Pub Date : 2025-03-03DOI: 10.3847/2041-8213/ad9eaf
Allison M. McCarthy, Johanna M. Vos, Philip S. Muirhead, Beth A. Biller, Caroline V. Morley, Jacqueline Faherty, Ben Burningham, Emily Calamari, Nicolas B. Cowan, Kelle L. Cruz, Eileen Gonzales, Mary Anne Limbach, Pengyu Liu, Evert Nasedkin, Genaro Suárez, Xianyu Tan, Cian O’Toole, Channon Visscher, Niall Whiteford and Yifan Zhou
Isolated planetary-mass objects share their mass range with planets but do not orbit a star. They lack the necessary mass to support fusion in their cores and thermally radiate their heat from formation as they cool, primarily at infrared wavelengths. Many isolated planetary-mass objects show variations in their infrared brightness consistent with nonuniform atmospheric features modulated by their rotation. SIMP J013656.5+093347.3 is a rapidly rotating isolated planetary-mass object, and previous infrared monitoring suggests complex atmospheric features rotating in and out of view. The physical nature of these features is not well understood, with clouds, temperature variations, thermochemical instabilities, and infrared-emitting aurora all proposed as contributing mechanisms. Here we report JWST time-resolved low-resolution spectroscopy from 0.8 to 11 μm of SIMP J013656.5+093347.3, which supports the presence of three specific features in the atmosphere: clouds, hot spots, and changing carbon chemistry. We show that no single mechanism can explain the variations in the time-resolved spectra. When combined with previous studies of this object indicating patchy clouds and aurorae, these measurements reveal the rich complexity of the atmosphere of SIMP J013656.5+093347.3. Gas giant planets in the solar system, specifically Jupiter and Saturn, also have multiple cloud layers and high-altitude hot spots, suggesting these phenomena are also present in worlds both within and beyond our solar system.
{"title":"The JWST Weather Report from the Isolated Exoplanet Analog SIMP 0136+0933: Pressure-dependent Variability Driven by Multiple Mechanisms","authors":"Allison M. McCarthy, Johanna M. Vos, Philip S. Muirhead, Beth A. Biller, Caroline V. Morley, Jacqueline Faherty, Ben Burningham, Emily Calamari, Nicolas B. Cowan, Kelle L. Cruz, Eileen Gonzales, Mary Anne Limbach, Pengyu Liu, Evert Nasedkin, Genaro Suárez, Xianyu Tan, Cian O’Toole, Channon Visscher, Niall Whiteford and Yifan Zhou","doi":"10.3847/2041-8213/ad9eaf","DOIUrl":"https://doi.org/10.3847/2041-8213/ad9eaf","url":null,"abstract":"Isolated planetary-mass objects share their mass range with planets but do not orbit a star. They lack the necessary mass to support fusion in their cores and thermally radiate their heat from formation as they cool, primarily at infrared wavelengths. Many isolated planetary-mass objects show variations in their infrared brightness consistent with nonuniform atmospheric features modulated by their rotation. SIMP J013656.5+093347.3 is a rapidly rotating isolated planetary-mass object, and previous infrared monitoring suggests complex atmospheric features rotating in and out of view. The physical nature of these features is not well understood, with clouds, temperature variations, thermochemical instabilities, and infrared-emitting aurora all proposed as contributing mechanisms. Here we report JWST time-resolved low-resolution spectroscopy from 0.8 to 11 μm of SIMP J013656.5+093347.3, which supports the presence of three specific features in the atmosphere: clouds, hot spots, and changing carbon chemistry. We show that no single mechanism can explain the variations in the time-resolved spectra. When combined with previous studies of this object indicating patchy clouds and aurorae, these measurements reveal the rich complexity of the atmosphere of SIMP J013656.5+093347.3. Gas giant planets in the solar system, specifically Jupiter and Saturn, also have multiple cloud layers and high-altitude hot spots, suggesting these phenomena are also present in worlds both within and beyond our solar system.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143532551","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 : 2025-02-28DOI: 10.3847/2041-8213/adb613
