Pub Date : 2025-01-22DOI: 10.3847/2041-8213/ad9eb5
Sean M. Ressler, Luciano Combi, Bart Ripperda and Elias R. Most
Supermassive binary black holes in galactic centers are potential multimessenger sources in gravitational waves and electromagnetic radiation. To find such objects, isolating unique electromagnetic signatures of their accretion flow is key. With the aid of three-dimensional general-relativistic magnetohydrodynamic simulations that utilize an approximate, semianalytic, superimposed spacetime metric, we identify two such signatures for merging binaries. Both involve magnetic reconnection and are analogous to plasma processes observed in the solar corona. The first, like colliding flux tubes that can cause solar flares, involves colliding jets that form an extended reconnection layer, dissipating magnetic energy and causing the two jets to merge. The second, akin to coronal mass ejection events, involves the accretion of magnetic field lines onto both black holes; these magnetic fields then twist, inflate, and form a trailing current sheet, ultimately reconnecting and driving a hot outflow. We provide estimates for the associated electromagnetic emission for both processes, showing that they likely accelerate electrons to high energies and are promising candidates for continuous, stochastic, and/or quasi-periodic higher-energy electromagnetic emission. We also show that the accretion flows around each black hole can display features associated with the magnetically arrested state. However, simulations with black hole spins misaligned with the orbital plane and simulations with larger Bondi radii saturate at lower values of horizon-penetrating magnetic flux than standard magnetically arrested disks, leading to weaker, intermittent jets owing to feedback from the weak jets or equatorial flux tubes ejected by reconnecting field lines near the horizon.
{"title":"Dual Jet Interaction, Magnetically Arrested Flows, and Flares in Accreting Binary Black Holes","authors":"Sean M. Ressler, Luciano Combi, Bart Ripperda and Elias R. Most","doi":"10.3847/2041-8213/ad9eb5","DOIUrl":"https://doi.org/10.3847/2041-8213/ad9eb5","url":null,"abstract":"Supermassive binary black holes in galactic centers are potential multimessenger sources in gravitational waves and electromagnetic radiation. To find such objects, isolating unique electromagnetic signatures of their accretion flow is key. With the aid of three-dimensional general-relativistic magnetohydrodynamic simulations that utilize an approximate, semianalytic, superimposed spacetime metric, we identify two such signatures for merging binaries. Both involve magnetic reconnection and are analogous to plasma processes observed in the solar corona. The first, like colliding flux tubes that can cause solar flares, involves colliding jets that form an extended reconnection layer, dissipating magnetic energy and causing the two jets to merge. The second, akin to coronal mass ejection events, involves the accretion of magnetic field lines onto both black holes; these magnetic fields then twist, inflate, and form a trailing current sheet, ultimately reconnecting and driving a hot outflow. We provide estimates for the associated electromagnetic emission for both processes, showing that they likely accelerate electrons to high energies and are promising candidates for continuous, stochastic, and/or quasi-periodic higher-energy electromagnetic emission. We also show that the accretion flows around each black hole can display features associated with the magnetically arrested state. However, simulations with black hole spins misaligned with the orbital plane and simulations with larger Bondi radii saturate at lower values of horizon-penetrating magnetic flux than standard magnetically arrested disks, leading to weaker, intermittent jets owing to feedback from the weak jets or equatorial flux tubes ejected by reconnecting field lines near the horizon.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"103 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142992322","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 : 2025-01-21DOI: 10.3847/2041-8213/ada3d1
Sho Shibata and Andre Izidoro
The solar system's planetary architecture has been proposed to be consistent with the terrestrial and giant planets forming from material rings at ∼1 au and ∼5 au, respectively. Here, we show that super-Earths and mini-Neptunes may share a similar formation pathway. In our simulations conducted with a disk α-viscosity of 4 × 10−3, super-Earths accrete from rings of rocky material in the inner disk, growing predominantly via planetesimal accretion. Mini-Neptunes primarily originate from rings located beyond the water snowline, forming via pebble accretion. Our simulations broadly match the period-ratio distribution, the intrasystem size uniformity, and the planet multiplicity distribution of exoplanets. The radius valley constrains the typical total mass available for rocky planet formation to be less than 3–6 M⊕. Our results predict that planets at ∼1 au in systems with close-in super-Earths and mini-Neptunes are predominantly water-rich. Though relatively uncommon, at ∼1% level, such systems might also host rocky Earth-sized planets in the habitable zone that underwent late giant impacts, akin to the Moon-forming event.
