The science of radio astronomy focuses on the observation and study of celestial objects by reading their radio waves. The 5 meter radio-telescope is able to observe different radio sources using a C-band LNB. This re...The science of radio astronomy focuses on the observation and study of celestial objects by reading their radio waves. The 5 meter radio-telescope is able to observe different radio sources using a C-band LNB. This research was essentially focused on Crab Nebula, also known as Taurus A. The study led to interesting observations, which were validated numerically using various scientific computing software. The radio waves emitted by Taurus A are readable by the RTL-SDR, a software defined radio receiver. This device is capable of reading radio frequencies in the range of 0.5 MHZ to 1700 MHZ.展开更多
The Crab nebula is a prominent pulsar wind nebula detected in multiband observations ranging from radio to very high-energyγ-rays.Recently,γ-rays with energies above 1 PeV have been detected by the Large High Altitu...The Crab nebula is a prominent pulsar wind nebula detected in multiband observations ranging from radio to very high-energyγ-rays.Recently,γ-rays with energies above 1 PeV have been detected by the Large High Altitude Air Shower Observatory,and the energy of the most energetic particles in the nebula can be constrained.In this paper,we investigate the broadest spectral energy distribution of the Crab nebula and the energy distribution of the electrons emitting the multiwavelength nonthermal emission based on a one-zone time-dependent model.The nebula is powered by the pulsar,and highenergy electrons/positrons with a broken power-law spectrum are continually injected in the nebula as the pulsar spins down.Multiwavelength nonthermal emission is generated by the leptons through synchrotron radiation and inverse Compton scattering.Using appropriate parameters,the detected fluxes for the nebula can be well reproduced,especially for theγ-rays from 10^(2) MeV to 1 PeV.The results show that the detectedγ-rays can be produced by the leptons via the inverse Compton scattering,and the lower limit of the Lorentz factor of the most energetic leptons is~8.5×10^(9).It can be concluded that there exist electrons/positrons with energies higher than 4.3 PeV in the Crab nebula.展开更多
The Chinese first reported the Crab Nebula supernova on 1054 July 5. Ecclesiastical documents from the near east reported it in April and May of 1054. More than 33 petroglyphs made by Native Americans in the US and Me...The Chinese first reported the Crab Nebula supernova on 1054 July 5. Ecclesiastical documents from the near east reported it in April and May of 1054. More than 33 petroglyphs made by Native Americans in the US and Mexico are consistent with sightings both before and after conjunction with the Sun on 1054 May 27. We found a petroglyph showing the new star close to Venus and the Moon, which occurred on 1054 April 12 and April 13, respectively. Collins et al., using the four historical dates, derived a light curve that is like that of a Type Ia supernova. The only remaining problem with this identification is that this supernova was near maximum light for 85 d, which is unlike the behavior of any known supernova.展开更多
A sub-array of the Large High Altitude Air Shower Observatory(LHAASO),KM2A is mainly designed to observe a large fraction of the northern sky to hunt for γ-ray sources at energies above 10 TeV.Even though the detecto...A sub-array of the Large High Altitude Air Shower Observatory(LHAASO),KM2A is mainly designed to observe a large fraction of the northern sky to hunt for γ-ray sources at energies above 10 TeV.Even though the detector construction is still underway,half of the KM2A array has been operating stably since the end of 2019.In this paper,we present the KM2A data analysis pipeline and the first observation of the Crab Nebula,a standard candle in very high energy γ-ray astronomy.We detect γ-ray signals from the Crab Nebula in both energy ranges of 10-100 TeV and>100 TeV with high significance,by analyzing the KM2A data of 136 live days between December 2019 and May 2020.With the observations,we test the detector performance,including angular resolution,pointing accuracy and cosmic-ray background rejection power.The energy spectrum of the Crab Nebula in the energy range 10-250 TeV fits well with a single power-law function dN/dE=(1.13±0.05stat±0.08sys)×10^(-14).(E/20 TeV)-309±0.06stat±0.02syscm^(-2) s^(-1) TeV^(-1).It is consistent with previous measurements by other experiments.This opens a new window of γ-ray astronomy above 0.1 PeV through which new ultrahigh-energy γ-ray phenomena,such as cosmic PeVatrons,might be discovered.展开更多
