Pub Date : 2023-07-21DOI: 10.3847/2041-8213/ace437
Rui Wang, Ying D. Liu, Xiaowei Zhao, Huidong Hu
Small-scale eruptions could play an important role in coronal heating, generation of solar energetic particles (SEPs), and mass source of the solar wind. However, they are poorly observed, and their characteristics, distributions, and origins remain unclear. Here a mini coronal dimming was captured by the recently launched Solar Orbiter spacecraft. The observations indicate that a minifilament eruption results in the dimming and takes away approximately (1.65 ± 0.54) × 1013 g of mass, which also exhibits similar features as the sources of SEP events. The released magnetic free energy is of the order of ∼1027 erg. Our results suggest that weak constraining force makes the flux rope associated with the minifilament easily enter a torus-unstable domain. We discuss that weak magnetic constraints from low-altitude background fields may be a general condition for the quiet-Sun eruptions, which provide a possible mechanism for the transport of coronal material and energy from the lower to the middle or even higher corona.
{"title":"Observations of Mini Coronal Dimmings Caused by Small-scale Eruptions in the Quiet Sun","authors":"Rui Wang, Ying D. Liu, Xiaowei Zhao, Huidong Hu","doi":"10.3847/2041-8213/ace437","DOIUrl":"https://doi.org/10.3847/2041-8213/ace437","url":null,"abstract":"Small-scale eruptions could play an important role in coronal heating, generation of solar energetic particles (SEPs), and mass source of the solar wind. However, they are poorly observed, and their characteristics, distributions, and origins remain unclear. Here a mini coronal dimming was captured by the recently launched Solar Orbiter spacecraft. The observations indicate that a minifilament eruption results in the dimming and takes away approximately (1.65 ± 0.54) × 1013 g of mass, which also exhibits similar features as the sources of SEP events. The released magnetic free energy is of the order of ∼1027 erg. Our results suggest that weak constraining force makes the flux rope associated with the minifilament easily enter a torus-unstable domain. We discuss that weak magnetic constraints from low-altitude background fields may be a general condition for the quiet-Sun eruptions, which provide a possible mechanism for the transport of coronal material and energy from the lower to the middle or even higher corona.","PeriodicalId":179976,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129089665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-19DOI: 10.3847/2041-8213/ace82b
Long Li, S. Zhong, Z. Dai
Whether binary neutron star mergers are the only astrophysical site of rapid neutron-capture process (r-process) nucleosynthesis remains unknown. Collapsars associated with long gamma-ray bursts (GRBs) and hypernovae are promising candidates. Simulations have shown that outflows from collapsar accretion disks can produce enough r-process materials to explain the abundances in the universe. However, there is no observational evidence to confirm this result at present. SN 2020bvc is a broad-lined Type Ic (Ic-BL) supernova (SN) possibly associated with a low-luminosity GRB. Based on semi-analytic SN emission models with and without r-process materials, we perform a fitting to the multiband light curves and photospheric velocities of SN 2020bvc. We find that in a r-process-enriched model the mixing of r-process materials slows down the photospheric recession and therefore matches the velocity evolution better. The fitting results show that r-process materials with mass of ≈0.36 M ⊙ and opacity of ≈4 cm2 g−1 is needed to mix with about half of the SN ejecta. Our fitting results are weakly dependent on the nebular emission. Future statistical analysis of a sample of Type Ic-BL SNe helps us understand the contribution of collapsars to the r-process abundance.