{"title":"Formation of Super-Earths and Mini-Neptunes from Rings of Planetesimals","authors":"Sho Shibata and Andre Izidoro","doi":"10.3847/2041-8213/ada3d1","DOIUrl":"https://doi.org/10.3847/2041-8213/ada3d1","url":null,"abstract":"The solar system's planetary architecture has been proposed to be consistent with the terrestrial and giant planets forming from material rings at ∼1 au and ∼5 au, respectively. Here, we show that super-Earths and mini-Neptunes may share a similar formation pathway. In our simulations conducted with a disk α-viscosity of 4 × 10−3, super-Earths accrete from rings of rocky material in the inner disk, growing predominantly via planetesimal accretion. Mini-Neptunes primarily originate from rings located beyond the water snowline, forming via pebble accretion. Our simulations broadly match the period-ratio distribution, the intrasystem size uniformity, and the planet multiplicity distribution of exoplanets. The radius valley constrains the typical total mass available for rocky planet formation to be less than 3–6 M⊕. Our results predict that planets at ∼1 au in systems with close-in super-Earths and mini-Neptunes are predominantly water-rich. Though relatively uncommon, at ∼1% level, such systems might also host rocky Earth-sized planets in the habitable zone that underwent late giant impacts, akin to the Moon-forming event.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"57 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143020596","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 : 2025-01-21DOI: 10.3847/2041-8213/ad9de2
T. Eftekhari, Y. Dong, 雨欣 董, W. Fong, V. Shah, S. Simha, B. C. Andersen, S. Andrew, M. Bhardwaj, T. Cassanelli, S. Chatterjee, D. A. Coulter, E. Fonseca, B. M. Gaensler, A. C. Gordon, J. W. T. Hessels, A. L. Ibik, R. C. Joseph, L. A. Kahinga, V. Kaspi, B. Kharel, C. D. Kilpatrick, A. E. Lanman, M. Lazda, C. Leung, C. Liu, L. Mas-Ribas, K. W. Masui, R. Mckinven, J. Mena-Parra, A. A. Miller, K. Nimmo, A. Pandhi, S. S. Patil, A. B. Pearlman, Z. Pleunis, J. X. Prochaska, M. Rafiei-Ravandi, M. Sammons, P. Scholz, K. Shin, K. Smith and I. Stairs
The discovery and localization of FRB 20240209A by the Canadian Hydrogen Intensity Mapping Fast Radio Burst (CHIME/FRB) experiment marks the first repeating FRB localized with the CHIME/FRB Outriggers and adds to the small sample of repeating FRBs with associated host galaxies. Here we present Keck and Gemini observations of the host that reveal a redshift z = 0.1384 ± 0.0004. We perform stellar population modeling to jointly fit the optical through mid-IR data of the host and infer a median stellar mass log(M*/M⊙) = 11.35 ± 0.01 and a mass-weighted stellar population age ~11 Gyr, corresponding to the most massive and oldest FRB host discovered to date. Coupled with a star formation rate <0.31 M⊙ yr−1, the specific star formation rate <10−11.9 yr−1 classifies the host as quiescent. Through surface brightness profile modeling, we determine an elliptical galaxy morphology, marking the host as the first confirmed elliptical FRB host. The discovery of a quiescent early-type host galaxy within a transient class predominantly characterized by late-type star-forming hosts is reminiscent of short-duration gamma-ray bursts, Type Ia supernovae, and ultraluminous X-ray sources. Based on these shared host demographics, coupled with a large offset as demonstrated in our companion Letter, we conclude that preferred sources for FRB 20240209A include magnetars formed through merging binary neutron stars/white dwarfs or the accretion-induced collapse of a white dwarf, or a luminous X-ray binary. Together with FRB 20200120E localized to a globular cluster in M81, our findings provide strong evidence that some fraction of FRBs may arise from a process distinct from the core collapse of massive stars.