The first Water Cherenkov detector of the LHAASO experiment(WCDA-1)has been operating since April 2019.The data for the first year have been analyzed to test its performance by observing the Crab Nebula as a standard ...The first Water Cherenkov detector of the LHAASO experiment(WCDA-1)has been operating since April 2019.The data for the first year have been analyzed to test its performance by observing the Crab Nebula as a standard candle.The WCDA-1 achieves a sensitivity of 65 mCU per year,with a statistical threshold of 5 cr.To accomplish this,a 97.7%cosmic-ray background rejection rate around 1 TeV and 99.8%around 6 TeV with an ap proximate photon acceptance of 50%is achieved after applying an algorithm to separate gamma-induced showers.The angular resolution is measured using the Crab Nebula as a point source to be approximately 0.45°at 1 TeV and better than 0.2°above 6 TeV,with a pointing accuracy better than 0.05°.These values all match the design specifications.The energy resolution is found to be 33%for gamma rays around 6 TeV.The spectral energy distribution of the Crab Nebula in the range from 500 GeV to 15.8 TeV is measured and found to be in agreement with the results from other TeV gamma ray observatories.展开更多
Crab-like supernova remnants (plerions) are a kind of SNR which has a central neutron star or pulsar. It is generally believed that the central pulsar drives the evolution of the plerion. A statistical relation betwee...Crab-like supernova remnants (plerions) are a kind of SNR which has a central neutron star or pulsar. It is generally believed that the central pulsar drives the evolution of the plerion. A statistical relation between the soft X-ray (0.2—4 keV )luminosity L_x of the synchrotron nebula (including the pulsar)and the pulsar rotating energy loss rate展开更多
文摘The science of radio astronomy focuses on the observation and study of celestial objects by reading their radio waves. The 5 meter radio-telescope is able to observe different radio sources using a C-band LNB. This research was essentially focused on Crab Nebula, also known as Taurus A. The study led to interesting observations, which were validated numerically using various scientific computing software. The radio waves emitted by Taurus A are readable by the RTL-SDR, a software defined radio receiver. This device is capable of reading radio frequencies in the range of 0.5 MHZ to 1700 MHZ.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11873042, U2031107, and 12063004)the Program for Excellent Young Talents, Yunnan University (WX069051, 2017YDYQ01)+1 种基金the Candidate Talents Training Fund of Yunnan Province (2017HB003)the National Key R&D Program of China (2018YFA0404204)
文摘The Crab nebula is a prominent pulsar wind nebula detected in multiband observations ranging from radio to very high-energyγ-rays.Recently,γ-rays with energies above 1 PeV have been detected by the Large High Altitude Air Shower Observatory,and the energy of the most energetic particles in the nebula can be constrained.In this paper,we investigate the broadest spectral energy distribution of the Crab nebula and the energy distribution of the electrons emitting the multiwavelength nonthermal emission based on a one-zone time-dependent model.The nebula is powered by the pulsar,and highenergy electrons/positrons with a broken power-law spectrum are continually injected in the nebula as the pulsar spins down.Multiwavelength nonthermal emission is generated by the leptons through synchrotron radiation and inverse Compton scattering.Using appropriate parameters,the detected fluxes for the nebula can be well reproduced,especially for theγ-rays from 10^(2) MeV to 1 PeV.The results show that the detectedγ-rays can be produced by the leptons via the inverse Compton scattering,and the lower limit of the Lorentz factor of the most energetic leptons is~8.5×10^(9).It can be concluded that there exist electrons/positrons with energies higher than 4.3 PeV in the Crab nebula.
