Pub Date : 2024-02-05DOI: 10.3847/1538-4357/ad27d9
Alejandro H. C'orsico, L. Althaus
Breathing pulses are mixing episodes that could develop during the core helium-burning phase of low- and intermediate-mass stars. The occurrence of breathing pulses is expected to bear consequences on the formation and evolution of white dwarfs, particularly on the core chemical structure, which can be probed by asteroseismology. We aim to explore the consequences of breathing pulses on the chemical profiles and pulsational properties of variable white dwarf stars with hydrogen-rich envelopes, known as ZZ Ceti stars. We compute stellar models with masses of 1.0M ⊙ and 2.5M ⊙ in the zero-age main sequence and evolve them through the core helium-burning phase to the thermal pulses on the asymptotic giant branch, and finally to advanced stages of white dwarf cooling. We compare the chemical structure of the core of white dwarfs whose progenitors have experienced breathing pulses during the core helium-burning phase with the case in which breathing pulses have not occurred. We find that when breathing pulses occur, the white dwarf cores are larger and the central abundances of oxygen are higher than for the case in which the breathing pulses are suppressed, in line with previous studies. However, the occurrence of breathing pulses is not sufficient to explain the large cores and the excessive oxygen abundances that characterize recently derived asteroseismological models of pulsating white dwarfs. We find absolute differences of up to ∼30 s when we compare pulsation periods of white dwarfs coming from progenitors that have experienced breathing pulses with the case in which the progenitors have not suffered breathing pulses.
{"title":"The Impact of Breathing Pulses during Core Helium Burning on the Core Chemical Structure and Pulsations of Hydrogen-rich Atmosphere White Dwarfs","authors":"Alejandro H. C'orsico, L. Althaus","doi":"10.3847/1538-4357/ad27d9","DOIUrl":"https://doi.org/10.3847/1538-4357/ad27d9","url":null,"abstract":"\u0000 Breathing pulses are mixing episodes that could develop during the core helium-burning phase of low- and intermediate-mass stars. The occurrence of breathing pulses is expected to bear consequences on the formation and evolution of white dwarfs, particularly on the core chemical structure, which can be probed by asteroseismology. We aim to explore the consequences of breathing pulses on the chemical profiles and pulsational properties of variable white dwarf stars with hydrogen-rich envelopes, known as ZZ Ceti stars. We compute stellar models with masses of 1.0M\u0000 ⊙ and 2.5M\u0000 ⊙ in the zero-age main sequence and evolve them through the core helium-burning phase to the thermal pulses on the asymptotic giant branch, and finally to advanced stages of white dwarf cooling. We compare the chemical structure of the core of white dwarfs whose progenitors have experienced breathing pulses during the core helium-burning phase with the case in which breathing pulses have not occurred. We find that when breathing pulses occur, the white dwarf cores are larger and the central abundances of oxygen are higher than for the case in which the breathing pulses are suppressed, in line with previous studies. However, the occurrence of breathing pulses is not sufficient to explain the large cores and the excessive oxygen abundances that characterize recently derived asteroseismological models of pulsating white dwarfs. We find absolute differences of up to ∼30 s when we compare pulsation periods of white dwarfs coming from progenitors that have experienced breathing pulses with the case in which the progenitors have not suffered breathing pulses.","PeriodicalId":504209,"journal":{"name":"The Astrophysical Journal","volume":"123 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140461565","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 : 2024-02-01DOI: 10.3847/1538-4357/ad24ed
J. P. Halpern
1RXS J083842.1−282723 is a nearly synchronous magnetic cataclysmic variable with a simple X-ray light curve. While its orbital period was fairly well established at P orb = 98.4 minutes from optical spectroscopy, indirect estimates of P spin/P orb ranged from 0.90 to 0.96 because the short X-ray light curves could not determine the beat period to a factor of 2. We analyze a recent 50 days TESS observation, and ground-based optical time-series photometry spanning 9 yr, that together measure precise beat, orbit, and spin periods and enable the X-ray and optical modulations to be phase aligned. Although the X-ray light curves do not distinguish between a beat period of 16.11 or 32.22 hr, all of the optical evidence favors the longer value, with complete pole switching of accretion every half beat cycle. This would require P spin/P orb = 0.952. Long-term optical monitoring also shows a decline in accretion rate, and a change in the beat-folded light curve. It would be useful to obtain a new X-ray/optical observation of at least 32 hr duration to examine any associated change in accretion structure, and to confirm the spin and beat periods.