{"title":"The Massive and Quiescent Elliptical Host Galaxy of the Repeating Fast Radio Burst FRB 20240209A","authors":"T. Eftekhari, Y. Dong, 雨欣 董, W. Fong, V. Shah, S. Simha, B. C. Andersen, S. Andrew, M. Bhardwaj, T. Cassanelli, S. Chatterjee, D. A. Coulter, E. Fonseca, B. M. Gaensler, A. C. Gordon, J. W. T. Hessels, A. L. Ibik, R. C. Joseph, L. A. Kahinga, V. Kaspi, B. Kharel, C. D. Kilpatrick, A. E. Lanman, M. Lazda, C. Leung, C. Liu, L. Mas-Ribas, K. W. Masui, R. Mckinven, J. Mena-Parra, A. A. Miller, K. Nimmo, A. Pandhi, S. S. Patil, A. B. Pearlman, Z. Pleunis, J. X. Prochaska, M. Rafiei-Ravandi, M. Sammons, P. Scholz, K. Shin, K. Smith and I. Stairs","doi":"10.3847/2041-8213/ad9de2","DOIUrl":"https://doi.org/10.3847/2041-8213/ad9de2","url":null,"abstract":"The discovery and localization of FRB 20240209A by the Canadian Hydrogen Intensity Mapping Fast Radio Burst (CHIME/FRB) experiment marks the first repeating FRB localized with the CHIME/FRB Outriggers and adds to the small sample of repeating FRBs with associated host galaxies. Here we present Keck and Gemini observations of the host that reveal a redshift z = 0.1384 ± 0.0004. We perform stellar population modeling to jointly fit the optical through mid-IR data of the host and infer a median stellar mass log(M*/M⊙) = 11.35 ± 0.01 and a mass-weighted stellar population age ~11 Gyr, corresponding to the most massive and oldest FRB host discovered to date. Coupled with a star formation rate <0.31 M⊙ yr−1, the specific star formation rate <10−11.9 yr−1 classifies the host as quiescent. Through surface brightness profile modeling, we determine an elliptical galaxy morphology, marking the host as the first confirmed elliptical FRB host. The discovery of a quiescent early-type host galaxy within a transient class predominantly characterized by late-type star-forming hosts is reminiscent of short-duration gamma-ray bursts, Type Ia supernovae, and ultraluminous X-ray sources. Based on these shared host demographics, coupled with a large offset as demonstrated in our companion Letter, we conclude that preferred sources for FRB 20240209A include magnetars formed through merging binary neutron stars/white dwarfs or the accretion-induced collapse of a white dwarf, or a luminous X-ray binary. Together with FRB 20200120E localized to a globular cluster in M81, our findings provide strong evidence that some fraction of FRBs may arise from a process distinct from the core collapse of massive stars.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"46 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142992324","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 : 2025-01-21DOI: 10.3847/2041-8213/ad9ddc
Vishwangi Shah, Kaitlyn Shin, Calvin Leung, Wen-fai Fong, Tarraneh Eftekhari, Mandana Amiri, Bridget C. Andersen, Shion Andrew, Mohit Bhardwaj, Charanjot Brar, Tomas Cassanelli, Shami Chatterjee, Alice Curtin, Matt Dobbs, Yuxin Dong, 雨欣 董, Fengqiu Adam Dong, Emmanuel Fonseca, B. M. Gaensler, Mark Halpern, Jason W. T. Hessels, Adaeze L. Ibik, Naman Jain, Ronniy C. Joseph, Jane Kaczmarek, Lordrick A. Kahinga, Victoria M. Kaspi, Bikash Kharel, Tom Landecker, Adam E. Lanman, Mattias Lazda, Robert Main, Lluis Mas-Ribas, Kiyoshi W. Masui, Ryan Mckinven, Juan Mena-Parra, Bradley W. Meyers, Daniele Michilli, Kenzie Nimmo, Ayush Pandhi, Swarali Shivraj Patil, Aaron B. Pearlman, Ziggy Pleunis, J. Xavier Prochaska, Masoud Rafiei-Ravandi, Mawson Sammons, Ketan R. Sand, Paul Scholz, Kendrick Smith and Ingrid Stairs
We report the discovery of the repeating fast radio burst (FRB) source FRB 20240209A using the Canadian Hydrogen Intensity Mapping Experiment (CHIME)/FRB telescope. We detected 22 bursts from this repeater between 2024 February and July, 6 of which were also recorded at the Outrigger station k’niʔatn k’l⌣stk’masqt (KKO). The multiple very long baseline interferometry localizations using the 66 km long CHIME–KKO baseline, each with a different baseline vector orientation due to the repeater’s high decl. of ∼86°, enabled the combined localization region to be constrained to 1″ × 2″. We present deep Gemini optical observations that, combined with the FRB localization, enabled a robust association of FRB 20240209A to the outskirts of a luminous galaxy (P(O∣x) = 0.99; L ≈ 5.3 × 1010L⊙). FRB 20240209A has a projected physical offset of 40 ± 5 kpc from the center of its host galaxy, making it the FRB with the largest host galaxy offset to date. When normalized by the host galaxy size, the offset of FRB 20240209A (5.1 Reff) is comparable to that of FRB 20200120E (5.7 Reff), the only FRB source known to originate in a globular cluster. We consider several explanations for the large offset, including a progenitor that was kicked from the host galaxy or in situ formation in a low-luminosity satellite galaxy of the putative host, but find the most plausible scenario to be a globular cluster origin. This, coupled with the quiescent, elliptical nature of the host as demonstrated in our companion Letter, provides strong evidence for a delayed formation channel for the progenitor of the FRB source.
