We derive the gravitational-wave(GW)strain upper limits from resolvable supermassive black-hole binaries using the data from the Five-hundred-meter Aperture Spherical radio Telescope,in the context of the Chinese Puls...We derive the gravitational-wave(GW)strain upper limits from resolvable supermassive black-hole binaries using the data from the Five-hundred-meter Aperture Spherical radio Telescope,in the context of the Chinese Pulsar Timing Array project.We focus on circular orbits in theμHz GW frequency band between 10^(−7)and 3×10^(−6)Hz.This frequency band is higher than the traditional pulsar timing array band and is less explored.We used the data of the millisecond pulsar PSR J1713+5307 observed between 2019 August and 2021 April.A dense observation campaign was carried out in 2020 September to allow for theμHz band coverage.Our sky-averaged continuous source upper limit at the 95%confidence level at 1μHz is 1.26×10^(−12),while the same limit in the direction of the pulsar is 4.77×10^(−13).展开更多
Fast Radio Bursts(FRBs) are enigmatic millisecond-duration radio transients of extra-galactic origin, whose underlying mechanisms and progenitors remain poorly understood. FRBs are broadly classified into two categori...Fast Radio Bursts(FRBs) are enigmatic millisecond-duration radio transients of extra-galactic origin, whose underlying mechanisms and progenitors remain poorly understood. FRBs are broadly classified into two categories: repeating FRBs, which emit multiple bursts over time, and one-off FRBs, which are detected as single events. A central question in FRB research is whether these two classes share a common origin. In this study, we present observations of FRB 20240114A, a repeating FRB that entered a hyperactive phase in 2024 January. We conducted a 318 hr monitoring campaign using the Kunming 40-Meter Radio Telescope(KM40M) in the S-band(2.187–2.311 GHz), during which we detected eight radio bursts. We analyzed their properties, including dispersion measure, bandwidth, pulse width, flux, fluence, and energy. Additionally, we searched for counterparts in overlapping data from the Five-hundred-meter Aperture Spherical Telescope(FAST) in the L-band(1.0–1.5 GHz). While no bursts were temporally aligned between the two telescopes, we identified one FAST burst that arrived approximately 6 ms after one of the KM40M bursts. The absence of FAST counterparts for the KM40M bursts suggests that individual bursts from FRB 20240114A are likely narrow-band, with fractional bandwidths less than 10%. By comparing the cumulative event rates from KM40M and FAST observations, we found that the two measurements are compatible, indicating a possible flattening of the event rate at higher energies. This feature aligns with observations of one-off FRBs, supporting the hypothesis that repeating and oneoff FRBs may share a common origin.展开更多
Sulfur-bearing species are widely utilized to investigate the physical structure of star-forming regions in interstellar media;however,the underlying sulfur chemistry in these environments remains poorly understood.Th...Sulfur-bearing species are widely utilized to investigate the physical structure of star-forming regions in interstellar media;however,the underlying sulfur chemistry in these environments remains poorly understood.Therefore,further studies of S-bearing species are fundamentally important,as they can enhance our understanding of the physical evolution of star-forming regions.This study presents observations of C_(2)S and C_(3)S in L1544,acquired using the Nanshan 26-m radio telescope,along with simulations of their chemical behavior using a one-dimensional physical model.The simulation results reveal significant radial variations in the column densities of C_(2)S and C_(3)S.Additionally,the column densities of both molecules are found to be sensitive to the cosmic ray ionization rate at several radial positions,while variations in the C/O ratio have comparatively minimal impact on L1544.展开更多
The Five-hundred-meter Aperture Spherical radio Telescope(FAST) will become one of the world-leading telescopes for pulsar timing array(PTA) research. The primary goals for PTAs are to detect(and subsequently study) u...The Five-hundred-meter Aperture Spherical radio Telescope(FAST) will become one of the world-leading telescopes for pulsar timing array(PTA) research. The primary goals for PTAs are to detect(and subsequently study) ultra-low-frequency gravitational waves, to develop a pulsar-based time standard and to improve solar system planetary ephemerides. FAST will have the sensitivity to observe known pulsars with significantly improved signal-to-noise ratios and will discover a large number of currently unknown pulsars. We describe how FAST will contribute to PTA research and show that jitter-and timing-noise will be the limiting noise processes for FAST data sets. Jitter noise will limit the timing precision achievable over data spans of a few years while timing noise will limit the precision achievable over many years.展开更多
For high-precision pulsar timing analysis and low-frequency gravitational wave detection,it is essential to accurately determine pulsar pulse times of arrival(ToAs)and associated uncertainties.To measure the ToAs and ...For high-precision pulsar timing analysis and low-frequency gravitational wave detection,it is essential to accurately determine pulsar pulse times of arrival(ToAs)and associated uncertainties.To measure the ToAs and their uncertainties,various cross-correlation-based techniques can be employed.We develop methodologies to investigate the impact of the template-matching method,profile shape,signal-to-noise ratio of both template and observation on ToA uncertainties.These methodologies are then applied to data from the International Pulsar Timing Array.We demonstrate that the Fourier domain Markov chain Monte Carlo method is generally superior to other methods,while the Gaussian interpolation shift method outperforms other methods in certain cases,such as profiles with large duty cycles or smooth profiles without sharp features.However,it is important to note that our study focuses solely on ToA uncertainty,and the optimal method for determining both ToA and ToA uncertainty may differ.展开更多
Infrared bubbles provide a unique opportunity to study the interactions between massive stars and surrounding material.We conduct a multi-wavelength study on the environment and star formation around an infrared bubbl...Infrared bubbles provide a unique opportunity to study the interactions between massive stars and surrounding material.We conduct a multi-wavelength study on the environment and star formation around an infrared bubble N13.Three dust clumps and two molecular clumps are identified around N 13,which are all distributed on the layer.Young stellar objects(YSOs)are carefully searched using infrared colors and YSO candidates of WISE and Gaia DR2,and three Class I/II YSOs are found in N 13.In addition,four O-type stars identified in N 13 are probably the exciting stars.The dynamical and fragmentation ages of N 13 are 0.32-0.35 and 1.37-2.80 Myr respectively,which suggest that the radiation-driven implosion model may be dominant in N 13.By comparing the small-size bubble N 13(R~1.9 pc)and the larger-size bubble G15.684-0.29(R~15.7 pc)we found that star formation activity is more active in the large-size bubble.Brief comparisons of ten bubbles show that small-size bubbles have a small ratio of kinetic age versus the fragmentation time.Triggering star formation may be more active in bubbles with larger ratio between kinetic and fragmentation ages.Furthermore,the collect and collapse mechanism may play the dominant role in the large-size ones.展开更多