{"title":"Photospheric Velocity Evolution of SN 2020bvc: Signature of r-process Nucleosynthesis from a Collapsar","authors":"Long Li, S. Zhong, Z. Dai","doi":"10.3847/2041-8213/ace82b","DOIUrl":"https://doi.org/10.3847/2041-8213/ace82b","url":null,"abstract":"Whether binary neutron star mergers are the only astrophysical site of rapid neutron-capture process (r-process) nucleosynthesis remains unknown. Collapsars associated with long gamma-ray bursts (GRBs) and hypernovae are promising candidates. Simulations have shown that outflows from collapsar accretion disks can produce enough r-process materials to explain the abundances in the universe. However, there is no observational evidence to confirm this result at present. SN 2020bvc is a broad-lined Type Ic (Ic-BL) supernova (SN) possibly associated with a low-luminosity GRB. Based on semi-analytic SN emission models with and without r-process materials, we perform a fitting to the multiband light curves and photospheric velocities of SN 2020bvc. We find that in a r-process-enriched model the mixing of r-process materials slows down the photospheric recession and therefore matches the velocity evolution better. The fitting results show that r-process materials with mass of ≈0.36 M ⊙ and opacity of ≈4 cm2 g−1 is needed to mix with about half of the SN ejecta. Our fitting results are weakly dependent on the nebular emission. Future statistical analysis of a sample of Type Ic-BL SNe helps us understand the contribution of collapsars to the r-process abundance.","PeriodicalId":179976,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114018131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-12DOI: 10.3847/2041-8213/ace529
L. Flagg, J. Turner, E. Deibert, A. Ridden-Harper, E. D. de Mooij, R. MacDonald, R. Jayawardhana, N. Gibson, Adam B Langeveld, D. Sing
Exoplanet atmosphere studies are often enriched by synergies with brown dwarf analogs. However, many key molecules commonly seen in brown dwarfs have yet to be confirmed in exoplanet atmospheres. An important example is chromium hydride (CrH), which is often used to probe atmospheric temperatures and classify brown dwarfs into spectral types. Recently, tentative evidence for CrH was reported in the low-resolution transmission spectrum of the hot Jupiter WASP-31b. Here, we present high spectral resolution observations of WASP-31b’s transmission spectrum from GRACES/Gemini North and UVES/Very Large Telescope. We detect CrH at 5.6σ confidence, representing the first metal hydride detection in an exoplanet atmosphere at high spectral resolution. Our findings constitute a critical step in understanding the role of metal hydrides in exoplanet atmospheres.
{"title":"ExoGemS Detection of a Metal Hydride in an Exoplanet Atmosphere at High Spectral Resolution","authors":"L. Flagg, J. Turner, E. Deibert, A. Ridden-Harper, E. D. de Mooij, R. MacDonald, R. Jayawardhana, N. Gibson, Adam B Langeveld, D. Sing","doi":"10.3847/2041-8213/ace529","DOIUrl":"https://doi.org/10.3847/2041-8213/ace529","url":null,"abstract":"Exoplanet atmosphere studies are often enriched by synergies with brown dwarf analogs. However, many key molecules commonly seen in brown dwarfs have yet to be confirmed in exoplanet atmospheres. An important example is chromium hydride (CrH), which is often used to probe atmospheric temperatures and classify brown dwarfs into spectral types. Recently, tentative evidence for CrH was reported in the low-resolution transmission spectrum of the hot Jupiter WASP-31b. Here, we present high spectral resolution observations of WASP-31b’s transmission spectrum from GRACES/Gemini North and UVES/Very Large Telescope. We detect CrH at 5.6σ confidence, representing the first metal hydride detection in an exoplanet atmosphere at high spectral resolution. Our findings constitute a critical step in understanding the role of metal hydrides in exoplanet atmospheres.","PeriodicalId":179976,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124771947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-11DOI: 10.3847/2041-8213/ace630
Daniel C. M. Palumbo, G. Wong, A. Chael, Michael D. Johnson
Images of supermassive black hole accretion flows contain features of both curved spacetime and plasma structure. Inferring properties of the spacetime from images requires modeling the plasma properties, and vice versa. The Event Horizon Telescope Collaboration has imaged near-horizon millimeter emission from both Messier 87* (M87*) and Sagittarius A* (Sgr A*) with very long baseline interferometry (VLBI) and has found a preference for magnetically arrested disk (MAD) accretion in each case. MAD accretion enables spacetime measurements through future observations of the photon ring, the image feature composed of near-orbiting photons. The ordered fields and relatively weak Faraday rotation of MADs yield rotationally symmetric polarization when viewed at modest inclination. In this letter, we utilize this symmetry along with parallel transport symmetries to construct a gain-robust interferometric quantity that detects the transition between the weakly lensed accretion flow image and the strongly lensed photon ring. We predict a shift in polarimetric phases on long baselines and demonstrate that the photon rings in M87* and Sgr A* can be unambiguously detected with sensitive, long-baseline measurements. For M87*, we find that photon ring detection in snapshot observations requires ∼1 mJy sensitivity on >15 Gλ baselines at 230 GHz and above, which could be achieved with space-VLBI or higher-frequency ground-based VLBI. For Sgr A*, we find that interstellar scattering inhibits photon ring detectability at 230 GHz, but ∼10 mJy sensitivity on >12 Gλ baselines at 345 GHz is sufficient and is accessible from the ground. For both sources, these sensitivity requirements may be relaxed by repeated observations and averaging.