1RXS J083842.1-282723 是一个几乎同步的磁暴变星，其 X 射线光变曲线很简单。我们分析了最近一次为期 50 天的 TESS 观测，以及跨越 9 年的地基光学时间序列光度测量，它们共同测量出了精确的跳动、轨道和自旋周期，并使 X 射线和光学调制相位对齐。虽然 X 射线光变曲线并不能区分拍动周期是 16.11 小时还是 32.22 小时，但所有的光学证据都表明拍动周期更长，每半个拍动周期就会有一次完全的极点切换。这需要 P spin/P orb = 0.952。长期的光学监测也显示出增殖速度的下降，以及节拍折叠光曲线的变化。最好能获得至少持续 32 小时的新的 X 射线/光学观测数据，以检查吸积结构的任何相关变化，并确认自旋和节拍周期。
{"title":"Resolving the Periods of the Asynchronous Polar 1RXS J083842.1–282723","authors":"J. P. Halpern","doi":"10.3847/1538-4357/ad24ed","DOIUrl":"https://doi.org/10.3847/1538-4357/ad24ed","url":null,"abstract":"\u0000 1RXS J083842.1−282723 is a nearly synchronous magnetic cataclysmic variable with a simple X-ray light curve. While its orbital period was fairly well established at P\u0000 orb = 98.4 minutes from optical spectroscopy, indirect estimates of P\u0000 spin/P\u0000 orb ranged from 0.90 to 0.96 because the short X-ray light curves could not determine the beat period to a factor of 2. We analyze a recent 50 days TESS observation, and ground-based optical time-series photometry spanning 9 yr, that together measure precise beat, orbit, and spin periods and enable the X-ray and optical modulations to be phase aligned. Although the X-ray light curves do not distinguish between a beat period of 16.11 or 32.22 hr, all of the optical evidence favors the longer value, with complete pole switching of accretion every half beat cycle. This would require P\u0000 spin/P\u0000 orb = 0.952. Long-term optical monitoring also shows a decline in accretion rate, and a change in the beat-folded light curve. It would be useful to obtain a new X-ray/optical observation of at least 32 hr duration to examine any associated change in accretion structure, and to confirm the spin and beat periods.","PeriodicalId":504209,"journal":{"name":"The Astrophysical Journal","volume":"302 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140463022","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 : 2024-02-01DOI: 10.3847/1538-4357/ad18b2
L. Matilsky, N. Brummell, B. Hindman, J. Toomre
We recently presented the first 3D numerical simulation of the solar interior for which tachocline confinement was achieved by a dynamo-generated magnetic field. In this follow-up study, we analyze the degree of confinement as the magnetic field strength changes (controlled by varying the magnetic Prandtl number) in a coupled radiative zone (RZ) and convection zone (CZ) system. We broadly find three solution regimes, corresponding to weak, medium, and strong dynamo magnetic field strengths. In the weak-field regime, the large-scale magnetic field is mostly axisymmetric with regular, periodic polarity reversals (reminiscent of the observed solar cycle) but fails to create a confined tachocline. In the strong-field regime, the large-scale field is mostly nonaxisymmetric with irregular, quasi-periodic polarity reversals and creates a confined tachocline. In the medium-field regime, the large-scale field resembles a strong-field dynamo for extended intervals but intermittently weakens to allow temporary epochs of strong differential rotation. In all regimes, the amplitude of poloidal field strength in the RZ is very well explained by skin-depth arguments, wherein the oscillating field that gives rise to the skin depth (in the medium- and strong-field cases) is a nonaxisymmetric field structure at the base of the CZ that rotates with respect to the RZ. These simulations suggest a new picture of solar tachocline confinement by the dynamo, in which nonaxisymmetric, very long-lived (effectively permanent) field structures rotating with respect to the RZ play the primary role, instead of the regularly reversing axisymmetric field associated with the 22 yr cycle.