With the possible spacial association to the Fermi/LAT source 3 FGL J 1330.0-3818,TOL 1326-379 may be the first one that is identified as a 7-ray emitting Fanaroff-Riley type 0 radio galaxy(FRO RG).We analyze the~12 y...With the possible spacial association to the Fermi/LAT source 3 FGL J 1330.0-3818,TOL 1326-379 may be the first one that is identified as a 7-ray emitting Fanaroff-Riley type 0 radio galaxy(FRO RG).We analyze the~12 yr Fermi/LAT observation data of thisγ-ray source and examine its association to TOL 1326-379.We show that theγ-ray source(named as J1331.0-3818)is tentatively detected with a TS value of 28.7,3 FGL J 1330.0-3818 is out of the 95%containment of J1331.0-3818,and their positions are spatially separated~0°.2.4 FGL J1331.3-3818 falls into the 68%containment of J1331.0-3818,suggesting that our result agrees with that reported in the Fourth Fermi LAT Source Catalog.TOL 1326-379 is out of the 95%containment of J1331.0-3818,and their positions are spatially separated~0°.4,indicating that the association between J1331.0-3818 and TOL 1326-379 is quite ambiguous.However,we do not find other possible potential radio or X-ray counterpart within the circle centered at J1331.0-3818 with a radius of 0°.4.The spectral energy distribution(SED)of TOL 1326-379 shows a bimodal feature as seen in theγ-ray emitting RGs.We fit the SED with the one-zone leptonic model and find that the average energy spectrum of J1331.0-3818 agrees with the model prediction.Assuming that J1331.0-3818 is an unidentified 7-ray source,we derive the upper-limit of theγ-ray flux for TOL 1326-379.It is not tight enough to exclude this possibility with the SED modeling.Based on these results,we cautiously argue that theγ-ray source J1331.0-3818 is associated with TOL 1326-379 and its jet radiation physic is similar to thoseγ-ray emitting RGs.展开更多
We present total-intensity and polarized-intensity images of the Cygnus Loop supernova remnant(SNR)observed by the Five-hundred-meter Aperture Spherical radio Telescope.The high angular-resolution and high-sensitivity...We present total-intensity and polarized-intensity images of the Cygnus Loop supernova remnant(SNR)observed by the Five-hundred-meter Aperture Spherical radio Telescope.The high angular-resolution and high-sensitivity images enable us to thoroughly compare the properties of the northern part with the southern part of the SNR.The central filament in the northern part and the southern part have a similar foreground rotation measure,meaning their distances are likely similar.The polarization analysis indicates that the random magnetic field is larger than the regular field in the northern part,but negligible in the southern part.The total-intensity image is decomposed into components of various angular scales,and the brightness-temperature spectral index of the shell structures in the northern part is similar to that in the southern part in the component images.All the evidence suggests that the northern and southern parts of the Cygnus Loop are situated and thus evolved in different environments of interstellar medium,while belonging to the same SNR.展开更多
The search for periodic behavior in Blazars has been an important subject, which is helpful for providing significant clues to the structure and physical processes of their central energy engine. A binary black hole s...The search for periodic behavior in Blazars has been an important subject, which is helpful for providing significant clues to the structure and physical processes of their central energy engine. A binary black hole system has recently been suggested for causing precession of relativistic jets and rotation of the ejection position angle of VLBI knots in superluminal sources. It has been suggested that in QSO 3C345, the ejection direction of the superluminal knots rotates due to the precession of the central engine and thus the ejection position angle of the successive knots shows a periodic behavior. Some authors argue for a period of precession being ～5.6 yr （Abraham ＆ Caproni）, ～8-10 yr （Klare et al.） and ～9.5 yr （Lobanov ＆ Roland）. Applying the helical model proposed by Qian et al. and selecting appropriate parameters to fit the initial trajectories （within 0.3 mas） of all the components （C4 to C10）, we derive the relation between the ejection position angle of the components and their precession phase, and thus find a 6.9-year precession period （4.3 yr in the source frame）, which can fit the ejection position angle of all these superluminal knots well. Since the VLBI observations have covered more than two precession periods, confirmation in one or more future periods would be important. In addition, we emphasize that the initial parts of the trajectories of these knots can be fitted by a common helical pattern （channel） through a precessing of its initial phase. This scenario （or helical precessing model） is different from the usual ballistic precessing model in which the individual superluminal knots move along straight-lines after ejection （Tateyama ＆ Kingham）.展开更多
We study the vertical distribution of the highly inclined galaxies from the Continuum Halos in Nearby Galaxies—an EVLA Survey(CHANG-ES).We explore the feasibility of photometrically deriving the HⅠdisk scale heights...We study the vertical distribution of the highly inclined galaxies from the Continuum Halos in Nearby Galaxies—an EVLA Survey(CHANG-ES).We explore the feasibility of photometrically deriving the HⅠdisk scale heights from the moment-0 images of the relatively edge-on galaxies with inclination>80°,by quantifying the systematic broadening effects and thus deriving correction equations for direct measurements.The corrected HⅠdisk scale heights of the relatively edge-on galaxies from the CHANG-ES sample show trends consistent with the quasiequilibrium model of the vertical structure of gas disks.The procedure provides a convenient way to derive the scale heights and can easily be applied to statistical samples in the future.展开更多