{"title":"A Repeating Fast Radio Burst Source in the Outskirts of a Quiescent Galaxy","authors":"Vishwangi Shah, Kaitlyn Shin, Calvin Leung, Wen-fai Fong, Tarraneh Eftekhari, Mandana Amiri, Bridget C. Andersen, Shion Andrew, Mohit Bhardwaj, Charanjot Brar, Tomas Cassanelli, Shami Chatterjee, Alice Curtin, Matt Dobbs, Yuxin Dong, 雨欣 董, Fengqiu Adam Dong, Emmanuel Fonseca, B. M. Gaensler, Mark Halpern, Jason W. T. Hessels, Adaeze L. Ibik, Naman Jain, Ronniy C. Joseph, Jane Kaczmarek, Lordrick A. Kahinga, Victoria M. Kaspi, Bikash Kharel, Tom Landecker, Adam E. Lanman, Mattias Lazda, Robert Main, Lluis Mas-Ribas, Kiyoshi W. Masui, Ryan Mckinven, Juan Mena-Parra, Bradley W. Meyers, Daniele Michilli, Kenzie Nimmo, Ayush Pandhi, Swarali Shivraj Patil, Aaron B. Pearlman, Ziggy Pleunis, J. Xavier Prochaska, Masoud Rafiei-Ravandi, Mawson Sammons, Ketan R. Sand, Paul Scholz, Kendrick Smith and Ingrid Stairs","doi":"10.3847/2041-8213/ad9ddc","DOIUrl":"https://doi.org/10.3847/2041-8213/ad9ddc","url":null,"abstract":"We report the discovery of the repeating fast radio burst (FRB) source FRB 20240209A using the Canadian Hydrogen Intensity Mapping Experiment (CHIME)/FRB telescope. We detected 22 bursts from this repeater between 2024 February and July, 6 of which were also recorded at the Outrigger station k’niʔatn k’l⌣stk’masqt (KKO). The multiple very long baseline interferometry localizations using the 66 km long CHIME–KKO baseline, each with a different baseline vector orientation due to the repeater’s high decl. of ∼86°, enabled the combined localization region to be constrained to 1″ × 2″. We present deep Gemini optical observations that, combined with the FRB localization, enabled a robust association of FRB 20240209A to the outskirts of a luminous galaxy (P(O∣x) = 0.99; L ≈ 5.3 × 1010L⊙). FRB 20240209A has a projected physical offset of 40 ± 5 kpc from the center of its host galaxy, making it the FRB with the largest host galaxy offset to date. When normalized by the host galaxy size, the offset of FRB 20240209A (5.1 Reff) is comparable to that of FRB 20200120E (5.7 Reff), the only FRB source known to originate in a globular cluster. We consider several explanations for the large offset, including a progenitor that was kicked from the host galaxy or in situ formation in a low-luminosity satellite galaxy of the putative host, but find the most plausible scenario to be a globular cluster origin. This, coupled with the quiescent, elliptical nature of the host as demonstrated in our companion Letter, provides strong evidence for a delayed formation channel for the progenitor of the FRB source.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142992323","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: 10.3847/2041-8213/ada3d2
Sebastiano D. von Fellenberg, Tamojeet Roychowdhury, Joseph M. Michail, Zach Sumners, Grace Sanger-Johnson, Giovanni G. Fazio, Daryl Haggard, Joseph L. Hora, Alexander Philippov, Bart Ripperda, Howard A. Smith, S. P. Willner, Gunther Witzel, Shuo Zhang, Eric E. Becklin, Geoffrey C. Bower, Sunil Chandra, Tuan Do, Macarena Garcia Marin, Mark A. Gurwell, Nicole M. Ford, Kazuhiro Hada, Sera Markoff, Mark R. Morris, Joey Neilsen, Nadeen B. Sabha and Braden Seefeldt-Gail
The time-variable emission from the accretion flow of Sgr A*, the supermassive black hole at the Galactic center, has long been examined in the radio-to-millimeter, near-infrared (NIR), and X-ray regimes of the electromagnetic spectrum. However, until now, sensitivity and angular resolution have been insufficient in the crucial mid-infrared (MIR) regime. The MIRI instrument on JWST has changed that, and we report the first MIR detection of Sgr A*. The detection was during a flare that lasted about 40 minutes, a duration similar to NIR and X-ray flares, and the source's spectral index steepened as the flare ended. The steepening suggests that synchrotron cooling is an important process for Sgr A*'s variability and implies magnetic fields strengths ~ 40–70 G in the emission zone. Observations at 1.3 mm with the Submillimeter Array revealed a counterpart flare lagging the MIR flare by ≈10 minutes. The observations can be self-consistently explained as synchrotron radiation from a single population of gradually cooling high-energy electrons accelerated through (a combination of) magnetic reconnection and/or magnetized turbulence.
