Pub Date : 2025-01-06DOI: 10.3847/2041-8213/ad93cc
Hong-Peng Lu, Hui Tian, Li-Yun Zhang, He-Chao Chen, Ying Li, Zi-Hao Yang, Jia-Sheng Wang, Jia-Le Zhang and Zheng Sun
We report the detection of an extreme stellar prominence eruption on the M dwarf Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) J044431.62+235627.9, observed through time-domain Hα spectroscopy with the LAMOST. This prominence eruption was accompanied by a superflare lasting over 160.4 minutes. The Hα line profile exhibits significant blue-wing enhancement during the impulsive phase and near the flare peak, with a projected bulk blueshift velocity of −228 ± 11 km s−1 and a maximum blueshift velocity reaching −605 ± 15 km s−1. Velocity analysis of the eruptive prominence at various heights above the stellar surface indicates that some of the projected ejection velocities along the line of sight exceed the corresponding escape velocities, suggesting a potential coronal mass ejection (CME). The equivalent width (EW) of the Hα blue-wing enhancement in this eruption appears to be the largest observed to date and is comparable to the EW of the Hα line profile during the quiescent phase of the host star. We performed a two-cloud modeling for the prominence and the associated flare, which suggests that the eruptive prominence has a mass ranging from 1.6 × 1019 to 7.2 × 1019 g. More importantly, the mass ratio of the erupting prominence to its host star is the largest among all reported stellar prominence eruptions/CMEs.
我们报告了在M矮星大空域多目标光纤光谱望远镜（LAMOST） J044431.62+235627.9上通过时域Hα光谱观测到的一次极端恒星日珥喷发。这次日珥喷发伴随着持续超过160.4分钟的超级耀斑。在脉冲阶段和耀斑峰附近，Hα谱线呈现出明显的蓝翼增强，投射体蓝移速度为- 228±11 km s - 1，最大蓝移速度为- 605±15 km s - 1。对恒星表面以上不同高度的喷发日珥的速度分析表明，沿着视线的一些投射的喷射速度超过了相应的逃逸速度，这表明可能存在日冕物质抛射（CME）。在这次喷发中，Hα蓝翼增强的等效宽度（EW）似乎是迄今为止观测到的最大的，与主恒星静止阶段的Hα线剖面的EW相当。我们对日珥和相关耀斑进行了双云建模，结果表明，爆发日珥的质量在1.6 × 1019到7.2 × 1019 g之间。更重要的是，这次爆发的日珥与其主恒星的质量比是所有报道的日珥爆发/ cme中最大的。
{"title":"An Extreme Stellar Prominence Eruption Observed by LAMOST Time-domain Spectroscopy","authors":"Hong-Peng Lu, Hui Tian, Li-Yun Zhang, He-Chao Chen, Ying Li, Zi-Hao Yang, Jia-Sheng Wang, Jia-Le Zhang and Zheng Sun","doi":"10.3847/2041-8213/ad93cc","DOIUrl":"https://doi.org/10.3847/2041-8213/ad93cc","url":null,"abstract":"We report the detection of an extreme stellar prominence eruption on the M dwarf Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) J044431.62+235627.9, observed through time-domain Hα spectroscopy with the LAMOST. This prominence eruption was accompanied by a superflare lasting over 160.4 minutes. The Hα line profile exhibits significant blue-wing enhancement during the impulsive phase and near the flare peak, with a projected bulk blueshift velocity of −228 ± 11 km s−1 and a maximum blueshift velocity reaching −605 ± 15 km s−1. Velocity analysis of the eruptive prominence at various heights above the stellar surface indicates that some of the projected ejection velocities along the line of sight exceed the corresponding escape velocities, suggesting a potential coronal mass ejection (CME). The equivalent width (EW) of the Hα blue-wing enhancement in this eruption appears to be the largest observed to date and is comparable to the EW of the Hα line profile during the quiescent phase of the host star. We performed a two-cloud modeling for the prominence and the associated flare, which suggests that the eruptive prominence has a mass ranging from 1.6 × 1019 to 7.2 × 1019 g. More importantly, the mass ratio of the erupting prominence to its host star is the largest among all reported stellar prominence eruptions/CMEs.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"167 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142935046","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 : 2025-01-06DOI: 10.3847/2041-8213/ada1cd
Maokai Hu, Yiping Ao, Yi Yang, Lei Hu, Fulin Li, Lifan Wang and Xiaofeng Wang
The short-lived ionized emission lines in early spectroscopy of the nearby Type II supernova SN 2024ggi signify the presence of dense circumstellar matter (CSM) close to its progenitor star. We proposed the Atacama Large Millimeter/submillimeter Array (ALMA) observations by its Director's Discretionary Time program to catch the potential synchrotron radiation associated with the ejecta–CSM interaction. Multiepoch observations were conducted using ALMA band 6 at +8, +13, and +17 days after the discovery. The data show nondetections at the position of SN 2024ggi with a 3σ upper limit of less than 0.15 mJy, corresponding to a luminosity of approximately 8 × 1024 erg s−1 Hz−1. In this paper, we leverage the nondetections to place constraints on the properties of CSM surrounding SN 2024ggi. We investigate both the Wind and Eruptive models for the radial distribution of CSM, assuming a constant mass-loss rate in the Wind model and a distance-variant mass-loss rate in the Eruptive model. The derived CSM distribution for the Wind model does not align with the early-time spectral features, while the ALMA observations suggest a mass-loss rate of ~5 × 10−3M⊙ yr−1 for the Eruptive model. Conducting multiepoch millimeter/submillimeter observations shortly after the explosion, with a cadence of a few days, could offer a promising opportunity to capture the observable signature of the Eruptive model.