{"title":"Demonstrating Photon Ring Existence with Single-baseline Polarimetry","authors":"Daniel C. M. Palumbo, G. Wong, A. Chael, Michael D. Johnson","doi":"10.3847/2041-8213/ace630","DOIUrl":"https://doi.org/10.3847/2041-8213/ace630","url":null,"abstract":"Images of supermassive black hole accretion flows contain features of both curved spacetime and plasma structure. Inferring properties of the spacetime from images requires modeling the plasma properties, and vice versa. The Event Horizon Telescope Collaboration has imaged near-horizon millimeter emission from both Messier 87* (M87*) and Sagittarius A* (Sgr A*) with very long baseline interferometry (VLBI) and has found a preference for magnetically arrested disk (MAD) accretion in each case. MAD accretion enables spacetime measurements through future observations of the photon ring, the image feature composed of near-orbiting photons. The ordered fields and relatively weak Faraday rotation of MADs yield rotationally symmetric polarization when viewed at modest inclination. In this letter, we utilize this symmetry along with parallel transport symmetries to construct a gain-robust interferometric quantity that detects the transition between the weakly lensed accretion flow image and the strongly lensed photon ring. We predict a shift in polarimetric phases on long baselines and demonstrate that the photon rings in M87* and Sgr A* can be unambiguously detected with sensitive, long-baseline measurements. For M87*, we find that photon ring detection in snapshot observations requires ∼1 mJy sensitivity on >15 Gλ baselines at 230 GHz and above, which could be achieved with space-VLBI or higher-frequency ground-based VLBI. For Sgr A*, we find that interstellar scattering inhibits photon ring detectability at 230 GHz, but ∼10 mJy sensitivity on >12 Gλ baselines at 345 GHz is sufficient and is accessible from the ground. For both sources, these sensitivity requirements may be relaxed by repeated observations and averaging.","PeriodicalId":179976,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114544252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-10DOI: 10.3847/2041-8213/ace625
Jiazheng Zhu, N. Jiang, Ting-gui Wang, Shifeng Huang, Zheyu Lin, Yibo Wang, Jianguo Wang
We report the discovery of a faint optical tidal disruption event (TDE) in the nearby star-forming galaxy NGC 3799. Identification of the TDE is based on its position at the galaxy nucleus, a light curve declining as t −5/3, a blue continuum with an almost constant blackbody temperature of ∼12,000 K, broad (≈15,000 km s−1) Balmer lines, and characteristic He ii 4686 Å emission. The light curve of AT 2023clx peaked at an absolute magnitude of −17.16 mag in the g band and a maximum blackbody bolometric luminosity of 4.56 × 1042 erg s−1, making it the faintest TDE discovered to date. With a redshift of 0.01107 and a corresponding luminosity distance of 47.8 Mpc, it is also the closest optical TDE ever discovered to the best of our knowledge. Furthermore, our analysis of Swift/XRT observations of AT 2023clx yields a very tight 3σ upper limit of 9.53 × 1039 erg s−1 in the range 0.3–10 keV. AT 2023clx, together with very few other faint TDEs such as AT 2020wey, prove that there are probably a large number of faint TDEs yet to be discovered at higher redshifts, which is consistent with the prediction of luminosity functions (LFs). The upcoming deeper optical time-domain surveys, such as the Legacy Survey of Space and Time and the Wide Field Survey Telescope, will discover more TDEs at even lower luminosities, allowing for a more precise constraint of the low end of the LF.