{"title":"Solar Tachocline Confinement by the Nonaxisymmetric Modes of a Dynamo Magnetic Field","authors":"L. Matilsky, N. Brummell, B. Hindman, J. Toomre","doi":"10.3847/1538-4357/ad18b2","DOIUrl":"https://doi.org/10.3847/1538-4357/ad18b2","url":null,"abstract":"\u0000 We recently presented the first 3D numerical simulation of the solar interior for which tachocline confinement was achieved by a dynamo-generated magnetic field. In this follow-up study, we analyze the degree of confinement as the magnetic field strength changes (controlled by varying the magnetic Prandtl number) in a coupled radiative zone (RZ) and convection zone (CZ) system. We broadly find three solution regimes, corresponding to weak, medium, and strong dynamo magnetic field strengths. In the weak-field regime, the large-scale magnetic field is mostly axisymmetric with regular, periodic polarity reversals (reminiscent of the observed solar cycle) but fails to create a confined tachocline. In the strong-field regime, the large-scale field is mostly nonaxisymmetric with irregular, quasi-periodic polarity reversals and creates a confined tachocline. In the medium-field regime, the large-scale field resembles a strong-field dynamo for extended intervals but intermittently weakens to allow temporary epochs of strong differential rotation. In all regimes, the amplitude of poloidal field strength in the RZ is very well explained by skin-depth arguments, wherein the oscillating field that gives rise to the skin depth (in the medium- and strong-field cases) is a nonaxisymmetric field structure at the base of the CZ that rotates with respect to the RZ. These simulations suggest a new picture of solar tachocline confinement by the dynamo, in which nonaxisymmetric, very long-lived (effectively permanent) field structures rotating with respect to the RZ play the primary role, instead of the regularly reversing axisymmetric field associated with the 22 yr cycle.","PeriodicalId":504209,"journal":{"name":"The Astrophysical Journal","volume":"75 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140470063","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 : 2024-02-01DOI: 10.3847/1538-4357/ad18c2
S. Mukherjee, J. Fortney, C. Morley, N. Batalha, M. Marley, T. Karalidi, C. Visscher, Roxana Lupu, R. Freedman, E. Gharib-Nezhad
Disequilibrium chemistry due to vertical mixing in the atmospheres of many brown dwarfs and giant exoplanets is well established. Atmosphere models for these objects typically parameterize mixing with the highly uncertain K zz diffusion parameter. The role of mixing in altering the abundances of C-N-O-bearing molecules has mostly been explored for atmospheres with a solar composition. However, atmospheric metallicity and the C/O ratio also impact atmospheric chemistry. Therefore, we present the Sonora Elf Owl grid of self-consistent cloud-free 1D radiative-convective equilibrium model atmospheres for JWST observations, which includes a variation in K zz across several orders of magnitude and also encompasses subsolar to supersolar metallicities and C/O ratios. We find that the impact of K zz on the T(P) profile and spectra is a strong function of both T eff and metallicity. For metal-poor objects, K zz has large impacts on the atmosphere at significantly higher T eff than in metal-rich atmospheres, where the impact of K zz is seen to occur at lower T eff. We identify significant spectral degeneracies between varying K zz and metallicity in multiple wavelength windows, in particular, at 3–5 μm. We use the Sonora Elf Owl atmospheric grid to fit the observed spectra of a sample of nine early to late T-type objects from T eff = 550–1150 K. We find evidence for very inefficient vertical mixing in these objects, with inferred K zz values lying in the range between ∼101 and 104 cm2 s−1. Using self-consistent models, we find that this slow vertical mixing is due to the observations, which probe mixing in the deep detached radiative zone in these atmospheres.
{"title":"The Sonora Substellar Atmosphere Models. IV. Elf Owl: Atmospheric Mixing and Chemical Disequilibrium with Varying Metallicity and C/O Ratios","authors":"S. Mukherjee, J. Fortney, C. Morley, N. Batalha, M. Marley, T. Karalidi, C. Visscher, Roxana Lupu, R. Freedman, E. Gharib-Nezhad","doi":"10.3847/1538-4357/ad18c2","DOIUrl":"https://doi.org/10.3847/1538-4357/ad18c2","url":null,"abstract":"\u0000 Disequilibrium chemistry due to vertical mixing in the atmospheres of many brown dwarfs and giant exoplanets is well established. Atmosphere models for these objects typically parameterize mixing with the highly uncertain K\u0000 \u0000 zz\u0000 diffusion parameter. The role of mixing in altering the abundances of C-N-O-bearing molecules has mostly been explored for atmospheres with a solar composition. However, atmospheric metallicity and the C/O ratio also impact atmospheric chemistry. Therefore, we present the Sonora Elf Owl grid of self-consistent cloud-free 1D radiative-convective equilibrium model atmospheres for JWST observations, which includes a variation in K\u0000 \u0000 zz\u0000 across several orders of magnitude and also encompasses subsolar to supersolar metallicities and C/O ratios. We find that the impact of K\u0000 \u0000 zz\u0000 on the T(P) profile and spectra is a strong function of both T\u0000 eff and metallicity. For metal-poor objects, K\u0000 \u0000 zz\u0000 has large impacts on the atmosphere at significantly higher T\u0000 eff than in metal-rich atmospheres, where the impact of K\u0000 \u0000 zz\u0000 is seen to occur at lower T\u0000 eff. We identify significant spectral degeneracies between varying K\u0000 \u0000 zz\u0000 and metallicity in multiple wavelength windows, in particular, at 3–5 μm. We use the Sonora Elf Owl atmospheric grid to fit the observed spectra of a sample of nine early to late T-type objects from T\u0000 eff = 550–1150 K. We find evidence for very inefficient vertical mixing in these objects, with inferred K\u0000 \u0000 zz\u0000 values lying in the range between ∼101 and 104 cm2 s−1. Using self-consistent models, we find that this slow vertical mixing is due to the observations, which probe mixing in the deep detached radiative zone in these atmospheres.","PeriodicalId":504209,"journal":{"name":"The Astrophysical Journal","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140464130","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 : 2024-02-01DOI: 10.3847/1538-4357/ad2065
Jack T. Dinsmore, R. Romani
By measuring photoelectron tracks, the gas pixel detectors of the Imaging X-ray Polarimetry Explorer satellite provide estimates of the photon detection location and its electric vector position angle (EVPA). However, imperfections in reconstructing event positions blur the image, and EVPA-position correlations result in artificial polarized halos around bright sources. We introduce a new model describing this “polarization leakage” and use it to recover the on-orbit telescope point-spread functions, useful for faint-source detection and image reconstruction. These point-spread functions are more accurate than previous approximations or ground-calibrated products (Δχ 2 ≈ 3 × 104 and 4 × 104 respectively for a bright 106-count source). We also define an algorithm for polarization leakage correction substantially more accurate than existing prescriptions (Δχ 2 ≈ 1 × 103). These corrections depend on the reconstruction method, and we supply prescriptions for the mission-standard “Moments” methods as well as for “Neural Net” event reconstruction. Finally, we present a method to isolate leakage contributions to polarization observations of extended sources and show that an accurate PSF allows the extraction of sub-PSF-scale polarization patterns.
