Pub Date : 2025-01-20DOI: 10.3847/1538-4357/ad9918
A. Maragkoudakis, C. Boersma, P. Temi, J. D. Bregman, L. J. Allamandola, V. J. Esposito, A. Ricca and E. Peeters
We have conducted a sensitivity analysis on the mid-infrared spectral decomposition of galaxies and the modeling of the polycyclic aromatic hydrocarbon (PAH) emission spectrum with the NASA Ames PAH Infrared Spectroscopic Database (PAHdb) to assess the variance on the average galaxy PAH population properties under a grid of different modeling parameters. We find that the short-low and short-low+long-low Spitzer-IRS decomposition with PAHFIT provides consistent modeling and recovery of the 5–15 μm PAH emission spectrum. For PAHdb modeling, application of a redshift to the calculated spectra to account for anharmonic effects introduces a 15%–20% variance on the derived parameters, while its absence improves the fits by ∼13%. The 4.00-α release of PAHdb achieves the complete modeling of the 6–15 μm PAH spectrum, including the full 6.2 μm band, improving the average fitting uncertainty by a factor of 2. The optimal PAHdb modeling configuration requires selection of pure PAHs without applying a redshift to the bands. Although quantitatively the PAHdb-derived parameters change under different modeling configurations or database versions, their variation follows a linear scaling, with previously reported trends remaining qualitatively valid. PAHdb modeling of JWST observations, and JWST observations smoothed and resampled to the Spitzer-IRS resolution and dispersion have consistent PAHdb derived parameters. Decomposition with different codes, such as PAHFIT and CAFE, produce PAH emission spectra with noticeable variation in the 11–15 μm region, driving a ∼7% difference in the neutral PAH fraction under PAHdb modeling. A new library of galaxy PAH emission templates is delivered to be utilized in galaxy spectral energy distribution modeling.
{"title":"A Sensitivity Analysis of the Modeling of Polycyclic Aromatic Hydrocarbon Emission in Galaxies","authors":"A. Maragkoudakis, C. Boersma, P. Temi, J. D. Bregman, L. J. Allamandola, V. J. Esposito, A. Ricca and E. Peeters","doi":"10.3847/1538-4357/ad9918","DOIUrl":"https://doi.org/10.3847/1538-4357/ad9918","url":null,"abstract":"We have conducted a sensitivity analysis on the mid-infrared spectral decomposition of galaxies and the modeling of the polycyclic aromatic hydrocarbon (PAH) emission spectrum with the NASA Ames PAH Infrared Spectroscopic Database (PAHdb) to assess the variance on the average galaxy PAH population properties under a grid of different modeling parameters. We find that the short-low and short-low+long-low Spitzer-IRS decomposition with PAHFIT provides consistent modeling and recovery of the 5–15 μm PAH emission spectrum. For PAHdb modeling, application of a redshift to the calculated spectra to account for anharmonic effects introduces a 15%–20% variance on the derived parameters, while its absence improves the fits by ∼13%. The 4.00-α release of PAHdb achieves the complete modeling of the 6–15 μm PAH spectrum, including the full 6.2 μm band, improving the average fitting uncertainty by a factor of 2. The optimal PAHdb modeling configuration requires selection of pure PAHs without applying a redshift to the bands. Although quantitatively the PAHdb-derived parameters change under different modeling configurations or database versions, their variation follows a linear scaling, with previously reported trends remaining qualitatively valid. PAHdb modeling of JWST observations, and JWST observations smoothed and resampled to the Spitzer-IRS resolution and dispersion have consistent PAHdb derived parameters. Decomposition with different codes, such as PAHFIT and CAFE, produce PAH emission spectra with noticeable variation in the 11–15 μm region, driving a ∼7% difference in the neutral PAH fraction under PAHdb modeling. A new library of galaxy PAH emission templates is delivered to be utilized in galaxy spectral energy distribution modeling.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142990063","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 : 2025-01-20DOI: 10.3847/1538-4357/ad9aa2
Takahiro Morishita, Massimo Stiavelli, Stefan Schuldt and Claudio Grillo