我们报告在附近的恒星形成星系NGC 3799中发现了一个微弱的光学潮汐破坏事件(TDE)。TDE的识别是基于它在星系核的位置，一个随t - 5/3衰减的光曲线，一个几乎恒定的黑体温度为~ 12,000 K的蓝色连续体，宽(≈15,000 km s - 1)的巴尔默线，以及He ii 4686 Å的特征发射。at2023clx的光曲线在g波段达到绝对星等为- 17.16等的峰值，黑体的最大热光度为4.56 × 1042 erg s - 1，是迄今为止发现的最微弱的TDE。它的红移为0.01107，对应的光度距离为47.8 Mpc，这也是迄今为止发现的最接近我们所知的光学TDE。此外，我们对AT 2023clx的Swift/XRT观测结果的分析在0.3-10 keV范围内得到了9.53 × 1039 erg s−1的非常严格的3σ上限。at2023clx和极少数微弱的tde，如at2020wey，证明在更高的红移上可能有大量的微弱tde尚未被发现，这与光度函数(LFs)的预测是一致的。即将进行的更深入的光学时域巡天，如传统时空巡天和宽视场巡天望远镜，将在更低的光度下发现更多的tde，从而更精确地约束LF的低端。
{"title":"AT 2023clx: The Faintest and Closest Optical Tidal Disruption Event Discovered in Nearby Star-forming Galaxy NGC 3799","authors":"Jiazheng Zhu, N. Jiang, Ting-gui Wang, Shifeng Huang, Zheyu Lin, Yibo Wang, Jianguo Wang","doi":"10.3847/2041-8213/ace625","DOIUrl":"https://doi.org/10.3847/2041-8213/ace625","url":null,"abstract":"We report the discovery of a faint optical tidal disruption event (TDE) in the nearby star-forming galaxy NGC 3799. Identification of the TDE is based on its position at the galaxy nucleus, a light curve declining as t −5/3, a blue continuum with an almost constant blackbody temperature of ∼12,000 K, broad (≈15,000 km s−1) Balmer lines, and characteristic He ii 4686 Å emission. The light curve of AT 2023clx peaked at an absolute magnitude of −17.16 mag in the g band and a maximum blackbody bolometric luminosity of 4.56 × 1042 erg s−1, making it the faintest TDE discovered to date. With a redshift of 0.01107 and a corresponding luminosity distance of 47.8 Mpc, it is also the closest optical TDE ever discovered to the best of our knowledge. Furthermore, our analysis of Swift/XRT observations of AT 2023clx yields a very tight 3σ upper limit of 9.53 × 1039 erg s−1 in the range 0.3–10 keV. AT 2023clx, together with very few other faint TDEs such as AT 2020wey, prove that there are probably a large number of faint TDEs yet to be discovered at higher redshifts, which is consistent with the prediction of luminosity functions (LFs). The upcoming deeper optical time-domain surveys, such as the Legacy Survey of Space and Time and the Wide Field Survey Telescope, will discover more TDEs at even lower luminosities, allowing for a more precise constraint of the low end of the LF.","PeriodicalId":179976,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125810835","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-10DOI: 10.3847/2041-8213/aceda5
Angelo Ricarte, R. Narayan, B. Curd
A spinning black hole (BH) accreting from a disk of strongly magnetized plasma via a magnetically arrested disk is known to produce an efficient electromagnetic jet powered by the BH’s spin energy. We present general relativistic radiative magnetohydrodynamic simulations of magnetically arrested systems covering a range of sub- to super-Eddington accretion rates. Using the numerical results from these simulations, we develop formulae to describe the magnetization, jet efficiency, and spin evolution of an accreting BH as a function of its spin and accretion rate. A BH with near-Eddington accretion experiences a mild degree of spin-down because of angular momentum loss through the jet, leading to an equilibrium spin of 0.8 rather than 1.0 at the Eddington limit. As the accretion rate increases above Eddington, the spin-down effect becomes progressively stronger, ultimately converging on previous predictions based on nonradiative simulations. In particular, spin evolution drives highly super-Eddington systems toward a BH spin near zero. The formulae developed in this letter may be applied to galaxy- and cosmological-scale simulations that include BHs. If magnetically arrested disk accretion is common among supermassive BHs, the present results have broad implications for active galactic nucleus feedback and cosmological spin evolution.
