Pub Date : 2025-01-17DOI: 10.3847/1538-4357/ad9929
Jing-Yi Wang, Kai Li, Xiang Gao, Di-Fu Guo, Li-Heng Wang, Dong-Yang Gao, Ling-Zhi Li, Ya-Ni Guo, Xing Gao and Guo-You Sun
Eclipsing binaries (EBs) play an important astrophysical role in studying stellar properties and evolution. By analyzing photometric data in the the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Medium-Resolution Survey field, R.A.: 23h01m51 00, decl.: +34 , 48 EBs are detected and two are newly discovered. This specific field has been observed 52 times by the LAMOST Medium-Resolution Survey DR 9, which facilitates a comprehensive analysis of the EBs. For EBs with LAMOST medium-resolution spectra, radial velocity curves were obtained, and their precise orbital parameters were determined by simultaneously analyzing photometric light curves and radial velocity curves. For the other EBs with only photometric light curves, we used the q-search or the temperature ratio method to determine their initial mass ratios and then determined the orbital parameters. It is found that 15 EBs belong to detached systems, one to semi-detached systems, and 32 to contact systems. Based on the O − C analysis for 26 EBs with sufficient eclipsing times, we found a long-term decrease in the orbital period of 11 EBs and a continuous increase of five EBs, which are due to the material transfer between the two components. The O − C curve of 1 EB shows a distinct periodic variation, which is caused by the light travel time effect, and the third body is likely to be a black hole. By applying the spectral subtraction method to 13 EBs with LAMOST medium-resolution spectra, 10 systems exhibit distinct Hα emission lines, in which one system exhibits double-peaked lines near phases 0.25 and 0.75, implying strong chromospheric activity. In the massluminosities and mass–radius distributions, most of the more massive components are less evolved than the less massive ones.
{"title":"Search for and Analysis of Eclipsing Binaries in the LAMOST Medium-resolution Survey Field. I. R.A.: 23h01m51s, Decl.: +34°36′45″","authors":"Jing-Yi Wang, Kai Li, Xiang Gao, Di-Fu Guo, Li-Heng Wang, Dong-Yang Gao, Ling-Zhi Li, Ya-Ni Guo, Xing Gao and Guo-You Sun","doi":"10.3847/1538-4357/ad9929","DOIUrl":"https://doi.org/10.3847/1538-4357/ad9929","url":null,"abstract":"Eclipsing binaries (EBs) play an important astrophysical role in studying stellar properties and evolution. By analyzing photometric data in the the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Medium-Resolution Survey field, R.A.: 23h01m51 00, decl.: +34 , 48 EBs are detected and two are newly discovered. This specific field has been observed 52 times by the LAMOST Medium-Resolution Survey DR 9, which facilitates a comprehensive analysis of the EBs. For EBs with LAMOST medium-resolution spectra, radial velocity curves were obtained, and their precise orbital parameters were determined by simultaneously analyzing photometric light curves and radial velocity curves. For the other EBs with only photometric light curves, we used the q-search or the temperature ratio method to determine their initial mass ratios and then determined the orbital parameters. It is found that 15 EBs belong to detached systems, one to semi-detached systems, and 32 to contact systems. Based on the O − C analysis for 26 EBs with sufficient eclipsing times, we found a long-term decrease in the orbital period of 11 EBs and a continuous increase of five EBs, which are due to the material transfer between the two components. The O − C curve of 1 EB shows a distinct periodic variation, which is caused by the light travel time effect, and the third body is likely to be a black hole. By applying the spectral subtraction method to 13 EBs with LAMOST medium-resolution spectra, 10 systems exhibit distinct Hα emission lines, in which one system exhibits double-peaked lines near phases 0.25 and 0.75, implying strong chromospheric activity. In the massluminosities and mass–radius distributions, most of the more massive components are less evolved than the less massive ones.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"42 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142987327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-17DOI: 10.3847/1538-4357/ad9b27
Julio Hernandez Camero, Lucie M. Green and Alex Piñel Neparidze
Identifying the source regions of coronal mass ejections (CMEs) is crucial for understanding their origins and improving space weather forecasting. We present an automated algorithm for matching CMEs detected by the Large Angle Spectrometric Coronagraph with their source active regions, specifically Space Weather HMI Active Region Patches (SHARPs), between 2010 May and 2019 January. Our method uses posteruptive signatures, including flares and coronal dimmings, to associate CMEs with potential source regions. Out of 4190 CMEs, we successfully match 1132, achieving a recall rate of ~57% for frontside events. We find that the algorithm performs better for complex SHARP regions containing multiple NOAA regions and for faster CMEs, consistent with expectations that more energetic events produce stronger eruption signatures. We find that CME–flare association rates increase with flare intensity, aligning with previous studies. While our approach has limitations, such as focusing exclusively on SHARP regions and relying on a limited set of posteruptive signatures, it significantly reduces the time required for CME source identification while providing transparent, reproducible results. We encourage the solar physics community to build upon this work, developing improved automated tools for CME source identification. The resulting catalog of CME–source region associations is made publicly available, offering a valuable resource for statistical studies and machine learning applications in solar physics and space weather forecasting.