Jianwei Lyu, 建伟 吕, George H. Rieke, Meredith Stone, Jane Morrison, Stacey Alberts, Xiangyu Jin, Yongda Zhu, Weizhe Liu, 伟哲 刘 and Jinyi Yang
The majority of most luminous quasars during the epoch of reionization accrete near or above the Eddington limit, marking the vigorous growth of primitive supermassive black holes (SMBHs). However, their subsequent evolution and environmental impact remain poorly characterized. We present JWST/NIRSpec prism integral field unit observations of HSC J2239+0207, a low-luminosity quasar at z ∼ 6.25 likely in a late stage of mass assembly with an overmassive SMBH relative to its host galaxy. Using Hβ and Hα broad emission lines, we estimate an SMBH mass MBH ∼ 3 × 108 M⊙ and confirm its sub-Eddington accretion at λEdd ∼ 0.4. Strong Fe ii emission and a proximity zone of typical size suggest a metal-rich, highly evolved system. In the far-UV, this quasar presents strong broad absorption line features, indicative of high-velocity winds (ν ∼ 104 km s−1). Meanwhile, minimal dust reddening is inferred from the quasar continuum and broad-line Balmer decrement, suggesting little dust along the polar direction. Most interestingly, we identify a gas companion ∼5 kpc from the quasar with a high [O iii]/Hβ ratio (≳10), likely representing outflowing gas blown away by active galactic nucleus (AGN) feedback. These results highlight HSC J2239+0207 as a likely fading quasar in transition, providing rare insights into SMBH evolution, AGN feedback, and AGN–galaxy interactions in the early Universe.
在再电离时代，大多数最亮的类星体都是在接近或超过爱丁顿极限的地方吸积的，这标志着原始超大质量黑洞（SMBHs）的蓬勃发展。然而，它们的后续演化和环境影响仍然特征不清。我们展示了JWST/NIRSpec棱镜积分场单元对HSC J2239+0207的观测结果，这是一颗z∼6.25的低亮度类星体，相对于其宿主星系，很可能处于质量集合的后期阶段，具有超大质量黑洞。利用Hβ和Hα宽发射线，我们估算出SMBH的质量为MBH ∼ 3 × 108 M⊙，并确认了其在λEdd ∼ 0.4时的亚爱丁顿吸积。强烈的 Fe ii 发射和典型大小的邻近区表明这是一个富含金属的高度演化系统。在远紫外波段，这个类星体呈现出很强的宽吸收线特征，表明存在高速风（ν ∼ 104 km s-1）。同时，从类星体的连续波和宽线巴尔默衰减中可以推断出极小的尘埃变红，这表明沿极地方向几乎没有尘埃。最有趣的是，我们在距离类星体 5 kpc 的地方发现了一个气体伴星，它的[O iii]/Hβ 比值很高（≳10），很可能是被活动星系核（AGN）反馈吹走的外流气体。这些结果突出表明，HSC J2239+0207 很可能是一颗正在褪变的类星体，为研究早期宇宙中的 SMBH 演化、AGN 反馈以及 AGN 与星系的相互作用提供了难得的见解。
{"title":"Fading Light, Fierce Winds: JWST Snapshot of a Sub-Eddington Quasar at Cosmic Dawn","authors":"Jianwei Lyu, 建伟 吕, George H. Rieke, Meredith Stone, Jane Morrison, Stacey Alberts, Xiangyu Jin, Yongda Zhu, Weizhe Liu, 伟哲 刘 and Jinyi Yang","doi":"10.3847/2041-8213/adb613","DOIUrl":"https://doi.org/10.3847/2041-8213/adb613","url":null,"abstract":"The majority of most luminous quasars during the epoch of reionization accrete near or above the Eddington limit, marking the vigorous growth of primitive supermassive black holes (SMBHs). However, their subsequent evolution and environmental impact remain poorly characterized. We present JWST/NIRSpec prism integral field unit observations of HSC J2239+0207, a low-luminosity quasar at z ∼ 6.25 likely in a late stage of mass assembly with an overmassive SMBH relative to its host galaxy. Using Hβ and Hα broad emission lines, we estimate an SMBH mass MBH ∼ 3 × 108 M⊙ and confirm its sub-Eddington accretion at λEdd ∼ 0.4. Strong Fe ii emission and a proximity zone of typical size suggest a metal-rich, highly evolved system. In the far-UV, this quasar presents strong broad absorption line features, indicative of high-velocity winds (ν ∼ 104 km s−1). Meanwhile, minimal dust reddening is inferred from the quasar continuum and broad-line Balmer decrement, suggesting little dust along the polar direction. Most interestingly, we identify a gas companion ∼5 kpc from the quasar with a high [O iii]/Hβ ratio (≳10), likely representing outflowing gas blown away by active galactic nucleus (AGN) feedback. These results highlight HSC J2239+0207 as a likely fading quasar in transition, providing rare insights into SMBH evolution, AGN feedback, and AGN–galaxy interactions in the early Universe.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"51 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143518035","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 : 2025-02-28DOI: 10.3847/2041-8213/adae03
Yukta Ajay, Dheeraj R. Pasham, Thomas Wevers, Eric R. Coughlin, Francesco Tombesi, Muryel Guolo and James F. Steiner