We report JWST/NIRSpec observations of a star-forming galaxy at z = 2.76, MACS J1149-WR1. We securely detect two temperature-sensitive auroral lines, [S iii] 6312 (7.4σ) and [O ii] 7320+7331 doublets (10σ), and tentatively [n ii] 5755 (2.3σ) for the first time in an individual galaxy at z > 1. We perform a detailed analysis of its interstellar media (ISM), and derive electron temperatures, various heavy element abundances (O/H, N/O, S/O, and Ar/O) in the hot ionized region, and the neutral fraction in the warm ionized region. MACS J1149-WR1 shows a broad feature at the wavelength of He ii 4686, which consists of a broad (∼1000 km s−1), blueshifted (∼−110 km s−1) line component. Taken together with its mildly elevated N/O abundance, we conclude that MACS J1149-WR1 is experiencing a young starburst (≲10 Myr), likely hosting a large number of Wolf–Rayet (W-R) stars. None of its spectral features support the presence of active galactic nuclei, including (i) the absence of broad components and velocity shifts in hydrogen recombination lines, (ii) low [Fe ii]1.257 μm/Paβ ratio, and (iii) the absence of high-ionization lines. Our analysis using He i lines reveals a higher electron temperature and a higher attenuation value, indicating that He i may probe a smaller spatial scale than H i, presumably the region dominated by the aforementioned W-R stars. The star formation rates derived from various He i lines broadly agree with those from hydrogen recombination lines. We thus advocate that He i can be an excellent, independent probe of multiphase ISM in the era of JWST.
{"title":"Dissecting the Interstellar Media of a Wolf–Rayet Galaxy at z = 2.76","authors":"Takahiro Morishita, Massimo Stiavelli, Stefan Schuldt and Claudio Grillo","doi":"10.3847/1538-4357/ad9aa2","DOIUrl":"https://doi.org/10.3847/1538-4357/ad9aa2","url":null,"abstract":"We report JWST/NIRSpec observations of a star-forming galaxy at z = 2.76, MACS J1149-WR1. We securely detect two temperature-sensitive auroral lines, [S iii] 6312 (7.4σ) and [O ii] 7320+7331 doublets (10σ), and tentatively [n ii] 5755 (2.3σ) for the first time in an individual galaxy at z > 1. We perform a detailed analysis of its interstellar media (ISM), and derive electron temperatures, various heavy element abundances (O/H, N/O, S/O, and Ar/O) in the hot ionized region, and the neutral fraction in the warm ionized region. MACS J1149-WR1 shows a broad feature at the wavelength of He ii 4686, which consists of a broad (∼1000 km s−1), blueshifted (∼−110 km s−1) line component. Taken together with its mildly elevated N/O abundance, we conclude that MACS J1149-WR1 is experiencing a young starburst (≲10 Myr), likely hosting a large number of Wolf–Rayet (W-R) stars. None of its spectral features support the presence of active galactic nuclei, including (i) the absence of broad components and velocity shifts in hydrogen recombination lines, (ii) low [Fe ii]1.257 μm/Paβ ratio, and (iii) the absence of high-ionization lines. Our analysis using He i lines reveals a higher electron temperature and a higher attenuation value, indicating that He i may probe a smaller spatial scale than H i, presumably the region dominated by the aforementioned W-R stars. The star formation rates derived from various He i lines broadly agree with those from hydrogen recombination lines. We thus advocate that He i can be an excellent, independent probe of multiphase ISM in the era of JWST.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142990068","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 : 2025-01-20DOI: 10.3847/1538-4357/ad99d5
Avery Kiihne, Sabrina M. Appel, Blakesley Burkhart, Vadim A. Semenov and Christoph Federrath
We use a suite of 3D simulations of star-forming molecular clouds, with and without stellar feedback and magnetic fields, to investigate the effectiveness of different fitting methods for volume and column density probability distribution functions (PDFs). The first method fits a piecewise lognormal and power-law (PL) function to recover PDF parameters such as the PL slope and transition density. The second method fits a polynomial spline function and examines the first and second derivatives of the spline to determine the PL slope and the functional transition density. The first PL (set by the transition between lognormal and PL function) can also be visualized in the derivatives directly. In general, the two methods produce fits that agree reasonably well for volume density but vary for column density, likely due to the increased statistical noise in the column density PDFs as compared to the volume density PDFs. We test a well-known conversion for estimating volume density PL slopes from column density slopes and find that the spline method produces a better match (χ2 of 3.34 versus χ2 of 5.92), albeit with a significant scatter. Ultimately, we recommend the use of both fitting methods on column density data to mitigate the effects of noise.