{"title":"Recipes for Jet Feedback and Spin Evolution of Black Holes with Strongly Magnetized Super-Eddington Accretion Disks","authors":"Angelo Ricarte, R. Narayan, B. Curd","doi":"10.3847/2041-8213/aceda5","DOIUrl":"https://doi.org/10.3847/2041-8213/aceda5","url":null,"abstract":"A spinning black hole (BH) accreting from a disk of strongly magnetized plasma via a magnetically arrested disk is known to produce an efficient electromagnetic jet powered by the BH’s spin energy. We present general relativistic radiative magnetohydrodynamic simulations of magnetically arrested systems covering a range of sub- to super-Eddington accretion rates. Using the numerical results from these simulations, we develop formulae to describe the magnetization, jet efficiency, and spin evolution of an accreting BH as a function of its spin and accretion rate. A BH with near-Eddington accretion experiences a mild degree of spin-down because of angular momentum loss through the jet, leading to an equilibrium spin of 0.8 rather than 1.0 at the Eddington limit. As the accretion rate increases above Eddington, the spin-down effect becomes progressively stronger, ultimately converging on previous predictions based on nonradiative simulations. In particular, spin evolution drives highly super-Eddington systems toward a BH spin near zero. The formulae developed in this letter may be applied to galaxy- and cosmological-scale simulations that include BHs. If magnetically arrested disk accretion is common among supermassive BHs, the present results have broad implications for active galactic nucleus feedback and cosmological spin evolution.","PeriodicalId":179976,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126394753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-06DOI: 10.3847/2041-8213/acf21d
S. Dichiara, D. Tsang, E. Troja, D. Neill, J. Norris, Y.-H. Yang
GRB 230307A is an extremely bright long-duration GRB with an observed gamma-ray fluence of ≳3 × 10−3 erg cm−2 (10–1000 keV), second only to GRB 221009A. Despite its long duration, it is possibly associated with a kilonova, thus resembling the case of GRB 211211A. In analogy with GRB 211211A, we distinguish three phases in the prompt gamma-ray emission of GRB 230307A: an initial short duration, spectrally soft emission; a main long duration, spectrally hard burst; and a temporally extended and spectrally soft tail. We interpret the initial soft pulse as a bright precursor to the main burst and compare its properties with models of precursors from compact binary mergers. We find that to explain the brightness of GRB 230307A, a magnetar-like (≳1015 G) magnetic field should be retained by the progenitor neutron star. Alternatively, in the postmerger scenario, the luminous precursor could point to the formation of a rapidly rotating massive neutron star.
