Pub Date : 2024-11-25DOI: 10.3847/1538-4357/ad8b4d
Mengke Zhao, Guang-Xing Li and Keping Qiu
The electromagnetic field is a fundamental force in nature that regulates the formation of stars in the Universe. Despite decades of efforts, a reliable assessment of the importance of the magnetic fields in star formation relations remains missing. In star formation research, our acknowledgment of the importance of magnetic fields is best summarized by the R. M. Crutcher et al. B–ρ relation, whose interpretation remains controversial. The relation is either interpreted as proof of the importance of a magnetic field in gravitational collapse or as the result of self-similar collapse where the role of the magnetic field is secondary to gravity. Using simulations, we find a fundamental relation, –kB−ρ (the slope of the B–ρ relation): This fundamental B–ρ slope relation enables one to measure the Alfvénic Mach number, a direct indicator of the importance of the magnetic field, using the distribution of data in the B–ρ plane. It allows us to apply the following empirical B–ρ relation: which offers an excellent fit to the Crutcher et al. data, where we assume an relation ( ). The foundational relation provides an independent way to measure the importance of the magnetic field against the kinematic motion using multiple magnetic-field measurements. Our approach offers a new interpretation of the classical B–ρ relation, where a gradual decrease in the importance of B at higher densities is implied.
{"title":"Slope of Magnetic Field–Density Relation as an Indicator of Magnetic Dominance","authors":"Mengke Zhao, Guang-Xing Li and Keping Qiu","doi":"10.3847/1538-4357/ad8b4d","DOIUrl":"https://doi.org/10.3847/1538-4357/ad8b4d","url":null,"abstract":"The electromagnetic field is a fundamental force in nature that regulates the formation of stars in the Universe. Despite decades of efforts, a reliable assessment of the importance of the magnetic fields in star formation relations remains missing. In star formation research, our acknowledgment of the importance of magnetic fields is best summarized by the R. M. Crutcher et al. B–ρ relation, whose interpretation remains controversial. The relation is either interpreted as proof of the importance of a magnetic field in gravitational collapse or as the result of self-similar collapse where the role of the magnetic field is secondary to gravity. Using simulations, we find a fundamental relation, –kB−ρ (the slope of the B–ρ relation): This fundamental B–ρ slope relation enables one to measure the Alfvénic Mach number, a direct indicator of the importance of the magnetic field, using the distribution of data in the B–ρ plane. It allows us to apply the following empirical B–ρ relation: which offers an excellent fit to the Crutcher et al. data, where we assume an relation ( ). The foundational relation provides an independent way to measure the importance of the magnetic field against the kinematic motion using multiple magnetic-field measurements. Our approach offers a new interpretation of the classical B–ρ relation, where a gradual decrease in the importance of B at higher densities is implied.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142697046","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}
We investigated two consecutive solar eruption events in the solar active region 12994 at the solar eastern limb on 2022 April 15. We found that the flare loops formed by the first eruption were involved in the second eruption. During the initial stage of the second flare, the middle part of these flare loops (E-loops) erupted outward along with the flux ropes below, while the parts of the flare loops (I-loops1 and I-loops2) on either side of the E-loops first rose and then contracted. Approximately 1 hr after the eruption, the heights of I-loops1 and I-loops2 decreased by 9 Mm and 45 Mm, respectively, compared to before the eruption. Their maximum descent velocities were 30 km s−1 and 130 km s−1, respectively. The differential emission measure results indicate that the plasma above I-loops1 and I-loops2 began to be heated about 23 minutes and 44 minutes after the start of the second flare, respectively. Within ∼20 minutes, the plasma temperature in these regions increased from ∼3 MK to ∼6 MK. We proposed an adiabatic heating mechanism where magnetic energy would be converted into thermal and kinetic energy when the prestretched loops contract. Our calculations show that the magnetic energy required to heat the two high-temperature regions are 1029–1030 erg, which correspond to a loss of field strength of 2–3 G.