Recently, Sun et al. published new Galactic 3D-models of magnetic fields in the disk and halo of the Milky Way and the distribution of cosmic-ray electron density by taking into account the thermal electron density mo...Recently, Sun et al. published new Galactic 3D-models of magnetic fields in the disk and halo of the Milky Way and the distribution of cosmic-ray electron density by taking into account the thermal electron density model NE2001 by Cordes ＆ Lazio. The models successfully reproduce observed continuum and polarization all-sky maps and the distribution of rotation measures of extragalactic sources across the sky. However, the model parameters obtained for the Galactic halo, although reproducing the observations, seem physically unreasonable： the magnetic field needs to be significantly stronger in the Galactic halo than in the plane and the cosmic-ray distribution must be truncated at about 1 kpc to avoid excessive synchrotron emission from the halo. The reason for these unrealistic parameters was the low scale-height of the warm thermal gas of about 1 kpc adopted in the NE2001 model. However, this scale- height seemed reasonable and was well studied by numerous investigations. Recently, the scale-height of the warm gas in the Galaxy was revised by Gaensler et al. to about 1.8 kpc, by showing that the 1 kpc scale-height results from a systematic bias in the analysis of pulsar data. This implies a higher thermal electron density in the Galactic halo, which in turn reduces the halo magnetic field strength to account for the observed rotation measures of extragalactic sources. We slightly modified the NE2001 model according to the new scale-height and revised the Sun et al. model parameters accordingly： the strength of the regular halo magnetic field is now 2 μG or lower, and the physically unrealistic cutoff in z for the cosmic-ray electron density is removed. The simulations based on the revised 3D-models reproduce all-sky observations as before.展开更多
We present high resolution （- 1″） H2CO maser and 5 GHz radio continuum observations toward nearby merging galaxy NGC 6240 made with the Very Large Array in an A configuration. Two concentrations of H2CO emission at...We present high resolution （- 1″） H2CO maser and 5 GHz radio continuum observations toward nearby merging galaxy NGC 6240 made with the Very Large Array in an A configuration. Two concentrations of H2CO emission at about a 6or level have been detected, one of which is associated with the strongest CO peak in the overlap region while the other is about 2″ southwest of the southem galaxy. Both H2CO concentrations are associated with near infrared H2 emission, which is thought to be from shocked molecular gas. The total H2CO line luminosity in NGC 6240 is about 60% of that in Arp 220. Based on the distribution of H2CO emission in NGC 6240, which has both active galactic nuclei and an extreme starburst, the H2CO megamaser is likely to be related to the effect of the starburst instead of nuclear activity. Radio continuum cannot be the inversion mechanism of H2CO megamasers, because the two H2CO concentrations in NGC 6240 are not associated with radio continuum emission. Instead, with the association of near infrared H2 emission, shock dynamics may produce the inverted population of H2CO needed to generate megamasers.展开更多
A very rapid polarization position angle swing of -180° （with a time scale of ,-6 hours） observed at 2 cm in QSO 1150＋812 （z = 1.25） was reported by Kochenov ＆ Gabuzda. This very rare event is difficult to ...A very rapid polarization position angle swing of -180° （with a time scale of ,-6 hours） observed at 2 cm in QSO 1150＋812 （z = 1.25） was reported by Kochenov ＆ Gabuzda. This very rare event is difficult to explain. We found a possible interpretation in the framework of a source model consisting of three polarized components, in which two compact polarized components are nearly simultaneously occulted by an interstellar cloud, with consequent focusing-defocusing effects. A specific plasma-lens model is proposed which can reasonably fit the polarized flux density curve with results derived for the two lensed components. Some physical parameters of the plasma-lens and the source components are estimated. The two compact polarized components are estimated to have brightness temperatures of -6 ×10^12 K. Thus a bulk relativistic motion with a Lorentz factor less than 10 is required to meet the inverse-Compton limit.展开更多
Leveraging the high resolution,sensitivity,and wide frequency coverage of the Atacama Large Millimeter/submillimeter Array(ALMA),the QUARKS survey,standing for“Querying Underlying mechanisms of massive star formation...Leveraging the high resolution,sensitivity,and wide frequency coverage of the Atacama Large Millimeter/submillimeter Array(ALMA),the QUARKS survey,standing for“Querying Underlying mechanisms of massive star formation with ALMA-Resolved gas Kinematics and Structures”,is observing 139 massive starforming clumps at ALMA Band 6(λ~1.3 mm).This paper introduces the Atacama Compact Array(ACA)7 m data of the QUARKS survey,describing the ACA observations and data reduction.Combining multiwavelength data,we provide the first edition of QUARKS atlas,offering insights into the multiscale and multiphase interstellar medium in high-mass star formation.The ACA 1.3 mm catalog includes 207 continuum sources that are called ACA sources.Their gas kinetic temperatures are estimated using three formaldehyde transitions with a non-LTE radiation transfer model,and the mass and density are derived from a dust emission model.The ACA sources are massive(16–84 percentile values of 6–160 M_(⊙)),gravity-dominated(M∝R^(1.1))fragments within massive clumps,with supersonic turbulence(M>1)and embedded star-forming protoclusters.We find a linear correlation between the masses of the fragments and the massive clumps,with a ratio of 6%between the two.When considering fragments as representative of dense gas,the ratio indicates a dense gas fraction(DGF)of 6%,although with a wide scatter ranging from 1%to 10%.If we consider the QUARKS massive clumps to be what is observed at various scales,then the size-independent DGF indicates a self-similar fragmentation or collapsing mode in protocluster formation.With the ACA data over four orders of magnitude of luminosity-to-mass ratio(L/M),we find that the DGF increases significantly with L/M,which indicates clump evolutionary stage.We observed a limited fragmentation at the subclump scale,which can be explained by a dynamic global collapse process.展开更多
We present the most comprehensive catalog of 12.2 GHz methanol maser sources within the Milky Way to date,consisting of 45712.2 GHz methanol masers associated with 10856.7 GHz methanol masers,resulting in a detection ...We present the most comprehensive catalog of 12.2 GHz methanol maser sources within the Milky Way to date,consisting of 45712.2 GHz methanol masers associated with 10856.7 GHz methanol masers,resulting in a detection rate of 42%.Distances to these sources are derived from the Bar and Spiral Structure Legacy Survey project Distance Calculator.Our analysis shows that both 6.7 and 12.2 GHz methanol masers are more likely to be excited near galactocentric distances of 5–6 kpc,with the detection rate of 12.2 GHz methanol masers decreasing as the galactocentric distance increases.There are no significant differences in the detection rates of 12.2 GHz masers across the four spiral arms,which consistently range between 40%and 50%.However,the detection rate of12.2 GHz methanol masers tends to be higher in the heads of the spiral arms compared to the tails.Analysis of data from the APEX Telescope Large Area Survey of the Galaxy(ATLASGAL)indicates that the luminosity of6.7 GHz masers peaks at a clump dust temperature of about 30 K,while that of 12.2 GHz masers grows with increasing dust temperature.Clumps associated with 12.2 GHz methanol masers generally have higher dust temperatures,bolometric luminosities,and hydrogen densities than those associated only with 6.7 GHz methanol masers or without either maser.Furthermore,clumps in the HⅡregion stage exhibit a higher detection rate of12.2 GHz masers compared to those in other stages,as indicated by the evolutionary stages derived from the ATLASGAL survey results.展开更多