{"title":"Identifying Coronal Mass Ejection Active Region Sources: An Automated Approach","authors":"Julio Hernandez Camero, Lucie M. Green and Alex Piñel Neparidze","doi":"10.3847/1538-4357/ad9b27","DOIUrl":"https://doi.org/10.3847/1538-4357/ad9b27","url":null,"abstract":"Identifying the source regions of coronal mass ejections (CMEs) is crucial for understanding their origins and improving space weather forecasting. We present an automated algorithm for matching CMEs detected by the Large Angle Spectrometric Coronagraph with their source active regions, specifically Space Weather HMI Active Region Patches (SHARPs), between 2010 May and 2019 January. Our method uses posteruptive signatures, including flares and coronal dimmings, to associate CMEs with potential source regions. Out of 4190 CMEs, we successfully match 1132, achieving a recall rate of ~57% for frontside events. We find that the algorithm performs better for complex SHARP regions containing multiple NOAA regions and for faster CMEs, consistent with expectations that more energetic events produce stronger eruption signatures. We find that CME–flare association rates increase with flare intensity, aligning with previous studies. While our approach has limitations, such as focusing exclusively on SHARP regions and relying on a limited set of posteruptive signatures, it significantly reduces the time required for CME source identification while providing transparent, reproducible results. We encourage the solar physics community to build upon this work, developing improved automated tools for CME source identification. The resulting catalog of CME–source region associations is made publicly available, offering a valuable resource for statistical studies and machine learning applications in solar physics and space weather forecasting.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142987331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-17DOI: 10.3847/1538-4357/ad9c38
Guozhen Hu, 国真 胡, Zhengyi Shao, 正义 邵, Erbil Gügercinoǧlu, Wenyuan Cui and 文元 崔
We explore the metal-poor regime of the Galactic disk on the distribution of stars in the [α/M]–Vϕ plane, to identify the most metal-poor thin disk (MPTnD) stars belonging to the low-α sequence. Chemical abundances and velocities of sample stars are either taken or derived from APOGEE DR17 and Gaia DR3 catalogs. We find the existence of a well-separated extension of the kinematically thin disk stars in the metallicity range of −1.2 < [M/H] < −0.8 dex. Based on two-by-two distributions of [Mg/Mn], [Al/Fe] and [C+N/Fe], we further confirmed 56 high-possibility metal-poor thin disk (HP-MPTnD) giant stars and suggested the lower metallicity limit of the thin disk below −0.95 dex. A comparative analysis of the HP-MPTnD sample with other Galactic components revealed its chemo-dynamical similarities with canonical thin disk stars. These low-α metal-poor stars are predominantly located in the outer disk region and formed in the early stage of the formation of thin disk. Their existence provides compelling support for the two-infall model of the Milky Way's disk formation. Moreover, these stars impose observational constraints on the timing and metallicity of the second gas infall event.