{"title":"Simultaneous Eruption and Shrinkage of Preexisting Flare Loops during a Subsequent Solar Eruption","authors":"Huadong Chen, 华东 陈, Lyndsay Fletcher, Guiping Zhou, 桂萍 周, Xin Cheng, 鑫 程, Ya Wang, 亚 汪, Sargam Mulay, Ruisheng Zheng, 瑞生 郑, Suli Ma, 素丽 马, Xiaofan Zhang and 小凡 张","doi":"10.3847/1538-4357/ad8c25","DOIUrl":"https://doi.org/10.3847/1538-4357/ad8c25","url":null,"abstract":"We investigated two consecutive solar eruption events in the solar active region 12994 at the solar eastern limb on 2022 April 15. We found that the flare loops formed by the first eruption were involved in the second eruption. During the initial stage of the second flare, the middle part of these flare loops (E-loops) erupted outward along with the flux ropes below, while the parts of the flare loops (I-loops1 and I-loops2) on either side of the E-loops first rose and then contracted. Approximately 1 hr after the eruption, the heights of I-loops1 and I-loops2 decreased by 9 Mm and 45 Mm, respectively, compared to before the eruption. Their maximum descent velocities were 30 km s−1 and 130 km s−1, respectively. The differential emission measure results indicate that the plasma above I-loops1 and I-loops2 began to be heated about 23 minutes and 44 minutes after the start of the second flare, respectively. Within ∼20 minutes, the plasma temperature in these regions increased from ∼3 MK to ∼6 MK. We proposed an adiabatic heating mechanism where magnetic energy would be converted into thermal and kinetic energy when the prestretched loops contract. Our calculations show that the magnetic energy required to heat the two high-temperature regions are 1029–1030 erg, which correspond to a loss of field strength of 2–3 G.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"189 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142697066","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 : 2024-11-25DOI: 10.3847/1538-4357/ad8238
Alejandro J. Olvera, Sanchayeeta Borthakur, Mansi Padave, Timothy Heckman, Hansung B. Gim, Brad Koplitz, Christopher Dupuis, Emmanuel Momjian and Rolf A. Jansen
As a part of the Deciphering the Interplay between the Interstellar medium, Stars, and the Circumgalactic medium (DIISC) survey, we investigate indirect evidence of gas inflow into the disk of the galaxy NGC 99. We combine optical spectra from the Binospec spectrograph on the MMT telescope with optical imaging data from the Vatican Advanced Technology Telescope, radio H i 21 cm emission images from the NSF Karl G. Jansky’s Very Large Array, and UV spectroscopy from the Cosmic Origins Spectrograph on the Hubble Space Telescope. We measure emission lines (Hα, Hβ, [O iii]λ5007, [N ii]λ6583, and [S ii]λ6717, 31) in 26 H ii regions scattered about the galaxy and estimate a radial metallicity gradient of −0.017 dex kpc−1 using the N2 metallicity indicator. Two regions in the sample exhibit an anomalously low metallicity (ALM) of 12 + log(O/H) = 8.36 dex, which is ∼0.16 dex lower than other regions at that galactocentric radius. They also show a high difference between their H i and Hα line of sight velocities on the order of 35 km s−1. Chemical evolution modeling indicates gas accretion as the cause of the ALM regions. We find evidence for corotation between the interstellar medium of NGC 99 and Lyα clouds in its circumgalactic medium, which suggests a possible pathway for low metallicity gas accretion. We also calculate the resolved Fundamental Metallicity Relation (rFMR) on subkiloparsec scales using localized gas-phase metallicity, stellar mass surface density, and star formation rate surface density. The rFMR shows a similar trend as that found by previous localized and global FMR relations.
作为 "解密星际介质、恒星和环银河介质之间的相互作用（DIISC）"调查的一部分，我们研究了气体流入 NGC 99 星系盘面的间接证据。我们将来自 MMT 望远镜上 Binospec 摄谱仪的光学光谱与来自梵蒂冈先进技术望远镜的光学成像数据、来自美国国家科学基金会 Karl G. Jansky's 超大阵列的射电 H i 21 厘米发射图像以及来自哈勃太空望远镜上宇宙起源摄谱仪的紫外光谱相结合。我们测量了散布在星系周围的 26 个 H ii 区域的发射线（Hα、Hβ、[O iii]λ5007 、[N ii]λ6583 和 [S ii]λ6717, 31），并利用 N2 金属性指标估算出径向金属性梯度为-0.017 dex kpc-1。样本中有两个区域显示出异常低的金属性（ALM），为12 + log(O/H) = 8.36 dex，比该银河系半径上的其他区域低0.16 dex。它们的 H i 和 Hα 视线速度也相差很大，约为 35 km s-1。化学演化模型表明，气体吸积是形成 ALM 区域的原因。我们发现了NGC 99的星际介质与其环星系介质中的Lyα云之间存在相关性的证据，这表明低金属度气体吸积可能是一种途径。我们还利用局部气相金属性、恒星质量表面密度和恒星形成率表面密度计算了亚千亿秒尺度上的解析基本金属性关系（rFMR）。rFMR显示出与以往局部和全局FMR关系类似的趋势。