{"title":"Early-time Millimeter Observations of the Nearby Type II SN 2024ggi","authors":"Maokai Hu, Yiping Ao, Yi Yang, Lei Hu, Fulin Li, Lifan Wang and Xiaofeng Wang","doi":"10.3847/2041-8213/ada1cd","DOIUrl":"https://doi.org/10.3847/2041-8213/ada1cd","url":null,"abstract":"The short-lived ionized emission lines in early spectroscopy of the nearby Type II supernova SN 2024ggi signify the presence of dense circumstellar matter (CSM) close to its progenitor star. We proposed the Atacama Large Millimeter/submillimeter Array (ALMA) observations by its Director's Discretionary Time program to catch the potential synchrotron radiation associated with the ejecta–CSM interaction. Multiepoch observations were conducted using ALMA band 6 at +8, +13, and +17 days after the discovery. The data show nondetections at the position of SN 2024ggi with a 3σ upper limit of less than 0.15 mJy, corresponding to a luminosity of approximately 8 × 1024 erg s−1 Hz−1. In this paper, we leverage the nondetections to place constraints on the properties of CSM surrounding SN 2024ggi. We investigate both the Wind and Eruptive models for the radial distribution of CSM, assuming a constant mass-loss rate in the Wind model and a distance-variant mass-loss rate in the Eruptive model. The derived CSM distribution for the Wind model does not align with the early-time spectral features, while the ALMA observations suggest a mass-loss rate of ~5 × 10−3M⊙ yr−1 for the Eruptive model. Conducting multiepoch millimeter/submillimeter observations shortly after the explosion, with a cadence of a few days, could offer a promising opportunity to capture the observable signature of the Eruptive model.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142935049","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 : 2025-01-03DOI: 10.3847/2041-8213/ad9a53
Michaela Vítková, Rafael Brahm, Trifon Trifonov, Petr Kabáth, Andrés Jordán, Thomas Henning, Melissa J. Hobson, Jan Eberhardt, Marcelo Tala Pinto, Felipe I. Rojas, Nestor Espinoza, Martin Schlecker, Matías I. Jones, Maximiliano Moyano, Susana Eyheramendy, Carl Ziegler, Jack J. Lissauer, Andrew Vanderburg, Karen A. Collins, Bill Wohler, David Watanabe, George R. Ricker, Roland Vanderspek, Sara Seager, Joshua N. Winn, Jon M. Jenkins and Marek Skarka
We present a joint analysis of transit timing variations (TTVs) and Doppler data for the transiting exoplanet system TOI-4504. TOI-4504 c is a warm Jupiter-mass planet that exhibits the largest known TTVs, with a peak-to-node amplitude of ∼2 days, the largest value ever observed, and a superperiod of ~930 days. TOI-4504 b and c were identified in public Transiting Exoplanet Survey Satellite (TESS) data, while the TTVs observed in TOI-4504 c, together with radial velocity (RV) data collected with FEROS, allowed us to uncover a third, nontransiting planet in this system, TOI-4504 d. We were able to detect transits of TOI-4504 b in the TESS data with a period of 2.4261 ± 0.0001 days and derive a radius of 2.69 ± 0.19 R⊕. The RV scatter of TOI-4504 was too large to constrain the mass of TOI-4504 b, but the RV signals of TOI-4504 c and d were sufficiently large to measure their masses. The TTV+RV dynamical model we apply confirms TOI-4504 c as a warm Jupiter planet with an osculating period of 82.54 ± 0.02 days, a mass of 3.77 ± 0.18 MJ, and a radius of 0.99 ± 0.05 RJ, while the nontransiting planet TOI-4504 d has an orbital period of 40.56 ± 0.04 days and a mass of 1.42 MJ. We present the discovery of a system with three exoplanets: a hot sub-Neptune and two warm Jupiter planets. The gas giant pair is stable and likely locked in a first-order 2:1 mean-motion resonance (MMR). The TOI-4504 system is an important addition to MMR pairs, whose increasing occurrence supports a smooth migration into a resonant configuration during the protoplanetary disk phase.
