The Astrophysical Journal最新文献

{"title":"Do Strong Bars Exhibit Strong Noncircular Motions?","authors":"Taehyun Kim, Dimitri A. Gadotti, Yun Hee Lee, Carlos López-Cobá, Woong-Tae Kim, Minjin Kim and Myeong-gu Park","doi":"10.3847/1538-4357/ad8573","DOIUrl":"https://doi.org/10.3847/1538-4357/ad8573","url":null,"abstract":"Galactic bars induce characteristic motions deviating from pure circular rotation, known as noncircular motions. As bars are nonaxisymmetric structures, stronger bars are expected to show stronger noncircular motions. However, this has not yet been confirmed by observations. We use a bisymmetric model to account for the stellar kinematics of 14 barred galaxies obtained with the Multi-Unit Spectroscopic Explorer and characterize the degree of bar-driven noncircular motions. For the first time, we find tight relations between the bar strength (bar ellipticity and torque parameter) and the degree of stellar noncircular motions. We also find that the bar strength is strongly associated with the stellar radial velocity driven by bars. Our results imply that stronger bars exhibit stronger noncircular motions. Noncircular motions beyond the bar are found to be weak, comprising less than 10% of the strength of the circular motions. We find that galaxies with a boxy/peanut (B/P) bulge exhibit a higher degree of noncircular motions and higher stellar radial velocity compared to galaxies without a B/P bulge, by 30% ∼ 50%. However, this effect could be attributed to the presence of strong bars in galaxies with a B/P feature in our sample, which would naturally result in higher radial motions, rather than to the B/P bulges themselves inducing stronger radial motions. More observational studies, utilizing both stellar and gaseous kinematics on statistically complete samples, along with numerical studies are necessary to draw a comprehensive view of the impact that B/P bulges have on bar-driven noncircular motions.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142713240","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}

{"title":"Periodic Gamma-Ray Modulation of the Blazar PG 1553+113 Confirmed by Fermi-LAT and Multiwavelength Observations","authors":"S. Abdollahi, L. Baldini, G. Barbiellini, R. Bellazzini, B. Berenji, E. Bissaldi, R. D. Blandford, R. Bonino, P. Bruel, S. Buson, R. A. Cameron, P. A. Caraveo, F. Casaburo, E. Cavazzuti, C. C. Cheung, G. Chiaro, S. Ciprini, G. Cozzolongo, P. Cristarella Orestano, S. Cutini, F. D’Ammando, N. Di Lalla, F. Dirirsa, L. Di Venere, A. Domínguez, S. J. Fegan, E. C. Ferrara, A. Fiori, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, S. Garrappa, D. Gasparrini, S. Germani, N. Giglietto, F. Giordano, M. Giroletti, D. Green, I. A. Grenier, S. Guiriec, E. Hays, D. Horan, M. Kuss, S. Larsson, M. Laurenti, J. Li, I. Liodakis, F. Longo, F. Loparco, B. Lott, M. N. Lovellette, P. Lubrano, S. Maldera, D. Malyshev, A. Manfreda, L. Marcotulli, G. Martí-Devesa, M. N. Mazziotta, I. Mereu, P. F. Michelson, W. Mitthumsiri, T. Mizuno, M. E. Monzani, A. Morselli, I. V. Moskalenko, M. Negro, N. Omodei, M. Orienti, E. Orlando, J. F. Ormes, D. Paneque, M. Perri, M. Persic, M. Pesce-Rollins, T. A. Porter, G. P..","doi":"10.3847/1538-4357/ad64c5","DOIUrl":"https://doi.org/10.3847/1538-4357/ad64c5","url":null,"abstract":"A 2.1 yr periodic oscillation of the gamma-ray flux from the blazar PG 1553+113 has previously been tentatively identified in ∼7 yr of data from the Fermi Large Area Telescope. After 15 yr of Fermi sky-survey observations, doubling the total time range, we report >7 cycle gamma-ray modulation with an estimated significance of 4σ against stochastic red noise. Independent determinations of oscillation period and phase in the earlier and the new data are in close agreement (chance probability <0.01). Pulse timing over the full light curve is also consistent with a coherent periodicity. Multiwavelength new data from Swift X-Ray Telescope, Burst Alert Telescope, and UVOT, and from KAIT, Catalina Sky Survey, All-Sky Automated Survey for Supernovae, and Owens Valley Radio Observatory ground-based observatories as well as archival Rossi X-Ray Timing Explorer satellite-All Sky Monitor data, published optical data of Tuorla, and optical historical Harvard plates data are included in our work. Optical and radio light curves show clear correlations with the gamma-ray modulation, possibly with a nonconstant time lag for the radio flux. We interpret the gamma-ray periodicity as possibly arising from a pulsational accretion flow in a sub-parsec binary supermassive black hole system of elevated mass ratio, with orbital modulation of the supplied material and energy in the jet. Other astrophysical scenarios introduced include instabilities, disk and jet precession, rotation or nutation, and perturbations by massive stars or intermediate-mass black holes in polar orbit.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142697138","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}