{"title":"First Mid-infrared Detection and Modeling of a Flare from Sgr A*","authors":"Sebastiano D. von Fellenberg, Tamojeet Roychowdhury, Joseph M. Michail, Zach Sumners, Grace Sanger-Johnson, Giovanni G. Fazio, Daryl Haggard, Joseph L. Hora, Alexander Philippov, Bart Ripperda, Howard A. Smith, S. P. Willner, Gunther Witzel, Shuo Zhang, Eric E. Becklin, Geoffrey C. Bower, Sunil Chandra, Tuan Do, Macarena Garcia Marin, Mark A. Gurwell, Nicole M. Ford, Kazuhiro Hada, Sera Markoff, Mark R. Morris, Joey Neilsen, Nadeen B. Sabha and Braden Seefeldt-Gail","doi":"10.3847/2041-8213/ada3d2","DOIUrl":"https://doi.org/10.3847/2041-8213/ada3d2","url":null,"abstract":"The time-variable emission from the accretion flow of Sgr A*, the supermassive black hole at the Galactic center, has long been examined in the radio-to-millimeter, near-infrared (NIR), and X-ray regimes of the electromagnetic spectrum. However, until now, sensitivity and angular resolution have been insufficient in the crucial mid-infrared (MIR) regime. The MIRI instrument on JWST has changed that, and we report the first MIR detection of Sgr A*. The detection was during a flare that lasted about 40 minutes, a duration similar to NIR and X-ray flares, and the source's spectral index steepened as the flare ended. The steepening suggests that synchrotron cooling is an important process for Sgr A*'s variability and implies magnetic fields strengths ~ 40–70 G in the emission zone. Observations at 1.3 mm with the Submillimeter Array revealed a counterpart flare lagging the MIR flare by ≈10 minutes. The observations can be self-consistently explained as synchrotron radiation from a single population of gradually cooling high-energy electrons accelerated through (a combination of) magnetic reconnection and/or magnetized turbulence.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142991447","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: 10.3847/2041-8213/ada5c7
Alexander D. Rathcke, Lars A. Buchhave, Julien de Wit, Benjamin V. Rackham, Prune C. August, Hannah Diamond-Lowe, João M. MendonÇa, Aaron Bello-Arufe, Mercedes López-Morales, Daniel Kitzmann and Kevin Heng
Stellar surface heterogeneities, such as spots and faculae, often contaminate exoplanet transit spectra, hindering precise atmospheric characterization. We demonstrate a novel, epoch-based, model-independent method to mitigate stellar contamination, applicable to multiplanet systems with at least one airless planet. We apply this method using quasi-simultaneous transits of TRAPPIST-1 b and TRAPPIST-1 c observed on 2024 July 9, with JWST/NIRSpec PRISM. These two planets, with nearly identical radii and impact parameters, are likely to either be bare rocks or possess thin, low-pressure atmospheres, making them ideal candidates for this technique, as variations in their transit spectra would be primarily attributed to stellar activity. Our observations reveal their transit spectra exhibit consistent features, indicating similar levels of stellar contamination. We use TRAPPIST-1 b to correct the transit spectrum of TRAPPIST-1 c, achieving a 2.5 × reduction in stellar contamination at shorter wavelengths. At longer wavelengths, lower signal-to-noise ratio prevents clear detection of contamination or full assessment of mitigation. Still, out-of-transit analysis reveals variations across the spectrum, suggesting contamination extends into the longer wavelengths. Based on the success of the correction at shorter wavelengths, we argue that contamination is also reduced at longer wavelengths to a similar extent. This shifts the challenge of detecting atmospheric features to a predominantly white noise issue, which can be addressed by stacking observations. This method enables epoch-specific stellar contamination corrections, allowing coaddition of planetary spectra for reliable searches of secondary atmospheres with signals of 60–250 ppm. Additionally, we identify small-scale cold (∼2000 K) and warm (∼2600 K) regions almost uniformly distributed on TRAPPIST-1, with overall covering fractions varying by ∼0.1% per hour.