{"title":"Investigating the Lower Limit of Metallicity for the Galactic Thin Disk","authors":"Guozhen Hu, 国真 胡, Zhengyi Shao, 正义 邵, Erbil Gügercinoǧlu, Wenyuan Cui and 文元 崔","doi":"10.3847/1538-4357/ad9c38","DOIUrl":"https://doi.org/10.3847/1538-4357/ad9c38","url":null,"abstract":"We explore the metal-poor regime of the Galactic disk on the distribution of stars in the [α/M]–Vϕ plane, to identify the most metal-poor thin disk (MPTnD) stars belonging to the low-α sequence. Chemical abundances and velocities of sample stars are either taken or derived from APOGEE DR17 and Gaia DR3 catalogs. We find the existence of a well-separated extension of the kinematically thin disk stars in the metallicity range of −1.2 < [M/H] < −0.8 dex. Based on two-by-two distributions of [Mg/Mn], [Al/Fe] and [C+N/Fe], we further confirmed 56 high-possibility metal-poor thin disk (HP-MPTnD) giant stars and suggested the lower metallicity limit of the thin disk below −0.95 dex. A comparative analysis of the HP-MPTnD sample with other Galactic components revealed its chemo-dynamical similarities with canonical thin disk stars. These low-α metal-poor stars are predominantly located in the outer disk region and formed in the early stage of the formation of thin disk. Their existence provides compelling support for the two-infall model of the Milky Way's disk formation. Moreover, these stars impose observational constraints on the timing and metallicity of the second gas infall event.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142987385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-17DOI: 10.3847/1538-4357/ad9826
Anne E. Blackwell and Joel N. Bregman
An early enrichment population (EEP) has been theorized to produce the observed intracluster medium (ICM) metallicity of galaxy clusters. This population likely existed at high redshifts (z ∼ 10), relics of which we posit exist today as dwarf galaxies. Previous work has argued that the initial mass function (IMF) of the EEP must be flatter than those found at lower redshifts, but with considerable uncertainties. In this work, we present a more quantitative model for the EEP and demonstrate how observational constraints can be applied to the IMF using supernova Type Ia (SN Ia) rates, delay time distributions (DTDs), and the luminosity functions (LFs) of galaxy clusters. We determine best-fit values for the slope and mass break of the IMF by comparing IMFs from literature with observed DTDs and the low-luminosity component (M(R) > −12) of the Coma LF. We derive two best-fit IMFs, flatter than standard IMFs: (1) αlo = −0.13 ± 0.24 for 0.07 < M/M⊙ < 1.75 and αhi = 0.53 ± 0.01 for 1.75 < M/M⊙ < 150; and (2) αlo = 1.06 ± 0.11 for 0.07 < M/M⊙ < 6 and αhi = 0.53 ± 0.01 for 6 < M/M⊙ < 150. We compare these with sl-5 from M. Loewenstein (2013), with α = 0.5 for 0.07 < M/M⊙ < 8 and α = 0.3 for 8 < M/M⊙ < 150. This EEP model, along with stars formed at later times, can produce the observed ICM metallicity, is consistent with observations, and predicts a significant rise in the SN Ia rate at increasing redshift.
{"title":"Early Enrichment Population Theory at High Redshift","authors":"Anne E. Blackwell and Joel N. Bregman","doi":"10.3847/1538-4357/ad9826","DOIUrl":"https://doi.org/10.3847/1538-4357/ad9826","url":null,"abstract":"An early enrichment population (EEP) has been theorized to produce the observed intracluster medium (ICM) metallicity of galaxy clusters. This population likely existed at high redshifts (z ∼ 10), relics of which we posit exist today as dwarf galaxies. Previous work has argued that the initial mass function (IMF) of the EEP must be flatter than those found at lower redshifts, but with considerable uncertainties. In this work, we present a more quantitative model for the EEP and demonstrate how observational constraints can be applied to the IMF using supernova Type Ia (SN Ia) rates, delay time distributions (DTDs), and the luminosity functions (LFs) of galaxy clusters. We determine best-fit values for the slope and mass break of the IMF by comparing IMFs from literature with observed DTDs and the low-luminosity component (M(R) > −12) of the Coma LF. We derive two best-fit IMFs, flatter than standard IMFs: (1) αlo = −0.13 ± 0.24 for 0.07 < M/M⊙ < 1.75 and αhi = 0.53 ± 0.01 for 1.75 < M/M⊙ < 150; and (2) αlo = 1.06 ± 0.11 for 0.07 < M/M⊙ < 6 and αhi = 0.53 ± 0.01 for 6 < M/M⊙ < 150. We compare these with sl-5 from M. Loewenstein (2013), with α = 0.5 for 0.07 < M/M⊙ < 8 and α = 0.3 for 8 < M/M⊙ < 150. This EEP model, along with stars formed at later times, can produce the observed ICM metallicity, is consistent with observations, and predicts a significant rise in the SN Ia rate at increasing redshift.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-17DOI: 10.3847/1538-4357/ad9a50