文摘The Chinese first reported the Crab Nebula supernova on 1054 July 5. Ecclesiastical documents from the near east reported it in April and May of 1054. More than 33 petroglyphs made by Native Americans in the US and Mexico are consistent with sightings both before and after conjunction with the Sun on 1054 May 27. We found a petroglyph showing the new star close to Venus and the Moon, which occurred on 1054 April 12 and April 13, respectively. Collins et al., using the four historical dates, derived a light curve that is like that of a Type Ia supernova. The only remaining problem with this identification is that this supernova was near maximum light for 85 d, which is unlike the behavior of any known supernova.
基金Supported in China by National Key R&D program of China under the grants(2018YF A0404201.2018YFA0404202.2018YF A0404203)by NSFC(12022502,190527,135011,11761141001.U1931112,11775131,U1931201,11905043,U1931108)by NSFSPC(ZR2019MA014),and in Thailand by RTA6280002 from Thailand Science Research and Innovation。
文摘A sub-array of the Large High Altitude Air Shower Observatory(LHAASO),KM2A is mainly designed to observe a large fraction of the northern sky to hunt for γ-ray sources at energies above 10 TeV.Even though the detector construction is still underway,half of the KM2A array has been operating stably since the end of 2019.In this paper,we present the KM2A data analysis pipeline and the first observation of the Crab Nebula,a standard candle in very high energy γ-ray astronomy.We detect γ-ray signals from the Crab Nebula in both energy ranges of 10-100 TeV and>100 TeV with high significance,by analyzing the KM2A data of 136 live days between December 2019 and May 2020.With the observations,we test the detector performance,including angular resolution,pointing accuracy and cosmic-ray background rejection power.The energy spectrum of the Crab Nebula in the energy range 10-250 TeV fits well with a single power-law function dN/dE=(1.13±0.05stat±0.08sys)×10^(-14).(E/20 TeV)-309±0.06stat±0.02syscm^(-2) s^(-1) TeV^(-1).It is consistent with previous measurements by other experiments.This opens a new window of γ-ray astronomy above 0.1 PeV through which new ultrahigh-energy γ-ray phenomena,such as cosmic PeVatrons,might be discovered.
基金Supported by the following grants:the National Key R&D program of China(2018YFA0404201,2018YFA0404202,2018YFA0404203)the National Natural Science Foundation of China(12022502,11905227,U1931112,11635011,11761141001,Y811A35,11675187,U1831208,U1931111)in Thailand by RTA6280002 from Thailand Science Research and Innovation。
文摘The first Water Cherenkov detector of the LHAASO experiment(WCDA-1)has been operating since April 2019.The data for the first year have been analyzed to test its performance by observing the Crab Nebula as a standard candle.The WCDA-1 achieves a sensitivity of 65 mCU per year,with a statistical threshold of 5 cr.To accomplish this,a 97.7%cosmic-ray background rejection rate around 1 TeV and 99.8%around 6 TeV with an ap proximate photon acceptance of 50%is achieved after applying an algorithm to separate gamma-induced showers.The angular resolution is measured using the Crab Nebula as a point source to be approximately 0.45°at 1 TeV and better than 0.2°above 6 TeV,with a pointing accuracy better than 0.05°.These values all match the design specifications.The energy resolution is found to be 33%for gamma rays around 6 TeV.The spectral energy distribution of the Crab Nebula in the range from 500 GeV to 15.8 TeV is measured and found to be in agreement with the results from other TeV gamma ray observatories.
基金Project supported by the National Natural Science Foundation of China
文摘Crab-like supernova remnants (plerions) are a kind of SNR which has a central neutron star or pulsar. It is generally believed that the central pulsar drives the evolution of the plerion. A statistical relation between the soft X-ray (0.2—4 keV )luminosity L_x of the synchrotron nebula (including the pulsar)and the pulsar rotating energy loss rate