{"title":"Stellar Contamination Correction Using Back-to-back Transits of TRAPPIST-1 b and c","authors":"Alexander D. Rathcke, Lars A. Buchhave, Julien de Wit, Benjamin V. Rackham, Prune C. August, Hannah Diamond-Lowe, João M. MendonÇa, Aaron Bello-Arufe, Mercedes López-Morales, Daniel Kitzmann and Kevin Heng","doi":"10.3847/2041-8213/ada5c7","DOIUrl":"https://doi.org/10.3847/2041-8213/ada5c7","url":null,"abstract":"Stellar surface heterogeneities, such as spots and faculae, often contaminate exoplanet transit spectra, hindering precise atmospheric characterization. We demonstrate a novel, epoch-based, model-independent method to mitigate stellar contamination, applicable to multiplanet systems with at least one airless planet. We apply this method using quasi-simultaneous transits of TRAPPIST-1 b and TRAPPIST-1 c observed on 2024 July 9, with JWST/NIRSpec PRISM. These two planets, with nearly identical radii and impact parameters, are likely to either be bare rocks or possess thin, low-pressure atmospheres, making them ideal candidates for this technique, as variations in their transit spectra would be primarily attributed to stellar activity. Our observations reveal their transit spectra exhibit consistent features, indicating similar levels of stellar contamination. We use TRAPPIST-1 b to correct the transit spectrum of TRAPPIST-1 c, achieving a 2.5 × reduction in stellar contamination at shorter wavelengths. At longer wavelengths, lower signal-to-noise ratio prevents clear detection of contamination or full assessment of mitigation. Still, out-of-transit analysis reveals variations across the spectrum, suggesting contamination extends into the longer wavelengths. Based on the success of the correction at shorter wavelengths, we argue that contamination is also reduced at longer wavelengths to a similar extent. This shifts the challenge of detecting atmospheric features to a predominantly white noise issue, which can be addressed by stacking observations. This method enables epoch-specific stellar contamination corrections, allowing coaddition of planetary spectra for reliable searches of secondary atmospheres with signals of 60–250 ppm. Additionally, we identify small-scale cold (∼2000 K) and warm (∼2600 K) regions almost uniformly distributed on TRAPPIST-1, with overall covering fractions varying by ∼0.1% per hour.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142990204","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 : 2025-01-17DOI: 10.3847/2041-8213/ada28f
Xiangyu Zhang, Brandon S. Hensley and Gregory M. Green
The first all-sky, high-resolution, 3D map of the optical extinction curve of the Milky Way revealed an unexpected steepening of the extinction curve in the moderate-density, “translucent” interstellar medium (ISM). We argue that this trend is driven by growth of the total mass of polycyclic aromatic hydrocarbons (PAHs) through gas-phase accretion. We find a strong anticorrelation between the slope of the optical extinction curve—parameterized by R(V)—and maps of the PAH mass fraction (relative to the total dust mass)—parameterized by qPAH—derived from infrared emission. The range of observed qPAH indicates PAH growth by a factor of ∼2 between AV ≃ 1 and 3. This implies a factor-of-2 stronger 2175 Å feature, which is sufficient to lower R(V) by the observed amount. This level of PAH growth is possible given rapid accretion timescales and the depletion of carbon in the translucent ISM. Spectral observations by JWST would provide a definitive test of this proposed explanation of R(V) variation.
第一张全天空、高分辨率、三维的银河系光学消光曲线图显示，在中等密度、"半透明 "星际介质（ISM）中，消光曲线出现了意想不到的陡峭化。我们认为这一趋势是由气相吸积导致的多环芳烃（PAHs）总质量增长所驱动的。我们发现，以R（V）为参数的光学消光曲线斜率与以qPAH为参数的多环芳烃（PAH）质量分数（相对于尘埃总质量）地图之间存在很强的反相关性。观测到的 qPAH 范围表明 PAH 在 AV ≃ 1 和 3 之间增长了 2 倍。这意味着 2175 Å 的特征增强了 2 倍，足以将 R(V) 降低到观测到的水平。考虑到快速增生的时间尺度和半透明 ISM 中碳的耗竭，这种程度的 PAH 增长是可能的。JWST 的光谱观测将对 R(V) 变化的这一拟议解释进行最终检验。
{"title":"Dust-extinction-curve Variation in the Translucent Interstellar Medium Is Driven by Polycyclic Aromatic Hydrocarbon Growth","authors":"Xiangyu Zhang, Brandon S. Hensley and Gregory M. Green","doi":"10.3847/2041-8213/ada28f","DOIUrl":"https://doi.org/10.3847/2041-8213/ada28f","url":null,"abstract":"The first all-sky, high-resolution, 3D map of the optical extinction curve of the Milky Way revealed an unexpected steepening of the extinction curve in the moderate-density, “translucent” interstellar medium (ISM). We argue that this trend is driven by growth of the total mass of polycyclic aromatic hydrocarbons (PAHs) through gas-phase accretion. We find a strong anticorrelation between the slope of the optical extinction curve—parameterized by R(V)—and maps of the PAH mass fraction (relative to the total dust mass)—parameterized by qPAH—derived from infrared emission. The range of observed qPAH indicates PAH growth by a factor of ∼2 between AV ≃ 1 and 3. This implies a factor-of-2 stronger 2175 Å feature, which is sufficient to lower R(V) by the observed amount. This level of PAH growth is possible given rapid accretion timescales and the depletion of carbon in the translucent ISM. Spectral observations by JWST would provide a definitive test of this proposed explanation of R(V) variation.