{"title":"DIISC-IV. DIISCovery of Anomalously Low Metallicity H ii Regions in NGC 99: Indirect Evidence of Gas Inflows","authors":"Alejandro J. Olvera, Sanchayeeta Borthakur, Mansi Padave, Timothy Heckman, Hansung B. Gim, Brad Koplitz, Christopher Dupuis, Emmanuel Momjian and Rolf A. Jansen","doi":"10.3847/1538-4357/ad8238","DOIUrl":"https://doi.org/10.3847/1538-4357/ad8238","url":null,"abstract":"As a part of the Deciphering the Interplay between the Interstellar medium, Stars, and the Circumgalactic medium (DIISC) survey, we investigate indirect evidence of gas inflow into the disk of the galaxy NGC 99. We combine optical spectra from the Binospec spectrograph on the MMT telescope with optical imaging data from the Vatican Advanced Technology Telescope, radio H i 21 cm emission images from the NSF Karl G. Jansky’s Very Large Array, and UV spectroscopy from the Cosmic Origins Spectrograph on the Hubble Space Telescope. We measure emission lines (Hα, Hβ, [O iii]λ5007, [N ii]λ6583, and [S ii]λ6717, 31) in 26 H ii regions scattered about the galaxy and estimate a radial metallicity gradient of −0.017 dex kpc−1 using the N2 metallicity indicator. Two regions in the sample exhibit an anomalously low metallicity (ALM) of 12 + log(O/H) = 8.36 dex, which is ∼0.16 dex lower than other regions at that galactocentric radius. They also show a high difference between their H i and Hα line of sight velocities on the order of 35 km s−1. Chemical evolution modeling indicates gas accretion as the cause of the ALM regions. We find evidence for corotation between the interstellar medium of NGC 99 and Lyα clouds in its circumgalactic medium, which suggests a possible pathway for low metallicity gas accretion. We also calculate the resolved Fundamental Metallicity Relation (rFMR) on subkiloparsec scales using localized gas-phase metallicity, stellar mass surface density, and star formation rate surface density. The rFMR shows a similar trend as that found by previous localized and global FMR relations.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142697075","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 : 2024-11-25DOI: 10.3847/1538-4357/ad7396
Stacey Alberts, Jianwei Lyu, 建伟 吕, Irene Shivaei, George H. Rieke, Pablo G. Pérez-González, Nina Bonaventura, Yongda Zhu, Jakob M. Helton, Zhiyuan Ji, Jane Morrison, Brant E. Robertson, Meredith A. Stone, Yang Sun, Christina C. Williams and Christopher N. A. Willmer
The James Webb Space Telescope is revolutionizing our view of the Universe through unprecedented sensitivity and resolution in the infrared, with some of the largest gains realized at its longest wavelengths. We present the Systematic Mid-infrared Instrument (MIRI) Legacy Extragalactic Survey (SMILES), an eight-band MIRI survey with Near-Infrared Spectrograph spectroscopic follow-up in the GOODS-S/HUDF region. SMILES takes full advantage of MIRI’s continuous coverage from 5.6 to 25.5 μm over an ∼34 arcmin2 area to greatly expand our understanding of the obscured Universe up to cosmic noon and beyond. This work, together with a companion paper by G. Rieke et al., covers the SMILES science drivers and technical design, early results with SMILES, data reduction, photometric catalog creation, and the first data release. As part of the discussion on early results, we additionally present a high-level science demonstration on how MIRI’s wavelength coverage and resolution will advance our understanding of cosmic dust using the full range of polycyclic aromatic hydrocarbon emission features from 3.3 to 18 μm. Using custom background subtraction, we produce robust reductions of the MIRI imaging that maximize the depths reached with our modest exposure times (∼0.6−2.2 ks per filter). Included in our initial data release are (1) eight MIRI imaging mosaics reaching depths of 0.2−18 μJy (5σ) and (2) a 5−25.5 μm photometric catalog with over 3000 sources. Building upon the rich legacy of extensive photometric and spectroscopy coverage of GOODS-S/HUDF from the X-ray to the radio, SMILES greatly expands our investigative power in understanding the obscured Universe.