The shell-type TeV source HESS J1912+101 was tentatively identified as an old supernova remnant, but is missing counterparts at radio and other frequencies. We analysed the Sino-German Urumqiλ6 cm survey and the Effe...The shell-type TeV source HESS J1912+101 was tentatively identified as an old supernova remnant, but is missing counterparts at radio and other frequencies. We analysed the Sino-German Urumqiλ6 cm survey and the Effelsberg λ11 cm and λ21 cm surveys to identify radio emission from HESS J1912+101 to clarify the question of a supernova origin. We find a partial shell of excessive polarisation at λ6 cm at the periphery of HESS J1912+101. At λ11 cm, its polarised emission is faint and suffers from depolarisation, while at λ21 cm, no related polarisation is seen. We could not separate the shell's total intensity signal from the confusing intense diffuse emission from the inner Galactic plane. However, a high percentage of polarisation in the shell's synchrotron emission is indicated. Our results support earlier suggestions that HESS J1912+101 is an old supernova remnant. The synchrotron emission is highly polarised,which is typical for evolved supernova remnants with low surface brightness.展开更多
This paper presents an overview of the QUARKS survey,which stands for Querying Underlying mechanisms of massive star formation with ALMA-Resolved gas Kinematics and Structures."The QUARKS survey is observing139 m...This paper presents an overview of the QUARKS survey,which stands for Querying Underlying mechanisms of massive star formation with ALMA-Resolved gas Kinematics and Structures."The QUARKS survey is observing139 massive clumps covered by 156 pointings at Atacama Large Millimeter/submillimeter Array(ALMA)Band 6(λ~1.3 mm).In conjunction with data obtained from the ALMA-ATOMS survey at Band 3(λ~3 mm),QUARKS aims to carry out an unbiased statistical investigation of massive star formation process within protoclusters down to a scale of 1000 au.This overview paper describes the observations and data reduction of the QUARKS survey,and gives a first look at an exemplar source,the mini-starburst Sgr B2(M).The wide-b and width(7.5 GHz)and high-angular-resolution(~0."3)observations of the QUARKS survey allow for the resolution of much more compact cores than those could be done by the ATOMS survey,and to detect previously unrevealed fainter filamentary structures.The spectral windows cover transitions of species including CO,SO,N_(2)D^(+),SiO,H_(30)α,H_(2)CO,CH_(3)CN,and many other complex organic molecules,tracing gas components with different temperatures and spatial extents.QUARKS aims to deepen our understanding of several scientific topics of massive star formation,such as the mass transport within protoclusters by(hub-)filamentary structures,the existence of massive starless cores,the physical and chemical properties of dense cores within protoclusters,and the feedback from already formed high-mass young protostars.展开更多
Magnetic fields are pervasive throughout the Universe.They are integral to a wide array of astrophysical processes that span various physical scales and field strengths.The Galactic magnetic field,in particular,holds ...Magnetic fields are pervasive throughout the Universe.They are integral to a wide array of astrophysical processes that span various physical scales and field strengths.The Galactic magnetic field,in particular,holds significant importance in shaping the evolution of our Galaxy.However,our understanding of its behavior on small scales remains poor,especially when considering its penetration into the Galactic halo[1].展开更多
Annual variations of interstellar scintillation can be modelled to constrain parameters of the ionized interstellar medium.If a pulsar is in a binary system,then investigating the orbital parameters is possible throug...Annual variations of interstellar scintillation can be modelled to constrain parameters of the ionized interstellar medium.If a pulsar is in a binary system,then investigating the orbital parameters is possible through analysis of the orbital variation of scintillation.In observations carried out from 2011 to 2020 by the European Pulsar Timing Array radio telescopes,PSRs J0613-0200and J0636+5128 show strong annual variations in their scintillation velocity,while the former additionally exhibits an orbital fluctuation.Bayesian theory and Markov-chain-Monte-Carlo methods are used to interpret these periodic variations.We assume a thin and anisotropic scattering screen model,and discuss the mildly and extremely anisotropic scattering cases.PSR J0613-0200is best described by mildly anisotropic scattering,while PSR J0636+5128 exhibits extremely anisotropic scattering.We measure the distance,velocity,and degree of anisotropy of the scattering screen for our two pulsars,finding that scattering screen distances from Earth for PSRs J0613-0200 and J0636+5128 are 316_(-20)^(+28)pc and 262_(-38)^(+96)pc,respectively.The positions of these scattering screens are coincident with the shell of the Local Bubble towards both pulsars.These associations add to the growing evidence of the Local Bubble shell as a dominant region of scattering along many sightlines.展开更多
In this paper we describe the potential of the enhanced X-ray Timing and Polarimetry(eXTP) mission for studies related to accretion flows in the strong field gravity regime around both stellar-mass and supermassive bl...In this paper we describe the potential of the enhanced X-ray Timing and Polarimetry(eXTP) mission for studies related to accretion flows in the strong field gravity regime around both stellar-mass and supermassive black-holes. eXTP has the unique capability of using advanced "spectral-timing-polarimetry" techniques to analyze the rapid variations with three orthogonal diagnostics of the flow and its geometry, yielding unprecedented insight into the inner accreting regions, the effects of strong field gravity on the material within them and the powerful outflows which are driven by the accretion process.展开更多
基金supported by the FAST Key projectsupported by the National SKA Program of China (2020SKA0120100)+4 种基金the National Natural Science Foundation of China (NSFC, Grant Nos. 12041303 and 12250410246)the CAS-MPG LEGACY projectfunding from the Max-Planck Partner Groupsupport from the XPLORER PRIZE and 20 yr long-term support from Dr. Guojun Qiaosupported by Major Science and Technology Program of Xinjiang Uygur Autonomous Region No. 2022A03013-4
文摘We derive the gravitational-wave(GW)strain upper limits from resolvable supermassive black-hole binaries using the data from the Five-hundred-meter Aperture Spherical radio Telescope,in the context of the Chinese Pulsar Timing Array project.We focus on circular orbits in theμHz GW frequency band between 10^(−7)and 3×10^(−6)Hz.This frequency band is higher than the traditional pulsar timing array band and is less explored.We used the data of the millisecond pulsar PSR J1713+5307 observed between 2019 August and 2021 April.A dense observation campaign was carried out in 2020 September to allow for theμHz band coverage.Our sky-averaged continuous source upper limit at the 95%confidence level at 1μHz is 1.26×10^(−12),while the same limit in the direction of the pulsar is 4.77×10^(−13).
