Pub Date : 2024-07-02DOI: 10.1088/1674-4527/ad5df3
Bing-Ru Wang, Di Li, P. Goldsmith, Jingwen Wu, Chao-Wei Tsai, Donghui Quan, Xia Zhang, Junzhi Wang, G. J. Melnick, Jinzeng Li, Gary Fuller, Jinjin Xie
Molecular oxygen abundance is a key parameter in understanding the chemical network of the interstellar medium. We estimate the molecular oxygen column density and abundance for a sample of Galactic massive star formation regions based on observations from the Submillimiter Wave Astronomy Satellite ({it SWAS}) survey. We obtained an averaged O$_2$ spectrum based on this sample using the ({it SWAS}) survey data (O$_2$, 487.249 GHz, $N$ = 3-1, $J$ = 3-2). No emission or absorption feature is seen around the supposed central velocity with a total integration time of $t$$_{rm{total}}$ = 8.67 $times 10^3$ hours and a rms noise per channel of 1.45 mK. Assuming add{an kinetic temperature} T$_{rm{kin}}$ = 30 K, we derive the 3$sigma$ upper limit of the O$_2$ column density to be 3.3 $times 10^{15}$ cm$^{-2}$, close to the lowest values reported in Galactic massive star formation regions in previous studies. The corresponding O$_2$ abundance upper limit is 7.6 $times 10^{-8}$, lower than all previous results based on {it SWAS} observations and is close to the lowest reported value in massive star formation regions. On a galactic scale, our statistical results confirm a generally low O$_2$ abundance for Galactic massive star formation regions. This abundance is also lower than results reported in extragalactic sources.
{"title":"Molecular Oxygen Abundance in Galactic Massive Star Formation Regions Based on SWAS Observations","authors":"Bing-Ru Wang, Di Li, P. Goldsmith, Jingwen Wu, Chao-Wei Tsai, Donghui Quan, Xia Zhang, Junzhi Wang, G. J. Melnick, Jinzeng Li, Gary Fuller, Jinjin Xie","doi":"10.1088/1674-4527/ad5df3","DOIUrl":"https://doi.org/10.1088/1674-4527/ad5df3","url":null,"abstract":"\u0000 Molecular oxygen abundance is a key parameter in understanding the chemical network of the interstellar medium. We estimate the molecular oxygen column density and abundance for a sample of Galactic massive star formation regions based on observations from the Submillimiter Wave Astronomy Satellite ({it SWAS}) survey. We obtained an averaged O$_2$ spectrum based on this sample using the ({it SWAS}) survey data (O$_2$, 487.249 GHz, $N$ = 3-1, $J$ = 3-2). No emission or absorption feature is seen around the supposed central velocity with a total integration time of $t$$_{rm{total}}$ = 8.67 $times 10^3$ hours and a rms noise per channel of 1.45 mK. Assuming add{an kinetic temperature} T$_{rm{kin}}$ = 30 K, we derive the 3$sigma$ upper limit of the O$_2$ column density to be 3.3 $times 10^{15}$ cm$^{-2}$, close to the lowest values reported in Galactic massive star formation regions in previous studies. The corresponding O$_2$ abundance upper limit is 7.6 $times 10^{-8}$, lower than all previous results based on {it SWAS} observations and is close to the lowest reported value in massive star formation regions. On a galactic scale, our statistical results confirm a generally low O$_2$ abundance for Galactic massive star formation regions. This abundance is also lower than results reported in extragalactic sources.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"74 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141686949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.1088/1674-4527/ad639b
Yan Guo, C. Sengupta, T. C. Scott, P. Lagos, Y. Luo
{"title":"Erratum: “H i in High Gas-phase Metallicity Dwarf Galaxy WISEA J230615.06+143927.9” (2024, RAA, 24, 015024)","authors":"Yan Guo, C. Sengupta, T. C. Scott, P. Lagos, Y. Luo","doi":"10.1088/1674-4527/ad639b","DOIUrl":"https://doi.org/10.1088/1674-4527/ad639b","url":null,"abstract":"","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"4 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141846315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-03DOI: 10.1088/1674-4527/ad5399
Jianhong Hu, Dandan Xu, Cheng Li
Superthin galaxies are observed to have stellar disks with extremely small minor-to-major axis ratios. In this work, we investigate the formation of superthin galaxies in the TNG100 simulation. We trace the merger history and investigate the evolution of galaxy properties of a selected sample of superthin galaxies and a control sample of galaxies that share the same joint probability distribution in the stellar-mass and color diagram. Through making comparisons between the two galaxy samples, we find that present-day superthin galaxies had similar morphologies as the control sample counterparts at higher redshifts, but have developed extended flat `superthin' morphologies since $z sim 1$. During this latter evolution stage, superthin galaxies undergo overwhelmingly higher frequency of prograde mergers (with orbit-spin angle $theta_{rm orb} leqslant 40^circ$). Accordingly the spins of their dark matter halos have grown significantly and become noticeably higher than that of their normal disk counterparts. This further results in the buildup of their stellar disks at larger distances much beyond the regimes of normal disk galaxies. We also discuss the formation scenario of those superthin galaxies that live in larger dark matter halos as satellite galaxies therein.