{"title":"A Luminous Precursor in the Extremely Bright GRB 230307A","authors":"S. Dichiara, D. Tsang, E. Troja, D. Neill, J. Norris, Y.-H. Yang","doi":"10.3847/2041-8213/acf21d","DOIUrl":"https://doi.org/10.3847/2041-8213/acf21d","url":null,"abstract":"GRB 230307A is an extremely bright long-duration GRB with an observed gamma-ray fluence of ≳3 × 10−3 erg cm−2 (10–1000 keV), second only to GRB 221009A. Despite its long duration, it is possibly associated with a kilonova, thus resembling the case of GRB 211211A. In analogy with GRB 211211A, we distinguish three phases in the prompt gamma-ray emission of GRB 230307A: an initial short duration, spectrally soft emission; a main long duration, spectrally hard burst; and a temporally extended and spectrally soft tail. We interpret the initial soft pulse as a bright precursor to the main burst and compare its properties with models of precursors from compact binary mergers. We find that to explain the brightness of GRB 230307A, a magnetar-like (≳1015 G) magnetic field should be retained by the progenitor neutron star. Alternatively, in the postmerger scenario, the luminous precursor could point to the formation of a rapidly rotating massive neutron star.","PeriodicalId":179976,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123404557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-06DOI: 10.3847/2041-8213/acf1a0
M. Sikora, A. Zdziarski
We propose a model explaining the origin of transient/episodic jets in black hole X-ray binaries, in which they are caused by transitions from a collimated, strongly magnetized jet to a wide, uncollimated outflow. The change occurs when the accretion flow leaves the magnetically choked state due to an increase of the accretion rate for a weakly varying magnetic flux. The formed powerful jet then detaches from its base, and propagates as a discrete ejection. The uncollimated outflow then produces a relativistic plasma that fills the surroundings of the black hole, contributing to the formation of a low-density cavity. While the pressure in the cavity is in equilibrium with the surrounding interstellar medium (ISM), its inertia is orders of magnitude lower than that of the ISM. This implies that the plasma cannot efficiently decelerate the ejecta, explaining most of the observations. The modest deceleration within the cavities observed in some cases can then be due to the presence of clouds and/or filaments, forming a wide transition zone between the cavity and the ISM.
{"title":"Formation and Evolution of Transient Jets and Their Cavities in Black Hole X-Ray Binaries","authors":"M. Sikora, A. Zdziarski","doi":"10.3847/2041-8213/acf1a0","DOIUrl":"https://doi.org/10.3847/2041-8213/acf1a0","url":null,"abstract":"We propose a model explaining the origin of transient/episodic jets in black hole X-ray binaries, in which they are caused by transitions from a collimated, strongly magnetized jet to a wide, uncollimated outflow. The change occurs when the accretion flow leaves the magnetically choked state due to an increase of the accretion rate for a weakly varying magnetic flux. The formed powerful jet then detaches from its base, and propagates as a discrete ejection. The uncollimated outflow then produces a relativistic plasma that fills the surroundings of the black hole, contributing to the formation of a low-density cavity. While the pressure in the cavity is in equilibrium with the surrounding interstellar medium (ISM), its inertia is orders of magnitude lower than that of the ISM. This implies that the plasma cannot efficiently decelerate the ejecta, explaining most of the observations. The modest deceleration within the cavities observed in some cases can then be due to the presence of clouds and/or filaments, forming a wide transition zone between the cavity and the ISM.","PeriodicalId":179976,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114446024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-05DOI: 10.3847/2041-8213/acf0ba