基金supported by the National SKA Program of China (grant No. 2020SKA0120100)the Special Project of Foreign Science and Technology Cooperation, Yunnan Provincial Science and Technology Department (grant No. 202003AD150010)+4 种基金the National Key R&D Program of China (grant No. 2022YFC2205203)the National Natural Science Foundation of China (NSFC, grant Nos. 12073076, 12173087, 12041303, and 12063003)the CAS “Western Light Youth Project,” Yunnan Fundamental Research Projects (grant Nos. 202401AT070144 and 202505AO120021)funding from the Max-Planck Partner Groupsupport from the XPLORER PRIZE
文摘Fast Radio Bursts(FRBs) are enigmatic millisecond-duration radio transients of extra-galactic origin, whose underlying mechanisms and progenitors remain poorly understood. FRBs are broadly classified into two categories: repeating FRBs, which emit multiple bursts over time, and one-off FRBs, which are detected as single events. A central question in FRB research is whether these two classes share a common origin. In this study, we present observations of FRB 20240114A, a repeating FRB that entered a hyperactive phase in 2024 January. We conducted a 318 hr monitoring campaign using the Kunming 40-Meter Radio Telescope(KM40M) in the S-band(2.187–2.311 GHz), during which we detected eight radio bursts. We analyzed their properties, including dispersion measure, bandwidth, pulse width, flux, fluence, and energy. Additionally, we searched for counterparts in overlapping data from the Five-hundred-meter Aperture Spherical Telescope(FAST) in the L-band(1.0–1.5 GHz). While no bursts were temporally aligned between the two telescopes, we identified one FAST burst that arrived approximately 6 ms after one of the KM40M bursts. The absence of FAST counterparts for the KM40M bursts suggests that individual bursts from FRB 20240114A are likely narrow-band, with fractional bandwidths less than 10%. By comparing the cumulative event rates from KM40M and FAST observations, we found that the two measurements are compatible, indicating a possible flattening of the event rate at higher energies. This feature aligns with observations of one-off FRBs, supporting the hypothesis that repeating and oneoff FRBs may share a common origin.
基金the support from the Natural Science Foundation of Xinjiang Uygur Autonomous Region(Grant No.2024D01E37)the National Science Foundation of China(Grant No.12473025)+5 种基金funded by the National Natural Science Foundation of China(Grant Nos.12373026,12203091,12173075,and 11973076)the Xinjiang Tianchi Talent Program(2024)the support from the Xinjiang Tianchi Talent Program(2023)the Shanghai Natural Science Foundation(Grant No.22ZR1421400)the Natural Science Foundation of Xinjiang Uygur Autonomous Region(Grant No.2022D01A156)partially funded by the Regional Collaborative Innovation Project of Xin jiang Uyghur Autonomous Region(Grant No.2022E01050)。
文摘Sulfur-bearing species are widely utilized to investigate the physical structure of star-forming regions in interstellar media;however,the underlying sulfur chemistry in these environments remains poorly understood.Therefore,further studies of S-bearing species are fundamentally important,as they can enhance our understanding of the physical evolution of star-forming regions.This study presents observations of C_(2)S and C_(3)S in L1544,acquired using the Nanshan 26-m radio telescope,along with simulations of their chemical behavior using a one-dimensional physical model.The simulation results reveal significant radial variations in the column densities of C_(2)S and C_(3)S.Additionally,the column densities of both molecules are found to be sensitive to the cosmic ray ionization rate at several radial positions,while variations in the C/O ratio have comparatively minimal impact on L1544.
基金support from the Australian Research Council (ARC) Future Fellowship programmesupport from the National Natural Science Foundation of China (11225314)
文摘The Five-hundred-meter Aperture Spherical radio Telescope(FAST) will become one of the world-leading telescopes for pulsar timing array(PTA) research. The primary goals for PTAs are to detect(and subsequently study) ultra-low-frequency gravitational waves, to develop a pulsar-based time standard and to improve solar system planetary ephemerides. FAST will have the sensitivity to observe known pulsars with significantly improved signal-to-noise ratios and will discover a large number of currently unknown pulsars. We describe how FAST will contribute to PTA research and show that jitter-and timing-noise will be the limiting noise processes for FAST data sets. Jitter noise will limit the timing precision achievable over data spans of a few years while timing noise will limit the precision achievable over many years.
基金support by the Deutsche Forschungsgemeinschaft(DFG)through the Heisenberg program(Project No.433075039)。
文摘For high-precision pulsar timing analysis and low-frequency gravitational wave detection,it is essential to accurately determine pulsar pulse times of arrival(ToAs)and associated uncertainties.To measure the ToAs and their uncertainties,various cross-correlation-based techniques can be employed.We develop methodologies to investigate the impact of the template-matching method,profile shape,signal-to-noise ratio of both template and observation on ToA uncertainties.These methodologies are then applied to data from the International Pulsar Timing Array.We demonstrate that the Fourier domain Markov chain Monte Carlo method is generally superior to other methods,while the Gaussian interpolation shift method outperforms other methods in certain cases,such as profiles with large duty cycles or smooth profiles without sharp features.However,it is important to note that our study focuses solely on ToA uncertainty,and the optimal method for determining both ToA and ToA uncertainty may differ.
基金funded by the CAS“Light of West China”Program under Grant No.2021-XBQNXZ-028the National Key R&D Program of China No.2022YFA1603103+5 种基金the National Natural Science Foundation of China(NSFC,Grant Nos.12103082,11973076,11903070 and 12173075)partially funded by the CAS“Light of West China”Program under Grant No.2020-XBQNXZ-017the CAS Presidents International Fellowship Initiative with Grant No.2022VMA0019the Natural Science Foundation of Xinjiang Uygur Autonomous Region under Grant No.2022D01E06the Project of Xinjiang Uygur Autonomous Region of China for Flexibly Fetching in Upscale Talentsthe support from Youth Innovation Promotion Association CAS。
文摘Infrared bubbles provide a unique opportunity to study the interactions between massive stars and surrounding material.We conduct a multi-wavelength study on the environment and star formation around an infrared bubble N13.Three dust clumps and two molecular clumps are identified around N 13,which are all distributed on the layer.Young stellar objects(YSOs)are carefully searched using infrared colors and YSO candidates of WISE and Gaia DR2,and three Class I/II YSOs are found in N 13.In addition,four O-type stars identified in N 13 are probably the exciting stars.The dynamical and fragmentation ages of N 13 are 0.32-0.35 and 1.37-2.80 Myr respectively,which suggest that the radiation-driven implosion model may be dominant in N 13.By comparing the small-size bubble N 13(R~1.9 pc)and the larger-size bubble G15.684-0.29(R~15.7 pc)we found that star formation activity is more active in the large-size bubble.Brief comparisons of ten bubbles show that small-size bubbles have a small ratio of kinetic age versus the fragmentation time.Triggering star formation may be more active in bubbles with larger ratio between kinetic and fragmentation ages.Furthermore,the collect and collapse mechanism may play the dominant role in the large-size ones.