{"title":"Formation of super-thin galaxies in Illustris-TNG","authors":"Jianhong Hu, Dandan Xu, Cheng Li","doi":"10.1088/1674-4527/ad5399","DOIUrl":"https://doi.org/10.1088/1674-4527/ad5399","url":null,"abstract":"\u0000 Superthin galaxies are observed to have stellar disks with extremely small minor-to-major axis ratios. In this work, we investigate the formation of superthin galaxies in the TNG100 simulation. We trace the merger history and investigate the evolution of galaxy properties of a selected sample of superthin galaxies and a control sample of galaxies that share the same joint probability distribution in the stellar-mass and color diagram. Through making comparisons between the two galaxy samples, we find that present-day superthin galaxies had similar morphologies as the control sample counterparts at higher redshifts, but have developed extended flat `superthin' morphologies since $z sim 1$. During this latter evolution stage, superthin galaxies undergo overwhelmingly higher frequency of prograde mergers (with orbit-spin angle $theta_{rm orb} leqslant 40^circ$). Accordingly the spins of their dark matter halos have grown significantly and become noticeably higher than that of their normal disk counterparts. This further results in the buildup of their stellar disks at larger distances much beyond the regimes of normal disk galaxies. We also discuss the formation scenario of those superthin galaxies that live in larger dark matter halos as satellite galaxies therein.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"38 49","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141270076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Accurate flux density calibration is essential for precise analysis and interpretation of observations across different observation modes and instruments. In this research, we introduce the flux calibration model incorporated in HIFAST pipeline, designed for processing HI 21-cm spectra. Furthermore, we investigate different calibration techniques and assess the dependence of the gain parameter on the time and environmental factors. A comparison is carried out in various observation modes (e.g. tracking and scanning modes) to determine the flux density gain (G), revealing insignificant discrepancies in G among different methods. Long-term monitoring data shows a linear correlation between G and atmospheric temperature. After subtracting the G - Temperature dependence, the dispersion of G is reduced to <3% over a one-year time scale. The stability of the receiver response of FAST is considered sufficient to facilitate HI observations that can accommodate a moderate error in flux calibration (e.g., >~5%) when utilizing a constant G for calibration purposes. Our study will serve as a useful addition to the results provided by Jiang et al (2020). Detailed measurements of G for the 19 beams of FAST, covering the frequency range 1000 MHz - 1500 MHz can be found on the HIFAST homepage: https://hifast.readthedocs.io/fluxgain
准确的通量密度校准对于精确分析和解释不同观测模式和仪器的观测结果至关重要。在这项研究中，我们介绍了 HIFAST 管道中的通量校准模型，该模型专为处理 HI 21-cm 光谱而设计。此外，我们还研究了不同的校准技术，并评估了增益参数对时间和环境因素的依赖性。我们对各种观测模式（如跟踪和扫描模式）进行了比较，以确定通量密度增益（G），发现不同方法的 G 值差异不大。长期监测数据显示，G 与大气温度呈线性相关。在减去 G 与温度的相关性后，当使用恒定 G 进行校准时，G 的离散性降低到 ~5%。我们的研究将是对 Jiang 等人（2020 年）研究结果的有益补充。关于 FAST 19 个波束的 G 的详细测量结果（覆盖频率范围 1000 MHz - 1500 MHz），请访问 HIFAST 主页：https://hifast.readthedocs.io/fluxgain。
{"title":"HIFAST: An HI Data Calibration and Imaging Pipeline for FAST II. Flux Density Calibration","authors":"Ziming Liu, Jie Wang, Ying-Jie Jing, Zhiyu Zhang, Chen Xu, Qingze Chen, Ningyu Tang, Qingliang Yang, Tiantian Liang","doi":"10.1088/1674-4527/ad5398","DOIUrl":"https://doi.org/10.1088/1674-4527/ad5398","url":null,"abstract":"\u0000 Accurate flux density calibration is essential for precise analysis and interpretation of observations across different observation modes and instruments. In this research, we introduce the flux calibration model incorporated in HIFAST pipeline, designed for processing HI 21-cm spectra. Furthermore, we investigate different calibration techniques and assess the dependence of the gain parameter on the time and environmental factors. A comparison is carried out in