M. Nicholl, S. Srivastav, M. Fulton, S. Gomez, M. Huber, S. Oates, P. Ramsden, L. Rhodes, S. Smartt, K. Smith, A. Aamer, J. Anderson, F. Bauer, E. Berger, T. D. de Boer, K. Chambers, P. Charalampopoulos, T.-W. Chen, R. Fender, M. Fraser, H. Gao, D. Green, L. Galbany, B. Gompertz, M. Gromadzki, C. P. Guti'errez, D. Howell, C. Inserra, P. Jonker, M. Kopsacheili, T. Lowe, E. Magnier, C. McCully, S. McGee, T. Moore, T. Müller-Bravo, M. Newsome, E. P. Gonzalez, C. Pellegrino, T. Pessi, M. Pursiainen, A. Rest, E. Ridley, B. Shappee, X. Sheng, G. Smith, G. Terreran, M. Tucker, J. Vink'o, R. Wainscoat, P. Wiseman, D. Young
We present the discovery and extensive follow-up of a remarkable fast-evolving optical transient, AT 2022aedm, detected by the Asteroid Terrestrial impact Last Alert Survey (ATLAS). In the ATLAS o band, AT 2022aedm exhibited a rise time of 9 ± 1 days, reaching a luminous peak with M g ≈ −22 mag. It faded by 2 mag in the g band during the next 15 days. These timescales are consistent with other rapidly evolving transients, though the luminosity is extreme. Most surprisingly, the host galaxy is a massive elliptical with negligible current star formation. Radio and X-ray observations rule out a relativistic AT 2018cow–like explosion. A spectrum in the first few days after explosion showed short-lived He ii emission resembling young core-collapse supernovae, but obvious broad supernova features never developed; later spectra showed only a fast-cooling continuum and narrow, blueshifted absorption lines, possibly arising in a wind with v ≈ 2700 km s−1. We identify two further transients in the literature (Dougie in particular, as well as AT 2020bot) that share similarities in their luminosities, timescales, color evolution, and largely featureless spectra and propose that these may constitute a new class of transients: luminous fast coolers. All three events occurred in passive galaxies at offsets of ∼4–10 kpc from the nucleus, posing a challenge for progenitor models involving massive stars or black holes. The light curves and spectra appear to be consistent with shock breakout emission, though this mechanism is usually associated with core-collapse supernovae. The encounter of a star with a stellar-mass black hole may provide a promising alternative explanation.
我们提出了一个显著的快速发展的光学瞬态，at2022aedm的发现和广泛的后续研究，由小行星地球撞击最后警报调查(ATLAS)检测到。在atlas0波段，at2022aedm的上升时间为9±1天，达到M g≈−22等的发光峰值，在接下来的15天内，它在g波段衰减了2等。这些时间尺度与其他快速演变的瞬态相一致，尽管亮度是极端的。最令人惊讶的是，宿主星系是一个巨大的椭圆星系，目前的恒星形成可以忽略不计。射电和x射线观测排除了相对论性的AT 2018cow式爆炸。爆炸后最初几天的光谱显示出短暂的He ii发射，类似于年轻的核心坍缩超新星，但没有明显的广泛的超新星特征;后来的光谱显示只有一个快速冷却的连续体和窄的蓝移吸收线，可能是在v≈2700 km s−1的风中产生的。我们在文献中确定了两个进一步的瞬态(特别是Dougie，以及AT 2020bot)，它们在光度，时间尺度，颜色演变和大部分无特征光谱方面具有相似性，并提出这些可能构成一类新的瞬态:发光快速冷却器。这三个事件都发生在被动星系中，距离原子核的偏移量为~ 4 - 10kpc，这对涉及大质量恒星或黑洞的祖星系模型提出了挑战。光曲线和光谱似乎与激波爆发发射一致，尽管这种机制通常与核心坍缩超新星有关。恒星与恒星质量黑洞的相遇可能提供另一种有希望的解释。
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Pub Date : 2023-07-04DOI: 10.3847/2041-8213/ace3c0
F. Aharonian, F. Benkhali, J. Aschersleben, H. Ashkar, Michael Backes, V. B. Martins, J. Barnard, R. Batzofin, Y. Becherini, D. Berge, K. Bernloehr, B. Bi, M. D. B. Lavergne, M. Boettcher, C. Boisson, J. Bolmont, J. Borowska, M. Bouyahiaoui, F. Bradascio, M. Breuhaus, R. Brose, A. Brown, F. Brun, B. Bruno, T. Bulik, C. Burger-Scheidlin, S. Caroff, S. Casanova, R. Cecil, J. Celić, M. Cerruti, T. Chand, S. Chandra, A. Chen, J. Chibueze, O. Chibueze, G. Cotter, J. D. Mbarubucyeye, I. Davids, A. Djannati-Atai, A. Dmytriiev, V. Doroshenko, K. Egberts, S. Einecke, J. Ernenwein, S. Fegan, G. Fontaine, M. Fuessling, S. Funk, S. Gabici, S. Ghafourizadeh, G. Giavitto, D. Glawion, J. Glicenstein, P. Goswami, G. Grolleron, L. Haerer, W. Hofmann, T. Holch, M. Holler, D. Horns, M. Jamrozy, F. Jankowsky, V. Joshi, I. Jung-Richardt, E. Kasai, K. Katarzyski, R. Khatoon, B. Khélifi, W. Klu'zniak, N. Komin, K. Kosack, D. Kostunin, R. G. Lang, S. L. Stum, F. Leitl, A. Lemière, J. Lenain, F. Leuschner, A. Luashvili, J. Mackey