{"title":"TOI-4504: Exceptionally Large Transit Timing Variations Induced by Two Resonant Warm Gas Giants in a Three-planet System","authors":"Michaela Vítková, Rafael Brahm, Trifon Trifonov, Petr Kabáth, Andrés Jordán, Thomas Henning, Melissa J. Hobson, Jan Eberhardt, Marcelo Tala Pinto, Felipe I. Rojas, Nestor Espinoza, Martin Schlecker, Matías I. Jones, Maximiliano Moyano, Susana Eyheramendy, Carl Ziegler, Jack J. Lissauer, Andrew Vanderburg, Karen A. Collins, Bill Wohler, David Watanabe, George R. Ricker, Roland Vanderspek, Sara Seager, Joshua N. Winn, Jon M. Jenkins and Marek Skarka","doi":"10.3847/2041-8213/ad9a53","DOIUrl":"https://doi.org/10.3847/2041-8213/ad9a53","url":null,"abstract":"We present a joint analysis of transit timing variations (TTVs) and Doppler data for the transiting exoplanet system TOI-4504. TOI-4504 c is a warm Jupiter-mass planet that exhibits the largest known TTVs, with a peak-to-node amplitude of ∼2 days, the largest value ever observed, and a superperiod of ~930 days. TOI-4504 b and c were identified in public Transiting Exoplanet Survey Satellite (TESS) data, while the TTVs observed in TOI-4504 c, together with radial velocity (RV) data collected with FEROS, allowed us to uncover a third, nontransiting planet in this system, TOI-4504 d. We were able to detect transits of TOI-4504 b in the TESS data with a period of 2.4261 ± 0.0001 days and derive a radius of 2.69 ± 0.19 R⊕. The RV scatter of TOI-4504 was too large to constrain the mass of TOI-4504 b, but the RV signals of TOI-4504 c and d were sufficiently large to measure their masses. The TTV+RV dynamical model we apply confirms TOI-4504 c as a warm Jupiter planet with an osculating period of 82.54 ± 0.02 days, a mass of 3.77 ± 0.18 MJ, and a radius of 0.99 ± 0.05 RJ, while the nontransiting planet TOI-4504 d has an orbital period of 40.56 ± 0.04 days and a mass of 1.42 MJ. We present the discovery of a system with three exoplanets: a hot sub-Neptune and two warm Jupiter planets. The gas giant pair is stable and likely locked in a first-order 2:1 mean-motion resonance (MMR). The TOI-4504 system is an important addition to MMR pairs, whose increasing occurrence supports a smooth migration into a resonant configuration during the protoplanetary disk phase.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"84 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142924970","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 : 2025-01-03DOI: 10.3847/2041-8213/ad9d11
Hiromasa Suzuki, Naomi Tsuji, Yoshiaki Kanemaru, Megumi Shidatsu, Laura Olivera-Nieto, Samar Safi-Harb, Shigeo S. Kimura, Eduardo de la Fuente, Sabrina Casanova, Kaya Mori, Xiaojie Wang, Sei Kato, Dai Tateishi, Hideki Uchiyama, Takaaki Tanaka, Hiroyuki Uchida, Shun Inoue, Dezhi Huang, Marianne Lemoine-Goumard, Daiki Miura, Shoji Ogawa, Shogo B. Kobayashi, Chris Done, Maxime Parra, Maria Díaz Trigo, Teo Muñoz-Darias, Montserrat Armas Padilla, Ryota Tomaru and Yoshihiro Ueda
A recent report on the detection of very-high-energy gamma rays from V4641 Sagittarii (V4641 Sgr) up to ≈0.8 PeV has made it the second confirmed “PeVatron” microquasar. Here we report on the observation of V4641 Sgr with X-Ray Imaging and Spectroscopy Mission (XRISM) in 2024 September. Thanks to the large field of view and low background, the CCD imager Xtend successfully detected for the first time X-ray extended emission around V4641 Sgr with a significance of ≳4.5σ and >10σ based on our imaging and spectral analysis, respectively. The spatial extent is estimated to have a radius of 7′ ± 3′ (13 ± 5 pc at a distance of 6.2 kpc) assuming a Gaussian-like radial distribution, which suggests that the particle acceleration site is within ~10 pc of the microquasar. If the X-ray morphology traces the diffusion of accelerated electrons, this spatial extent can be explained by either an enhanced magnetic field (∼80 μG) or a suppressed diffusion coefficient (∼1027 cm2 s−1 at 100 TeV). The integrated X-ray flux, (4–6) × 10−12 erg s−1 cm−2 (2–10 keV), would require a magnetic field strength higher than the Galactic mean (≳8 μG) if the diffuse X-ray emission originates from synchrotron radiation and the gamma-ray emission is predominantly hadronic. If the X-rays are of thermal origin, the measured extension, temperature, and plasma density can be explained by a jet with a luminosity of ∼2 × 1039 erg s−1, which is comparable to the Eddington luminosity of this system.