Kylie Yui Dan, Jerome Seebeck, Sylvain Veilleux, David Rupke, Eduardo Gonzalez-Alfonso, Ismael Garcia-Bernete, Weizhe Liu, Dieter Lutz, Marcio Melendez, Miguel Pereira Santaella, Eckhard Sturm and Francesco Tombesi
We present new James Webb Space Telescope (JWST) Mid-Infrared Instrument Medium-Resolution Spectrometer observations of the nearby ultraluminous infrared galaxy (ULIRG) F08572+3915 NW. These integral field spectroscopic (IFS) data reveal a kpc-scale warm-molecular rotating disk and biconical outflow traced by the H2ν = 0–0 S(1), S(2), S(3), and S(5) rotational transitions. The outflow maintains a relatively constant median (maximum) projected velocity of 1100 km s−1 (3000 km s−1) out to ∼1.4 kpc from the nucleus. The outflowing H2 material is slightly warmer (640–700 K) than the rotating disk material (460–520 K), perhaps due to shock heating in the highly turbulent outflowing material. This outflow shares the same kinematics and orientation as the sub-kiloparsec scale warm H2 outflow traced by the rovibrational H2 lines in Keck AO near-infrared IFS data. However, this warm H2 outflow is significantly faster than the sub-kiloparsec-scale cold molecular outflow derived from multi-transition far-infrared OH observations with Herschel and the greater than or equivalent to kiloparsec-scale cold molecular outflow mapped by millimeter-wave interferometric CO 1–0 observations with IRAM-PdBI and NOEMA. The new JWST data bolster the scenario where the buried quasar in this ULIRG is excavating the dust screen, accelerating perhaps as much as 60% of the dusty warm molecular material to velocities beyond the escape velocity, and thus influencing the evolution of the host galaxy.
{"title":"JWST Discovery of a Very Fast Biconical Outflow of Warm Molecular Gas in the Nearby Ultraluminous Infrared Galaxy F08572+3915 NW","authors":"Kylie Yui Dan, Jerome Seebeck, Sylvain Veilleux, David Rupke, Eduardo Gonzalez-Alfonso, Ismael Garcia-Bernete, Weizhe Liu, Dieter Lutz, Marcio Melendez, Miguel Pereira Santaella, Eckhard Sturm and Francesco Tombesi","doi":"10.3847/1538-4357/ad9a50","DOIUrl":"https://doi.org/10.3847/1538-4357/ad9a50","url":null,"abstract":"We present new James Webb Space Telescope (JWST) Mid-Infrared Instrument Medium-Resolution Spectrometer observations of the nearby ultraluminous infrared galaxy (ULIRG) F08572+3915 NW. These integral field spectroscopic (IFS) data reveal a kpc-scale warm-molecular rotating disk and biconical outflow traced by the H2ν = 0–0 S(1), S(2), S(3), and S(5) rotational transitions. The outflow maintains a relatively constant median (maximum) projected velocity of 1100 km s−1 (3000 km s−1) out to ∼1.4 kpc from the nucleus. The outflowing H2 material is slightly warmer (640–700 K) than the rotating disk material (460–520 K), perhaps due to shock heating in the highly turbulent outflowing material. This outflow shares the same kinematics and orientation as the sub-kiloparsec scale warm H2 outflow traced by the rovibrational H2 lines in Keck AO near-infrared IFS data. However, this warm H2 outflow is significantly faster than the sub-kiloparsec-scale cold molecular outflow derived from multi-transition far-infrared OH observations with Herschel and the greater than or equivalent to kiloparsec-scale cold molecular outflow mapped by millimeter-wave interferometric CO 1–0 observations with IRAM-PdBI and NOEMA. The new JWST data bolster the scenario where the buried quasar in this ULIRG is excavating the dust screen, accelerating perhaps as much as 60% of the dusty warm molecular material to velocities beyond the escape velocity, and thus influencing the evolution of the host galaxy.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142987328","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-17DOI: 10.3847/1538-4357/ad9b0e
Yuehui Ma, Miaomiao Zhang, Hongchi Wang, Min Fang, Zhenyi Yue, Xuepeng Chen, Ji Yang, Fujun Du, Yang Su, Suziye He, Haoran Feng, Yan Sun, Chong Li, Qing-Zeng Yan, Zhiwei Chen, Shaobo Zhang and Xin Zhou