{"title":"SMILES Initial Data Release: Unveiling the Obscured Universe with MIRI Multiband Imaging","authors":"Stacey Alberts, Jianwei Lyu, 建伟 吕, Irene Shivaei, George H. Rieke, Pablo G. Pérez-González, Nina Bonaventura, Yongda Zhu, Jakob M. Helton, Zhiyuan Ji, Jane Morrison, Brant E. Robertson, Meredith A. Stone, Yang Sun, Christina C. Williams and Christopher N. A. Willmer","doi":"10.3847/1538-4357/ad7396","DOIUrl":"https://doi.org/10.3847/1538-4357/ad7396","url":null,"abstract":"The James Webb Space Telescope is revolutionizing our view of the Universe through unprecedented sensitivity and resolution in the infrared, with some of the largest gains realized at its longest wavelengths. We present the Systematic Mid-infrared Instrument (MIRI) Legacy Extragalactic Survey (SMILES), an eight-band MIRI survey with Near-Infrared Spectrograph spectroscopic follow-up in the GOODS-S/HUDF region. SMILES takes full advantage of MIRI’s continuous coverage from 5.6 to 25.5 μm over an ∼34 arcmin2 area to greatly expand our understanding of the obscured Universe up to cosmic noon and beyond. This work, together with a companion paper by G. Rieke et al., covers the SMILES science drivers and technical design, early results with SMILES, data reduction, photometric catalog creation, and the first data release. As part of the discussion on early results, we additionally present a high-level science demonstration on how MIRI’s wavelength coverage and resolution will advance our understanding of cosmic dust using the full range of polycyclic aromatic hydrocarbon emission features from 3.3 to 18 μm. Using custom background subtraction, we produce robust reductions of the MIRI imaging that maximize the depths reached with our modest exposure times (∼0.6−2.2 ks per filter). Included in our initial data release are (1) eight MIRI imaging mosaics reaching depths of 0.2−18 μJy (5σ) and (2) a 5−25.5 μm photometric catalog with over 3000 sources. Building upon the rich legacy of extensive photometric and spectroscopy coverage of GOODS-S/HUDF from the X-ray to the radio, SMILES greatly expands our investigative power in understanding the obscured Universe.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"80 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142697140","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 : 2024-11-25DOI: 10.3847/1538-4357/ad8bab
Tonghua Liu, Xinyi Zhong, Marek Biesiada and Jieci Wang
The sound horizon scale is a key theoretical prediction of the cosmological model that depends on the speed of sound in the baryon-photon fluid and the rate of expansion of the early Universe, before matter and radiation decoupled. Baryon acoustic oscillations (BAOs) offer the direct measurement of this important scale imprinted in the distribution of galaxies. We propose a new model-independent method to calibrate the sound horizon (relative standard ruler) by using the latest observations of Type Ia supernovae (SNe Ia) and 2D BAO measurements. The final result is Mpc h−1 in the framework of the Pantheon SN Ia data set. This result changes to Mpc h−1 when the Pantheon+ data set is used. To highlight our analysis and results, we also use BAO DESI measurements and obtain the best-fitting value Mpc h−1. Note that even without an estimate of the dimensionless Hubble constant h, the combination of 2D BAO and SN Ia data sets already constrains the low-redshift standard ruler scale at the ∼1.26% level (at the ∼1.00% level in the framework of BAO DESI data set). More importantly, it is interesting to note that most of the obtained at high redshifts have systematically larger values: 9 out of 15 results are larger than the result obtained by combining all 2D BAOs. This finding may give us a better understanding of the discordance between the data sets, shed light on the Hubble tension, or reveal the need for new physics beyond the standard cosmological model.
声界尺度是宇宙学模型的一个关键理论预测，它取决于重子-光子流体中的声速以及物质和辐射脱钩之前早期宇宙的膨胀率。重子声学振荡（BAOs）提供了对这一印刻在星系分布中的重要尺度的直接测量。我们提出了一种独立于模型的新方法，利用对 Ia 型超新星（SNe Ia）的最新观测和二维 BAO 测量来校准声平线（相对标准尺）。在 Pantheon SN Ia 数据集的框架内，最终结果为 Mpc h-1。当使用 Pantheon+ 数据集时，这一结果变为 Mpc h-1。为了突出我们的分析和结果，我们还使用了 BAO DESI 测量数据，并得到了最佳拟合值 Mpc h-1。需要注意的是，即使不估算无量纲哈勃常数h，二维BAO和SN Ia数据集的组合也已经将低红移标准尺度约束在了∼1.26%的水平上（在BAO DESI数据集的框架下为∼1.00%的水平）。更重要的是，值得注意的是，大多数在高红移下得到的结果都有系统性的较大值：在 15 个结果中，有 9 个的数值大于综合所有二维 BAO 得到的结果。这一发现可能会让我们更好地理解数据集之间的不一致，揭示哈勃张力，或者揭示标准宇宙学模型之外的新物理学需求。