various observation modes (e.g. tracking and scanning modes) to determine the flux density gain (G), revealing insignificant discrepancies in G among different methods. Long-term monitoring data shows a linear correlation between G and atmospheric temperature. After subtracting the G - Temperature dependence, the dispersion of G is reduced to <3% over a one-year time scale. The stability of the receiver response of FAST is considered sufficient to facilitate HI observations that can accommodate a moderate error in flux calibration (e.g., >~5%) when utilizing a constant G for calibration purposes. Our study will serve as a useful addition to the results provided by Jiang et al (2020). Detailed measurements of G for the 19 beams of FAST, covering the frequency range 1000 MHz - 1500 MHz can be found on the HIFAST homepage: https://hifast.readthedocs.io/fluxgain","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"39 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141270072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-03DOI: 10.1088/1674-4527/ad539a
Shuhong Yang, Jie Jiang, Zifan Wang, Yijun Hou, Chunlan Jin, Qiao Song, Yukun Luo, Ting Li, Jun Zhang, Yuzong Zhang, Guiping Zhou, Yuanyong Deng, Jingxiu Wang
The polar magnetic fields of the Sun play an important role in governing solar activity and powering fast solar wind. However, because our view of the Sun is limited in the ecliptic plane, the polar regions remain largely uncharted. Using the high spatial resolution and polarimetric precision vector magnetograms observed by Hinode from 2012 to 2021, we investigate the long-term variation of the magnetic fields in polar caps at different latitudes. The Hinode magnetic measurements shows that the polarity reversal processes in the north and south polar caps are non-simultaneous. The variation of the averaged radial magnetic flux density reveals that, in each polar cap, the polarity reversal is completed successively from the 70$degr$ latitude to the pole, reflecting a poleward magnetic flux migration therein. These results clarify the polar magnetic polarity reversal process at different latitudes.
{"title":"Long-term variation of the solar polar magnetic fields at different latitudes","authors":"Shuhong Yang, Jie Jiang, Zifan Wang, Yijun Hou, Chunlan Jin, Qiao Song, Yukun Luo, Ting Li, Jun Zhang, Yuzong Zhang, Guiping Zhou, Yuanyong Deng, Jingxiu Wang","doi":"10.1088/1674-4527/ad539a","DOIUrl":"https://doi.org/10.1088/1674-4527/ad539a","url":null,"abstract":"\u0000 The polar magnetic fields of the Sun play an important role in governing solar activity and powering fast solar wind. However, because our view of the Sun is limited in the ecliptic plane, the polar regions remain largely uncharted. Using the high spatial resolution and polarimetric precision vector magnetograms observed by Hinode from 2012 to 2021, we investigate the long-term variation of the magnetic fields in polar caps at different latitudes. The Hinode magnetic measurements shows that the polarity reversal processes in the north and south polar caps are non-simultaneous. The variation of the averaged radial magnetic flux density reveals that, in each polar cap, the polarity reversal is completed successively from the 70$degr$ latitude to the pole, reflecting a poleward magnetic flux migration therein. These results clarify the polar magnetic polarity reversal process at different latitudes.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"45 39","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141269980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-01DOI: 10.1088/1674-4527/ad539b
Arijit Manna, Sabyasachi Pal