{"title":"Polarization Leakage and the IXPE Point-spread Function","authors":"Jack T. Dinsmore, R. Romani","doi":"10.3847/1538-4357/ad2065","DOIUrl":"https://doi.org/10.3847/1538-4357/ad2065","url":null,"abstract":"\u0000 By measuring photoelectron tracks, the gas pixel detectors of the Imaging X-ray Polarimetry Explorer satellite provide estimates of the photon detection location and its electric vector position angle (EVPA). However, imperfections in reconstructing event positions blur the image, and EVPA-position correlations result in artificial polarized halos around bright sources. We introduce a new model describing this “polarization leakage” and use it to recover the on-orbit telescope point-spread functions, useful for faint-source detection and image reconstruction. These point-spread functions are more accurate than previous approximations or ground-calibrated products (Δχ\u0000 2 ≈ 3 × 104 and 4 × 104 respectively for a bright 106-count source). We also define an algorithm for polarization leakage correction substantially more accurate than existing prescriptions (Δχ\u0000 2 ≈ 1 × 103). These corrections depend on the reconstruction method, and we supply prescriptions for the mission-standard “Moments” methods as well as for “Neural Net” event reconstruction. Finally, we present a method to isolate leakage contributions to polarization observations of extended sources and show that an accurate PSF allows the extraction of sub-PSF-scale polarization patterns.","PeriodicalId":504209,"journal":{"name":"The Astrophysical Journal","volume":"394 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140464793","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 : 2024-02-01DOI: 10.3847/1538-4357/ad24ec
Takato Otsu, A. Asai
This paper presents a multiwavelength Sun-as-a-star analysis of the M8.7 flare on 2022 October 2, which was associated with a filament eruption and the subsequent coronal mass ejection. The Sun-as-a-star analysis was performed using Hα data taken by Solar Dynamics Doppler Imager on board the Solar Magnetic Activity Research Telescope at Hida Observatory, Kyoto University, and full-disk integrated extreme ultraviolet (EUV) spectra taken by the Extreme ultraviolet Variability Experiment (EVE) on board the Solar Dynamics Observatory. The Sun-as-a-star Hα spectra showed blueshifted absorption corresponding to the filament eruption. Furthermore, the EVE O v 629.7 Å spectra showed blueshifted brightening, which can also be attributed to the filament eruption. Even when the blueshifted absorption became almost invisible in the Sun-as-a-star Hα spectra, the O v blueshifted brightening up to −400 km s−1 was still clearly visible. This result indicates that even when the shifted components—which are expected to originate from stellar eruptions—become almost invisible in the spatially integrated stellar Hα spectra, the erupting materials may still be present and observable in EUV spectra. Additionally, the Sun-as-a-star Hα and O v spectra exhibited redshifted absorption and brightening, respectively, during the decay phase of the flare. These components probably originate from the post-flare loops, providing clues to the multitemperature nature of the post-flare loops in the spatially integrated observation. Our Sun-as-a-star results suggest that the combination of Hα and EUV lines allows the investigation of the multitemperature structure and temporal development of stellar active phenomena even in spatially integrated spectra.