{"title":"Model-independent Calibration for Sound Horizon: Combining Observations of Supernovae and Baryon Acoustic Oscillation Measurements","authors":"Tonghua Liu, Xinyi Zhong, Marek Biesiada and Jieci Wang","doi":"10.3847/1538-4357/ad8bab","DOIUrl":"https://doi.org/10.3847/1538-4357/ad8bab","url":null,"abstract":"The sound horizon scale is a key theoretical prediction of the cosmological model that depends on the speed of sound in the baryon-photon fluid and the rate of expansion of the early Universe, before matter and radiation decoupled. Baryon acoustic oscillations (BAOs) offer the direct measurement of this important scale imprinted in the distribution of galaxies. We propose a new model-independent method to calibrate the sound horizon (relative standard ruler) by using the latest observations of Type Ia supernovae (SNe Ia) and 2D BAO measurements. The final result is Mpc h−1 in the framework of the Pantheon SN Ia data set. This result changes to Mpc h−1 when the Pantheon+ data set is used. To highlight our analysis and results, we also use BAO DESI measurements and obtain the best-fitting value Mpc h−1. Note that even without an estimate of the dimensionless Hubble constant h, the combination of 2D BAO and SN Ia data sets already constrains the low-redshift standard ruler scale at the ∼1.26% level (at the ∼1.00% level in the framework of BAO DESI data set). More importantly, it is interesting to note that most of the obtained at high redshifts have systematically larger values: 9 out of 15 results are larger than the result obtained by combining all 2D BAOs. This finding may give us a better understanding of the discordance between the data sets, shed light on the Hubble tension, or reveal the need for new physics beyond the standard cosmological model.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142697047","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 : 2024-11-25DOI: 10.3847/1538-4357/ad87f2
Souvik Manna, Subhashis Roy and Tapas Baug
We present the results of deep radio observations of seven nearby large galaxies observed using the upgraded Giant Metrewave Radio Telescope (uGMRT) 0.3–0.5 GHz receivers with an angular resolution of ∼10″. The achieved sensitivities of these observations range from ≈15 to 50 μJy beam−1, which is a factor of ≈3–4 lower than the previous observations at these frequencies. For two galaxies (NGC 3344 and NGC 3627) with moderate inclination angles, significant diffuse emissions are seen for the first time. The detected radio halos in the vertical direction are significantly larger in our 0.4 GHz maps compared to the observations at ∼1.5 GHz for four nearly edge-on galaxies—NGC 3623, NGC 4096, NGC 4594, and NGC 4631. For these four galaxies, significantly larger halos are also detected along the galaxy disk. For NGC 3623 and NGC 4594, we could detect elongated radio disks that were not seen before. We also present new uGMRT images of NGC 3344 and NGC 3623 at 1.3 GHz and a new VLA image of NGC 3627 at 1.5 GHz. We fitted an exponential function to the flux densities along different cross-cuts and found a significantly wider distribution at the 0.4 GHz uGMRT images compared to the high-frequency images at ∼1.5 GHz. Using maps at 0.144, 0.4, and ∼1.5 GHz, we made spectral index maps of the seven sample galaxies and found a steepening of the spectrum up to a value of ∼−1.5 in the halo regions of the galaxies.
我们展示了利用升级版巨型移波射电望远镜（uGMRT）0.3-0.5 GHz 接收器对附近七个大星系进行的深度射电观测结果，其角度分辨率为 10″。这些观测的灵敏度从 ≈15 到 50 μJy 波束-1，比以前在这些频率上的观测低 ≈3-4 倍。在两个倾角适中的星系（NGC 3344 和 NGC 3627）中，首次看到了明显的弥散发射。对于四个接近边缘的星系--NGC 3623、NGC 4096、NGC 4594 和 NGC 4631，我们的 0.4 GHz 地图在垂直方向上探测到的射电光晕比在～1.5 GHz 的观测结果大得多。在这四个星系中，沿星系盘也探测到了明显更大的光晕。在 NGC 3623 和 NGC 4594 中，我们还探测到了以前从未见过的细长射电盘。我们还展示了 NGC 3344 和 NGC 3623 在 1.3 GHz 下的新 uGMRT 图像，以及 NGC 3627 在 1.5 GHz 下的新 VLA 图像。我们对不同截面的通量密度进行了指数函数拟合，发现与 ∼1.5 GHz 的高频图像相比，0.4 GHz uGMRT 图像的通量密度分布明显更广。利用 0.144、0.4 和 ∼1.5 GHz 的光谱指数图，我们绘制了七个样本星系的光谱指数图，发现在星系的光晕区，光谱的陡峭程度可达 ∼-1.5。
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Pub Date : 2024-11-25DOI: 10.3847/1538-4357/ad863b
Simon Blouin, Mukremin Kilic, Loïc Albert, Bianca Azartash-Namin and Patrick Dufour
Infrared-faint white dwarfs are cool white dwarfs exhibiting significant infrared flux deficits, most often attributed to collision-induced absorption (CIA) from H2–He in mixed hydrogen–helium atmospheres. We present James Webb Space Telescope (JWST) near- and mid-infrared spectra of three such objects using Near-Infrared Spectrograph (0.6–5.3 μm) and Mid-Infrared Instrument (5–14 μm): LHS 3250, WD J1922+0233, and LHS 1126. Surprisingly, for LHS 3250, we detect no H2–He CIA absorption at 2.4 μm, instead observing an unexpected small flux bump at this wavelength. WD J1922+0233 exhibits the anticipated strong absorption feature centered at 2.4 μm, but with an unexpected narrow emission-like feature inside this absorption band. LHS 1126 shows no CIA features and follows a λ−2 power law in the mid-infrared. LHS 1126's lack of CIA features suggests a very low hydrogen abundance, with its infrared flux depletion likely caused by He–He–He CIA. For LHS 3250 and WD J1922+0233, the absence of a 1.2 μm CIA feature in both stars argues against ultracool temperatures, supporting recent suggestions that infrared-faint (IR-faint) white dwarfs are warmer and more massive than previously thought. This conclusion is further solidified by Keck near-infrared spectroscopy of seven additional objects. We explore possible explanations for the unexpected emission-like features in both stars, and temperature inversions above the photosphere emerge as a promising hypothesis. Such inversions may be common among the IR-faint population, and since they significantly affect the infrared spectral energy distribution, this would impact their photometric fits. Further JWST observations are needed to confirm the prevalence of this phenomenon and guide the development of improved atmospheric models.