We present a systematic analysis of the velocity structure functions (VSFs) of 167 molecular clouds with angular sizes greater than ~176 arcmin2 in three sectors of the Galactic midplane. We calculated the first-to-third-order VSFs and found that 60% of the VSFs exhibit power-law distributions. The relative power-law exponents are consistent with predictions from intermittent turbulence models. Column density weighting reduces the proportion of power-law VSFs and steepens the VSF slopes, implying a reduction of turbulent energy in high-density regions. All clouds show small-scale intermittency, with slightly stronger intermittency in those molecular clouds showing “none” power-law VSFs. Negative VSF exponents that may indicate gravitational collapse are not observed in our sample. The scaling exponents of the observed VSFs do not correlate with the virial parameters of the molecular clouds. These two observations suggest that gravity-dominated scales in molecular clouds still need further investigation. Consistent VSF scaling exponents for the molecular clouds with significant power-law VSFs suggest large-scale external driving of turbulence in these molecular clouds. However, the driving mechanisms are likely not universal, as the power-law scaling coefficients in our results show relatively large scatter. The fact that nearly 40% of the VSFs deviate to some extent from power-law distributions suggests that the influence of local environments on the internal turbulence of molecular clouds may not be negligible.
{"title":"Examining Turbulence in Galactic Molecular Clouds. I. A Statistical Analysis of Velocity Structures","authors":"Yuehui Ma, Miaomiao Zhang, Hongchi Wang, Min Fang, Zhenyi Yue, Xuepeng Chen, Ji Yang, Fujun Du, Yang Su, Suziye He, Haoran Feng, Yan Sun, Chong Li, Qing-Zeng Yan, Zhiwei Chen, Shaobo Zhang and Xin Zhou","doi":"10.3847/1538-4357/ad9b0e","DOIUrl":"https://doi.org/10.3847/1538-4357/ad9b0e","url":null,"abstract":"We present a systematic analysis of the velocity structure functions (VSFs) of 167 molecular clouds with angular sizes greater than ~176 arcmin2 in three sectors of the Galactic midplane. We calculated the first-to-third-order VSFs and found that 60% of the VSFs exhibit power-law distributions. The relative power-law exponents are consistent with predictions from intermittent turbulence models. Column density weighting reduces the proportion of power-law VSFs and steepens the VSF slopes, implying a reduction of turbulent energy in high-density regions. All clouds show small-scale intermittency, with slightly stronger intermittency in those molecular clouds showing “none” power-law VSFs. Negative VSF exponents that may indicate gravitational collapse are not observed in our sample. The scaling exponents of the observed VSFs do not correlate with the virial parameters of the molecular clouds. These two observations suggest that gravity-dominated scales in molecular clouds still need further investigation. Consistent VSF scaling exponents for the molecular clouds with significant power-law VSFs suggest large-scale external driving of turbulence in these molecular clouds. However, the driving mechanisms are likely not universal, as the power-law scaling coefficients in our results show relatively large scatter. The fact that nearly 40% of the VSFs deviate to some extent from power-law distributions suggests that the influence of local environments on the internal turbulence of molecular clouds may not be negligible.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142987330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-17DOI: 10.3847/1538-4357/ad9b13
R. Michael Jennings, Alaina Henry, Valentin Mauerhofer, Timothy Heckman, Claudia Scarlata, Cody Carr, Xinfeng Xu, Mason Huberty, Simon Gazagnes, Anne E. Jaskot, Jeremy Blaizot, Anne Verhamme, Sophia R. Flury, Alberto Saldana-Lopez, Matthew J. Hayes and Maxime Trebitsch
Ultraviolet absorption line spectroscopy is a sensitive diagnostic for the properties of interstellar and circumgalactic gas. Down-the-barrel observations, where the absorption is measured against the galaxy itself, are commonly used to study feedback from galactic outflows and to make predictions about the leakage of H i ionizing photons into the intergalactic medium. Nonetheless, the interpretation of these observations is challenging, and observational compromises are often made in terms of signal-to-noise ratio, spectral resolution, or the use of stacking analyses. In this paper, we present a novel quantitative assessment of UV absorption line measurement techniques by using mock observations of a hydrodynamical simulation. We use a simulated galaxy to create 22,500 spectra in the commonly used Si ii lines while also modeling the signal-to-noise ratio and spectral resolution of recent rest-frame UV galaxy surveys at both high and low redshifts. We show that the residual flux of absorption features is easily overestimated for single line measurements and for stacked spectra. Additionally, we explore the robustness of the partial covering model for estimating column densities from spectra and find underpredictions on an average of 1.25 dex. We show that the underprediction is likely caused by high-column-density sight lines that are optically thick to dust making them invisible in UV spectra.