本文介绍了对2022年10月2日M8.7耀斑的多波长日-星分析，这次耀斑与丝状爆发和随后的日冕物质抛射有关。日像星分析是利用京都大学飞騨天文台太阳磁活动研究望远镜上的太阳动力学多普勒成像仪拍摄的Hα数据和太阳动力学天文台上的极紫外变异实验（EVE）拍摄的全盘集成极紫外（EUV）光谱进行的。太阳即恒星的 Hα 光谱显示出与灯丝爆发相对应的蓝移吸收。此外，EVE 的 O v 629.7 Å 光谱显示了蓝移增亮，这也可归因于灯丝喷发。即使蓝移吸收在太阳即恒星的 Hα 光谱中变得几乎不可见，但高达 -400 km s-1 的 O v 蓝移增亮仍然清晰可见。这一结果表明，即使在空间整合恒星 Hα 光谱中几乎看不到移位成分（预计这些成分来自恒星爆发），爆发物质仍然可能存在，并可在超紫外光谱中观测到。此外，在耀斑的衰减阶段，太阳即恒星的 Hα 和 O v 光谱分别表现出红移吸收和增亮。这些成分可能来自耀斑后的环路，为空间综合观测中耀斑后环路的多温度性质提供了线索。我们的 "太阳-恒星 "观测结果表明，结合使用 Hα 和 EUV 线，即使在空间综合光谱中也能研究恒星活动现象的多温结构和时间发展。
{"title":"Multiwavelength Sun-as-a-star Analysis of the M8.7 Flare on 2022 October 2 Using Hα and EUV Spectra Taken by SMART/SDDI and SDO/EVE","authors":"Takato Otsu, A. Asai","doi":"10.3847/1538-4357/ad24ec","DOIUrl":"https://doi.org/10.3847/1538-4357/ad24ec","url":null,"abstract":"\u0000 This paper presents a multiwavelength Sun-as-a-star analysis of the M8.7 flare on 2022 October 2, which was associated with a filament eruption and the subsequent coronal mass ejection. The Sun-as-a-star analysis was performed using Hα data taken by Solar Dynamics Doppler Imager on board the Solar Magnetic Activity Research Telescope at Hida Observatory, Kyoto University, and full-disk integrated extreme ultraviolet (EUV) spectra taken by the Extreme ultraviolet Variability Experiment (EVE) on board the Solar Dynamics Observatory. The Sun-as-a-star Hα spectra showed blueshifted absorption corresponding to the filament eruption. Furthermore, the EVE O v 629.7 Å spectra showed blueshifted brightening, which can also be attributed to the filament eruption. Even when the blueshifted absorption became almost invisible in the Sun-as-a-star Hα spectra, the O v blueshifted brightening up to −400 km s−1 was still clearly visible. This result indicates that even when the shifted components—which are expected to originate from stellar eruptions—become almost invisible in the spatially integrated stellar Hα spectra, the erupting materials may still be present and observable in EUV spectra. Additionally, the Sun-as-a-star Hα and O v spectra exhibited redshifted absorption and brightening, respectively, during the decay phase of the flare. These components probably originate from the post-flare loops, providing clues to the multitemperature nature of the post-flare loops in the spatially integrated observation. Our Sun-as-a-star results suggest that the combination of Hα and EUV lines allows the investigation of the multitemperature structure and temporal development of stellar active phenomena even in spatially integrated spectra.","PeriodicalId":504209,"journal":{"name":"The Astrophysical Journal","volume":"227 19","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140468682","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 : 2024-02-01DOI: 10.3847/1538-4357/ad10ad
Alexander Navarre, G. Khullar, M. Bayliss, H. Dahle, M. Florian, M. Gladders, Keunho J. Kim, M. R. Owens, J. Rigby, Joshua Roberson, K. Sharon, T. Shibuya, Ryan Walker
We present six strongly gravitationally lensed Lyα emitters (LAEs) at z ∼ 4–5 with Hubble Space Telescope (HST) narrowband imaging isolating Lyα. Through complex radiative transfer Lyα encodes information about the spatial distribution and kinematics of the neutral hydrogen upon which it scatters. We investigate the galaxy properties and Lyα morphologies of our sample. Many previous studies of high-redshift LAEs have been limited in Lyα spatial resolution. In this work we take advantage of high-resolution Lyα imaging boosted by lensing magnification, allowing us to probe subgalactic scales that are otherwise inaccessible at these redshifts. We use broadband imaging from HST (rest-frame UV) and Spitzer (rest-frame optical) in spectral energy distribution fitting, providing estimates of the stellar masses (∼108–109 M ⊙), stellar population ages (t 50 < 40 Myr), and amounts of dust (A V ∼ 0.1–0.6, statistically consistent with zero). We employ nonparametric star formation histories to probe the young stellar populations which create the Lyα. We also examine the offsets between the Lyα and stellar continuum, finding small upper limits of offsets (<0.″1) consistent with studies of low-redshift LAEs, indicating our galaxies are not interacting or merging. Finally, we find a bimodality in our sample’s Lyα morphologies: clumpy and extended. We find a suggestive trend: our LAEs with clumpy Lyα are generally younger than the LAEs with extended Lyα, suggesting a possible correlation with age.