ASASSN-14li is a low-redshift (z= 0.0206) tidal disruption event (TDE) that has been studied extensively across the entire electromagnetic spectrum and has provided one of the most sensitive measurements of a TDE to date. Its X-ray spectrum is soft and thermal (kT ∼ 0.05 keV) and shows a residual broad absorption feature between 0.6 and 0.8 keV, which can be associated with a blueshifted O vii line (rest-frame energy 0.57 keV) resulting from an ultrafast outflow at early times (within 40 days of optical discovery). By carefully accounting for photon pileup and using XSTAR photoionization models tailored to the evolving disk continuum properties, we analyze the entire archival X-ray data from XMM-Newton and track the evolution of this absorption feature for ∼4.5 yr post-disruption. Our main finding is that the absorption feature is transient and intermittent. Assuming the same underlying physical model (i.e., outflows) for the recurring absorption feature in ASASSN-14li, the outflow is seen to disappear and reappear multiple times during the first ∼1.5 yr of its evolution. No observable spectral imprint is detected thereafter. While theoretical studies suggest the launch of outflows in the early phases of the outburst during the super-Eddington regime, the outflow’s intermittent behavior for multiple years after disruption is unusual. We discuss this peculiar behavior within the context of varying inner-disk truncation, radiation pressure, and magnetically driven outflow scenarios.
ASASSN-14li是一个低红移（z= 0.0206）潮汐扰动事件（TDE），对它的整个电磁波谱进行了广泛的研究，并提供了迄今为止对TDE最灵敏的测量之一。它的 X 射线光谱是软的和热的（kT ∼ 0.05 keV），在 0.6 和 0.8 keV 之间显示出一个残留的宽吸收特征，这可能与早期（光学发现后 40 天内）超快外流产生的蓝移 O vii 线（静帧能量 0.57 keV）有关。通过仔细考虑光子堆积并使用根据不断变化的磁盘连续面特性定制的 XSTAR 光电离模型，我们分析了来自 XMM-Newton 的全部 X 射线存档数据，并跟踪了该吸收特征在中断后 4.5 年的演变过程。我们的主要发现是，该吸收特征是瞬态和间歇性的。假设ASASSN-14li中反复出现的吸收特征具有相同的基本物理模型（即外流），可以看到外流在其演化的最初∼1.5年期间多次消失和重新出现。此后就再也没有探测到可观测到的光谱印记了。虽然理论研究表明在超爱丁顿机制的爆发早期阶段会有流出，但流出在中断后多年的间歇行为是不寻常的。我们将根据不同的内盘截断、辐射压力和磁驱动外流情况来讨论这种奇特的行为。
{"title":"Episodic X-Ray Outflows from the Tidal Disruption Event ASASSN-14li","authors":"Yukta Ajay, Dheeraj R. Pasham, Thomas Wevers, Eric R. Coughlin, Francesco Tombesi, Muryel Guolo and James F. Steiner","doi":"10.3847/2041-8213/adae03","DOIUrl":"https://doi.org/10.3847/2041-8213/adae03","url":null,"abstract":"ASASSN-14li is a low-redshift (z= 0.0206) tidal disruption event (TDE) that has been studied extensively across the entire electromagnetic spectrum and has provided one of the most sensitive measurements of a TDE to date. Its X-ray spectrum is soft and thermal (kT ∼ 0.05 keV) and shows a residual broad absorption feature between 0.6 and 0.8 keV, which can be associated with a blueshifted O vii line (rest-frame energy 0.57 keV) resulting from an ultrafast outflow at early times (within 40 days of optical discovery). By carefully accounting for photon pileup and using XSTAR photoionization models tailored to the evolving disk continuum properties, we analyze the entire archival X-ray data from XMM-Newton and track the evolution of this absorption feature for ∼4.5 yr post-disruption. Our main finding is that the absorption feature is transient and intermittent. Assuming the same underlying physical model (i.e., outflows) for the recurring absorption feature in ASASSN-14li, the outflow is seen to disappear and reappear multiple times during the first ∼1.5 yr of its evolution. No observable spectral imprint is detected thereafter. While theoretical studies suggest the launch of outflows in the early phases of the outburst during the super-Eddington regime, the outflow’s intermittent behavior for multiple years after disruption is unusual. We discuss this peculiar behavior within the context of varying inner-disk truncation, radiation pressure, and magnetically driven outflow scenarios.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"52 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143526000","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 : 2025-02-28DOI: 10.3847/2041-8213/adb0be
