The Astrophysical Journal Letters最新文献

{"title":"Bipolar Blobs as Evidence of Hidden AGN Activities in the Low-mass Galaxies","authors":"Yao Yao, Enci Wang, Zhicheng He, Zheyu Lin, Yu Rong, Hong-Xin Zhang and Xu Kong","doi":"10.3847/2041-8213/ad6f8c","DOIUrl":"https://doi.org/10.3847/2041-8213/ad6f8c","url":null,"abstract":"We report evidence of a hidden black hole (BH) in a low-mass galaxy, MaNGA 9885-9102, and provide a new method to identify active BHs in low-mass galaxies. This galaxy is originally selected from the MaNGA survey with distinctive bipolar Hα blobs at the minor axis. The bipolar feature can be associated with active galactic nuclei (AGN) activity, while the two blobs are classified as the H ii regions on the BPT diagram, making the origins confusing. The Swift UV continuum shows that the two blobs do not have UV counterparts, suggesting that the source of ionization is out of the blobs. Consistent with this, the detailed photoionization models prefer AGN rather than the star-forming origin with a significance of 5.8σ. The estimated BH mass is MBH ∼ 7.2 × 105M⊙ from the MBH–σ* relationship. This work introduces a novel method for detecting the light echo of BHs, potentially extending to intermediate mass, in low-metallicity environments where the traditional BPT diagram fails.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142100977","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}

{"title":"How Rare Are TESS Free-floating Planets?","authors":"Hongjing Yang, 弘靖 杨, Weicheng Zang, 伟呈 臧, Tianjun Gan, 天君 干, Renkun Kuang, 仁昆 匡, Andrew Gould, Shude Mao and 淑德 毛","doi":"10.3847/2041-8213/ad6c3c","DOIUrl":"https://doi.org/10.3847/2041-8213/ad6c3c","url":null,"abstract":"Recently, Kunimoto et al. claimed that a short-lived signal in the Transiting Exoplanet Survey Satellite (TESS) Sector 61 database was possibly caused by a microlensing event with a terrestrial-mass free-floating planet (FFP) lens. In this study, we investigate TESS's ability to detect microlensing FFPs by considering the detailed source information (e.g., distance and radius), the TESS photometric accuracy, and finite-source effects. Using the FFP mass function from microlensing surveys toward the Galactic bulge, we find that only 0.0018 microlensing events are expected to be detected in TESS Sector 61 for the entire planetary mass range. The reported signal is unlikely to be a real microlensing event, which is consistent with the evidence from the long-term Optical Gravitational Lensing Experiment data that the signal was likely due to a stellar flare. By extrapolating our result to fainter stars until T = 16 mag and adopting a possible optimized search algorithm, we find that only ∼1 FFP event can be detected in the entire TESS mission within the first 7 yr. Significant improvements in our understanding of FFPs still require future satellite missions, such as Roman and Earth 2.0, which can detect thousands of FFPs.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142084906","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}

{"title":"Discovery of a Relativistic Stripped-envelope Type Ic-BL Supernova at z = 2.83 with JWST","authors":"M. R. Siebert, C. DeCoursey, D. A. Coulter, M. Engesser, J. D. R. Pierel, A. Rest, E. Egami, M. Shahbandeh, W. Chen, O. D. Fox, Y. Zenati, T. J. Moriya, A. J. Bunker, P. A. Cargile, M. Curti, D. J. Eisenstein, S. Gezari, S. Gomez, M. Guolo, B. D. Johnson, B. A. Joshi, M. Karmen, R. Maiolino, R. M. Quimby, B. Robertson, L. G. Strolger, F. Sun, Q. Wang and T. Wevers","doi":"10.3847/2041-8213/ad6c32","DOIUrl":"https://doi.org/10.3847/2041-8213/ad6c32","url":null,"abstract":"We present James Webb Space Telescope (JWST) NIRCam and NIRSpec observations of a Type Ic supernova (SN Ic) and its host galaxy (JADES-GS+53.13533-27.81457) at z = 2.83. This SN (named SN 2023adta) was identified in deep JWST/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) program. Follow-up observations with JWST/NIRSpec provided a spectroscopic redshift of z = 2.83 and the classification as an SN Ic-BL. The light curve of SN 2023adta matches well with other stripped-envelope SNe, and we find a high peak luminosity, MV = −19.0 ± 0.2 mag, based on the distribution of best-fit SNe. The broad absorption features in its spectrum are consistent with other SNe Ic-BL 1–3 weeks after peak brightness. We measure a Ca ii near-IR triplet expansion velocity of 29,000 ± 2000 km s−1. The host galaxy of SN 2023adta is irregular, and modeling of its spectral energy distribution indicates a metallicity of . This environment is consistent with the population of low-z SNe Ic-BL that prefer lower metallicities relative to other stripped-envelope SNe and track long-duration γ-ray burst environments. We do not identify any γ-ray bursts that are coincident with SN 2023adta. Given the rarity of SNe Ic-BL in the local Universe, the detection of an SN Ic-BL at z = 2.83 could indicate that their rates are enhanced at high redshift.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142084910","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}