我们利用哈勃太空望远镜（HST）的窄带成像技术分离出了六个 z ∼ 4-5 的强引力透镜 Lyα 发光体（LAEs）。通过复杂的辐射传递，Lyα编码了它所散射的中性氢的空间分布和运动学信息。我们研究了样本星系的性质和Lyα形态。以前对高红移LAE的许多研究都限制了Lyα的空间分辨率。在这项工作中，我们利用了由透镜放大增强的高分辨率Lyα成像，使我们能够探测到在这些红移下无法探测到的亚星系尺度。我们在光谱能量分布拟合中使用了来自 HST（静止帧紫外）和 Spitzer（静止帧光学）的宽带成像，提供了恒星质量（∼108-109 M ⊙）、恒星群年龄（t 50 < 40 Myr）和尘埃量（A V ∼ 0.1-0.6，统计上与零一致）的估计值。我们采用非参数恒星形成历史来探测产生 Lyα 的年轻恒星群。我们还研究了 Lyα 和恒星连续面之间的偏移，发现偏移上限很小（<0.″1），这与低红移 LAE 的研究结果一致，表明我们的星系没有发生相互作用或合并。最后，我们发现样本中的 Lyα 形态具有双峰性：块状和扩展状。我们发现了一个暗示性的趋势：Lyα呈块状的LAE一般比Lyα呈延伸状的LAE年轻，这表明Lyα可能与年龄有关。
{"title":"Resolving Clumpy versus Extended Lyα in Strongly Lensed, High-redshift Lyα Emitters","authors":"Alexander Navarre, G. Khullar, M. Bayliss, H. Dahle, M. Florian, M. Gladders, Keunho J. Kim, M. R. Owens, J. Rigby, Joshua Roberson, K. Sharon, T. Shibuya, Ryan Walker","doi":"10.3847/1538-4357/ad10ad","DOIUrl":"https://doi.org/10.3847/1538-4357/ad10ad","url":null,"abstract":"\u0000 We present six strongly gravitationally lensed Lyα emitters (LAEs) at z ∼ 4–5 with Hubble Space Telescope (HST) narrowband imaging isolating Lyα. Through complex radiative transfer Lyα encodes information about the spatial distribution and kinematics of the neutral hydrogen upon which it scatters. We investigate the galaxy properties and Lyα morphologies of our sample. Many previous studies of high-redshift LAEs have been limited in Lyα spatial resolution. In this work we take advantage of high-resolution Lyα imaging boosted by lensing magnification, allowing us to probe subgalactic scales that are otherwise inaccessible at these redshifts. We use broadband imaging from HST (rest-frame UV) and Spitzer (rest-frame optical) in spectral energy distribution fitting, providing estimates of the stellar masses (∼108–109\u0000 M\u0000 ⊙), stellar population ages (t\u0000 50 < 40 Myr), and amounts of dust (A\u0000 \u0000 V\u0000 ∼ 0.1–0.6, statistically consistent with zero). We employ nonparametric star formation histories to probe the young stellar populations which create the Lyα. We also examine the offsets between the Lyα and stellar continuum, finding small upper limits of offsets (<0.″1) consistent with studies of low-redshift LAEs, indicating our galaxies are not interacting or merging. Finally, we find a bimodality in our sample’s Lyα morphologies: clumpy and extended. We find a suggestive trend: our LAEs with clumpy Lyα are generally younger than the LAEs with extended Lyα, suggesting a possible correlation with age.","PeriodicalId":504209,"journal":{"name":"The Astrophysical Journal","volume":"278 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140468915","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 : 2024-02-01DOI: 10.3847/1538-4357/ad1520
B. Backhaus, J. Trump, N. Pirzkal, G. Barro, S. Finkelstein, P. Arrabal Haro, R. Simons, Jessica Wessner, N. Cleri, Micaela B. Bagley, M. Hirschmann, D. Nicholls, Mark Dickinson, J. Kartaltepe, C. Papovich, D. Kocevski, A. Koekemoer, L. Bisigello, A. Jaskot, R. Lucas, I. Jung, S. Wilkins, L. Yung, Henry C. Ferguson, A. Fontana, A. Grazian, N. Grogin, L. Kewley, Allison Kirkpatrick, J. Lotz, L. Pentericci, P. Pérez-González, S. Ravindranath, R. Somerville, Guang Yang, B. Holwerda, P. Kurczynski, N. Hathi, Caitlin Rose, Kelcey Davis
We use James Webb Space Telescope Near-Infrared Camera Wide Field Slitless Spectroscopy (NIRCam WFSS) and the Near-Infrared spectrograph (NIRSpec) in the Cosmic Evolution Early Release survey to measure rest-frame optical emission-line ratios of 155 galaxies at z > 2. The blind NIRCam grism observations include a sample of galaxies with bright emission lines that were not observed on the NIRSpec masks. We study the changes of the Hα, [O III]/Hβ, and [Ne III]/[O II] emission lines in terms of redshift by comparing to lower-redshift SDSS, CLEAR, and MOSDEF samples. We find a significant (>3σ) correlation between [O III]/Hβ with redshift, while [Ne III]/[O II] has a marginal (2σ) correlation with redshift. We compare [O III]/Hβ and [Ne III]/[O II] to stellar mass and Hβ SFR. We find that both emission-line ratios have a correlation with Hβ SFR and an anticorrelation with stellar mass across the redshifts 0 < z < 9. Comparison with MAPPINGS V models indicates that these trends are consistent with lower metallicity and higher ionization in low-mass and high-SFR galaxies. We additionally compare to IllustrisTNG predictions and find that they effectively describe the highest [O III]/Hβ ratios observed in our sample, without the need to invoke MAPPINGS models with significant shock ionization components.