In 2021 July, PKS 1510−089 exhibited a significant flux drop in the high-energy γ-ray (by a factor 10) and optical (by a factor 5) bands and remained in this low state throughout 2022. Similarly, the optical polarization in the source vanished, resulting in the optical spectrum being fully explained through the steady flux of the accretion disk and the broad-line region. Unlike the aforementioned bands, the very-high-energy γ-ray and X-ray fluxes did not exhibit a significant flux drop from year to year. This suggests that the steady-state very-high-energy γ-ray and X-ray fluxes originate from a different emission region than the vanished parts of the high-energy γ-ray and optical jet fluxes. The latter component has disappeared through either a swing of the jet away from the line of sight or a significant drop in the photon production efficiency of the jet close to the black hole. Either change could become visible in high-resolution radio images.
{"title":"The Vanishing of the Primary Emission Region in PKS 1510–089","authors":"F. Aharonian, F. Benkhali, J. Aschersleben, H. Ashkar, Michael Backes, V. B. Martins, J. Barnard, R. Batzofin, Y. Becherini, D. Berge, K. Bernloehr, B. Bi, M. D. B. Lavergne, M. Boettcher, C. Boisson, J. Bolmont, J. Borowska, M. Bouyahiaoui, F. Bradascio, M. Breuhaus, R. Brose, A. Brown, F. Brun, B. Bruno, T. Bulik, C. Burger-Scheidlin, S. Caroff, S. Casanova, R. Cecil, J. Celić, M. Cerruti, T. Chand, S. Chandra, A. Chen, J. Chibueze, O. Chibueze, G. Cotter, J. D. Mbarubucyeye, I. Davids, A. Djannati-Atai, A. Dmytriiev, V. Doroshenko, K. Egberts, S. Einecke, J. Ernenwein, S. Fegan, G. Fontaine, M. Fuessling, S. Funk, S. Gabici, S. Ghafourizadeh, G. Giavitto, D. Glawion, J. Glicenstein, P. Goswami, G. Grolleron, L. Haerer, W. Hofmann, T. Holch, M. Holler, D. Horns, M. Jamrozy, F. Jankowsky, V. Joshi, I. Jung-Richardt, E. Kasai, K. Katarzyski, R. Khatoon, B. Khélifi, W. Klu'zniak, N. Komin, K. Kosack, D. Kostunin, R. G. Lang, S. L. Stum, F. Leitl, A. Lemière, J. Lenain, F. Leuschner, A. Luashvili, J. Mackey","doi":"10.3847/2041-8213/ace3c0","DOIUrl":"https://doi.org/10.3847/2041-8213/ace3c0","url":null,"abstract":"In 2021 July, PKS 1510−089 exhibited a significant flux drop in the high-energy γ-ray (by a factor 10) and optical (by a factor 5) bands and remained in this low state throughout 2022. Similarly, the optical polarization in the source vanished, resulting in the optical spectrum being fully explained through the steady flux of the accretion disk and the broad-line region. Unlike the aforementioned bands, the very-high-energy γ-ray and X-ray fluxes did not exhibit a significant flux drop from year to year. This suggests that the steady-state very-high-energy γ-ray and X-ray fluxes originate from a different emission region than the vanished parts of the high-energy γ-ray and optical jet fluxes. The latter component has disappeared through either a swing of the jet away from the line of sight or a significant drop in the photon production efficiency of the jet close to the black hole. Either change could become visible in high-resolution radio images.","PeriodicalId":179976,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133302510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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