{"title":"Detection of Extended X-Ray Emission around the PeVatron Microquasar V4641 Sgr with XRISM","authors":"Hiromasa Suzuki, Naomi Tsuji, Yoshiaki Kanemaru, Megumi Shidatsu, Laura Olivera-Nieto, Samar Safi-Harb, Shigeo S. Kimura, Eduardo de la Fuente, Sabrina Casanova, Kaya Mori, Xiaojie Wang, Sei Kato, Dai Tateishi, Hideki Uchiyama, Takaaki Tanaka, Hiroyuki Uchida, Shun Inoue, Dezhi Huang, Marianne Lemoine-Goumard, Daiki Miura, Shoji Ogawa, Shogo B. Kobayashi, Chris Done, Maxime Parra, Maria Díaz Trigo, Teo Muñoz-Darias, Montserrat Armas Padilla, Ryota Tomaru and Yoshihiro Ueda","doi":"10.3847/2041-8213/ad9d11","DOIUrl":"https://doi.org/10.3847/2041-8213/ad9d11","url":null,"abstract":"A recent report on the detection of very-high-energy gamma rays from V4641 Sagittarii (V4641 Sgr) up to ≈0.8 PeV has made it the second confirmed “PeVatron” microquasar. Here we report on the observation of V4641 Sgr with X-Ray Imaging and Spectroscopy Mission (XRISM) in 2024 September. Thanks to the large field of view and low background, the CCD imager Xtend successfully detected for the first time X-ray extended emission around V4641 Sgr with a significance of ≳4.5σ and >10σ based on our imaging and spectral analysis, respectively. The spatial extent is estimated to have a radius of 7′ ± 3′ (13 ± 5 pc at a distance of 6.2 kpc) assuming a Gaussian-like radial distribution, which suggests that the particle acceleration site is within ~10 pc of the microquasar. If the X-ray morphology traces the diffusion of accelerated electrons, this spatial extent can be explained by either an enhanced magnetic field (∼80 μG) or a suppressed diffusion coefficient (∼1027 cm2 s−1 at 100 TeV). The integrated X-ray flux, (4–6) × 10−12 erg s−1 cm−2 (2–10 keV), would require a magnetic field strength higher than the Galactic mean (≳8 μG) if the diffuse X-ray emission originates from synchrotron radiation and the gamma-ray emission is predominantly hadronic. If the X-rays are of thermal origin, the measured extension, temperature, and plasma density can be explained by a jet with a luminosity of ∼2 × 1039 erg s−1, which is comparable to the Eddington luminosity of this system.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142924972","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 : 2025-01-03DOI: 10.3847/2041-8213/ada02a
Weixiang Sun, Han Shen, Biwei Jiang and Xiaowei Liu
Galactic disk warp has been widely characterized by stellar distributions and stellar kinematics but has not been traced by stellar chemistry. Here, we use a sample with over 170,000 red clump (RC) stars selected from LAMOST and APOGEE first to establish a correlation between the north–south asymmetry in metallicity ([Fe/H]) and the disk warp. Our results indicate that the height of the [Fe/H] midplane for the whole RC sample stars is accurately described as Zw = 0.017 (R − 7.112)2 sin(ϕ − 9.218). This morphology aligns closely with the warp traced by Cepheids, suggesting that the disk north–south asymmetry in [Fe/H] may serve as a new tracer for the Galactic warp. Our detailed analysis of the young/thin disk stars of this RC sample suggests that its warp is well modeled as Zw = 0.016 (R − 6.507)2 sin(ϕ − 4.240), indicating that the line of node of the Galactic warp is oriented at 4.240 degrees.