{"title":"CEERS Key Paper. VIII. Emission-line Ratios from NIRSpec and NIRCam Wide-Field Slitless Spectroscopy at z > 2","authors":"B. Backhaus, J. Trump, N. Pirzkal, G. Barro, S. Finkelstein, P. Arrabal Haro, R. Simons, Jessica Wessner, N. Cleri, Micaela B. Bagley, M. Hirschmann, D. Nicholls, Mark Dickinson, J. Kartaltepe, C. Papovich, D. Kocevski, A. Koekemoer, L. Bisigello, A. Jaskot, R. Lucas, I. Jung, S. Wilkins, L. Yung, Henry C. Ferguson, A. Fontana, A. Grazian, N. Grogin, L. Kewley, Allison Kirkpatrick, J. Lotz, L. Pentericci, P. Pérez-González, S. Ravindranath, R. Somerville, Guang Yang, B. Holwerda, P. Kurczynski, N. Hathi, Caitlin Rose, Kelcey Davis","doi":"10.3847/1538-4357/ad1520","DOIUrl":"https://doi.org/10.3847/1538-4357/ad1520","url":null,"abstract":"\u0000 We use James Webb Space Telescope Near-Infrared Camera Wide Field Slitless Spectroscopy (NIRCam WFSS) and the Near-Infrared spectrograph (NIRSpec) in the Cosmic Evolution Early Release survey to measure rest-frame optical emission-line ratios of 155 galaxies at z > 2. The blind NIRCam grism observations include a sample of galaxies with bright emission lines that were not observed on the NIRSpec masks. We study the changes of the Hα, [O III]/Hβ, and [Ne III]/[O II] emission lines in terms of redshift by comparing to lower-redshift SDSS, CLEAR, and MOSDEF samples. We find a significant (>3σ) correlation between [O III]/Hβ with redshift, while [Ne III]/[O II] has a marginal (2σ) correlation with redshift. We compare [O III]/Hβ and [Ne III]/[O II] to stellar mass and Hβ SFR. We find that both emission-line ratios have a correlation with Hβ SFR and an anticorrelation with stellar mass across the redshifts 0 < z < 9. Comparison with MAPPINGS V models indicates that these trends are consistent with lower metallicity and higher ionization in low-mass and high-SFR galaxies. We additionally compare to IllustrisTNG predictions and find that they effectively describe the highest [O III]/Hβ ratios observed in our sample, without the need to invoke MAPPINGS models with significant shock ionization components.","PeriodicalId":504209,"journal":{"name":"The Astrophysical Journal","volume":"26 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140470126","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 : 2024-02-01DOI: 10.3847/1538-4357/ad1604
R. Essick, M. Fishbach
Hierarchical Bayesian inference can simultaneously account for both measurement uncertainty and selection effects within astronomical catalogs. In particular, the imposed hierarchy encodes beliefs about the interdependence of the physical processes that generate the observed data. We show that several proposed approximations within the literature actually correspond to inferences that are incompatible with any physical detection process. This generically leads to biases and is associated with the assumption that detectability is independent of the observed data given the true source parameters. We show several examples of how this error can affect astrophysical inferences based on catalogs of coalescing binaries observed through gravitational waves, including misestimating the redshift evolution of the merger rate as well as incorrectly inferring that general relativity is the correct theory of gravity when it is not. In general, one cannot directly fit for the “detected distribution” and “divide out” the selection effects in post-processing. Similarly, when comparing theoretical predictions to observations, it is better to simulate detected data (including both measurement noise and selection effects) rather than comparing estimates of the detected distributions of event parameters (which include only selection effects). While the biases introduced by model misspecification from incorrect assumptions may be smaller than statistical uncertainty for moderate catalog sizes (O(100) events), they will nevertheless pose a significant barrier to precision measurements of astrophysical populations.