Soumya Roy, Durgesh Tripathi, Sreejith Padinhatteeri, A. N. Ramaprakash, Abhilash R. Sarwade, Nived V. N., Janmejoy Sarkar, Rahul Gopalakrishnan, Rushikesh Deogaonkar, K. Sankarasubramanian, Sami K. Solanki, Dibyendu Nandy and Dipankar Banerjee
Solar flares are regularly observed in extreme-ultraviolet soft X-rays (SXRs) and hard X-rays (HXRs). However, those in near- and mid-ultraviolet are sparse. The Solar Ultraviolet Imaging Telescope (SUIT) on board the Aditya-L1, launched on 2023 September 2, provides regular observations in the 200–400 nm wavelength range through 11 filters. Here, we report the observation of the X6.3 flare on 2024 February 22 using eight narrowband (NB) filters of SUIT. We have also used co-spatiotemporal observations from Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA), Solar Orbiter/STIX, GONG Hα, Aditya-L1/SoLEXS, and GOES. We obtained light curves over the flaring region from AIA 1600 and 1700 Å and GONG Hα and compared them with the disk-integrated light curve obtained from GOES and SoLEXS SXRs and STIX HXRs. We find that the flare peaks in SUIT NB01, NB03, NB04, and NB08 filters simultaneously with HXRs 1600 and 1700 Å, along with the peak temperature obtained from SoLEXS. In contrast, in NB02 and NB05, the flare peaks ∼2 min later than the HXR peak, while in NB06 and NB07, the flare peaks ∼3 min after the GOES SXR peak. To the best of our knowledge, this is the first observation of a flare in these wavelengths (except in NB03, NB04, and NB05). Moreover, for the first time, we show the presence of a bright kernel in NB02. These results demonstrate the capabilities of SUIT observations in flare studies.
{"title":"Near- and Mid-ultraviolet Observations of X-6.3 Flare on 2024 February 22 Recorded by the Solar Ultraviolet Imaging Telescope on board Aditya-L1","authors":"Soumya Roy, Durgesh Tripathi, Sreejith Padinhatteeri, A. N. Ramaprakash, Abhilash R. Sarwade, Nived V. N., Janmejoy Sarkar, Rahul Gopalakrishnan, Rushikesh Deogaonkar, K. Sankarasubramanian, Sami K. Solanki, Dibyendu Nandy and Dipankar Banerjee","doi":"10.3847/2041-8213/adb0be","DOIUrl":"https://doi.org/10.3847/2041-8213/adb0be","url":null,"abstract":"Solar flares are regularly observed in extreme-ultraviolet soft X-rays (SXRs) and hard X-rays (HXRs). However, those in near- and mid-ultraviolet are sparse. The Solar Ultraviolet Imaging Telescope (SUIT) on board the Aditya-L1, launched on 2023 September 2, provides regular observations in the 200–400 nm wavelength range through 11 filters. Here, we report the observation of the X6.3 flare on 2024 February 22 using eight narrowband (NB) filters of SUIT. We have also used co-spatiotemporal observations from Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA), Solar Orbiter/STIX, GONG Hα, Aditya-L1/SoLEXS, and GOES. We obtained light curves over the flaring region from AIA 1600 and 1700 Å and GONG Hα and compared them with the disk-integrated light curve obtained from GOES and SoLEXS SXRs and STIX HXRs. We find that the flare peaks in SUIT NB01, NB03, NB04, and NB08 filters simultaneously with HXRs 1600 and 1700 Å, along with the peak temperature obtained from SoLEXS. In contrast, in NB02 and NB05, the flare peaks ∼2 min later than the HXR peak, while in NB06 and NB07, the flare peaks ∼3 min after the GOES SXR peak. To the best of our knowledge, this is the first observation of a flare in these wavelengths (except in NB03, NB04, and NB05). Moreover, for the first time, we show the presence of a bright kernel in NB02. These results demonstrate the capabilities of SUIT observations in flare studies.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"116 9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143518034","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 : 2025-02-27DOI: 10.3847/2041-8213/adace8
B. Rani, Jungeun Kim, I. Papadakis, K. C. Gendreau, M. Masterson, K. Hamaguchi, E. Kara, S.-S. Lee and R. Mushotzky