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"56 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988491","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 : 2025-01-17DOI: 10.3847/2041-8213/ada389
Jeremy L. Smallwood, Stephen H. Lubow, Rebecca G. Martin and Rebecca Nealon
We revisit the origin of the observed misaligned rings in the circumtriple disk around GW Ori. Previous studies appeared to disagree on whether disk breaking is caused by the differential precession driven in the disk by the triple star system. In this Letter, we show that the previous studies are in agreement with each other when using the same set of parameters. But for observationally motivated parameters of a typical protoplanetary disk, the disk is unlikely to break due to interactions with the triple star system. We run three-dimensional hydrodynamical simulations of a circumtriple disk around GW Ori with different disk aspect ratios. For a disk aspect ratio typical of protoplanetary disks, H/r ≳ 0.05, the disk does not break. An alternative scenario for the gap's origin consistent with the expected disk aspect ratio involves the presence of circumtriple planets orbiting GW Ori.
{"title":"Shedding Light on the Origin of the Broken Misaligned Circumtriple Disk around GW Ori","authors":"Jeremy L. Smallwood, Stephen H. Lubow, Rebecca G. Martin and Rebecca Nealon","doi":"10.3847/2041-8213/ada389","DOIUrl":"https://doi.org/10.3847/2041-8213/ada389","url":null,"abstract":"We revisit the origin of the observed misaligned rings in the circumtriple disk around GW Ori. Previous studies appeared to disagree on whether disk breaking is caused by the differential precession driven in the disk by the triple star system. In this Letter, we show that the previous studies are in agreement with each other when using the same set of parameters. But for observationally motivated parameters of a typical protoplanetary disk, the disk is unlikely to break due to interactions with the triple star system. We run three-dimensional hydrodynamical simulations of a circumtriple disk around GW Ori with different disk aspect ratios. For a disk aspect ratio typical of protoplanetary disks, H/r ≳ 0.05, the disk does not break. An alternative scenario for the gap's origin consistent with the expected disk aspect ratio involves the presence of circumtriple planets orbiting GW Ori.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988495","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 : 2025-01-17DOI: 10.3847/2041-8213/ada27a
Caitlyn Nojiri, Noémie Globus and Enrico Ramirez-Ruiz
The Earth sits inside a 300 pc-wide void that was carved by a series of supernova explosions that went off tens of millions of years ago, pushing away interstellar gas and creating a bubble-like structure. The 60Fe peak deposits found in the deep-sea crust have been interpreted by the imprints left by the ejecta of supernova explosions occurring about 2–3 and 5–6 Myr ago. It is likely that the 60Fe peak at about 2–3 Myr originated from a supernova occurring in the Upper Centaurus Lupus association in Scorpius Centaurus (≈140 pc) or the Tucana-Horologium association (≈70 pc), whereas the ≈5–6 Myr peak is likely attributed to the solar system's entrance into the bubble. In this Letter, we show that the supernova source responsible for synthesizing the 60Fe peak deposits ≈2–3 Myr ago can consistently explain the cosmic-ray spectrum and the large-scale anisotropy between 100 TeV and 100 PeV. The cosmic-ray knee could then potentially be attributed entirely to a single nearby “PeVatron” source. Matching the intensity and shape of the cosmic-ray spectrum allows us to place stringent constraints on the cosmic-ray energy content from the supernova as well as on the cosmic-ray diffusion coefficient. Making use of such constraints, we provide a robust estimate of the temporal variation of terrestrial ionizing cosmic radiation levels and discuss their implications in the development of early life on Earth by plausibly influencing the mutation rate and, as such, conceivably assisting in the evolution of complex organisms.