{"title":"Fitting Methods for Probability Distribution Functions in Turbulent Star-forming Clouds","authors":"Avery Kiihne, Sabrina M. Appel, Blakesley Burkhart, Vadim A. Semenov and Christoph Federrath","doi":"10.3847/1538-4357/ad99d5","DOIUrl":"https://doi.org/10.3847/1538-4357/ad99d5","url":null,"abstract":"We use a suite of 3D simulations of star-forming molecular clouds, with and without stellar feedback and magnetic fields, to investigate the effectiveness of different fitting methods for volume and column density probability distribution functions (PDFs). The first method fits a piecewise lognormal and power-law (PL) function to recover PDF parameters such as the PL slope and transition density. The second method fits a polynomial spline function and examines the first and second derivatives of the spline to determine the PL slope and the functional transition density. The first PL (set by the transition between lognormal and PL function) can also be visualized in the derivatives directly. In general, the two methods produce fits that agree reasonably well for volume density but vary for column density, likely due to the increased statistical noise in the column density PDFs as compared to the volume density PDFs. We test a well-known conversion for estimating volume density PL slopes from column density slopes and find that the spline method produces a better match (χ2 of 3.34 versus χ2 of 5.92), albeit with a significant scatter. Ultimately, we recommend the use of both fitting methods on column density data to mitigate the effects of noise.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"140 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142990117","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 : 2025-01-20DOI: 10.3847/1538-4357/ad9f61
James G. Rogers, Caroline Dorn, Vivasvaan Aditya Raj, Hilke E. Schlichting and Edward D. Young
Super-Earths are highly irradiated, small planets with bulk densities approximately consistent with Earth. We construct combined interior atmosphere models of super-Earths that trace the partitioning of water throughout a planet, including an iron-rich core, silicate-rich mantle, and steam atmosphere. We compare these models with exoplanet observations to infer a 1σ upper limit on the total water mass fraction of ≲3% at the population level. We consider end-member scenarios that may change this value, including the efficiency of mantle outgassing, escape of high mean molecular weight atmospheres, and increased iron core mass fractions. Although our constraints are agnostic as to the origin of water, we show that our upper limits are consistent with its production via chemical reactions of primordial hydrogen-dominated atmospheres with magma oceans. This mechanism has also been hypothesised to explain Earth's water content, possibly pointing to a unified channel for the origins of water on small terrestrial planets.
{"title":"Most Super-Earths Have Less Than 3% Water","authors":"James G. Rogers, Caroline Dorn, Vivasvaan Aditya Raj, Hilke E. Schlichting and Edward D. Young","doi":"10.3847/1538-4357/ad9f61","DOIUrl":"https://doi.org/10.3847/1538-4357/ad9f61","url":null,"abstract":"Super-Earths are highly irradiated, small planets with bulk densities approximately consistent with Earth. We construct combined interior atmosphere models of super-Earths that trace the partitioning of water throughout a planet, including an iron-rich core, silicate-rich mantle, and steam atmosphere. We compare these models with exoplanet observations to infer a 1σ upper limit on the total water mass fraction of ≲3% at the population level. We consider end-member scenarios that may change this value, including the efficiency of mantle outgassing, escape of high mean molecular weight atmospheres, and increased iron core mass fractions. Although our constraints are agnostic as to the origin of water, we show that our upper limits are consistent with its production via chemical reactions of primordial hydrogen-dominated atmospheres with magma oceans. This mechanism has also been hypothesised to explain Earth's water content, possibly pointing to a unified channel for the origins of water on small terrestrial planets.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142990202","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 : 2025-01-20DOI: 10.3847/1538-4357/ada282
Keiji Hayashi, Chin-Chun Wu and Kan Liou
The methodology of a new magnetohydrodynamics simulation model of the propagation of coronal mass ejections (CMEs) in the near-Sun solar wind region at 2.5R⊙ ≥ r ≥ 19R⊙ is presented. The simulation model first determines the steady state of the transonic/Alfvénic solar wind with the characteristic-based inner boundary treatment for the middle of the corona at r = 2.5R⊙ (K. Hayashi et al. 2023). To determine the numerical perturbation on the 2.5 R⊙inner boundary surface, a kinetic self-similar model with a torus-shaped magnetic-field rope and a spherically symmetric plasma structure translating and expanding at the constant speed (named TICK model) is developed. A solar-wind MHD model (C.-C. Wu et al. 2020b) traces the temporal evolution of the injected CME through the inner boundary surface. We conducted test simulations with various choices of plasma density and temperature. The test simulation results show that the injected CME, particularly its internal magnetic structure, can be substantially altered through the interactions with the preexisting slow and dense ambient solar wind at the early phase of the propagation in the near-Sun region. The propagation speed of the discontinuity front is found to be dependent on the plasma parameters of the CME perturbation. Therefore, for better simulating the propagation of the CME, it is important for the CME models to include the nonlinear MHD interactions in the subsonic/Alfvénic regions.