{"title":"A Simulated Galaxy Laboratory: Exploring the Observational Effects on UV Spectral Absorption Line Measurements","authors":"R. Michael Jennings, Alaina Henry, Valentin Mauerhofer, Timothy Heckman, Claudia Scarlata, Cody Carr, Xinfeng Xu, Mason Huberty, Simon Gazagnes, Anne E. Jaskot, Jeremy Blaizot, Anne Verhamme, Sophia R. Flury, Alberto Saldana-Lopez, Matthew J. Hayes and Maxime Trebitsch","doi":"10.3847/1538-4357/ad9b13","DOIUrl":"https://doi.org/10.3847/1538-4357/ad9b13","url":null,"abstract":"Ultraviolet absorption line spectroscopy is a sensitive diagnostic for the properties of interstellar and circumgalactic gas. Down-the-barrel observations, where the absorption is measured against the galaxy itself, are commonly used to study feedback from galactic outflows and to make predictions about the leakage of H i ionizing photons into the intergalactic medium. Nonetheless, the interpretation of these observations is challenging, and observational compromises are often made in terms of signal-to-noise ratio, spectral resolution, or the use of stacking analyses. In this paper, we present a novel quantitative assessment of UV absorption line measurement techniques by using mock observations of a hydrodynamical simulation. We use a simulated galaxy to create 22,500 spectra in the commonly used Si ii lines while also modeling the signal-to-noise ratio and spectral resolution of recent rest-frame UV galaxy surveys at both high and low redshifts. We show that the residual flux of absorption features is easily overestimated for single line measurements and for stacked spectra. Additionally, we explore the robustness of the partial covering model for estimating column densities from spectra and find underpredictions on an average of 1.25 dex. We show that the underprediction is likely caused by high-column-density sight lines that are optically thick to dust making them invisible in UV spectra.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142987762","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-17DOI: 10.3847/1538-4357/ad98f1
Jooyun Woo, Kaya Mori, Charles J. Hailey, Elizabeth Spira-Savett, Aya Bamba, Brian W. Grefenstette, Thomas B. Humensky, Reshmi Mukherjee, Samar Safi-Harb, Tea Temim and Naomi Tsuji
Young supernova remnants (SNRs) are believed to be the origin of energetic cosmic rays (CRs) below the “knee” of their spectrum at ∼3 PeV (1015 eV). Nevertheless, the precise location, duration, and operation of CR acceleration in young SNRs are open questions. Here, we report on multiepoch X-ray observations of Cassiopeia A (Cas A), a 350 yr old SNR, in the 15–50 keV band that probes the most energetic CR electrons. The observed X-ray flux decrease (15% ± 1% over 10 yr), contrary to the expected >90% decrease based on previous radio, X-ray, and gamma-ray observations, provides unambiguous evidence for CR electron acceleration operating in Cas A. A temporal model for the radio and X-ray data accounting for electron cooling and continuous injection finds that the freshly injected electron spectrum is significantly harder (exponential cutoff power-law index q = 2.15), and its cutoff energy is much higher (Ecut = 36 TeV), than the relic electron spectrum (q = 2.44 ± 0.03, Ecut = 4 ± 1 TeV). Both electron spectra are naturally explained by the recently developed modified nonlinear diffusive shock acceleration (mNLDSA) mechanism. The CR protons producing the observed gamma rays are likely accelerated at the same location by the same mechanism as the injected electrons. The Cas A observations and spectral modeling represent the first time radio, X-ray, gamma-ray, and CR spectra have been self-consistently tied to a specific acceleration mechanism—mNLDSA—in a young SNR.