基金supported by the National Natural Science Foundation of China(Grant Nos.12022305,11973050,12133003,U1731239)Guangxi Science Foundation(Grant Nos.2017AD22006 and 2019AC20334)。
文摘With the possible spacial association to the Fermi/LAT source 3 FGL J 1330.0-3818,TOL 1326-379 may be the first one that is identified as a 7-ray emitting Fanaroff-Riley type 0 radio galaxy(FRO RG).We analyze the~12 yr Fermi/LAT observation data of thisγ-ray source and examine its association to TOL 1326-379.We show that theγ-ray source(named as J1331.0-3818)is tentatively detected with a TS value of 28.7,3 FGL J 1330.0-3818 is out of the 95%containment of J1331.0-3818,and their positions are spatially separated~0°.2.4 FGL J1331.3-3818 falls into the 68%containment of J1331.0-3818,suggesting that our result agrees with that reported in the Fourth Fermi LAT Source Catalog.TOL 1326-379 is out of the 95%containment of J1331.0-3818,and their positions are spatially separated~0°.4,indicating that the association between J1331.0-3818 and TOL 1326-379 is quite ambiguous.However,we do not find other possible potential radio or X-ray counterpart within the circle centered at J1331.0-3818 with a radius of 0°.4.The spectral energy distribution(SED)of TOL 1326-379 shows a bimodal feature as seen in theγ-ray emitting RGs.We fit the SED with the one-zone leptonic model and find that the average energy spectrum of J1331.0-3818 agrees with the model prediction.Assuming that J1331.0-3818 is an unidentified 7-ray source,we derive the upper-limit of theγ-ray flux for TOL 1326-379.It is not tight enough to exclude this possibility with the SED modeling.Based on these results,we cautiously argue that theγ-ray source J1331.0-3818 is associated with TOL 1326-379 and its jet radiation physic is similar to thoseγ-ray emitting RGs.
基金supported by the Cultivation Project for FAST Scientific Payoff and Research Achievement of CAMS-CASsupported by the Science&Technology Department of Yunnan Province—Yunnan University Joint Funding(2019FY003005)supported by the CASNWO cooperation program(Grant No.GJHZ1865)。
文摘We present total-intensity and polarized-intensity images of the Cygnus Loop supernova remnant(SNR)observed by the Five-hundred-meter Aperture Spherical radio Telescope.The high angular-resolution and high-sensitivity images enable us to thoroughly compare the properties of the northern part with the southern part of the SNR.The central filament in the northern part and the southern part have a similar foreground rotation measure,meaning their distances are likely similar.The polarization analysis indicates that the random magnetic field is larger than the regular field in the northern part,but negligible in the southern part.The total-intensity image is decomposed into components of various angular scales,and the brightness-temperature spectral index of the shell structures in the northern part is similar to that in the southern part in the component images.All the evidence suggests that the northern and southern parts of the Cygnus Loop are situated and thus evolved in different environments of interstellar medium,while belonging to the same SNR.
文摘The search for periodic behavior in Blazars has been an important subject, which is helpful for providing significant clues to the structure and physical processes of their central energy engine. A binary black hole system has recently been suggested for causing precession of relativistic jets and rotation of the ejection position angle of VLBI knots in superluminal sources. It has been suggested that in QSO 3C345, the ejection direction of the superluminal knots rotates due to the precession of the central engine and thus the ejection position angle of the successive knots shows a periodic behavior. Some authors argue for a period of precession being ～5.6 yr （Abraham ＆ Caproni）, ～8-10 yr （Klare et al.） and ～9.5 yr （Lobanov ＆ Roland）. Applying the helical model proposed by Qian et al. and selecting appropriate parameters to fit the initial trajectories （within 0.3 mas） of all the components （C4 to C10）, we derive the relation between the ejection position angle of the components and their precession phase, and thus find a 6.9-year precession period （4.3 yr in the source frame）, which can fit the ejection position angle of all these superluminal knots well. Since the VLBI observations have covered more than two precession periods, confirmation in one or more future periods would be important. In addition, we emphasize that the initial parts of the trajectories of these knots can be fitted by a common helical pattern （channel） through a precessing of its initial phase. This scenario （or helical precessing model） is different from the usual ballistic precessing model in which the individual superluminal knots move along straight-lines after ejection （Tateyama ＆ Kingham）.
基金the National Natural Science Foundation of China(NSFC,Grant Nos.12073002 and 11721303)the High-performance Computing Platform of Peking University。
文摘We study the vertical distribution of the highly inclined galaxies from the Continuum Halos in Nearby Galaxies—an EVLA Survey(CHANG-ES).We explore the feasibility of photometrically deriving the HⅠdisk scale heights from the moment-0 images of the relatively edge-on galaxies with inclination>80°,by quantifying the systematic broadening effects and thus deriving correction equations for direct measurements.The corrected HⅠdisk scale heights of the relatively edge-on galaxies from the CHANG-ES sample show trends consistent with the quasiequilibrium model of the vertical structure of gas disks.The procedure provides a convenient way to derive the scale heights and can easily be applied to statistical samples in the future.
文摘Recently, Sun et al. published new Galactic 3D-models of magnetic fields in the disk and halo of the Milky Way and the distribution of cosmic-ray electron density by taking into account the thermal electron density model NE2001 by Cordes ＆ Lazio. The models successfully reproduce observed continuum and polarization all-sky maps and the distribution of rotation measures of extragalactic sources across the sky. However, the model parameters obtained for the Galactic halo, although reproducing the observations, seem physically unreasonable： the magnetic field needs to be significantly stronger in the Galactic halo than in the plane and the cosmic-ray distribution must be truncated at about 1 kpc to avoid excessive synchrotron emission from the halo. The reason for these unrealistic parameters was the low scale-height of the warm thermal gas of about 1 kpc adopted in the NE2001 model. However, this scale- height seemed reasonable and was well studied by numerous investigations. Recently, the scale-height of the warm gas in the Galaxy was revised by Gaensler et al. to about 1.8 kpc, by showing that the 1 kpc scale-height results from a systematic bias in the analysis of pulsar data. This implies a higher thermal electron density in the Galactic halo, which in turn reduces the halo magnetic field strength to account for the observed rotation measures of extragalactic sources. We slightly modified the NE2001 model according to the new scale-height and revised the Sun et al. model parameters accordingly： the strength of the regular halo magnetic field is now 2 μG or lower, and the physically unrealistic cutoff in z for the cosmic-ray electron density is removed. The simulations based on the revised 3D-models reproduce all-sky observations as before.