In the star formation regions, the complex organic molecules that contain peptide bonds (–NH–C(=O)–) play a major role in the metabolic process because –NH–C(=O)– is connected to amino acids (R-CHNH2–COOH). Over the past few decades, many complex organic molecules containing peptide-like bonds have been detected in hot molecular cores, hot corinos, and cold molecular clouds, however, their prebiotic chemistry is poorly understood. We present the first detection of the rotational emission lines of formamide (NH2CHO) and isocyanic acid (HNCO), which contain peptide-like bonds towards the chemically rich hot molecular core G358.93–0.03 MM1, using high-resolution and high-sensitivity Atacama Large Millimeter/submillimeter Array (ALMA) bands 6 and 7. We estimate that the column densities of NH2CHO and HNCO towards G358.93–0.03 MM1 are (2.80±0.29)×10^{15} cm^{−2} and (1.80±0.42)×10^{16} cm^{−2} with excitation temperatures of 165±21 K and 170±32 K, respectively. The fractional abundances of NH2CHO and HNCO towards G358.93–0.03 MM1 are (9.03±1.44)×10^{−10} and (5.80±2.09)×10^{−9}. We compare the estimated abundances of NH2CHO and HNCO with the existing three-phase warm-up chemical model abundance values and notice that the observed and modelled abundances are very close. We conclude that NH2CHO is produced by the reaction of NH2 and H2CO in the gas phase towards G358.93–0.03 MM1. Likewise, HNCO is produced on the surface of grains by the reaction of NH and CO towards G358.93–0.03 MM1. We also found that NH2CHO and HNCO are chemically linked towards G358.93–0.03 MM1.
{"title":"Observation of complex organic molecules containing peptide-like bonds towards hot core G358.93--0.03 MM1","authors":"Arijit Manna, Sabyasachi Pal","doi":"10.1088/1674-4527/ad539b","DOIUrl":"https://doi.org/10.1088/1674-4527/ad539b","url":null,"abstract":"\u0000 In the star formation regions, the complex organic molecules that contain peptide bonds (–NH–C(=O)–) play a major role in the metabolic process because –NH–C(=O)– is connected to amino acids (R-CHNH2–COOH). Over the past few decades, many complex organic molecules containing peptide-like bonds have been detected in hot molecular cores, hot corinos, and cold molecular clouds, however, their prebiotic chemistry is poorly understood. We present the first detection of the rotational emission lines of formamide (NH2CHO) and isocyanic acid (HNCO), which contain peptide-like bonds towards the chemically rich hot molecular core G358.93–0.03 MM1, using high-resolution and high-sensitivity Atacama Large Millimeter/submillimeter Array (ALMA) bands 6 and 7. We estimate that the column densities of NH2CHO and HNCO towards G358.93–0.03 MM1 are (2.80±0.29)×10^{15} cm^{−2} and (1.80±0.42)×10^{16} cm^{−2} with excitation temperatures of 165±21 K and 170±32 K, respectively. The fractional abundances of NH2CHO and HNCO towards G358.93–0.03 MM1 are (9.03±1.44)×10^{−10} and (5.80±2.09)×10^{−9}. We compare the estimated abundances of NH2CHO and HNCO with the existing three-phase warm-up chemical model abundance values and notice that the observed and modelled abundances are very close. We conclude that NH2CHO is produced by the reaction of NH2 and H2CO in the gas phase towards G358.93–0.03 MM1. Likewise, HNCO is produced on the surface of grains by the reaction of NH and CO towards G358.93–0.03 MM1. We also found that NH2CHO and HNCO are chemically linked towards G358.93–0.03 MM1.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"59 23","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141277142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-23DOI: 10.1088/1674-4527/ad4fc5
Ze-Yuan Tang, Jun-Jie Feng, Junhui Fan
A warm corona has been widely proposed to explain the soft X-ray excess (SE) above the 2--10 keV power law extrapolation in AGNs. In actual spectral fittings, the warm coronal seed photon temperature ($T_{rm s}$) is usually assumed to be far away from the soft X-ray, but $kT_{rm s}$ can reach close to 0.1 keV in standard accretion disc model. In this study, we used Monte Carlo simulations to obtain radiation spectra from a slab-like warm corona and fitted the spectra using the spherical-geometry-based routine textsc{thcomp} or a thermal component. Our findings reveal that high $T_{rm s}$ can influence the fitting results. A moderately high $kT_{rm s}$ (around 0.03 keV) can result in an apparent low-temperature and flat SE, while an extremely high $kT_{rm s}$ (around 0.07 keV) can even produce an unobserved blackbody-like SE. Our conclusions indicate that, for spectral fittings of the warm coronal radiation (SE in AGNs), $kT_{rm s}$ should be treated as a free parameter with an upper limit, and an accurate coronal geometry is necessary when $kT_{rm s}>0.01$ keV.
