The Astrophysical Journal最新文献_第7页

Chemical Evolution of Isotopically Labeled Carbon Dioxide (13CO2) Ice Exposed to Ionizing Radiation and Implications for Trans-Neptunian Objects

The Astrophysical Journal Pub Date : 2025-02-19 DOI: 10.3847/1538-4357/ada9e7

Chaojiang Zhang, Leslie A. Young and Ralf I. Kaiser

{"title":"Chemical Evolution of Isotopically Labeled Carbon Dioxide (13CO2) Ice Exposed to Ionizing Radiation and Implications for Trans-Neptunian Objects","authors":"Chaojiang Zhang, Leslie A. Young and Ralf I. Kaiser","doi":"10.3847/1538-4357/ada9e7","DOIUrl":"https://doi.org/10.3847/1538-4357/ada9e7","url":null,"abstract":"We present results on the radiation chemistry of isotopically labeled carbon dioxide (13CO2) ices induced by energetic electrons at 40 and 10 K to simulate the chemical evolution of carbon dioxide on trans-Neptunian objects exposed to galactic cosmic-ray particles. By collecting infrared spectra during the irradiation of 13CO2 ices, we have identified several radiolysis products, including carbon monoxide (13CO), ozone (O3), carbon trioxide (13CO3) with cyclic (C2v) and acyclic (D3h) isomers, carbon tetraoxide (13CO4), carbon pentaoxide (13CO5), and carbon hexaoxide (13CO6). The temporal profiles reveal that all products exhibit a rapid increase followed by a gradual decrease during prolonged irradiation, with the reduction at 40 K occurring faster than at 10 K. Furthermore, the ratio of 13CO to 13CO2 rises to constants of 0.20 at 40 K and 0.27 at 10 K as radiation accumulates within ices, which has potential implications for understanding the specific conditions of trans-Neptunian objects, such as galactic cosmic-ray exposure history, or other astrophysical scenarios characterized by abundant carbon dioxide.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"64 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443258","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}

引用次数: 0

Improving the Temporal Resolution of SOHO/MDI Magnetograms of Solar Active Regions Using a Deep Generative Model

The Astrophysical Journal Pub Date : 2025-02-19 DOI: 10.3847/1538-4357/adb032

Jialiang Li, Vasyl Yurchyshyn, Jason T. L. Wang, Haimin Wang, Yasser Abduallah, Khalid A. Alobaid, Chunhui Xu, Ruizhu Chen and Yan Xu

引用次数: 0

Precession for the Mode Change in a Gamma-Ray Pulsar

The Astrophysical Journal Pub Date : 2025-02-19 DOI: 10.3847/1538-4357/adaf1d

H. Tong and H. H. Wang

引用次数: 0

Impacts of UV Radiation from an AGN on Planetary Atmospheres and Consequences for Galactic Habitability

The Astrophysical Journal Pub Date : 2025-02-18 DOI: 10.3847/1538-4357/adac5d

Kendall I. Sippy, Jake K. Eager-Nash, Ryan C. Hickox, Nathan J. Mayne and McKinley C. Brumback

{"title":"Impacts of UV Radiation from an AGN on Planetary Atmospheres and Consequences for Galactic Habitability","authors":"Kendall I. Sippy, Jake K. Eager-Nash, Ryan C. Hickox, Nathan J. Mayne and McKinley C. Brumback","doi":"10.3847/1538-4357/adac5d","DOIUrl":"https://doi.org/10.3847/1538-4357/adac5d","url":null,"abstract":"We present a study of the effects of ultraviolet (UV) emission from active galactic nuclei (AGN) on the atmospheric composition of planets and potential impact on life. It is expected that all supermassive black holes, which reside at galactic centers, have gone through periods of high AGN activity in order to reach their current masses. We examine potential damaging effects on lifeforms on planets with different atmosphere types and receiving different levels of AGN flux, using data on the sensitivity of various species’ cells to UV radiation to determine when radiation becomes “dangerous.” We also consider potential chemical changes to planetary atmospheres as a result of UV radiation from AGN, using the Platform for Atmosphere, Land, Earth, and Ocean photochemical model. We find that the presence of sufficient initial oxygen (surface mixing ratio ≥10−3 mol mol−1) in the planet’s atmosphere allows a thicker ozone layer to form in response to AGN radiation, which reduces the level of dangerous UV radiation incident on the planetary surface from what it was in absence of an AGN. We estimate the fraction of solar systems in galaxies that would be affected by substantial AGN UV radiation, and find that the impact is most pronounced in compact galaxies such as “red nugget relics,” as compared to typical present-day ellipticals and spirals (using M87 and the Milky Way as examples).","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"35 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143435090","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}