{"title":"Spectrum and Location of Ongoing Extreme Particle Acceleration in Cassiopeia A","authors":"Jooyun Woo, Kaya Mori, Charles J. Hailey, Elizabeth Spira-Savett, Aya Bamba, Brian W. Grefenstette, Thomas B. Humensky, Reshmi Mukherjee, Samar Safi-Harb, Tea Temim and Naomi Tsuji","doi":"10.3847/1538-4357/ad98f1","DOIUrl":"https://doi.org/10.3847/1538-4357/ad98f1","url":null,"abstract":"Young supernova remnants (SNRs) are believed to be the origin of energetic cosmic rays (CRs) below the “knee” of their spectrum at ∼3 PeV (1015 eV). Nevertheless, the precise location, duration, and operation of CR acceleration in young SNRs are open questions. Here, we report on multiepoch X-ray observations of Cassiopeia A (Cas A), a 350 yr old SNR, in the 15–50 keV band that probes the most energetic CR electrons. The observed X-ray flux decrease (15% ± 1% over 10 yr), contrary to the expected >90% decrease based on previous radio, X-ray, and gamma-ray observations, provides unambiguous evidence for CR electron acceleration operating in Cas A. A temporal model for the radio and X-ray data accounting for electron cooling and continuous injection finds that the freshly injected electron spectrum is significantly harder (exponential cutoff power-law index q = 2.15), and its cutoff energy is much higher (Ecut = 36 TeV), than the relic electron spectrum (q = 2.44 ± 0.03, Ecut = 4 ± 1 TeV). Both electron spectra are naturally explained by the recently developed modified nonlinear diffusive shock acceleration (mNLDSA) mechanism. The CR protons producing the observed gamma rays are likely accelerated at the same location by the same mechanism as the injected electrons. The Cas A observations and spectral modeling represent the first time radio, X-ray, gamma-ray, and CR spectra have been self-consistently tied to a specific acceleration mechanism—mNLDSA—in a young SNR.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142987325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-17DOI: 10.3847/1538-4357/ad9d45
A. Ozdonmez, H. Er, M. Tekkesinoglu, E. Ege, M. E. Kenger, I. C. Ozkesen and A. Polatoğlu
This study presents analyses of the optical variability of the 1ES 1215+303 on diverse timescales using multiband observations, including observations in the optical BVRI bands carried out with the 0.6 and 1.0 m telescopes located at the Tübitak National Observatory (TUG) from 2022 to 2024 and Zwicky Transient Facility (ZTF) gri data from 2018 to 2023. Investigation of variability on intraday timescales revealed amplitudes of 4.0% and 5.6% on two nights, with a calculated duty cycle of 63%. We determined a minimum timescale of ~92 minutes from these observations, leading us to limit the radius for the optical emission region and the mass of the black hole. The blazar exhibits moderate short- and long-term variability, with variability amplitudes reaching up to 120% and decreasing as the wavelength shortens. Correlation analysis revealed a strong correlation between the optical multiband emissions without any time lag. Analysis of 109 nightly spectral energy distributions yielded spectral indices ranging from 0.772 to 1.413. The consistent trend of both spectral indices and color with respect to brightness suggests a mild bluer when brighter trend persists throughout the observation period, in contrast to the intraday timescale. Utilizing the weighted wavelet z-transform and Lomb–Scargle methods, we analyzed recurrent optical emission patterns on the combined R-band light curves from TUG, ZTF, and Tuorla observations, revealing a quasiperiodic signal at around 1000 days and a secondary signal at approximately 300 days. These signals were found to be insignificant after accounting for the stochastic process and the trial factor.