基金supported by the National Basic Research Program of China (973 Program, 2012CB821800)the Natural Science Foundation of China(Grant Nos. 10833006 and 11173013)
文摘We present high resolution （- 1″） H2CO maser and 5 GHz radio continuum observations toward nearby merging galaxy NGC 6240 made with the Very Large Array in an A configuration. Two concentrations of H2CO emission at about a 6or level have been detected, one of which is associated with the strongest CO peak in the overlap region while the other is about 2″ southwest of the southem galaxy. Both H2CO concentrations are associated with near infrared H2 emission, which is thought to be from shocked molecular gas. The total H2CO line luminosity in NGC 6240 is about 60% of that in Arp 220. Based on the distribution of H2CO emission in NGC 6240, which has both active galactic nuclei and an extreme starburst, the H2CO megamaser is likely to be related to the effect of the starburst instead of nuclear activity. Radio continuum cannot be the inversion mechanism of H2CO megamasers, because the two H2CO concentrations in NGC 6240 are not associated with radio continuum emission. Instead, with the association of near infrared H2 emission, shock dynamics may produce the inverted population of H2CO needed to generate megamasers.
文摘A very rapid polarization position angle swing of -180° （with a time scale of ,-6 hours） observed at 2 cm in QSO 1150＋812 （z = 1.25） was reported by Kochenov ＆ Gabuzda. This very rare event is difficult to explain. We found a possible interpretation in the framework of a source model consisting of three polarized components, in which two compact polarized components are nearly simultaneously occulted by an interstellar cloud, with consequent focusing-defocusing effects. A specific plasma-lens model is proposed which can reasonably fit the polarized flux density curve with results derived for the two lensed components. Some physical parameters of the plasma-lens and the source components are estimated. The two compact polarized components are estimated to have brightness temperatures of -6 ×10^12 K. Thus a bulk relativistic motion with a Lorentz factor less than 10 is required to meet the inverse-Compton limit.
基金upported by the National Natural Science Foundation of China(NSFC,Grant No.12033005)the National Key R&D Program of China(No.2022YFA1603102)+2 种基金the China Manned Space Project(CMS-CSST-2021-A09,CMS-CSST-2021-B06)the China-Chile Joint Research Fund(CCJRF No.2211)support from the Tianchi Talent Program of Xinjiang Uygur Autonomous Region。
文摘Leveraging the high resolution,sensitivity,and wide frequency coverage of the Atacama Large Millimeter/submillimeter Array(ALMA),the QUARKS survey,standing for“Querying Underlying mechanisms of massive star formation with ALMA-Resolved gas Kinematics and Structures”,is observing 139 massive starforming clumps at ALMA Band 6(λ~1.3 mm).This paper introduces the Atacama Compact Array(ACA)7 m data of the QUARKS survey,describing the ACA observations and data reduction.Combining multiwavelength data,we provide the first edition of QUARKS atlas,offering insights into the multiscale and multiphase interstellar medium in high-mass star formation.The ACA 1.3 mm catalog includes 207 continuum sources that are called ACA sources.Their gas kinetic temperatures are estimated using three formaldehyde transitions with a non-LTE radiation transfer model,and the mass and density are derived from a dust emission model.The ACA sources are massive(16–84 percentile values of 6–160 M_(⊙)),gravity-dominated(M∝R^(1.1))fragments within massive clumps,with supersonic turbulence(M>1)and embedded star-forming protoclusters.We find a linear correlation between the masses of the fragments and the massive clumps,with a ratio of 6%between the two.When considering fragments as representative of dense gas,the ratio indicates a dense gas fraction(DGF)of 6%,although with a wide scatter ranging from 1%to 10%.If we consider the QUARKS massive clumps to be what is observed at various scales,then the size-independent DGF indicates a self-similar fragmentation or collapsing mode in protocluster formation.With the ACA data over four orders of magnitude of luminosity-to-mass ratio(L/M),we find that the DGF increases significantly with L/M,which indicates clump evolutionary stage.We observed a limited fragmentation at the subclump scale,which can be explained by a dynamic global collapse process.
基金supported by the National Key R&D Program of China(2022YFA1603102)the National Natural Science Foundation of China(11873002,12011530065,and 11590781)China Postdoctoral Science Foundation(2023M740803)。
文摘We present the most comprehensive catalog of 12.2 GHz methanol maser sources within the Milky Way to date,consisting of 45712.2 GHz methanol masers associated with 10856.7 GHz methanol masers,resulting in a detection rate of 42%.Distances to these sources are derived from the Bar and Spiral Structure Legacy Survey project Distance Calculator.Our analysis shows that both 6.7 and 12.2 GHz methanol masers are more likely to be excited near galactocentric distances of 5–6 kpc,with the detection rate of 12.2 GHz methanol masers decreasing as the galactocentric distance increases.There are no significant differences in the detection rates of 12.2 GHz masers across the four spiral arms,which consistently range between 40%and 50%.However,the detection rate of12.2 GHz methanol masers tends to be higher in the heads of the spiral arms compared to the tails.Analysis of data from the APEX Telescope Large Area Survey of the Galaxy(ATLASGAL)indicates that the luminosity of6.7 GHz masers peaks at a clump dust temperature of about 30 K,while that of 12.2 GHz masers grows with increasing dust temperature.Clumps associated with 12.2 GHz methanol masers generally have higher dust temperatures,bolometric luminosities,and hydrogen densities than those associated only with 6.7 GHz methanol masers or without either maser.Furthermore,clumps in the HⅡregion stage exhibit a higher detection rate of12.2 GHz masers compared to those in other stages,as indicated by the evolutionary stages derived from the ATLASGAL survey results.