{"title":"Ancient Nova Shells of RX Pup Indicate Evolution of Mass Transfer Rate","authors":"Krystian Iłkiewicz, Joanna Mikołajewska, Michael M. Shara, Jacqueline K. Faherty and Simone Scaringi","doi":"10.3847/2041-8213/ad6e5a","DOIUrl":"https://doi.org/10.3847/2041-8213/ad6e5a","url":null,"abstract":"RX Pup is a symbiotic binary that experienced a nova outburst in the 1970s. Here we report a discovery of a ∼1300 yr old nova shell around the system and a possible detection of a ∼7000 yr old nova shell. Together with the nova shell ejected in the 1970s, this makes RX Pup the first system with three nova shells observed. This triad of eruptions suggests a change in the nova recurrence time. The most likely explanation is an alteration in the mass transfer rate attributed to evolutionary changes of the mass donor in the system. Notably, comparative analyses with theoretical models indicate an increase in the average mass transfer rate by a factor of 3 over the past 10,000 yr. This makes RX Pup a unique system, which allows us to probe millennium-scale evolution of mass transfer rates in binary systems.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142084905","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}

{"title":"Extended Shock Breakout and Early Circumstellar Interaction in SN 2024ggi","authors":"Manisha Shrestha, K. Azalee Bostroem, David J. Sand, Griffin Hosseinzadeh, Jennifer E. Andrews, Yize Dong, 一泽 董, Emily Hoang, Daryl Janzen, Jeniveve Pearson, Jacob E. Jencson, M. J. Lundquist, Darshana Mehta, Aravind P. Ravi, Nicolás Meza Retamal, Stefano Valenti, Peter J. Brown, Saurabh W. Jha, Colin Macrie, Brian Hsu, Joseph Farah, D. Andrew Howell, Curtis McCully, Megan Newsome, Estefania Padilla Gonzalez, Craig Pellegrino, Giacomo Terreran, Lindsey Kwok, Nathan Smith, Michaela Schwab, Aidan Martas, Ricardo R. Munoz, Gustavo E. Medina, Ting S. Li, Paula Diaz, Daichi Hiramatsu, Brad E. Tucker, J. C. Wheeler, Xiaofeng Wang, Qian Zhai, Jujia Zhang, Anjasha Gangopadhyay, Yi Yang and Claudia P. Gutiérrez","doi":"10.3847/2041-8213/ad6907","DOIUrl":"https://doi.org/10.3847/2041-8213/ad6907","url":null,"abstract":"We present high-cadence photometric and spectroscopic observations of supernova (SN) 2024ggi, a Type II SN with flash spectroscopy features, which exploded in the nearby galaxy NGC 3621 at ∼7 Mpc. The light-curve evolution over the first 30 hr can be fit by two power-law indices with a break after 22 hr, rising from MV ≈ −12.95 mag at +0.66 day to MV ≈ −17.91 mag after 7 days. In addition, the densely sampled color curve shows a strong blueward evolution over the first few days and then behaves as a normal SN II with a redward evolution as the ejecta cool. Such deviations could be due to interaction with circumstellar material (CSM). Early high- and low-resolution spectra clearly show high-ionization flash features from the first spectrum to +3.42 days after the explosion. From the high-resolution spectra, we calculate the CSM velocity to be 37 ± 4 km s−1. We also see the line strength evolve rapidly from 1.22 to 1.49 days in the earliest high-resolution spectra. Comparison of the low-resolution spectra with CMFGEN models suggests that the pre-explosion mass-loss rate of SN 2024ggi falls in the range of 10−3–10−2M☉ yr−1, which is similar to that derived for SN 2023ixf. However, the rapid temporal evolution of the narrow lines in the spectra of SN 2024ggi (RCSM ∼ 2.7 <b>×</b> 1014 cm) could indicate a smaller spatial extent of the CSM than in SN 2023ixf (RCSM ∼ 5.4 <b>×</b> 1014 cm), which in turn implies a lower total CSM mass for SN 2024ggi.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142084904","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}