{"title":"Spectral fittings of warm coronal radiation with high seed photon temperature: apparent low-temperature and flat soft excess in AGNs","authors":"Ze-Yuan Tang, Jun-Jie Feng, Junhui Fan","doi":"10.1088/1674-4527/ad4fc5","DOIUrl":"https://doi.org/10.1088/1674-4527/ad4fc5","url":null,"abstract":"\u0000 A warm corona has been widely proposed to explain the soft X-ray excess (SE) above the 2--10 keV power law extrapolation in AGNs. In actual spectral fittings, the warm coronal seed photon temperature ($T_{rm s}$) is usually assumed to be far away from the soft X-ray, but $kT_{rm s}$ can reach close to 0.1 keV in standard accretion disc model. In this study, we used Monte Carlo simulations to obtain radiation spectra from a slab-like warm corona and fitted the spectra using the spherical-geometry-based routine textsc{thcomp} or a thermal component. Our findings reveal that high $T_{rm s}$ can influence the fitting results. A moderately high $kT_{rm s}$ (around 0.03 keV) can result in an apparent low-temperature and flat SE, while an extremely high $kT_{rm s}$ (around 0.07 keV) can even produce an unobserved blackbody-like SE. Our conclusions indicate that, for spectral fittings of the warm coronal radiation (SE in AGNs), $kT_{rm s}$ should be treated as a free parameter with an upper limit, and an accurate coronal geometry is necessary when $kT_{rm s}>0.01$ keV.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"29 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141105495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-23DOI: 10.1088/1674-4527/ad4fc1
Youhong Sun, Tao Zhang, Haodong Shi, Qiang Fu, Jianan Liu, Kaikai Wang, Chao Wang
Optical telescopes are an important tool for acquiring optical information about distant objects, and resolution is an important indicator that measures the ability to observe object details. However, due to the effects of system aberration, atmospheric vortex, and other factors, the observation image of ground-based telescopes is often degraded, resulting in reduced resolution. This paper proposes an optical-neural network joint optimization method to improve the resolution of the observed image by co-optimizing the point spread function (PSF) of the telescopic system and the image super-resolution network. To improve the speed of image reconstruction, we designed a generative adversarial net (LCR-GAN) with light parameters, which is much faster than the latest unsupervised networks. To reconstruct the PSF trained by the network in the optical path, a phase mask is introduced. It improves the image reconstruction effect of LCR-GAN by reconstructing the point spread function that best matches the network. The results of simulation and verification experiments show that compared with the pure deep learning method, the super-resolution image reconstructed by this method is rich in detail and easier to distinguish stars or stripes.