{"title":"Further Study of Starspot Activity and Measurement of Differential Rotation for SZ Piscium","authors":"Yue Xiang, Shenghong Gu, A. Collier Cameron, J. R. Barnes and Dongtao Cao","doi":"10.3847/1538-4357/ad86bd","DOIUrl":"https://doi.org/10.3847/1538-4357/ad86bd","url":null,"abstract":"We present a series of nine Doppler images of the magnetically active K component of the RS CVn-type binary SZ Piscium (SZ Psc), based on high-resolution spectroscopic data collected from 2014 to 2018. We apply least-squares deconvolution (LSD) to all spectra to extract the average profiles with high signal-to-noise ratios for Doppler imaging. The surface maps of the K subgiant show starspots widely distributed along its latitude and longitude. A prominent, nonaxisymmetric polar spot around phase 0 is revealed by all images with sufficient phase coverage, which may be a stable feature on the K component. The starspots evolve over a timescale of 1 month. We have determined the surface shear rate of the K component from starspot maps reconstructed 10 days apart in 2017 November–December through the cross-correlation method. The surface differential rotation parameters are Ωeq = 1.591 ± 0.002 rad day−1 and ΔΩ = 0.035 ± 0.003 rad day−1. The absorption lines contributed from the tertiary component of SZ Psc are detected in all LSD profiles, and we measure the radial velocity of the binary system and the tertiary component to derive an elliptical orbit with a period of 1530 ± 3 days and a mass of 0.75 ± 0.06 M⊙ for the tertiary component.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142697037","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}

{"title":"Assessing Core-powered Mass Loss in the Context of Early Boil-off: Minimal Long-lived Mass Loss for the Sub-Neptune Population","authors":"Yao Tang, Jonathan J. Fortney and Ruth Murray-Clay","doi":"10.3847/1538-4357/ad8567","DOIUrl":"https://doi.org/10.3847/1538-4357/ad8567","url":null,"abstract":"We develop a Python-based state-of-the-art sub-Neptune evolution model that incorporates both the post-formation boil-off at young ages ≤1 Myr and long-lived core-powered mass loss (∼Gyr) from interior cooling. We investigate the roles of initial H/He entropy, core luminosity, energy advection, radiative atmospheric structure, and the transition to an X-ray- and ultraviolet-driven mass-loss phase, with an eye on relevant timescales for planetary mass loss and thermal evolution. With particular attention to the re-equilibration process of the H/He envelope, including the energy sources that fuel the hydrodynamic wind, and energy transport timescales, we find that boil-off and core-powered escape are primarily driven by stellar bolometric radiation. We further find that both boil-off and core-powered escape are decoupled from the thermal evolution. We show that, with a boil-off phase that accounts for the initial H/He mass fraction and initial entropy, post-boil-off core-powered escape has an insignificant influence on the demographics of small planets, as it is only able to remove at most 0.1% of the H/He mass fraction. Our numerical results are directly compared to previous work on analytical core-powered mass-loss modeling for individual evolutionary trajectories and populations of small planets. We examine a number of assumptions made in previous studies that cause significant differences compared to our findings. We find that boil-off, though able to completely strip the gaseous envelope from a highly irradiated (F ≥ 100 F⊕) planet that has a low-mass core (Mc ≤ 4 M⊕), cannot by itself form a pronounced radius gap as is seen in the observed population.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142697041","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}

{"title":"The Disk Reverberation Mapping of the Lensed Quasar Q0957+561","authors":"Marcin Marculewicz, Mouyuan Sun, Zhixiang Zhang and Tuan Yi","doi":"10.3847/1538-4357/ad8b1a","DOIUrl":"https://doi.org/10.3847/1538-4357/ad8b1a","url":null,"abstract":"The measurement of continuum time lags in lensed quasars can effectively probe the accretion physics of quasars. This is because microlensing observations of lensed quasars can provide constraints on the half-light radii of quasar accretion disks. By combining the microlensing results with time lag measurements, one can, for the first time, estimate the propagation velocity of the physical process that drives interband time lags and cross correlations among disk emission (i.e., in UV/optical bands). In this study, we perform the disk reverberation mapping study for the well-studied lensed quasar, Q0957+561. The cross correlation between the Zwicky Transient Facility g and r bands was measured; the g variations lead the r ones by 6.4 ± 2.6 days in the rest frame. In combination with the half-light radius from the existing literature, we find that the propagation velocity of the variability mechanism should be times the speed of light. We discuss the possible outcomes of this result. Similar studies can be applied to other lensed quasars by utilizing the Legacy Survey of Space and Time observations.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"256 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142697045","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}