{"title":"JWST Resolves Collision-induced Absorption Features in White Dwarfs","authors":"Simon Blouin, Mukremin Kilic, Loïc Albert, Bianca Azartash-Namin and Patrick Dufour","doi":"10.3847/1538-4357/ad863b","DOIUrl":"https://doi.org/10.3847/1538-4357/ad863b","url":null,"abstract":"Infrared-faint white dwarfs are cool white dwarfs exhibiting significant infrared flux deficits, most often attributed to collision-induced absorption (CIA) from H2–He in mixed hydrogen–helium atmospheres. We present James Webb Space Telescope (JWST) near- and mid-infrared spectra of three such objects using Near-Infrared Spectrograph (0.6–5.3 μm) and Mid-Infrared Instrument (5–14 μm): LHS 3250, WD J1922+0233, and LHS 1126. Surprisingly, for LHS 3250, we detect no H2–He CIA absorption at 2.4 μm, instead observing an unexpected small flux bump at this wavelength. WD J1922+0233 exhibits the anticipated strong absorption feature centered at 2.4 μm, but with an unexpected narrow emission-like feature inside this absorption band. LHS 1126 shows no CIA features and follows a λ−2 power law in the mid-infrared. LHS 1126's lack of CIA features suggests a very low hydrogen abundance, with its infrared flux depletion likely caused by He–He–He CIA. For LHS 3250 and WD J1922+0233, the absence of a 1.2 μm CIA feature in both stars argues against ultracool temperatures, supporting recent suggestions that infrared-faint (IR-faint) white dwarfs are warmer and more massive than previously thought. This conclusion is further solidified by Keck near-infrared spectroscopy of seven additional objects. We explore possible explanations for the unexpected emission-like features in both stars, and temperature inversions above the photosphere emerge as a promising hypothesis. Such inversions may be common among the IR-faint population, and since they significantly affect the infrared spectral energy distribution, this would impact their photometric fits. Further JWST observations are needed to confirm the prevalence of this phenomenon and guide the development of improved atmospheric models.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142697040","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 : 2024-11-25DOI: 10.3847/1538-4357/ad890f
Deepika Venkattu, Peter Lundqvist, Miguel Pérez Torres, Etienne Bonnassieux, Cyril Tasse, Anne-Laure Melchior and Francoise Combes
We present the first LOFAR image of the center of M31 at a frequency of 150 MHz. We clearly detect three supernova remnants, which, along with archival VLA data at 3 GHz and other published radio and X-ray data, allows us to characterize them in detail. Our observations also allow us to obtain upper limits of the historical SN 1885A, which is undetected even at a low frequency of 150 MHz. From analytical modeling, we find that SN 1885A will stay in its free-expansion phase for at least another couple of centuries. We find an upper limit of nH ≲ 0.04 cm−3 for the interstellar medium of SN 1885A, and that the SN ejecta density is not shallower than ∝r−9 (on average). From the 2.6σ tentative detection in X-ray, our analysis shows that nonthermal emission is expected to dominate the SN 1885A emission. Comparing our results with those on G1.9+0.3, we find that it is likely that the asymmetries in G1.9+0.3 make it a more efficient radio and X-ray emitter than SN 1885A. For Braun 80, 95, and 101, the other remnants in this region, we estimate ages of 5200, 8100, and 13,100 yr, and shock speeds of 1150, 880, and 660 km s−1, respectively. Based on this, the supernova rate in the central 0.5 kpc × 0.6 kpc of M31 is at least one per ∼3000 yr. We estimate radio spectral indices of −0.66 ± 0.05, −0.37 ± 0.03, and −0.50 ± 0.03 for the remnants, respectively, which match fairly well with previous studies.