Variability studies offer a compelling glimpse into black hole dynamics, and Neutron Star Interior Composition Explorer's (NICER’s) remarkable temporal resolution propels us even further. NICER observations of an active galactic nucleus (AGN), NGC 4051, have charted the geometry of the emission region of the central supermassive black hole. Our investigation of X-ray variability in NGC 4051 has detected extreme variations spanning a factor of 40–50 over a mere 10–12 hr. For the first time, we have constrained the X-ray power spectral density (PSD) of the source to 0.1 Hz, corresponding to a temporal frequency of 104 Hz in a galactic X-ray binary with a mass of 10 M⊙. No extra high-frequency break/bend or any quasiperiodic oscillations are found. Through detailed analysis of energy-dependent PSDs, we found that the PSD normalization, the high-frequency PSD slope, as well as the bending frequency remain consistent across all energies within the 0.3–3 keV band, revealing the presence of a constant temperature corona. These significant findings impose critical constraints on current models of X-ray emission and variability in AGN.
{"title":"High-frequency Power Spectrum of Active Galactic Nucleus NGC 4051 Revealed by NICER","authors":"B. Rani, Jungeun Kim, I. Papadakis, K. C. Gendreau, M. Masterson, K. Hamaguchi, E. Kara, S.-S. Lee and R. Mushotzky","doi":"10.3847/2041-8213/adace8","DOIUrl":"https://doi.org/10.3847/2041-8213/adace8","url":null,"abstract":"Variability studies offer a compelling glimpse into black hole dynamics, and Neutron Star Interior Composition Explorer's (NICER’s) remarkable temporal resolution propels us even further. NICER observations of an active galactic nucleus (AGN), NGC 4051, have charted the geometry of the emission region of the central supermassive black hole. Our investigation of X-ray variability in NGC 4051 has detected extreme variations spanning a factor of 40–50 over a mere 10–12 hr. For the first time, we have constrained the X-ray power spectral density (PSD) of the source to 0.1 Hz, corresponding to a temporal frequency of 104 Hz in a galactic X-ray binary with a mass of 10 M⊙. No extra high-frequency break/bend or any quasiperiodic oscillations are found. Through detailed analysis of energy-dependent PSDs, we found that the PSD normalization, the high-frequency PSD slope, as well as the bending frequency remain consistent across all energies within the 0.3–3 keV band, revealing the presence of a constant temperature corona. These significant findings impose critical constraints on current models of X-ray emission and variability in AGN.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"52 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143518098","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 : 2025-02-27DOI: 10.3847/2041-8213/adb61a
Chen Wang, Lee Patrick, Abel Schootemeijer, Selma E. de Mink, Norbert Langer, Nikolay Britavskiy, Xiao-Tian Xu, Julia Bodensteiner, Eva Laplace, Ruggero Valli, Alejandro Vigna-Gómez, Jakub Klencki, Stephen Justham, Cole Johnston and Jing-ze Ma
Red supergiants (RSGs) represent a late evolutionary stage of massive stars. Recent observations reveal that the observed luminosity range of RSGs in young open clusters is wider than expected from single-star evolution models. Binary evolution effects have been suggested as a possible explanation. Here, we analyze 3670 detailed binary-evolution models, as well as corresponding single-star models, to probe the contribution of binary mass transfer and binary mergers to the luminosity distribution of RSGs in star clusters with ages up to 100 Myr. We confirm that the expected luminosity range of RSGs in a coeval population can span a factor of 10, as a consequence of mergers between two main-sequence stars, which reproduces the observed RSG luminosity ranges in rich clusters well. While the luminosity increase as consequence of mass transfer is more limited, it may help to increase the number of overluminous RSGs. However, our results also demonstrate that binary effects alone are insufficient to account for the number of RSGs found with luminosities of up to 3 times those predicted by current single-star models. We discuss observational accuracy, rotational mixing, age spread, and intrinsic RSG variability as possible explanations. Further observations of RSGs in young open clusters, in particular studies of their intrinsic brightness variability, appear crucial for disentangling these effects.