{"title":"The Galactic Disk North–South Asymmetry in Metallicity May Be a New Tracer for the Disk Warp","authors":"Weixiang Sun, Han Shen, Biwei Jiang and Xiaowei Liu","doi":"10.3847/2041-8213/ada02a","DOIUrl":"https://doi.org/10.3847/2041-8213/ada02a","url":null,"abstract":"Galactic disk warp has been widely characterized by stellar distributions and stellar kinematics but has not been traced by stellar chemistry. Here, we use a sample with over 170,000 red clump (RC) stars selected from LAMOST and APOGEE first to establish a correlation between the north–south asymmetry in metallicity ([Fe/H]) and the disk warp. Our results indicate that the height of the [Fe/H] midplane for the whole RC sample stars is accurately described as Zw = 0.017 (R − 7.112)2 sin(ϕ − 9.218). This morphology aligns closely with the warp traced by Cepheids, suggesting that the disk north–south asymmetry in [Fe/H] may serve as a new tracer for the Galactic warp. Our detailed analysis of the young/thin disk stars of this RC sample suggests that its warp is well modeled as Zw = 0.016 (R − 6.507)2 sin(ϕ − 4.240), indicating that the line of node of the Galactic warp is oriented at 4.240 degrees.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"66 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142924973","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 : 2025-01-03DOI: 10.3847/2041-8213/ada02b
Xingyu Zhang, Hai-Bo Yu, Daneng Yang and Ethan O. Nadler
The GD-1 stellar stream exhibits spur and gap structures that may result from a close encounter with a dense substructure. When interpreted as a dark matter subhalo, the perturber is denser than predicted in the standard cold dark matter (CDM) model. In self-interacting dark matter (SIDM), however, a halo could evolve into a phase of gravothermal collapse, resulting in a higher central density than its CDM counterpart. We conduct high-resolution controlled N-body simulations to show that a collapsed SIDM halo could account for the GD-1 perturber's high density. We model a progenitor halo with a mass of 3 × 108 M⊙, motivated by a cosmological simulation of a Milky Way analog, and evolve it in the Milky Way's tidal field. For a cross section per mass of σ/m ≈ 30–100 cm2 g−1 at , the enclosed mass of the SIDM halo within the inner 10 pc can be increased by more than 1 order of magnitude compared to its CDM counterpart, leading to a good agreement with the properties of the GD-1 perturber. Our findings indicate that stellar streams provide a novel probe into the self-interacting nature of dark matter.
{"title":"The GD-1 Stellar Stream Perturber as a Core-collapsed Self-interacting Dark Matter Halo","authors":"Xingyu Zhang, Hai-Bo Yu, Daneng Yang and Ethan O. Nadler","doi":"10.3847/2041-8213/ada02b","DOIUrl":"https://doi.org/10.3847/2041-8213/ada02b","url":null,"abstract":"The GD-1 stellar stream exhibits spur and gap structures that may result from a close encounter with a dense substructure. When interpreted as a dark matter subhalo, the perturber is denser than predicted in the standard cold dark matter (CDM) model. In self-interacting dark matter (SIDM), however, a halo could evolve into a phase of gravothermal collapse, resulting in a higher central density than its CDM counterpart. We conduct high-resolution controlled N-body simulations to show that a collapsed SIDM halo could account for the GD-1 perturber's high density. We model a progenitor halo with a mass of 3 × 108 M⊙, motivated by a cosmological simulation of a Milky Way analog, and evolve it in the Milky Way's tidal field. For a cross section per mass of σ/m ≈ 30–100 cm2 g−1 at , the enclosed mass of the SIDM halo within the inner 10 pc can be increased by more than 1 order of magnitude compared to its CDM counterpart, leading to a good agreement with the properties of the GD-1 perturber. Our findings indicate that stellar streams provide a novel probe into the self-interacting nature of dark matter.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142924974","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 : 2025-01-03DOI: 10.3847/2041-8213/ad9913
G. Mastroserio, B. De Marco, M. C. Baglio, F. Carotenuto, S. Fabiani, T. D. Russell, F. Capitanio, Y. Cavecchi, S. Motta, D. M. Russell, M. Dovčiak, M. Del Santo, K. Alabarta, A. Ambrifi, S. Campana, P. Casella, S. Covino, G. Illiano, E. Kara, E. V. Lai, G. Lodato, A. Manca, I. Mariani, A. Marino, C. Miceli, P. Saikia, A. W. Shaw, J. Svoboda, F. M. Vincentelli and J. Wang
We present the first X-ray polarization measurements of GX 339–4. IXPE observed this source twice during its 2023–2024 outburst, once in the soft-intermediate state and again during a soft state. The observation taken during the intermediate state shows a significant (4σ) polarization degree PX = 1.3% ± 0.3% and polarization angle θX = −74° ± 7° only in the 3–8 keV band. FORS2 at the Very Large Telescope observed the source simultaneously, detecting optical polarization in the B, V, R, and I bands (between ∼0.1% and ∼0.7%), all roughly aligned with the X-ray polarization. We also detect a discrete jet knot from radio observations with the Australia Telescope Compact Array taken later in time; this knot would have been ejected from the system around the same time as the hard-to-soft X-ray state transition, and a bright radio flare occurred ∼3 months earlier. The proper motion of the jet knot provides a direct measurement of the jet orientation angle on the plane of the sky at the time of the ejection. We find that both the X-ray and optical polarization angles are aligned with the direction of the ballistic jet.