引用次数: 0

Measuring Star Formation Rates in the Milky Way from Hi-GAL 70 μm Observations

The Astrophysical Journal Pub Date : 2025-02-18 DOI: 10.3847/1538-4357/adaeb2

Davide Elia, Neal J. Evans, Juan D. Soler, Francesco Strafella, Eugenio Schisano, Sergio Molinari, Andrea Giannetti and Sudeshna Patra

{"title":"Measuring Star Formation Rates in the Milky Way from Hi-GAL 70 μm Observations","authors":"Davide Elia, Neal J. Evans, Juan D. Soler, Francesco Strafella, Eugenio Schisano, Sergio Molinari, Andrea Giannetti and Sudeshna Patra","doi":"10.3847/1538-4357/adaeb2","DOIUrl":"https://doi.org/10.3847/1538-4357/adaeb2","url":null,"abstract":"Three methods for computing the total star formation rate (SFR) of the Milky Way agree well with a reference value of 1.65 ± 0.19 M⊙ yr−1. They are then used to determine the radial dependence of the SFR and face-on map for the Milky Way. First, the method based on a model of star formation in Hi-GAL-defined dense clumps, adjusted for an increase in the gas-to-dust ratio with Galactocentric radius, predicts 1.65 ± 0.61 M⊙ yr−1. Second, the method using the 70 μm emission, commonly used in other galaxies, with a technique to assign distances to the extended emission, predicts M⊙ yr−1. Finally, a method based on theoretical predictions of star formation efficiency as a function of virial parameter, with masses corrected for metallicity dependence, applied to a catalog of molecular clouds also predicts a value in agreement at 1.47 M⊙ yr−1. The three methods predict the radial variation of the SFR, with remarkably good agreement from the Central Molecular Zone out to about 20 kpc. More differences were seen in face-on maps with a resolution of 0.5 kpc made with the three approaches and in comparisons to the local (within 3 kpc) SFR, indicating limitations of the methods when applied to smaller scales. The 70 μm SFR follows very closely the surface density of molecular gas, corrected for a metallicity-dependent CO conversion factor. A molecular gas depletion time of 1 Gyr is consistent with the data, as is a molecular Kennicutt–Schmidt relation with a power-law slope of 1.10 ± 0.06.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"49 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143435094","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}

引用次数: 0

Asteroseismology with TESS: Emergence of Dipole Mode Suppression from Subgiants?