{"title":"Super-resolution imaging of telescopic systems based on optical-neural network joint optimization","authors":"Youhong Sun, Tao Zhang, Haodong Shi, Qiang Fu, Jianan Liu, Kaikai Wang, Chao Wang","doi":"10.1088/1674-4527/ad4fc1","DOIUrl":"https://doi.org/10.1088/1674-4527/ad4fc1","url":null,"abstract":"\u0000 Optical telescopes are an important tool for acquiring optical information about distant objects, and resolution is an important indicator that measures the ability to observe object details. However, due to the effects of system aberration, atmospheric vortex, and other factors, the observation image of ground-based telescopes is often degraded, resulting in reduced resolution. This paper proposes an optical-neural network joint optimization method to improve the resolution of the observed image by co-optimizing the point spread function (PSF) of the telescopic system and the image super-resolution network. To improve the speed of image reconstruction, we designed a generative adversarial net (LCR-GAN) with light parameters, which is much faster than the latest unsupervised networks. To reconstruct the PSF trained by the network in the optical path, a phase mask is introduced. It improves the image reconstruction effect of LCR-GAN by reconstructing the point spread function that best matches the network. The results of simulation and verification experiments show that compared with the pure deep learning method, the super-resolution image reconstructed by this method is rich in detail and easier to distinguish stars or stripes.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"1 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141107039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-23DOI: 10.1088/1674-4527/ad4fc3
Xiao-Lan Liu, Ming Zhu, Jin-Long Xu, Peng Jiang, Chuan-Peng Zhang, N. Yu, Junjie Wang, Yanbin Yang
We report a new high-sensitivity H,{sc i} mapping observation of the NGC~5055 galaxy group over an area of $1.5^circtimes0.75^circ$ with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Our observation reveals that the warped H,{sc i} disk of NGC~5055 is more extended than what previously observed by WSRT, out to $ 23.9$ arcmin (61.7 kpc). The total HI mass of NGC~5055 is determined to be $rmsim 1.1times10^{10},M_odot$. We identified three H,{sc i} clouds with H,{sc i} masses of the order of $rm sim 10^7,M_odot$ at the southeastern edge of the H,{sc i} disk, as well as a candidate high-velocity cloud with an H,{sc i} mass of textcolor{blue}{$rm (1.2pm0.5) times10^6,M_odot$} to the north of NGC~5055. The HI content of UGCA 337 is robustly detected for the first time by the FAST observations. It has a narrow HI linewidth of textcolor{blue}{$W_{50}=17.4pm3.8$ km s$^{-1}$} with a total HI mass of textcolor{blue}{($rm 3.5pm0.3)times10^6,M_odot$}. Comparing the gas content and g-r color of UGCA~337 with typical low-mass dwarf galaxies, UGCA~337 appears relatively gas-poor despite its blue colour. This suggests that UGCA~337 may have undergone gas stripping in the past. We also analyzed the possible origin of the diffuse HI clouds located at the outskirts of NGC~5055, and speculate that they might be the remnant features of a merger event in the past.
{"title":"New H I observations toward the NGC 5055 Galaxy Group with FAST","authors":"Xiao-Lan Liu, Ming Zhu, Jin-Long Xu, Peng Jiang, Chuan-Peng Zhang, N. Yu, Junjie Wang, Yanbin Yang","doi":"10.1088/1674-4527/ad4fc3","DOIUrl":"https://doi.org/10.1088/1674-4527/ad4fc3","url":null,"abstract":"\u0000 We report a new high-sensitivity H,{sc i} mapping observation of the NGC~5055 galaxy group over an area of $1.5^circtimes0.75^circ$ with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Our observation reveals that the warped H,{sc i} disk of NGC~5055 is more extended than what previously observed by WSRT, out to $ 23.9$ arcmin (61.7 kpc). The total HI mass of NGC~5055 is determined to be $rmsim 1.1times10^{10},M_odot$. We identified three H,{sc i} clouds with H,{sc i} masses of the order of $rm sim 10^7,M_odot$ at the southeastern edge of the H,{sc i} disk, as well as a candidate high-velocity cloud with an H,{sc i} mass of textcolor{blue}{$rm (1.2pm0.5) times10^6,M_odot$} to the north of NGC~5055. The HI content of UGCA 337 is robustly detected for the first time by the FAST observations. It has a narrow HI linewidth of textcolor{blue}{$W_{50}=17.4pm3.8$ km s$^{-1}$} with a total HI mass of textcolor{blue}{($rm 3.5pm0.3)times10^6,M_odot$}. Comparing the gas content and g-r color of UGCA~337 with typical low-mass dwarf galaxies, UGCA~337 appears relatively gas-poor despite its blue colour. This suggests that UGCA~337 may have undergone gas stripping in the past. We also analyzed the possible origin of the diffuse HI clouds located at the outskirts of NGC~5055, and speculate that they might be the remnant features of a merger event in the past.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"30 36","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141103913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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