{"title":"Ensuring Consistency between Noise and Detection in Hierarchical Bayesian Inference","authors":"R. Essick, M. Fishbach","doi":"10.3847/1538-4357/ad1604","DOIUrl":"https://doi.org/10.3847/1538-4357/ad1604","url":null,"abstract":"\u0000 Hierarchical Bayesian inference can simultaneously account for both measurement uncertainty and selection effects within astronomical catalogs. In particular, the imposed hierarchy encodes beliefs about the interdependence of the physical processes that generate the observed data. We show that several proposed approximations within the literature actually correspond to inferences that are incompatible with any physical detection process. This generically leads to biases and is associated with the assumption that detectability is independent of the observed data given the true source parameters. We show several examples of how this error can affect astrophysical inferences based on catalogs of coalescing binaries observed through gravitational waves, including misestimating the redshift evolution of the merger rate as well as incorrectly inferring that general relativity is the correct theory of gravity when it is not. In general, one cannot directly fit for the “detected distribution” and “divide out” the selection effects in post-processing. Similarly, when comparing theoretical predictions to observations, it is better to simulate detected data (including both measurement noise and selection effects) rather than comparing estimates of the detected distributions of event parameters (which include only selection effects). While the biases introduced by model misspecification from incorrect assumptions may be smaller than statistical uncertainty for moderate catalog sizes (O(100) events), they will nevertheless pose a significant barrier to precision measurements of astrophysical populations.","PeriodicalId":504209,"journal":{"name":"The Astrophysical Journal","volume":"561 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140469706","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 : 2024-02-01DOI: 10.3847/1538-4357/ad0a66
R. Zhou, Y. G. Zheng, K. Zhu, S. Kang, X. P. Li
In this paper, we present a long-term multiwavelength investigation focusing on 12 distinct samples of Fermi-4LAC bright flat-spectrum radio quasars (FSRQs). Detailed variability and spectral analyses of γ-ray, X-ray, and ultraviolet/optical data obtained by the Fermi Large Area Telescope, the Swift X-ray Telescope, and the Swift Ultraviolet and Optical Telescope were performed over a period of about 14 yr, spanning from 2008 October to 2022 October. These analyses provide insights into characterizing the variations within different activity states. To efficiently reproduce the multiwavelength simultaneous/quasi-simultaneous spectral energy distributions (SEDs) of the samples, we propose a novel approach for constraining the model parameters. By analyzing the parameters of the energy spectral curvature (β), the peak frequency (ν pk), the peak luminosity (L pk), the Compton dominance parameter (A C), and the variability timescale (t var) in different activity states, we can estimate the values of the jet radiation region parameters for the samples. Subsequently, we utilize the synchrotron-self-Compton and external Compton processes, employing a logarithmic-parabolic spectral shape to approximate the observed spectra of the sample sources, while considering the induced regime for the physical parameters. The model results show that: (1) by effectively reproducing SEDs in various active states of bright FSRQs, the parameters within the emission region were reasonably constrained; (2) compared to other active states, the emission region of the jet exhibits a reduced radius during the high state, while the magnetic field strength increases during the low state; and (3) for bright FSRQs in a high-activity state, there is an enhancement of the Doppler factor, often exhibiting a tendency toward energy equipartition.
{"title":"Modeling the Multiwavelength Spectral Energy Distributions of the Fermi-4LAC Bright Flat-spectrum Radio Quasars","authors":"R. Zhou, Y. G. Zheng, K. Zhu, S. Kang, X. P. Li","doi":"10.3847/1538-4357/ad0a66","DOIUrl":"https://doi.org/10.3847/1538-4357/ad0a66","url":null,"abstract":"\u0000 In this paper, we present a long-term multiwavelength investigation focusing on 12 distinct samples of Fermi-4LAC bright flat-spectrum radio quasars (FSRQs). Detailed variability and spectral analyses of γ-ray, X-ray, and ultraviolet/optical data obtained by the Fermi Large Area Telescope, the Swift X-ray Telescope, and the Swift Ultraviolet and Optical Telescope were performed over a period of about 14 yr, spanning from 2008 October to 2022 October. These analyses provide insights into characterizing the variations within different activity states. To efficiently reproduce the multiwavelength simultaneous/quasi-simultaneous spectral energy distributions (SEDs) of the samples, we propose a novel approach for constraining the model parameters. By analyzing the parameters of the energy spectral curvature (β), the peak frequency (ν\u0000 pk), the peak luminosity (L\u0000 pk), the Compton dominance parameter (A\u0000 C), and the variability timescale (t\u0000 var) in different activity states, we can estimate the values of the jet radiation region parameters for the samples. Subsequently, we utilize the synchrotron-self-Compton and external Compton processes, employing a logarithmic-parabolic spectral shape to approximate the observed spectra of the sample sources, while considering the induced regime for the physical parameters. The model results show that: (1) by effectively reproducing SEDs in various active states of bright FSRQs, the parameters within the emission region were reasonably constrained; (2) compared to other active states, the emission region of the jet exhibits a reduced radius during the high state, while the magnetic field strength increases during the low state; and (3) for bright FSRQs in a high-activity state, there is an enhancement of the Doppler factor, often exhibiting a tendency toward energy equipartition.","PeriodicalId":504209,"journal":{"name":"The Astrophysical Journal","volume":"37 18","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139685620","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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