{"title":"Using Detailed Single-star and Binary-evolution Models to Probe the Large Observed Luminosity Spread of Red Supergiants in Young Open Star Clusters","authors":"Chen Wang, Lee Patrick, Abel Schootemeijer, Selma E. de Mink, Norbert Langer, Nikolay Britavskiy, Xiao-Tian Xu, Julia Bodensteiner, Eva Laplace, Ruggero Valli, Alejandro Vigna-Gómez, Jakub Klencki, Stephen Justham, Cole Johnston and Jing-ze Ma","doi":"10.3847/2041-8213/adb61a","DOIUrl":"https://doi.org/10.3847/2041-8213/adb61a","url":null,"abstract":"Red supergiants (RSGs) represent a late evolutionary stage of massive stars. Recent observations reveal that the observed luminosity range of RSGs in young open clusters is wider than expected from single-star evolution models. Binary evolution effects have been suggested as a possible explanation. Here, we analyze 3670 detailed binary-evolution models, as well as corresponding single-star models, to probe the contribution of binary mass transfer and binary mergers to the luminosity distribution of RSGs in star clusters with ages up to 100 Myr. We confirm that the expected luminosity range of RSGs in a coeval population can span a factor of 10, as a consequence of mergers between two main-sequence stars, which reproduces the observed RSG luminosity ranges in rich clusters well. While the luminosity increase as consequence of mass transfer is more limited, it may help to increase the number of overluminous RSGs. However, our results also demonstrate that binary effects alone are insufficient to account for the number of RSGs found with luminosities of up to 3 times those predicted by current single-star models. We discuss observational accuracy, rotational mixing, age spread, and intrinsic RSG variability as possible explanations. Further observations of RSGs in young open clusters, in particular studies of their intrinsic brightness variability, appear crucial for disentangling these effects.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143518099","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 : 2025-02-27DOI: 10.3847/2041-8213/adb62e
Andrzej A. Zdziarski, Srimanta Banerjee, Michał Szanecki, Ranjeev Misra and Gulab Dewangan
We have studied the accreting black hole binary GX 339–4 using two highly accurate broadband X-ray data sets in very soft spectral states from simultaneous NICER and NuSTAR observations. Joint fitting of both data sets with relativistic models of the disk and its Comptonization and reflection allows us to relatively accurately determine the black hole mass, spin, distance, and inclination. However, we find that the measured values strongly depend on the used disk model. With widely used Kerr disk models treating departures from local blackbody spectra using color corrections, we find relatively low black hole masses and strongly negative spins (i.e., retrograde accretion). Then, models employing radiative transfer calculations of the disk atmosphere predict moderately positive spins and high masses. When adding a warm corona above the disk (as proposed before for both active galactic nuclei and accreting binaries), we find that the spin is weakly constrained but consistent with zero. In all cases, the fitted inclination is low, ≈30°–34°. For the spin axis aligned with the binary axis, the mass function for this source implies large values of the mass, consistent only with those obtained with either disk-atmosphere models or the presence of a warm corona. We also test different disk models for an assumed set of mass, distance, and inclination. We find that different models yield values of the spin parameter differing by up to ∼0.3. Our results confirm previously found strong model dependencies of the measured black hole spin, now by comparing different disk models and for a low-mass X-ray binary.