The Astrophysical Journal Pub Date : 2025-02-18 DOI: 10.3847/1538-4357/adae9e

Shurui Lin, 书睿林, Tanda Li, 坦达李, Shude Mao, 淑德毛 and Jim Fuller

引用次数: 0

The Morphology of Dwarf Galaxies Hosting Variable Active Galactic Nuclei

The Astrophysical Journal Pub Date : 2025-02-18 DOI: 10.3847/1538-4357/adaebf

Erin Kimbro, Vivienne Baldassare, Guy Worthey, Marla Geha and Jenny Greene

{"title":"The Morphology of Dwarf Galaxies Hosting Variable Active Galactic Nuclei","authors":"Erin Kimbro, Vivienne Baldassare, Guy Worthey, Marla Geha and Jenny Greene","doi":"10.3847/1538-4357/adaebf","DOIUrl":"https://doi.org/10.3847/1538-4357/adaebf","url":null,"abstract":"We analyze Hubble Space Telescope optical imaging of eight low-mass galaxies hosting active galactic nuclei (AGN) identified via their photometric variability in V. F. Baldassare et al. We use GALFIT to model the 2D galaxy light profiles, and find a diversity of morphologies. The galaxies with regular morphologies are best fit with pseudobulges and disks, rather than classical bulges. We estimate black hole masses using scaling relations and find black hole masses of 103.7−6.6M⊙. We compare this sample to dwarf galaxies with AGN selected via optical spectroscopy. On average, the variable host galaxies have lower-mass black holes. We analyze the brightest point source in each galaxy and find their properties are not entirely consistent with star clusters, indicating that they are likely AGN. These point sources are found to have lower luminosities than spectroscopically selected dwarf AGN, but brighter than the point sources in dwarf galaxies not identified as AGN. Our detailed imaging analysis shows that variability selection has the potential to find lower-mass black holes and lower-luminosity AGN than optical spectroscopy. These active dwarfs may have been missed by spectroscopic searches due to star formation dilution or low gas content.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143435101","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}

引用次数: 0

Constraining the Nuclear Equation of State of a Neutron Star via High-frequency Quasi-periodic Oscillation in Short Gamma-Ray Bursts

The Astrophysical Journal Pub Date : 2025-02-18 DOI: 10.3847/1538-4357/adaceb

Jun-Xiang Huang, Hou-Jun Lü and En-Wei Liang

{"title":"Constraining the Nuclear Equation of State of a Neutron Star via High-frequency Quasi-periodic Oscillation in Short Gamma-Ray Bursts","authors":"Jun-Xiang Huang, Hou-Jun Lü and En-Wei Liang","doi":"10.3847/1538-4357/adaceb","DOIUrl":"https://doi.org/10.3847/1538-4357/adaceb","url":null,"abstract":"The determination of the equation of state (EOS) of a neutron star (NS) and its maximum mass is very important for understanding the formation and properties of NSs under extreme conditions, but they remain open questions. Short-duration gamma-ray bursts (GRBs) are believed to originate from the merger of binary NSs or giant flares (GFs) of soft gamma repeaters (SGRs). Recently, the high-frequency quasi-periodic oscillations (QPOs) have been claimed to be identified from two short GRBs (GRB 931101B and GRB 910711). In this paper, we propose that the observed high-frequency QPOs in these two short GRBs result from torsional oscillations in the GFs of SGRs associated with cold NSs, or from radial oscillations of hypermassive NSs as the hot remnants of binary NS mergers, and then to constrain the EOS of NSs. For torsional oscillations, the six selected EOSs (TM1, NL3, APR, SLy4, DDME2, and GM1) of NSs suitable for the zero-temperature condition exhibit significant overlap in mass ranges, suggesting that we cannot constrain the EOS of NSs. For radial oscillations, the six selected EOSs (IUF, TM1, TMA, FSG, BHBLp, and NL3) of NSs suitable for the high-temperature condition cannot be ruled out when redshift is considered. However, it is found that the EOS can only be constrained if the redshift and temperature of the remnant can be measured.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143435095","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}

引用次数: 0

Deep Rest-UV JWST/NIRSpec Spectroscopy of Early Galaxies: The Demographics of C iv and N-emitters in the Reionization Era

The Astrophysical Journal Pub Date : 2025-02-18 DOI: 10.3847/1538-4357/ada95c

Michael W. Topping, Daniel P. Stark, Peter Senchyna, Zuyi Chen, Adi Zitrin, Ryan Endsley, Stéphane Charlot, Lukas J. Furtak, Michael V. Maseda, Adele Plat, Renske Smit, Ramesh Mainali, Jacopo Chevallard, Stephen Molyneux and Jane R. Rigby