基金supported by the National Natural Science Foundation of China (Grant No.11763008)
文摘The shell-type TeV source HESS J1912+101 was tentatively identified as an old supernova remnant, but is missing counterparts at radio and other frequencies. We analysed the Sino-German Urumqiλ6 cm survey and the Effelsberg λ11 cm and λ21 cm surveys to identify radio emission from HESS J1912+101 to clarify the question of a supernova origin. We find a partial shell of excessive polarisation at λ6 cm at the periphery of HESS J1912+101. At λ11 cm, its polarised emission is faint and suffers from depolarisation, while at λ21 cm, no related polarisation is seen. We could not separate the shell's total intensity signal from the confusing intense diffuse emission from the inner Galactic plane. However, a high percentage of polarisation in the shell's synchrotron emission is indicated. Our results support earlier suggestions that HESS J1912+101 is an old supernova remnant. The synchrotron emission is highly polarised,which is typical for evolved supernova remnants with low surface brightness.
基金supported by the National Key R&D Program of China(No.2022YFA1603100)the National Natural Science Foundation of China(NSFC)through grants Nos.12203086,12033005,12073061,12122307,and 12103045+12 种基金supported by CPSF No.2022M723278the international partnership program of Chinese Academy of Sciences through grant No.114231K YSB20200009Shanghai Pujiang Program 20PJ1415500the science research grants from the China Manned Space Project with no.CMS-CSST-2021-B06Yunnan Fundamental Research Project(grant No.202301AT070118)sponsored by Natural Science Foundation of Shanghai(No.23ZR1482100)support from the National Natural Science Foundation of China(NSFC)through grants Nos.12273090&12322305the Chinese Academy of Sciences(CAS)‘Light of West China’Program(No.xbzgzdsys-202212)support from the ANID BASAL project FB210003support from the Fondecyt Regular(project code 1220610)partially supported by a Grant-in-Aid for Scientific Research(KAKENHI Number JP22H01271 and JP23H01221)of JSPSsupported by JSPS KAKENHI(grant No.JP20H05645)sponsored(in part)by the Chinese Academy of Sciences(CAS),through a grant to the CAS South America Center for Astronomy(CASSACA)in Santiago,Chile。
文摘This paper presents an overview of the QUARKS survey,which stands for Querying Underlying mechanisms of massive star formation with ALMA-Resolved gas Kinematics and Structures."The QUARKS survey is observing139 massive clumps covered by 156 pointings at Atacama Large Millimeter/submillimeter Array(ALMA)Band 6(λ~1.3 mm).In conjunction with data obtained from the ALMA-ATOMS survey at Band 3(λ~3 mm),QUARKS aims to carry out an unbiased statistical investigation of massive star formation process within protoclusters down to a scale of 1000 au.This overview paper describes the observations and data reduction of the QUARKS survey,and gives a first look at an exemplar source,the mini-starburst Sgr B2(M).The wide-b and width(7.5 GHz)and high-angular-resolution(~0."3)observations of the QUARKS survey allow for the resolution of much more compact cores than those could be done by the ATOMS survey,and to detect previously unrevealed fainter filamentary structures.The spectral windows cover transitions of species including CO,SO,N_(2)D^(+),SiO,H_(30)α,H_(2)CO,CH_(3)CN,and many other complex organic molecules,tracing gas components with different temperatures and spatial extents.QUARKS aims to deepen our understanding of several scientific topics of massive star formation,such as the mass transport within protoclusters by(hub-)filamentary structures,the existence of massive starless cores,the physical and chemical properties of dense cores within protoclusters,and the feedback from already formed high-mass young protostars.
基金supported by the National Natural Science Foundation of China(11988101,12103069,11725313,12273008,12373109,and 12203045)the National Key R&D Program of China(2017YFA0402600 and 2023YFB4503300)+4 种基金the National SKA Program of China(2022SKA0130100 and 2022SKA0130104)the Shandong Provincial Key R&D Program(2022CXGC020106)the Zhejiang Provincial grants(2023R01008 and 2024SSYS0012)Additional support came from the Pilot Project for Integrated Innovation of Science,Education and Industry of Qilu University of Technology(2022JBZ01-01)funding from NextGenerationEU under the Italian PNRR(Project IR0000034 CSTILES)。
文摘Magnetic fields are pervasive throughout the Universe.They are integral to a wide array of astrophysical processes that span various physical scales and field strengths.The Galactic magnetic field,in particular,holds significant importance in shaping the evolution of our Galaxy.However,our understanding of its behavior on small scales remains poor,especially when considering its penetration into the Galactic halo[1].
基金supported by the National Natural Science Foundation of China(Grant No.12003047)the Major Science and Technology Program of Xinjiang Uygur Autonomous Region(Grant No.2022A03013-2)+2 种基金the Natural Science Foundation of Xinjiang Uygur Autonomous Region(Grant No.2022D01D85)support by the Deutsche Forschungsgemeinschaft(DFG)through the Heisenberg programme(Project No.433075039)financial support from“Programme National de Cosmologie et Galaxies”(PNCG)of CNRS/INSU,France。
文摘Annual variations of interstellar scintillation can be modelled to constrain parameters of the ionized interstellar medium.If a pulsar is in a binary system,then investigating the orbital parameters is possible through analysis of the orbital variation of scintillation.In observations carried out from 2011 to 2020 by the European Pulsar Timing Array radio telescopes,PSRs J0613-0200and J0636+5128 show strong annual variations in their scintillation velocity,while the former additionally exhibits an orbital fluctuation.Bayesian theory and Markov-chain-Monte-Carlo methods are used to interpret these periodic variations.We assume a thin and anisotropic scattering screen model,and discuss the mildly and extremely anisotropic scattering cases.PSR J0613-0200is best described by mildly anisotropic scattering,while PSR J0636+5128 exhibits extremely anisotropic scattering.We measure the distance,velocity,and degree of anisotropy of the scattering screen for our two pulsars,finding that scattering screen distances from Earth for PSRs J0613-0200 and J0636+5128 are 316_(-20)^(+28)pc and 262_(-38)^(+96)pc,respectively.The positions of these scattering screens are coincident with the shell of the Local Bubble towards both pulsars.These associations add to the growing evidence of the Local Bubble shell as a dominant region of scattering along many sightlines.
基金financial contribution from the agreement ASI-INAF n.2017-14-H.Osupport of the Chinese Academy of Sciences through the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA15020100)the Polish National Science Centre(Grant No.2013/10/M/ST9/00729)
文摘In this paper we describe the potential of the enhanced X-ray Timing and Polarimetry(eXTP) mission for studies related to accretion flows in the strong field gravity regime around both stellar-mass and supermassive black-holes. eXTP has the unique capability of using advanced "spectral-timing-polarimetry" techniques to analyze the rapid variations with three orthogonal diagnostics of the flow and its geometry, yielding unprecedented insight into the inner accreting regions, the effects of strong field gravity on the material within them and the powerful outflows which are driven by the accretion process.