{"title":"Extended Cyclotron Resonant Heating of the Turbulent Solar Wind","authors":"Trevor A. Bowen, Ivan Y. Vasko, Stuart D. Bale, Benjamin D. G. Chandran, Alexandros Chasapis, Thierry Dudok de Wit, Alfred Mallet, Michael McManus, Romain Meyrand, Marc Pulupa and Jonathan Squire","doi":"10.3847/2041-8213/ad6b2e","DOIUrl":"https://doi.org/10.3847/2041-8213/ad6b2e","url":null,"abstract":"Circularly polarized, nearly parallel propagating waves are prevalent in the solar wind at ion-kinetic scales. At these scales, the spectrum of turbulent fluctuations in the solar wind steepens, often called the transition range, before flattening at sub-ion scales. Circularly polarized waves have been proposed as a mechanism to couple electromagnetic fluctuations to ion gyromotion, enabling ion-scale dissipation that results in observed ion-scale steepening. Here we study Parker Solar Probe observations of an extended stream of fast solar wind ranging from ∼15 to 55 R⊙. We demonstrate that, throughout the stream, transition range steepening at ion scales is associated with the presence of significant left-handed ion-kinetic-scale waves, which are thought to be ion cyclotron waves. We implement quasilinear theory to compute the rate at which ions are heated via cyclotron resonance with the observed circularly polarized waves given the empirically measured proton velocity distribution functions. We apply the Von Kármán decay law to estimate the turbulent decay of the large-scale fluctuations, which is equal to the turbulent energy cascade rate. We find that the ion cyclotron heating rates are correlated with, and amount to a significant fraction of, the turbulent energy cascade rate, implying that cyclotron heating is an important dissipation mechanism in the solar wind.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142045415","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}

{"title":"Magnetic Fields in Massive Star-forming Regions (MagMaR): Unveiling an Hourglass Magnetic Field in G333.46–0.16 Using ALMA","authors":"Piyali Saha, Patricio Sanhueza, Marco Padovani, Josep M. Girart, Paulo C. Cortés, Kaho Morii, Junhao Liu, Á. Sánchez-Monge, Daniele Galli, Shantanu Basu, Patrick M. Koch, Maria T. Beltrán, Shanghuo Li, Henrik Beuther, Ian W. Stephens, Fumitaka Nakamura, Qizhou Zhang, Wenyu Jiao, M. Fernández-López, Jihye Hwang, Eun Jung Chung, Kate Pattle, Luis A. Zapata, Fengwei Xu, Fernando A. Olguin, Ji-hyun Kang, Janik Karoly, Chi-Yan Law, Jia-Wei Wang, Timea Csengeri, Xing Lu, Yu Cheng, Jongsoo Kim, Spandan Choudhury, Huei-Ru Vivien Chen, Charles L. H. Hull","doi":"10.3847/2041-8213/ad660c","DOIUrl":"https://doi.org/10.3847/2041-8213/ad660c","url":null,"abstract":"The contribution of the magnetic field to the formation of high-mass stars is poorly understood. We report the high angular resolution (∼0.″3, 870 au) map of the magnetic field projected on the plane of the sky (<italic toggle=\"yes\">B</italic>\u0000_POS) toward the high-mass star-forming region G333.46−0.16 (G333), obtained with the Atacama Large Millimeter/submillimeter Array at 1.2 mm as part of the Magnetic fields in Massive star-forming Regions survey. The <italic toggle=\"yes\">B</italic>\u0000_POS morphology found in this region is consistent with a canonical “hourglass” with an embedded flattened envelope in a perpendicular direction, which suggests a dynamically important field. This region is fragmented into two protostars that appear to be gravitationally bound in a stable binary system with a separation of ∼1740 au. Interestingly, by analyzing H¹³CO⁺ (<italic toggle=\"yes\">J</italic> = 3–2) line emission, we find no velocity gradient over the extent of the continuum, which is consistent with a strong field. We model the <italic toggle=\"yes\">B</italic>\u0000_POS, obtaining a marginally supercritical mass-to-flux ratio of 1.43, suggesting an initially strongly magnetized environment. Based on the Davis–Chandrasekhar–Fermi method, the magnetic field strength toward G333 is estimated to be 5.7 mG. The absence of strong rotation and outflows toward the central region of G333 suggests strong magnetic braking, consistent with a highly magnetized environment. Our study shows that despite being a strong regulator, the magnetic energy fails to prevent the process of fragmentation, as revealed by the formation of the two protostars in the central region.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142025956","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}