{"title":"A Magnetohydrodynamics Simulation of Coronal Mass Ejections in the Upper Corona at 2.5R ⊙ ≤ r ≤ 19R ⊙","authors":"Keiji Hayashi, Chin-Chun Wu and Kan Liou","doi":"10.3847/1538-4357/ada282","DOIUrl":"https://doi.org/10.3847/1538-4357/ada282","url":null,"abstract":"The methodology of a new magnetohydrodynamics simulation model of the propagation of coronal mass ejections (CMEs) in the near-Sun solar wind region at 2.5R⊙ ≥ r ≥ 19R⊙ is presented. The simulation model first determines the steady state of the transonic/Alfvénic solar wind with the characteristic-based inner boundary treatment for the middle of the corona at r = 2.5R⊙ (K. Hayashi et al. 2023). To determine the numerical perturbation on the 2.5 R⊙inner boundary surface, a kinetic self-similar model with a torus-shaped magnetic-field rope and a spherically symmetric plasma structure translating and expanding at the constant speed (named TICK model) is developed. A solar-wind MHD model (C.-C. Wu et al. 2020b) traces the temporal evolution of the injected CME through the inner boundary surface. We conducted test simulations with various choices of plasma density and temperature. The test simulation results show that the injected CME, particularly its internal magnetic structure, can be substantially altered through the interactions with the preexisting slow and dense ambient solar wind at the early phase of the propagation in the near-Sun region. The propagation speed of the discontinuity front is found to be dependent on the plasma parameters of the CME perturbation. Therefore, for better simulating the propagation of the CME, it is important for the CME models to include the nonlinear MHD interactions in the subsonic/Alfvénic regions.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142990121","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 : 2025-01-20DOI: 10.3847/1538-4357/ad900f
Antoniu Fodor, Taylor Tomko, Mary Braun, Anne M. Medling, Thomas M. Johnson, Alexander Thompson, Victor D. Johnston, Matthew Newhouse, Yuanze Luo, K. Decker French, Justin A. Otter, Akshat Tripathi, Margaret E. Verrico, Katherine Alatalo, Kate Rowlands and Timothy Heckman
Shocked POstarburst Galaxies (SPOGs) exhibit both emission lines suggestive of shock-heated gas and poststarburst-like stellar absorption, resulting in a unique subset for galaxy evolution studies. We have observed 77 galaxies that fulfilled the SPOG criteria selection using the DeVeny Spectrograph on the Lowell Discovery Telescope. Our long-slit minor axis spectra detect Hα and [O III] in some SPOGs out to 6 kpc above the galactic plane. We find extraplanar ionized gas in 31 targets of our sample overall. Using their internal and external kinematics, we argue that 22 galaxies host outflows with ionized gas masses ranging from 102M⊙ to 105M⊙. The rest are likely extended diffuse ionized gas. A positive correlation exists between active galactic nuclei (AGN) luminosity and the extraplanar gas extent, velocity dispersion, and mass—suggesting that the AGN may indeed drive the outflows detected in AGN hosts. The low masses of the extraplanar gas suggest that these outflows are not depleting each galaxy’s gas reserves. The outflows, therefore, are not likely a significant quenching mechanism in these SPOGs.