我们首次以 150 MHz 的频率提供了 M31 中心的 LOFAR 图像。我们清楚地探测到了三颗超新星的残余物，这与 3 GHz 的 VLA 存档数据以及其他已发表的射电和 X 射线数据一起，使我们能够详细地描述它们的特征。我们的观测还让我们获得了历史上的 SN 1885A 的上限，即使在 150 MHz 的低频下，它也没有被探测到。通过分析建模，我们发现 SN 1885A 至少还将在自由膨胀阶段持续几个世纪。我们发现SN 1885A的星际介质上限为nH ≲ 0.04 cm-3，而且SN喷出物密度不浅于∝r-9（平均值）。从 X 射线的 2.6σ 暂定探测结果来看，我们的分析表明 SN 1885A 的非热辐射预计将占主导地位。将我们的结果与 G1.9+0.3 的结果相比较，我们发现 G1.9+0.3 的不对称性很可能使其成为比 SN 1885A 更有效的射电和 X 射线发射器。对于该区域的其他残余物布劳恩 80、95 和 101，我们估计其年龄分别为 5200、8100 和 13100 年，冲击速度分别为 1150、880 和 660 km s-1。据此推算，M31中心0.5 kpc × 0.6 kpc区域的超新星发生率至少为每 ∼3000 年一颗。我们估计这些残余物的射电光谱指数分别为-0.66 ± 0.05、-0.37 ± 0.03和-0.50 ± 0.03，与之前的研究结果相当吻合。
{"title":"SN 1885A and Supernova Remnants in the Centre of M31 with LOFAR","authors":"Deepika Venkattu, Peter Lundqvist, Miguel Pérez Torres, Etienne Bonnassieux, Cyril Tasse, Anne-Laure Melchior and Francoise Combes","doi":"10.3847/1538-4357/ad890f","DOIUrl":"https://doi.org/10.3847/1538-4357/ad890f","url":null,"abstract":"We present the first LOFAR image of the center of M31 at a frequency of 150 MHz. We clearly detect three supernova remnants, which, along with archival VLA data at 3 GHz and other published radio and X-ray data, allows us to characterize them in detail. Our observations also allow us to obtain upper limits of the historical SN 1885A, which is undetected even at a low frequency of 150 MHz. From analytical modeling, we find that SN 1885A will stay in its free-expansion phase for at least another couple of centuries. We find an upper limit of nH ≲ 0.04 cm−3 for the interstellar medium of SN 1885A, and that the SN ejecta density is not shallower than ∝r−9 (on average). From the 2.6σ tentative detection in X-ray, our analysis shows that nonthermal emission is expected to dominate the SN 1885A emission. Comparing our results with those on G1.9+0.3, we find that it is likely that the asymmetries in G1.9+0.3 make it a more efficient radio and X-ray emitter than SN 1885A. For Braun 80, 95, and 101, the other remnants in this region, we estimate ages of 5200, 8100, and 13,100 yr, and shock speeds of 1150, 880, and 660 km s−1, respectively. Based on this, the supernova rate in the central 0.5 kpc × 0.6 kpc of M31 is at least one per ∼3000 yr. We estimate radio spectral indices of −0.66 ± 0.05, −0.37 ± 0.03, and −0.50 ± 0.03 for the remnants, respectively, which match fairly well with previous studies.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142697044","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 : 2024-11-25DOI: 10.3847/1538-4357/ad84f8
Bo-Eun Choi, Jessica K. Werk, Kirill Tchernyshyov, J. Xavier Prochaska, Yong Zheng, Mary E. Putman, Drummond B. Fielding and Jay Strader
Metals in the diffuse, ionized gas at the boundary between the Milky Way’s interstellar medium (ISM) and circumgalactic medium, known as the disk–halo interface (DHI), are valuable tracers of the feedback processes that drive the Galactic fountain. However, metallicity measurements in this region are challenging due to obscuration by the Milky Way ISM and uncertain ionization corrections that affect the total hydrogen column density. In this work, we constrain ionization corrections to neutral hydrogen column densities using precisely measured electron column densities from the dispersion measures of pulsars that lie in the same globular clusters as UV-bright targets with high-resolution absorption spectroscopy. We address the blending of absorption lines with the ISM by jointly fitting Voigt profiles to all absorption components. We present our metallicity estimates for the DHI of the Milky Way based on detailed photoionization modeling of the absorption from ionized metal lines and ionization-corrected total hydrogen columns. Generally, the gas clouds show a large scatter in metallicity, ranging between 0.04 and 3.2 Z⊙, implying that the DHI consists of a mixture of gaseous structures having multiple origins. We estimate the inflow and outflow timescales of the DHI ionized clouds to be 6–35 Myr. We report the detection of an infalling cloud with supersolar metallicity that suggests a Galactic fountain mechanism, whereas at least one low-metallicity outflowing cloud (Z < 0.1 Z⊙) poses a challenge for Galactic fountain and feedback models.