{"title":"X-Ray and Optical Polarization Aligned with the Radio Jet Ejecta in GX 339–4","authors":"G. Mastroserio, B. De Marco, M. C. Baglio, F. Carotenuto, S. Fabiani, T. D. Russell, F. Capitanio, Y. Cavecchi, S. Motta, D. M. Russell, M. Dovčiak, M. Del Santo, K. Alabarta, A. Ambrifi, S. Campana, P. Casella, S. Covino, G. Illiano, E. Kara, E. V. Lai, G. Lodato, A. Manca, I. Mariani, A. Marino, C. Miceli, P. Saikia, A. W. Shaw, J. Svoboda, F. M. Vincentelli and J. Wang","doi":"10.3847/2041-8213/ad9913","DOIUrl":"https://doi.org/10.3847/2041-8213/ad9913","url":null,"abstract":"We present the first X-ray polarization measurements of GX 339–4. IXPE observed this source twice during its 2023–2024 outburst, once in the soft-intermediate state and again during a soft state. The observation taken during the intermediate state shows a significant (4σ) polarization degree PX = 1.3% ± 0.3% and polarization angle θX = −74° ± 7° only in the 3–8 keV band. FORS2 at the Very Large Telescope observed the source simultaneously, detecting optical polarization in the B, V, R, and I bands (between ∼0.1% and ∼0.7%), all roughly aligned with the X-ray polarization. We also detect a discrete jet knot from radio observations with the Australia Telescope Compact Array taken later in time; this knot would have been ejected from the system around the same time as the hard-to-soft X-ray state transition, and a bright radio flare occurred ∼3 months earlier. The proper motion of the jet knot provides a direct measurement of the jet orientation angle on the plane of the sky at the time of the ejection. We find that both the X-ray and optical polarization angles are aligned with the direction of the ballistic jet.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"41 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142924971","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 : 2025-01-02DOI: 10.3847/2041-8213/ad9bac
Mandy C. Chen, Hsiao-Wen Chen, Michael Rauch, Andrey Vayner, Weizhe Liu, David S. N. Rupke, Jenny E. Greene, Nadia L. Zakamska, Dominika Wylezalek, Guilin Liu, Sylvain Veilleux, Nicole P. H. Nesvadba and Caroline Bertemes
In this Letter, we investigate the turbulence and energy injection in the extended nebulae surrounding two luminous obscured quasars, WISEA J100211.29+013706.7 (z = 1.5933) and SDSS J165202.64+172852.3 (z = 2.9489). Utilizing high-resolution data from the NIRSpec integral field unit onboard the James Webb Space Telescope, we analyze the velocity fields of line-emitting gas in and around these quasars and construct the second-order velocity structure functions (VSFs) to quantify turbulent motions across different spatial scales. Our findings reveal a notable flattening in the VSFs from ≈ 3 kpc up to a scale of 10–20 kpc, suggesting that energy injection predominantly occurs at a scale ≲ 10 kpc, likely powered by quasar outflows and jet-driven bubbles. The extended spatial range of flat VSFs may also indicate the presence of multiple energy injection sources at these scales. For J1652, the turbulent energy in the host interstellar medium (ISM) is significantly higher than in tidally stripped gas, consistent with the expectation of active galactic nucleus (AGN) activities stirring up the host ISM. Compared to the VSFs observed on spatial scales of 10–50 kpc around lower-redshift UV-bright quasars, these obscured quasars exhibit higher turbulent energies in their immediate surroundings, implying different turbulence drivers between the ISM and halo-scale gas. Future studies with an expanded sample are essential to elucidate further the extent and the pivotal role of AGNs in shaping the gas kinematics of host galaxies and beyond.