{"title":"Shocked POststarburst Galaxy Survey. IV. Outflows in Shocked Poststarburst Galaxies Are Not Responsible for Quenching","authors":"Antoniu Fodor, Taylor Tomko, Mary Braun, Anne M. Medling, Thomas M. Johnson, Alexander Thompson, Victor D. Johnston, Matthew Newhouse, Yuanze Luo, K. Decker French, Justin A. Otter, Akshat Tripathi, Margaret E. Verrico, Katherine Alatalo, Kate Rowlands and Timothy Heckman","doi":"10.3847/1538-4357/ad900f","DOIUrl":"https://doi.org/10.3847/1538-4357/ad900f","url":null,"abstract":"Shocked POstarburst Galaxies (SPOGs) exhibit both emission lines suggestive of shock-heated gas and poststarburst-like stellar absorption, resulting in a unique subset for galaxy evolution studies. We have observed 77 galaxies that fulfilled the SPOG criteria selection using the DeVeny Spectrograph on the Lowell Discovery Telescope. Our long-slit minor axis spectra detect Hα and [O III] in some SPOGs out to 6 kpc above the galactic plane. We find extraplanar ionized gas in 31 targets of our sample overall. Using their internal and external kinematics, we argue that 22 galaxies host outflows with ionized gas masses ranging from 102M⊙ to 105M⊙. The rest are likely extended diffuse ionized gas. A positive correlation exists between active galactic nuclei (AGN) luminosity and the extraplanar gas extent, velocity dispersion, and mass—suggesting that the AGN may indeed drive the outflows detected in AGN hosts. The low masses of the extraplanar gas suggest that these outflows are not depleting each galaxy’s gas reserves. The outflows, therefore, are not likely a significant quenching mechanism in these SPOGs.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"101 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142990062","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 : 2025-01-20DOI: 10.3847/1538-4357/ad91b9
Yuto Kajikiya, Kosuke Namekata, Yuta Notsu, Hiroyuki Maehara, Bunei Sato and Daisaku Nogami
M dwarfs show frequent flares and associated coronal mass ejections (CMEs) may significantly impact close-in habitable planets. M dwarf flares sometimes show blue/red asymmetries in the Hα line profile, suggesting prominence eruptions as an early stage of CMEs. However, their high-time-cadence observations are limited. We conducted spectroscopic monitoring observations of the active M dwarf YZ Canis Minoris with an ∼1 minute time cadence using the Seimei telescope, simultaneously with the optical photometric observations by Transiting Exoplanet Survey Satellite. We detected 27 Hα flares with Hα energies ranging from 1.7 × 1029 to 3.8 × 1032 erg and durations from 8 to 319 minutes. Among them, we identified three blue asymmetry and five red asymmetry events based on criteria using the Bayesian information criterion. The maximum velocity of the blueshifted and redshifted components ranges from 200 to 450 km s−1 and 190 to 400 km s−1, respectively. The duration and time evolution show variety, and in particular, we discovered rapid, short-duration blue/red asymmetry events with the duration of 6–8 minutes. Among the eight blue/red asymmetry events, two blue and one red asymmetry events are interpreted as prominence eruptions because of their fast velocity and time evolution. Based on this interpretation, the lower limit of occurrence frequency of prominence eruptions can be estimated to be ∼1.1 events per day. Our discovery of short-duration events suggests that previous studies with low time cadence may have missed these events, potentially leading to an underestimation of the occurrence frequency of prominence eruptions/CMEs.