银河系星际介质（ISM）和环星系介质（即星盘-光环界面（DHI））边界弥漫电离气体中的金属，是驱动银河喷泉的反馈过程的重要示踪剂。然而，由于银河系 ISM 的遮挡和影响总氢柱密度的不确定电离校正，该区域的金属性测量具有挑战性。在这项工作中，我们利用高分辨率吸收光谱对位于同一球状星团中的脉冲星和紫外光目标的电子柱密度进行频散测量，精确测量了电子柱密度对中性氢柱密度的电离修正。我们通过联合拟合所有吸收成分的 Voigt 曲线，解决了吸收线与 ISM 的混合问题。我们根据电离金属线和电离校正总氢柱吸收的详细光电离模型，提出了银河系 DHI 的金属度估计值。一般来说，气体云的金属性散布很大，范围在 0.04 到 3.2 Z⊙之间，这意味着 DHI 是由多种来源的气体结构混合而成的。我们估计DHI电离云的流入和流出时间尺度为6-35 Myr。我们报告探测到了一个具有超太阳金属性的流入云，这表明了银河喷泉机制，而至少有一个低金属性的流出云（Z < 0.1 Z⊙）对银河喷泉和反馈模型提出了挑战。
{"title":"Metallicity Mapping of the Ionized Diffuse Gas at the Milky Way Disk–Halo Interface","authors":"Bo-Eun Choi, Jessica K. Werk, Kirill Tchernyshyov, J. Xavier Prochaska, Yong Zheng, Mary E. Putman, Drummond B. Fielding and Jay Strader","doi":"10.3847/1538-4357/ad84f8","DOIUrl":"https://doi.org/10.3847/1538-4357/ad84f8","url":null,"abstract":"Metals in the diffuse, ionized gas at the boundary between the Milky Way’s interstellar medium (ISM) and circumgalactic medium, known as the disk–halo interface (DHI), are valuable tracers of the feedback processes that drive the Galactic fountain. However, metallicity measurements in this region are challenging due to obscuration by the Milky Way ISM and uncertain ionization corrections that affect the total hydrogen column density. In this work, we constrain ionization corrections to neutral hydrogen column densities using precisely measured electron column densities from the dispersion measures of pulsars that lie in the same globular clusters as UV-bright targets with high-resolution absorption spectroscopy. We address the blending of absorption lines with the ISM by jointly fitting Voigt profiles to all absorption components. We present our metallicity estimates for the DHI of the Milky Way based on detailed photoionization modeling of the absorption from ionized metal lines and ionization-corrected total hydrogen columns. Generally, the gas clouds show a large scatter in metallicity, ranging between 0.04 and 3.2 Z⊙, implying that the DHI consists of a mixture of gaseous structures having multiple origins. We estimate the inflow and outflow timescales of the DHI ionized clouds to be 6–35 Myr. We report the detection of an infalling cloud with supersolar metallicity that suggests a Galactic fountain mechanism, whereas at least one low-metallicity outflowing cloud (Z < 0.1 Z⊙) poses a challenge for Galactic fountain and feedback models.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142697034","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 : 2024-11-25DOI: 10.3847/1538-4357/ad8b48
Yun-Ning Fan, Yong Shao and Wen-Cong Chen
Magnetic braking (MB) plays an important role in driving the evolution of low-mass X-ray binaries (LMXBs). The modified MB prescription, the convection and rotation boosted (CARB) model, is very successful in reproducing the detected mass-transfer rates of persistent neutron star (NS) LMXBs. In this work, we investigate whether the CARB MB prescription could account for the formation and evolution of some NS and black hole (BH) LMXBs with an observed orbital-period derivative. Using the MESA code, we perform a detailed binary evolution model for six NS and three BH LMXBs. Our simulations find that the CARB MB prescription can successfully reproduce the observed donor-star masses, orbital periods, and period derivatives of four NS LMXBs and one BH LMXB. Our calculated effective temperatures are in good agreement with the detected spectral types of two NS LMXBs and one BH LMXB. However, the standard MB model makes it difficult to produce the observed period derivatives of those LMXBs experiencing a rapid orbital shrinkage or expansion.
{"title":"Orbital-period Changes of Low-mass X-Ray Binaries Driven by Magnetic Braking","authors":"Yun-Ning Fan, Yong Shao and Wen-Cong Chen","doi":"10.3847/1538-4357/ad8b48","DOIUrl":"https://doi.org/10.3847/1538-4357/ad8b48","url":null,"abstract":"Magnetic braking (MB) plays an important role in driving the evolution of low-mass X-ray binaries (LMXBs). The modified MB prescription, the convection and rotation boosted (CARB) model, is very successful in reproducing the detected mass-transfer rates of persistent neutron star (NS) LMXBs. In this work, we investigate whether the CARB MB prescription could account for the formation and evolution of some NS and black hole (BH) LMXBs with an observed orbital-period derivative. Using the MESA code, we perform a detailed binary evolution model for six NS and three BH LMXBs. Our simulations find that the CARB MB prescription can successfully reproduce the observed donor-star masses, orbital periods, and period derivatives of four NS LMXBs and one BH LMXB. Our calculated effective temperatures are in good agreement with the detected spectral types of two NS LMXBs and one BH LMXB. However, the standard MB model makes it difficult to produce the observed period derivatives of those LMXBs experiencing a rapid orbital shrinkage or expansion.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142697067","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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