{"title":"Infrared Spectra of Solid HCN Embedded in Various Molecular Environments for Comparison with the Data Obtained with JWST","authors":"Maksim Ozhiganov, Mikhail Medvedev, Varvara Karteyeva, Ruslan Nakibov, Uliana Sapunova, Vadim Krushinsky, Ksenia Stepanova, Anastasia Tryastsina, Aleksandr Gorkovenko, Gleb Fedoseev and Anton Vasyunin","doi":"10.3847/2041-8213/ad6d5c","DOIUrl":"https://doi.org/10.3847/2041-8213/ad6d5c","url":null,"abstract":"Hydrogen cyanide (HCN) molecules serve as an important tracer for the chemical evolution of elemental nitrogen in the regions of star and planet formation. This is largely explained by the fact that N atoms and N2 molecules are poorly accessible for observation in the radio and infrared (IR) ranges. In turn, gas-phase HCN can be observed at various stages of star formation, including disks around young stars, cometary comas, and atmospheres of the planetary satellites. Despite the large geography of gas-phase observations, an identification of interstellar HCN ice is still lacking. In this work we present a series of IR spectroscopic measurements performed at the new ultrahigh vacuum cryogenic apparatus aiming to facilitate the search for interstellar HCN ice. A series of high-resolution laboratory IR spectra of HCN molecules embedded in the H2O, H2O:NH3, CO, CO2, and CH3OH ices at 10 K temperature is obtained. These interstellar ice analogues aim to simulate the surroundings of HCN molecules by the main constituents of the icy mantles on the surface of the interstellar grains. In addition, the spectra of HCN molecules embedded in the solid C6H6, C5H5N, and C6H5NH2 are obtained to somehow simulate the interaction of HCN molecules with carbonaceous material of the grains rich in polycyclic aromatic hydrocarbons. The acquired laboratory spectroscopic data are compared with the publicly available results of NIRSpec James Webb Space Telescope observations toward quiescent molecular clouds performed by the IceAge team.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142045417","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}

{"title":"Analysis of the Stellar Occultations during the Unprecedented Long-duration Flare","authors":"K. Bicz, R. Falewicz, P. Heinzel, M. Pietras and P. Preś","doi":"10.3847/2041-8213/ad6c06","DOIUrl":"https://doi.org/10.3847/2041-8213/ad6c06","url":null,"abstract":"In strong stellar and solar flares, flare loops typically appear during the decay phase, providing an additional contribution to the flare emission and, possibly, obscuring the flare emission. Superflares, common in active, cool stars, persist mostly from minutes to several hours and alter the star's luminosity across the electromagnetic spectrum. Recent observations of a young main-sequence star reveal a distinctive cool loop arcade forming above the flaring region during a 27 hr superflare event, obscuring the region multiple times. Analysis of these occultations enables the estimation of the arcade's geometry and physical properties. The arcade's size expanded from 0.213 to 0.391 R* at a speed of approximately 3.5 km s−1. The covering structure exhibited a thickness below 12,200 km, with electron densities ranging from 1013 to 1014 cm−3 and temperatures below 7600 K, 6400 K, and 5077 K for successive occultations. Additionally, the flare's maximum emission temperature has to exceed 12,000 K for the occultations to appear. Comparing these parameters with known values from other stars and the Sun suggests the structure's nature as an arcade of cool flare loops. For the first time, we present the physical parameters and the reconstructed geometry of the cool flare loops that obscure the flaring region during the gradual phase of a long-duration flare on a star other than the Sun.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142084907","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}

{"title":"Planet Formation Regulated by Galactic-scale Interstellar Turbulence","authors":"Andrew J. Winter, Myriam Benisty and Sean M. Andrews","doi":"10.3847/2041-8213/ad6d5d","DOIUrl":"https://doi.org/10.3847/2041-8213/ad6d5d","url":null,"abstract":"Planet formation occurs over a few Myr within protoplanetary disks of dust and gas, which are often assumed to evolve in isolation. However, extended gaseous structures have been uncovered around many protoplanetary disks, suggestive of late-stage infall from the interstellar medium (ISM). To quantify the prevalence of late-stage infall, we apply an excursion set formalism to track the local density and relative velocity of the ISM over the disk lifetime. We then combine the theoretical Bondi–Hoyle–Lyttleton (BHL) accretion rate with a simple disk evolution model, anchoring stellar accretion timescales to observational constraints. Disk lifetimes, masses, stellar accretion rates, and gaseous outer radii as a function of stellar mass and age are remarkably well reproduced by our simple model that includes only ISM accretion. We estimate that 20%−70% of disks may be mostly composed of material accreted in the most recent half of their lifetime, suggesting that disk properties are not a direct test of isolated evolution models. Our calculations indicate that BHL accretion can also supply sufficient energy to drive turbulence in the outer regions of protoplanetary disks with viscous αSS ∼ 10−5 to 10−1, although we emphasize that angular momentum transport and particularly accretion onto the star may still be driven by internal processes. Our simple approach can be easily applied to semianalytic models. Our results represent a compelling case for regulation of planet formation by large-scale turbulence, with broad consequences for planet formation theory. This possibility urgently motivates deep observational surveys to confirm or refute our findings.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142084909","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}