{"title":"Life in the Bubble: How a Nearby Supernova Left Ephemeral Footprints on the Cosmic-Ray Spectrum and Indelible Imprints on Life","authors":"Caitlyn Nojiri, Noémie Globus and Enrico Ramirez-Ruiz","doi":"10.3847/2041-8213/ada27a","DOIUrl":"https://doi.org/10.3847/2041-8213/ada27a","url":null,"abstract":"The Earth sits inside a 300 pc-wide void that was carved by a series of supernova explosions that went off tens of millions of years ago, pushing away interstellar gas and creating a bubble-like structure. The 60Fe peak deposits found in the deep-sea crust have been interpreted by the imprints left by the ejecta of supernova explosions occurring about 2–3 and 5–6 Myr ago. It is likely that the 60Fe peak at about 2–3 Myr originated from a supernova occurring in the Upper Centaurus Lupus association in Scorpius Centaurus (≈140 pc) or the Tucana-Horologium association (≈70 pc), whereas the ≈5–6 Myr peak is likely attributed to the solar system's entrance into the bubble. In this Letter, we show that the supernova source responsible for synthesizing the 60Fe peak deposits ≈2–3 Myr ago can consistently explain the cosmic-ray spectrum and the large-scale anisotropy between 100 TeV and 100 PeV. The cosmic-ray knee could then potentially be attributed entirely to a single nearby “PeVatron” source. Matching the intensity and shape of the cosmic-ray spectrum allows us to place stringent constraints on the cosmic-ray energy content from the supernova as well as on the cosmic-ray diffusion coefficient. Making use of such constraints, we provide a robust estimate of the temporal variation of terrestrial ionizing cosmic radiation levels and discuss their implications in the development of early life on Earth by plausibly influencing the mutation rate and, as such, conceivably assisting in the evolution of complex organisms.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988620","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 : 2025-01-16DOI: 10.3847/2041-8213/ada611
Baolin Tan, Yin Zhang, Jing Huang and Kaifan Ji
Solar flares stronger than X10 (S-flares, >X10) are the highest-class flares that significantly impact on the Sun's evolution and space weather. Based on observations of Geostationary Orbiting Environmental Satellites at soft X-ray wavelength and the daily sunspot numbers (DSNs) since 1975, we obtained some interesting and heuristic conclusions: (1) both S-flares and the more powerful extremely strong flares (ES-flares, >X14.3) mostly occur in the late phases of solar cycles (SCs) and low-latitude regions on the solar disk; (2) similar to X-class flares, the occurrence of S-flares in each SC is somewhat random, but the occurrence of ES-flares seems to be dominated by the mean DSN (Vm) and its rms deviation during the valley phase (Vd) before the cycle: the ES-flare number is strongly correlated with Vd, and the occurrence time of the first ES-flare is anticorrelated with Vd and Vm. These facts indicate that the higher the Vm and Vd, the stronger the SC, the more the ES-flares, and the earlier they occurred. We propose that the Sun may have a low-latitude active zone (LAZ), and most ES-flares are generated from the interaction between the LAZ and the newly emerging active regions. The correlations and the linear regression functions may provide an useful method to predict the occurrence of ES-flares in an upcoming SC, which derives that SC 25 will have about 2 ± 1 ES-flares after the spring of 2027.
{"title":"The Occurrence of Powerful Flares Stronger than X10 Class in Solar Cycles","authors":"Baolin Tan, Yin Zhang, Jing Huang and Kaifan Ji","doi":"10.3847/2041-8213/ada611","DOIUrl":"https://doi.org/10.3847/2041-8213/ada611","url":null,"abstract":"Solar flares stronger than X10 (S-flares, >X10) are the highest-class flares that significantly impact on the Sun's evolution and space weather. Based on observations of Geostationary Orbiting Environmental Satellites at soft X-ray wavelength and the daily sunspot numbers (DSNs) since 1975, we obtained some interesting and heuristic conclusions: (1) both S-flares and the more powerful extremely strong flares (ES-flares, >X14.3) mostly occur in the late phases of solar cycles (SCs) and low-latitude regions on the solar disk; (2) similar to X-class flares, the occurrence of S-flares in each SC is somewhat random, but the occurrence of ES-flares seems to be dominated by the mean DSN (Vm) and its rms deviation during the valley phase (Vd) before the cycle: the ES-flare number is strongly correlated with Vd, and the occurrence time of the first ES-flare is anticorrelated with Vd and Vm. These facts indicate that the higher the Vm and Vd, the stronger the SC, the more the ES-flares, and the earlier they occurred. We propose that the Sun may have a low-latitude active zone (LAZ), and most ES-flares are generated from the interaction between the LAZ and the newly emerging active regions. The correlations and the linear regression functions may provide an useful method to predict the occurrence of ES-flares in an upcoming SC, which derives that SC 25 will have about 2 ± 1 ES-flares after the spring of 2027.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142987393","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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