{"title":"High-time-cadence Spectroscopy and Photometry of Stellar Flares on M dwarf YZ Canis Minoris with the Seimei Telescope and TESS. I. Discovery of Rapid and Short-duration Prominence Eruptions","authors":"Yuto Kajikiya, Kosuke Namekata, Yuta Notsu, Hiroyuki Maehara, Bunei Sato and Daisaku Nogami","doi":"10.3847/1538-4357/ad91b9","DOIUrl":"https://doi.org/10.3847/1538-4357/ad91b9","url":null,"abstract":"M dwarfs show frequent flares and associated coronal mass ejections (CMEs) may significantly impact close-in habitable planets. M dwarf flares sometimes show blue/red asymmetries in the Hα line profile, suggesting prominence eruptions as an early stage of CMEs. However, their high-time-cadence observations are limited. We conducted spectroscopic monitoring observations of the active M dwarf YZ Canis Minoris with an ∼1 minute time cadence using the Seimei telescope, simultaneously with the optical photometric observations by Transiting Exoplanet Survey Satellite. We detected 27 Hα flares with Hα energies ranging from 1.7 × 1029 to 3.8 × 1032 erg and durations from 8 to 319 minutes. Among them, we identified three blue asymmetry and five red asymmetry events based on criteria using the Bayesian information criterion. The maximum velocity of the blueshifted and redshifted components ranges from 200 to 450 km s−1 and 190 to 400 km s−1, respectively. The duration and time evolution show variety, and in particular, we discovered rapid, short-duration blue/red asymmetry events with the duration of 6–8 minutes. Among the eight blue/red asymmetry events, two blue and one red asymmetry events are interpreted as prominence eruptions because of their fast velocity and time evolution. Based on this interpretation, the lower limit of occurrence frequency of prominence eruptions can be estimated to be ∼1.1 events per day. Our discovery of short-duration events suggests that previous studies with low time cadence may have missed these events, potentially leading to an underestimation of the occurrence frequency of prominence eruptions/CMEs.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142990066","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 : 2025-01-20DOI: 10.3847/1538-4357/ada2ea
Carl J. Grillmair
Using photometry and proper motions from Pan-STARRS, DECaLS, and Gaia Data Release 3, we detect a ∼35°–70° long trailing stellar debris stream associated with the globular cluster NGC 288. The trajectory of the trailing tail is not well matched by a model stream evolved in a static Galactic potential, but is reasonably well matched by a stream modeled in a potential that incorporates a massive, infalling Large Magellanic Cloud. We also detect a broad, at least ∼40° long leading tail that appears to be composed of at least two narrower, spatially offset, and kinematically distinct streams. Stream modeling predicts a similar broad composite of streams and suggests that these narrower components could each be made up of one or more generations of tidal tails, each formed during different orbits over the past few gigayears. On the other hand, NGC 288 is believed to have been brought into the Galactic halo during the Gaia–Enceladus–Sausage accretion event, and the tangential velocity dispersions of our stream candidates are indeed mostly consistent with having been stripped in a parent galaxy that had a large, cored dark matter halo. Tables of the most highly ranked stream star candidates are provided for ongoing and future spectroscopic surveys.
{"title":"The Multiple Extended Tidal Tails of NGC 288","authors":"Carl J. Grillmair","doi":"10.3847/1538-4357/ada2ea","DOIUrl":"https://doi.org/10.3847/1538-4357/ada2ea","url":null,"abstract":"Using photometry and proper motions from Pan-STARRS, DECaLS, and Gaia Data Release 3, we detect a ∼35°–70° long trailing stellar debris stream associated with the globular cluster NGC 288. The trajectory of the trailing tail is not well matched by a model stream evolved in a static Galactic potential, but is reasonably well matched by a stream modeled in a potential that incorporates a massive, infalling Large Magellanic Cloud. We also detect a broad, at least ∼40° long leading tail that appears to be composed of at least two narrower, spatially offset, and kinematically distinct streams. Stream modeling predicts a similar broad composite of streams and suggests that these narrower components could each be made up of one or more generations of tidal tails, each formed during different orbits over the past few gigayears. On the other hand, NGC 288 is believed to have been brought into the Galactic halo during the Gaia–Enceladus–Sausage accretion event, and the tangential velocity dispersions of our stream candidates are indeed mostly consistent with having been stripped in a parent galaxy that had a large, cored dark matter halo. Tables of the most highly ranked stream star candidates are provided for ongoing and future spectroscopic surveys.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142990211","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 : 2025-01-20DOI: 10.3847/1538-4357/ada14d
Qi Guo, Qi Tan and Benyun Shi
Gamma-ray bursts (GRBs) are considered the most violent explosions in the Universe. Numerous studies have analyzed the formation rate of long gamma-ray bursts (LGRBs), which originate from the core collapse of massive stars, in comparison with the star formation rate (SFR). It is found that the LGRB formation rate at redshift z < 1 is significantly distinct from the SFR and is higher. Moreover, due to the threshold of detectors, the structured jets of GRBs also affect detection numbers at different redshifts, which all influence the calculation of the formation rate. Thus we investigate the LGRB formation rate at low redshift and further explore the possible correlation between the LGRB formation rate under the influence of structural jets and the SFR. We use Lynden-Bell's c− method to study the luminosity function and rate of Swift LGRBs without any assumptions. After correcting for the redshift evolution, the luminosity function can be expressed as for dim LGRBs and for bright LGRBs, and the formation rate at z < 1 shows an increase. Then we use Monte Carlo simulations to create pseudo-GRBs with structured jets and calculate the formation rates assuming that the actual LGRB formation rate at low redshift is proportional to the SRF. The results demonstrate that structural jets increase the number of detections at low redshift in response to observational effects. Compared with the observed formation rate, the structured jet model with Gauss-cocoon is found to be relatively more efficient, and the parameters η of this model are limited and analyzed to [0.5, 5].