{"title":"Characterizing Multiband Optical Emission and Variability of 1ES 1215+303 on Diverse Timescales","authors":"A. Ozdonmez, H. Er, M. Tekkesinoglu, E. Ege, M. E. Kenger, I. C. Ozkesen and A. Polatoğlu","doi":"10.3847/1538-4357/ad9d45","DOIUrl":"https://doi.org/10.3847/1538-4357/ad9d45","url":null,"abstract":"This study presents analyses of the optical variability of the 1ES 1215+303 on diverse timescales using multiband observations, including observations in the optical BVRI bands carried out with the 0.6 and 1.0 m telescopes located at the Tübitak National Observatory (TUG) from 2022 to 2024 and Zwicky Transient Facility (ZTF) gri data from 2018 to 2023. Investigation of variability on intraday timescales revealed amplitudes of 4.0% and 5.6% on two nights, with a calculated duty cycle of 63%. We determined a minimum timescale of ~92 minutes from these observations, leading us to limit the radius for the optical emission region and the mass of the black hole. The blazar exhibits moderate short- and long-term variability, with variability amplitudes reaching up to 120% and decreasing as the wavelength shortens. Correlation analysis revealed a strong correlation between the optical multiband emissions without any time lag. Analysis of 109 nightly spectral energy distributions yielded spectral indices ranging from 0.772 to 1.413. The consistent trend of both spectral indices and color with respect to brightness suggests a mild bluer when brighter trend persists throughout the observation period, in contrast to the intraday timescale. Utilizing the weighted wavelet z-transform and Lomb–Scargle methods, we analyzed recurrent optical emission patterns on the combined R-band light curves from TUG, ZTF, and Tuorla observations, revealing a quasiperiodic signal at around 1000 days and a secondary signal at approximately 300 days. These signals were found to be insignificant after accounting for the stochastic process and the trial factor.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"6 16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142987388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-17DOI: 10.3847/1538-4357/ada123
Long Cheng, Erik Vigren, Moa Persson, Hao Gu and Jun Cui
The molecular dication CO2++ has, as previously reported, been detected in the Martian ionosphere by the Neutral Gas and Ion Mass Spectrometer on the Mars Atmosphere and Volatile Evolution (MAVEN) mission. Photochemical models have also been developed to reproduce the CO2++ density in the Martian dayside ionosphere but underestimate significantly the observations. In this study, we examine the influence of the CO2++ natural lifetime against spontaneous dissociation on its modeled density. We show that extending the assumed CO2++ lifetime significantly reduces the discrepancy between the photochemical model predictions and MAVEN observations. Specifically, when treating CO2++ as stable against natural dissociation, instead of invoking a lifetime of 4 s as done in previous studies, the data-to-model ratio comes close to unity throughout the altitude range 160–220 km. We argue that stability of CO2++ against natural dissociation does not necessarily conflict with results from a frequently cited experimental investigation. Our study provides new insights for advancing photochemical modeling of the Martian ionosphere and underscores the need for further laboratory measurements targeting fundamental properties of doubly charged ions.
{"title":"Advancing CO2 ++ Modeling in the Martian Dayside Ionosphere: Insights from Natural Lifetime Analysis","authors":"Long Cheng, Erik Vigren, Moa Persson, Hao Gu and Jun Cui","doi":"10.3847/1538-4357/ada123","DOIUrl":"https://doi.org/10.3847/1538-4357/ada123","url":null,"abstract":"The molecular dication CO2++ has, as previously reported, been detected in the Martian ionosphere by the Neutral Gas and Ion Mass Spectrometer on the Mars Atmosphere and Volatile Evolution (MAVEN) mission. Photochemical models have also been developed to reproduce the CO2++ density in the Martian dayside ionosphere but underestimate significantly the observations. In this study, we examine the influence of the CO2++ natural lifetime against spontaneous dissociation on its modeled density. We show that extending the assumed CO2++ lifetime significantly reduces the discrepancy between the photochemical model predictions and MAVEN observations. Specifically, when treating CO2++ as stable against natural dissociation, instead of invoking a lifetime of 4 s as done in previous studies, the data-to-model ratio comes close to unity throughout the altitude range 160–220 km. We argue that stability of CO2++ against natural dissociation does not necessarily conflict with results from a frequently cited experimental investigation. Our study provides new insights for advancing photochemical modeling of the Martian ionosphere and underscores the need for further laboratory measurements targeting fundamental properties of doubly charged ions.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"55 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142987390","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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