{"title":"Is the Spin of the Black Hole in GX 339–4 Negative?","authors":"Andrzej A. Zdziarski, Srimanta Banerjee, Michał Szanecki, Ranjeev Misra and Gulab Dewangan","doi":"10.3847/2041-8213/adb62e","DOIUrl":"https://doi.org/10.3847/2041-8213/adb62e","url":null,"abstract":"We have studied the accreting black hole binary GX 339–4 using two highly accurate broadband X-ray data sets in very soft spectral states from simultaneous NICER and NuSTAR observations. Joint fitting of both data sets with relativistic models of the disk and its Comptonization and reflection allows us to relatively accurately determine the black hole mass, spin, distance, and inclination. However, we find that the measured values strongly depend on the used disk model. With widely used Kerr disk models treating departures from local blackbody spectra using color corrections, we find relatively low black hole masses and strongly negative spins (i.e., retrograde accretion). Then, models employing radiative transfer calculations of the disk atmosphere predict moderately positive spins and high masses. When adding a warm corona above the disk (as proposed before for both active galactic nuclei and accreting binaries), we find that the spin is weakly constrained but consistent with zero. In all cases, the fitted inclination is low, ≈30°–34°. For the spin axis aligned with the binary axis, the mass function for this source implies large values of the mass, consistent only with those obtained with either disk-atmosphere models or the presence of a warm corona. We also test different disk models for an assumed set of mass, distance, and inclination. We find that different models yield values of the spin parameter differing by up to ∼0.3. Our results confirm previously found strong model dependencies of the measured black hole spin, now by comparing different disk models and for a low-mass X-ray binary.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143518100","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 : 2025-02-27DOI: 10.3847/2041-8213/adb5fd
Jens F. Mahlmann and Andrei M. Beloborodov
We investigate the energy release in the interacting magnetospheres of binary neutron stars (BNSs) with global 3D force-free electrodynamics simulations. The system dynamics depend on the inclinations χ1 and χ2 of the stars’ magnetic dipole moments relative to their orbital angular momentum. The simplest aligned configuration (χ1 = χ2 = 0∘) has no magnetic field lines connecting the two stars. Remarkably, it still develops separatrix current sheets warping around each star and a dissipative region at the interface of the two magnetospheres. A Kelvin–Helmholtz (KH)–type instability drives significant dissipation at the magnetospheric interface, generating local Alfvénic turbulence and escaping fast magnetosonic waves. Binaries with inclined magnetospheres release energy in two ways: via KH instability at the interface and via magnetic reconnection flares in the twisted flux bundles connecting the companions. Outgoing compressive waves occur in a broad range of BNS parameters, possibly developing shocks and sourcing fast radio bursts. We discuss implications for X-ray and radio precursors of BNS mergers.
{"title":"Electrodynamics and Dissipation in the Binary Magnetosphere of Premerger Neutron Stars","authors":"Jens F. Mahlmann and Andrei M. Beloborodov","doi":"10.3847/2041-8213/adb5fd","DOIUrl":"https://doi.org/10.3847/2041-8213/adb5fd","url":null,"abstract":"We investigate the energy release in the interacting magnetospheres of binary neutron stars (BNSs) with global 3D force-free electrodynamics simulations. The system dynamics depend on the inclinations χ1 and χ2 of the stars’ magnetic dipole moments relative to their orbital angular momentum. The simplest aligned configuration (χ1 = χ2 = 0∘) has no magnetic field lines connecting the two stars. Remarkably, it still develops separatrix current sheets warping around each star and a dissipative region at the interface of the two magnetospheres. A Kelvin–Helmholtz (KH)–type instability drives significant dissipation at the magnetospheric interface, generating local Alfvénic turbulence and escaping fast magnetosonic waves. Binaries with inclined magnetospheres release energy in two ways: via KH instability at the interface and via magnetic reconnection flares in the twisted flux bundles connecting the companions. Outgoing compressive waves occur in a broad range of BNS parameters, possibly developing shocks and sourcing fast radio bursts. We discuss implications for X-ray and radio precursors of BNS mergers.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"49 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143518558","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 : 2025-02-26DOI: 10.3847/2041-8213/adb30e
Adrien Saurety, Razvan Caracas and Sean N. Raymond
Giant impacts dominate the late stages of accretion of rocky planets. They contribute to the heating, melting, and sometimes vaporizing of the bodies involved in the impacts. Due to fractionation during melting and vaporization, planet-building impacts can significantly change the composition and geochemical signatures of rocky objects. Using first-principles molecular dynamics simulations, we analyze the shock behavior of complex realistic silicate systems, representative of both rocky bodies. We introduce a novel criterion for vapor formation that uses entropy calculations to determine the minimum impact velocity required to pass the threshold for vapor production. We derive impact velocity criteria for vapor formation—7.1 km s−1 for chondritic bodies—and show that this threshold is reached in 61% and 89% of impacts in dynamical simulations of the late stages of accretion with classical and annulus starting configuration (respectively) for analogs of Earth. These outcomes should be nuanced by factors such as the impact angle and the mass of the impacting bodies, which further influence the vaporization dynamics and the resultant material distribution. Our findings indicate that vaporization was common during accretion and likely played a crucial role in shaping the early environments and material properties of terrestrial planets.