{"title":"Resolving Turbulence Drivers in Two Luminous Obscured Quasars with JWST/NIRSpec Integral Field Unit","authors":"Mandy C. Chen, Hsiao-Wen Chen, Michael Rauch, Andrey Vayner, Weizhe Liu, David S. N. Rupke, Jenny E. Greene, Nadia L. Zakamska, Dominika Wylezalek, Guilin Liu, Sylvain Veilleux, Nicole P. H. Nesvadba and Caroline Bertemes","doi":"10.3847/2041-8213/ad9bac","DOIUrl":"https://doi.org/10.3847/2041-8213/ad9bac","url":null,"abstract":"In this Letter, we investigate the turbulence and energy injection in the extended nebulae surrounding two luminous obscured quasars, WISEA J100211.29+013706.7 (z = 1.5933) and SDSS J165202.64+172852.3 (z = 2.9489). Utilizing high-resolution data from the NIRSpec integral field unit onboard the James Webb Space Telescope, we analyze the velocity fields of line-emitting gas in and around these quasars and construct the second-order velocity structure functions (VSFs) to quantify turbulent motions across different spatial scales. Our findings reveal a notable flattening in the VSFs from ≈ 3 kpc up to a scale of 10–20 kpc, suggesting that energy injection predominantly occurs at a scale ≲ 10 kpc, likely powered by quasar outflows and jet-driven bubbles. The extended spatial range of flat VSFs may also indicate the presence of multiple energy injection sources at these scales. For J1652, the turbulent energy in the host interstellar medium (ISM) is significantly higher than in tidally stripped gas, consistent with the expectation of active galactic nucleus (AGN) activities stirring up the host ISM. Compared to the VSFs observed on spatial scales of 10–50 kpc around lower-redshift UV-bright quasars, these obscured quasars exhibit higher turbulent energies in their immediate surroundings, implying different turbulence drivers between the ISM and halo-scale gas. Future studies with an expanded sample are essential to elucidate further the extent and the pivotal role of AGNs in shaping the gas kinematics of host galaxies and beyond.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142911469","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 : 2025-01-02DOI: 10.3847/2041-8213/ad9f5d
J. S. Castellanos Durán, A. Korpi-Lagg, S. K. Solanki, M. van Noort and N. Milanovic
Recent solar observations of bipolar light bridges (BLBs) in sunspots have, in a few individual cases, revealed magnetic fields up to 8.2 kG, which is at least twice as strong as typical values measured in sunspot umbrae. However, the small number of such observations hinted that such strong fields in these bright photospheric features that separate two opposite-polarity umbrae are a rare phenomenon. We determine the field strength in a large sample of BLBs with the aim of establishing how prevalent such strong fields are in BLBs. We apply a state-of-the-art inversion technique that accounts for the degradation of the data by the intrinsic point-spread function of the telescope, to the so far largest set of spectropolarimetric observations, by Hinode/Solar Optical Telescope spectropolarimeter, of sunspots containing BLBs. We identified 98 individual BLBs within 51 distinct sunspot groups. Since 66.3% of the BLBs were observed multiple times, a total of 630 spectropolarimetric scans of these 98 BLBs were analyzed. All analyzed BLBs contain magnetic fields stronger than 4.5 kG at unit optical depth. The field strengths decrease faster with height than the fields in umbrae and penumbrae. BLBs display a unique continuum intensity and field strength combination, forming a population well separated from umbrae and the penumbrae. The high brightness of BLBs in spite of their very strong magnetic fields points to the presence of a so far largely unexplored regime of magnetoconvection.
{"title":"Superstrong Magnetic Fields in Sunspot Bipolar Light Bridges","authors":"J. S. Castellanos Durán, A. Korpi-Lagg, S. K. Solanki, M. van Noort and N. Milanovic","doi":"10.3847/2041-8213/ad9f5d","DOIUrl":"https://doi.org/10.3847/2041-8213/ad9f5d","url":null,"abstract":"Recent solar observations of bipolar light bridges (BLBs) in sunspots have, in a few individual cases, revealed magnetic fields up to 8.2 kG, which is at least twice as strong as typical values measured in sunspot umbrae. However, the small number of such observations hinted that such strong fields in these bright photospheric features that separate two opposite-polarity umbrae are a rare phenomenon. We determine the field strength in a large sample of BLBs with the aim of establishing how prevalent such strong fields are in BLBs. We apply a state-of-the-art inversion technique that accounts for the degradation of the data by the intrinsic point-spread function of the telescope, to the so far largest set of spectropolarimetric observations, by Hinode/Solar Optical Telescope spectropolarimeter, of sunspots containing BLBs. We identified 98 individual BLBs within 51 distinct sunspot groups. Since 66.3% of the BLBs were observed multiple times, a total of 630 spectropolarimetric scans of these 98 BLBs were analyzed. All analyzed BLBs contain magnetic fields stronger than 4.5 kG at unit optical depth. The field strengths decrease faster with height than the fields in umbrae and penumbrae. BLBs display a unique continuum intensity and field strength combination, forming a population well separated from umbrae and the penumbrae. The high brightness of BLBs in spite of their very strong magnetic fields points to the presence of a so far largely unexplored regime of magnetoconvection.