{"title":"An Effect Study of Structural Jets on the Long Gamma-Ray Burst Formation Rate at Low Redshift","authors":"Qi Guo, Qi Tan and Benyun Shi","doi":"10.3847/1538-4357/ada14d","DOIUrl":"https://doi.org/10.3847/1538-4357/ada14d","url":null,"abstract":"Gamma-ray bursts (GRBs) are considered the most violent explosions in the Universe. Numerous studies have analyzed the formation rate of long gamma-ray bursts (LGRBs), which originate from the core collapse of massive stars, in comparison with the star formation rate (SFR). It is found that the LGRB formation rate at redshift z < 1 is significantly distinct from the SFR and is higher. Moreover, due to the threshold of detectors, the structured jets of GRBs also affect detection numbers at different redshifts, which all influence the calculation of the formation rate. Thus we investigate the LGRB formation rate at low redshift and further explore the possible correlation between the LGRB formation rate under the influence of structural jets and the SFR. We use Lynden-Bell's c− method to study the luminosity function and rate of Swift LGRBs without any assumptions. After correcting for the redshift evolution, the luminosity function can be expressed as for dim LGRBs and for bright LGRBs, and the formation rate at z < 1 shows an increase. Then we use Monte Carlo simulations to create pseudo-GRBs with structured jets and calculate the formation rates assuming that the actual LGRB formation rate at low redshift is proportional to the SRF. The results demonstrate that structural jets increase the number of detections at low redshift in response to observational effects. Compared with the observed formation rate, the structured jet model with Gauss-cocoon is found to be relatively more efficient, and the parameters η of this model are limited and analyzed to [0.5, 5].","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142990201","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 : 2025-01-20DOI: 10.3847/1538-4357/ad9b15
Yundan Guan, Quanming Lu, San Lu and Rongsheng Wang
Recently, a new type of magnetic reconnection, electron-only reconnection—where there is no obvious ion flow and heating—has been observed in various plasma environments. Previous kinetic simulations have shown that electron-only reconnection is a precursor of standard reconnection. In this paper, by performing a 2.5-dimensional particle-in-cell simulation, we investigate the evolution of electron-only magnetic reconnection to standard magnetic reconnection in a current sheet, whose initial width is of the electron inertial length. In the electron-only reconnection stage, electron outflow produces the electron-scale pileup, and ions are slightly accelerated in the outflow direction by the Hall electric field force. As the reconnection electric field expands and is piled up to the ion scale, ions start to be further accelerated inside the ion diffusion region and reflected by the to the outflow direction. With pileup as the bond, ions gradually transit from being accelerated by the Hall electric field to being coupled in reconnection by the Lorentz force.
{"title":"Evolution of Magnetic Reconnection in an Electron-scale Current Sheet","authors":"Yundan Guan, Quanming Lu, San Lu and Rongsheng Wang","doi":"10.3847/1538-4357/ad9b15","DOIUrl":"https://doi.org/10.3847/1538-4357/ad9b15","url":null,"abstract":"Recently, a new type of magnetic reconnection, electron-only reconnection—where there is no obvious ion flow and heating—has been observed in various plasma environments. Previous kinetic simulations have shown that electron-only reconnection is a precursor of standard reconnection. In this paper, by performing a 2.5-dimensional particle-in-cell simulation, we investigate the evolution of electron-only magnetic reconnection to standard magnetic reconnection in a current sheet, whose initial width is of the electron inertial length. In the electron-only reconnection stage, electron outflow produces the electron-scale pileup, and ions are slightly accelerated in the outflow direction by the Hall electric field force. As the reconnection electric field expands and is piled up to the ion scale, ions start to be further accelerated inside the ion diffusion region and reflected by the to the outflow direction. With pileup as the bond, ions gradually transit from being accelerated by the Hall electric field to being coupled in reconnection by the Lorentz force.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"57 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142989746","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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