investigate the correlations between SMBH mass and their host galaxy properties. We apply the machine learning algorithms, such as Lasso regression, to establish the correlation between the SMBH mass and various photometric properties of their host galaxies. We find an empirical formula that can predict the SMBH mass according to galaxy luminosity, colors, surface brightness, and concentration. The root-mean-square error is 0.5 dex, comparable to the intrinsic scatter in SMBH mass measurements. The 1 sigma scatter in the relation between the SMBH mass and the combined galaxy properties relation is 0.48 dex, smaller than the scatter in the SMBH mass versus galaxy stellar mass relation. This relation could be used to study the SMBH mass function and the AGN duty cycles in the future.Mon, 19 Sep 2022 06:14:45 GMThttps://ir.bao.ac.cn:443/handle/114a11/879082022-09-19T06:14:45ZChina.Manned Space Project[CMS-CSST-2021-A03]
https://ir.bao.ac.cn:443/handle/114a11/87905
Title: China.Manned Space Project[CMS-CSST-2021-A03]Mon, 19 Sep 2022 06:14:44 GMThttps://ir.bao.ac.cn:443/handle/114a11/879052022-09-19T06:14:44ZNSFC[12033008]
https://ir.bao.ac.cn:443/handle/114a11/87904
Title: NSFC[12033008]Mon, 19 Sep 2022 06:14:44 GMThttps://ir.bao.ac.cn:443/handle/114a11/879042022-09-19T06:14:44ZClose Major-merger Pairs at z 0: Bulge-to-total Ratio and Star Formation Enhancement
https://ir.bao.ac.cn:443/handle/114a11/87903
Title: Close Major-merger Pairs at z 0: Bulge-to-total Ratio and Star Formation Enhancement
Authors: He, Chuan; Xu, Cong Kevin; Domingue, Donovan; Cao, Chen; Huang, Jia-sheng
Description: We present a study of the bulge-to-total ratio (B/T) of a Ks-band-selected sample of 88 close major-merger pairs of galaxies (H-KPAIR), based on two-dimensional decompositions of SDSS r-band images with galfit. We investigate the dependence of the interaction-induced specific star formation rate enhancement (sSFR(enh)) on the B/T ratio, and the effects of this dependence on the differences between star-forming galaxies (SFGs) in spiral+spiral (S+S) and spiral+elliptical (S+E) pairs. Of all the 132 spiral galaxies in H-KPAIR, the 44 in S+E pairs show higher B/T than those in the 44 S+S pairs, with means of B/T = 0.35 +/- 0.05 and B/T = 0.26 +/- 0.03, respectively. There is a strong negative dependence of sSFR(enh) on the B/T ratio, and only paired SFGs with B/T < 0.3 show significant (>5 sigma) enhancement. Paired SFGs in S+S pairs show a similar trend, and many disky SFGs (B/T < 0.1) in S+S pairs have strong sSFR enhancements (sSFR(enh) > 0.7 dex). For SFGs in S+E pairs, the sSFR has no clear B/T dependence, nor any significant enhancement in any B/T bin. Disky SFGs in S+S pairs show significant (>4 sigma) enhancement in molecular gas content (M-H2/M-star), while SFGs in S+E pairs have no such enhancement in any B/T bin. No significant enhancement of the total gas content (M-gas/M-star) is found in any B/T bin for paired galaxies. The star formation efficiency of either the total gas (SFEgas = SFR/M-gas) or molecular gas (SFEH2 = SFR/M-H2) does not depend on the B/T ratio. The only significant (> 4 sigma) SFE enhancement found for paired SFGs is the SFEgas for disky SFGs in S+S pairs.Mon, 19 Sep 2022 06:14:43 GMThttps://ir.bao.ac.cn:443/handle/114a11/879032022-09-19T06:14:43Z