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"55 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142916870","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 : 2025-01-02DOI: 10.3847/2041-8213/ad9ddd
Joseph H. Wang, Timothy S. Horbury, Lorenzo Matteini and Domenico Trotta
Helium nuclei (alpha particles) strongly influence the momentum and energy balance in the solar wind, comprising up to 20% of the solar wind mass density. In fast Alfvénic wind at heliocentric distances greater than 0.3 au, the alpha particles’ bulk flow speed is systematically different to that of the protons. This relative drift speed is of unknown origin and is often close to the local Alfvén wave speed. Novel Parker Solar Probe measurements of the solar wind below 0.3 au show that, closer to the Sun, the alpha–proton drift speed remains on the order of 100–200 km s−1, even where the Alfvén speed is greater than 600 km s−1. This relative speed is quantitatively similar to oxygen–hydrogen drift speeds observed in the transition region by remote sensing, suggesting similar selective acceleration processes in the corona. Due to the relative speed of the Alfvén wave to each particle population close to the Sun, the alphas fluctuate with velocity amplitudes comparable to those of the protons, altering the energy balance of the wave. As a result, alpha particles carry a significant fraction of the total kinetic energy in Alfvénic fluctuations in the near-Sun solar wind. The alpha–proton drift speed is comparable to the proton speed in the near-Sun wind, making the bulk flow of the alpha particles a significant contribution to the kinetic energy flux. These heavy-ion dynamics provide new observational constraints on quantifying the energy budget of the solar wind and the magnetic field evolution through the heliosphere.
氦核（α粒子）强烈影响太阳风的动量和能量平衡，占太阳风质量密度的20%。在日心距离大于0.3 au的高速阿尔法粒子风中，阿尔法粒子的体流速度与质子的体流速度有系统的不同。这种相对漂移速度的来源不明，通常接近当地的阿尔夫海姆波速度。新颖的帕克太阳探测器对小于0.3 au的太阳风的测量表明，在离太阳更近的地方，质子的漂移速度保持在100-200 km s - 1的量级，即使在alfv速度大于600 km s - 1的地方。这一相对速度在数量上与遥感在过渡区观测到的氧-氢漂移速度相似，表明日冕中有类似的选择性加速过程。由于alfvn波对靠近太阳的每个粒子群的相对速度，α的波动速度与质子的波动速度相当，从而改变了波的能量平衡。因此，在近太阳太阳风的阿尔法粒子波动中，阿尔法粒子携带了很大一部分总动能。α -质子的漂移速度与近太阳风中的质子速度相当，这使得α粒子的体积流动对动能通量有重要贡献。这些重离子动力学为量化太阳风的能量收支和通过日球层的磁场演化提供了新的观测约束。
{"title":"Alpha–Proton Relative Drift: Implications for the Origins and Dynamics of the Solar Wind","authors":"Joseph H. Wang, Timothy S. Horbury, Lorenzo Matteini and Domenico Trotta","doi":"10.3847/2041-8213/ad9ddd","DOIUrl":"https://doi.org/10.3847/2041-8213/ad9ddd","url":null,"abstract":"Helium nuclei (alpha particles) strongly influence the momentum and energy balance in the solar wind, comprising up to 20% of the solar wind mass density. In fast Alfvénic wind at heliocentric distances greater than 0.3 au, the alpha particles’ bulk flow speed is systematically different to that of the protons. This relative drift speed is of unknown origin and is often close to the local Alfvén wave speed. Novel Parker Solar Probe measurements of the solar wind below 0.3 au show that, closer to the Sun, the alpha–proton drift speed remains on the order of 100–200 km s−1, even where the Alfvén speed is greater than 600 km s−1. This relative speed is quantitatively similar to oxygen–hydrogen drift speeds observed in the transition region by remote sensing, suggesting similar selective acceleration processes in the corona. Due to the relative speed of the Alfvén wave to each particle population close to the Sun, the alphas fluctuate with velocity amplitudes comparable to those of the protons, altering the energy balance of the wave. As a result, alpha particles carry a significant fraction of the total kinetic energy in Alfvénic fluctuations in the near-Sun solar wind. The alpha–proton drift speed is comparable to the proton speed in the near-Sun wind, making the bulk flow of the alpha particles a significant contribution to the kinetic energy flux. These heavy-ion dynamics provide new observational constraints on quantifying the energy budget of the solar wind and the magnetic field evolution through the heliosphere.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"41 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142911483","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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