{"title":"Deep Rest-UV JWST/NIRSpec Spectroscopy of Early Galaxies: The Demographics of C iv and N-emitters in the Reionization Era","authors":"Michael W. Topping, Daniel P. Stark, Peter Senchyna, Zuyi Chen, Adi Zitrin, Ryan Endsley, Stéphane Charlot, Lukas J. Furtak, Michael V. Maseda, Adele Plat, Renske Smit, Ramesh Mainali, Jacopo Chevallard, Stephen Molyneux and Jane R. Rigby","doi":"10.3847/1538-4357/ada95c","DOIUrl":"https://doi.org/10.3847/1538-4357/ada95c","url":null,"abstract":"JWST has recently discovered a subset of reionization era galaxies with ionized gas that is metal-poor in oxygen and carbon but heavily enriched in nitrogen. This abundance pattern is almost never seen in lower-redshift galaxies but is commonly observed in globular cluster stars. We have recently demonstrated that this peculiar abundance pattern appears in a compact (≃20 pc) metal-poor galaxy undergoing a strong burst of star formation. This galaxy was originally selected based on strong C iv emission, indicating a hard radiation field rarely seen locally. In this paper, we present JWST/NIRSpec observations of another reionization-era galaxy known to power strong C iv emission, the z = 7.04 gravitationally lensed galaxy A1703-zd6. The emission-line spectrum reveals this is a metal-poor galaxy ( ) dominated by a young stellar population ( Myr) that powers a very hard ionizing spectrum (C iv equivalent width, EW = 19.4 Å, He ii EW = 2.2 Å). The interstellar medium is highly enriched in nitrogen ( ) with very high electron densities (8–19 × 104 cm−3) and extreme ionization conditions rarely seen at lower redshift. We also find intense CIV emission (EW ≳ 20 Å) in two new z ≳ 6 metal-poor galaxies. To put these results in context, we search for UV line emission in a sample of 737 z ≳ 4 galaxies with NIRSpec spectra, establishing that 40%(30%) of systems with [O iii]+Hβ EW > 2000 Å have N iv] (C iv) detections with EW > 5 Å(> 10 Å). These results suggest high N/O ratios, and hard ionizing sources appear in a brief phase following a burst of star formation in compact high-density stellar complexes.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143435087","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}

引用次数: 0

A Pilot Study for the CSST Slitless Spectroscopic Quasar Survey Based on Mock Data

The Astrophysical Journal Pub Date : 2025-02-18 DOI: 10.3847/1538-4357/adabdc

Yuxuan Pang, Xue-Bing Wu, Yuming Fu, Rui Zhu, Bing Lyu, Huimei Wang and Xiaotong Feng

{"title":"A Pilot Study for the CSST Slitless Spectroscopic Quasar Survey Based on Mock Data","authors":"Yuxuan Pang, Xue-Bing Wu, Yuming Fu, Rui Zhu, Bing Lyu, Huimei Wang and Xiaotong Feng","doi":"10.3847/1538-4357/adabdc","DOIUrl":"https://doi.org/10.3847/1538-4357/adabdc","url":null,"abstract":"The wide survey of the Chinese Space Station Telescope (CSST) will observe a large field of 17,500 deg2. The GU, GV, and GI grism observations of CSST will cover the wavelength range from 2550 to 10000 Å at a resolution of R ∼ 200 and a depth of about 22 AB magnitude for the continuum. In this paper, we present a pipeline to identify quasars and measure their physical properties with the CSST mock data. We simulate the raw images and extract the one-dimensional grism spectra for quasars, galaxies, and stars with r-band magnitudes of 18 < mr < 22 using the CSST Cycle 6 simulation code (https://csst-tb.bao.ac.cn/code/csst_sim/csst-simulation). Using a convolution neural network, we separate quasars from stars and galaxies. We measure the redshifts by identifying strong emission lines of quasars. We also fit the 1D slitless spectra with QSOFITMORE to estimate black hole masses and Eddington ratios. Our results show that CSST slitless spectroscopy can effectively separate quasars with redshifts z = 0−5 from other types of objects with an accuracy of 99%. Among those successfully classified quasars, 90% of them could have precise redshift measurements with σNMAD = 0.002. The scatters of black hole masses and Eddington ratios from the spectral fittings are 0.13 and 0.15 dex, respectively. The metallicity diagnosis line ratios have a scatter of 0.1–0.2 dex. Our results show that the CSST slitless spectroscopy survey has the potential to discover about 0.9 million new quasars and provide important contributions to the science of active galactic nuclei and cosmology.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443298","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}

引用次数: 0