{"title":"Impact-induced Vaporization during Accretion of Planetary Bodies","authors":"Adrien Saurety, Razvan Caracas and Sean N. Raymond","doi":"10.3847/2041-8213/adb30e","DOIUrl":"https://doi.org/10.3847/2041-8213/adb30e","url":null,"abstract":"Giant impacts dominate the late stages of accretion of rocky planets. They contribute to the heating, melting, and sometimes vaporizing of the bodies involved in the impacts. Due to fractionation during melting and vaporization, planet-building impacts can significantly change the composition and geochemical signatures of rocky objects. Using first-principles molecular dynamics simulations, we analyze the shock behavior of complex realistic silicate systems, representative of both rocky bodies. We introduce a novel criterion for vapor formation that uses entropy calculations to determine the minimum impact velocity required to pass the threshold for vapor production. We derive impact velocity criteria for vapor formation—7.1 km s−1 for chondritic bodies—and show that this threshold is reached in 61% and 89% of impacts in dynamical simulations of the late stages of accretion with classical and annulus starting configuration (respectively) for analogs of Earth. These outcomes should be nuanced by factors such as the impact angle and the mass of the impacting bodies, which further influence the vaporization dynamics and the resultant material distribution. Our findings indicate that vaporization was common during accretion and likely played a crucial role in shaping the early environments and material properties of terrestrial planets.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"85 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143506792","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 : 2025-02-26DOI: 10.3847/2041-8213/adb749
Akshay Singh, Damien Bégué and Asaf Pe’er
We study magnetically arrested disks (MADs) around rotating black holes (BHs) under the influence of radiative cooling. We introduce a critical value of the mass accretion rate for which the cooling by the synchrotron process efficiently radiates the thermal energy of the disk. We find , where is the Eddington mass accretion rate. The normalization constant depends on the saturated magnetic flux and on the ratio of electron to proton temperatures, but not on the BH mass. We verify our analytical estimate using a suite of general relativistic magnetohydrodynamic simulations for a range of BH spin parameters a ∈ {−0.94, −0.5, 0, 0.5, 0.94} and mass accretion rates ranging from to . We numerically observe that the MAD parameter and the jet efficiency vary by a factor of ≈2 as the mass accretion rate increases above , which confirms our analytical result. We further detail how the forces satisfying the quasi-equilibrium of the disk change, with the magnetic contribution increasing as the thermal contribution decreases.
{"title":"Radiative Cooling Changes the Dynamics of Magnetically Arrested Disks","authors":"Akshay Singh, Damien Bégué and Asaf Pe’er","doi":"10.3847/2041-8213/adb749","DOIUrl":"https://doi.org/10.3847/2041-8213/adb749","url":null,"abstract":"We study magnetically arrested disks (MADs) around rotating black holes (BHs) under the influence of radiative cooling. We introduce a critical value of the mass accretion rate for which the cooling by the synchrotron process efficiently radiates the thermal energy of the disk. We find , where is the Eddington mass accretion rate. The normalization constant depends on the saturated magnetic flux and on the ratio of electron to proton temperatures, but not on the BH mass. We verify our analytical estimate using a suite of general relativistic magnetohydrodynamic simulations for a range of BH spin parameters a ∈ {−0.94, −0.5, 0, 0.5, 0.94} and mass accretion rates ranging from to . We numerically observe that the MAD parameter and the jet efficiency vary by a factor of ≈2 as the mass accretion rate increases above , which confirms our analytical result. We further detail how the forces satisfying the quasi-equilibrium of the disk change, with the magnetic contribution increasing as the thermal contribution decreases.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"53 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143507093","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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