{"title":"Characterizing the Nanohertz Gravitational Wave Background Using a t-process Power Spectral Density","authors":"Shashwat C. Sardesai, Joseph Simon and Sarah J. Vigeland","doi":"10.3847/1538-4357/ad8a60","DOIUrl":"https://doi.org/10.3847/1538-4357/ad8a60","url":null,"abstract":"Pulsar timing arrays (PTAs) are sensitive to low-frequency gravitational waves (GWs), which induce correlated changes in millisecond pulsars’ timing residuals. PTA collaborations around the world have recently announced evidence of a nanohertz gravitational wave background (GWB), which may be produced by a population of supermassive black hole binaries (SMBHBs). The GWB is often modeled as following a power-law power spectral density (PSD); however, a GWB produced by a cosmological population of SMBHBs is expected to have a more complex power spectrum due to the discrete nature of the sources. In this paper, we investigate using a t-process PSD to model the GWB, which allows us to fit for both the underlying power-law amplitude and spectral index as well as deviations from that power law, which may be produced by individual nearby binaries. We create simulated data sets based on the properties of the NANOGrav 15 yr data set, and we demonstrate that the t-process PSD can accurately recover the PSD when deviations from a power law are present. With longer timed data sets and more pulsars, we expect the sensitivity of our PTAs to improve, which will allow us to precisely measure the PSD of the GWB and study the sources producing it.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142697068","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}

{"title":"A Study on the Nested Rings CME Structure Observed by the WISPR Imager Onboard Parker Solar Probe","authors":"Shaheda Begum Shaik, Mark G. Linton, Sarah E. Gibson, Phillip Hess, Robin C. Colaninno, Guillermo Stenborg, Carlos R. Braga and Erika Palmerio","doi":"10.3847/1538-4357/ad8354","DOIUrl":"https://doi.org/10.3847/1538-4357/ad8354","url":null,"abstract":"Despite the significance of coronal mass ejections (CMEs) in space weather, a comprehensive understanding of their interior morphology remains a scientific challenge, particularly with the advent of many state-of-the-art solar missions such as Parker Solar Probe (Parker) and Solar Orbiter (SO). In this study, we present an analysis of a complex CME as observed by the Wide-Field Imager for Solar PRobe (WISPR) heliospheric imager during Parker’s seventh solar encounter. The CME morphology does not fully conform with the general three-part density structure, exhibiting a front and core not significantly bright, with a highly structured overall configuration. In particular, its morphology reveals nonconcentric nested rings, which we argue are a signature of the embedded helical magnetic flux rope of the CME. For that, we analyze the morphological and kinematical properties of the nested density structures and demonstrate that they outline the projection of the three-dimensional structure of the flux rope as it crosses the lines of sight of the WISPR imager, thereby revealing the magnetic field geometry. Comparison of observations from various viewpoints suggests that the CME substructures can be discerned owing to the ideal viewing perspective, close proximity, and spatial resolution of the observing instrument.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"129 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142718362","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}

{"title":"Expanding the Inventory of Molecule-rich Planetary Nebulae: New Observations of M4-17, Hu 1-1, M1-59, and Na 2","authors":"K. R. Gold, D. R. Schmidt and L. M. Ziurys","doi":"10.3847/1538-4357/ad83be","DOIUrl":"https://doi.org/10.3847/1538-4357/ad83be","url":null,"abstract":"Molecular observations of four planetary nebulae (PNe), M4-17, Hu 1-1, M1-59, and Na 2, were conducted at 1–3 mm using the Arizona Radio Observatory’s 12 m antenna and Submillimeter Telescope, and the Institut de Radioastronomie Millimétrique 30 m Telescope. Toward M4-17, HNC (J = 3 → 2), CCH (N = 2 → 1, N = 3 → 2), CN (N = 1 → 0, N = 2 → 1), H2CO (JKa,Kc = 21,2 → 11,1, JKa,Kc = 20,2 → 10,1, JKa,Kc = 21,1 → 11,0), CS (J = 3 → 2, J = 5 → 4), and H13CN (J = 2 → 1) were detected. An almost identical set of transitions was identified toward Hu 1-1. Moreover, c–C3H2 was detected in Hu 1-1 via three 2 mm lines: JKa,Kc = 31,2 → 22,1, JKa,Kc = 41,4 → 30,3, and JKa,Kc = 32, 2 → 21,1. HNC, CCH, CN, CS, and H13CN were found in M1-59, as well as H2S via its JKa,Kc = 11,0 → 10,1 line—the first detection of this key sulfur species in PNe. In addition, CCH and CN were identified in the 27,000 yr old Na 2. Among these four sources, CN and CCH were the most prevalent molecules (after CO and H2) with fractional abundances, relative to H2, of f ∼ 0.9–7.5 × 10−7 and 0.8–7.5 × 10−7, respectively. CS and HNC have abundances in the range f ∼ 0.5–5 × 10−8, the latter resulting in HCN/HNC ∼ 3 across all three PNe. The unusual species H2CO, c–C3H2, and H2S had f ∼ 3–4 × 10−7, 10−8, and 6 × 10−8. This study suggests that elliptical PNe such as Hu 1-1 can have a diverse molecular composition. The presence of CN, CCH, and HCO+ in Na 2, with comparable abundances to younger PNe, demonstrates that molecular content is maintained into the late PN stage.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"81 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142684260","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}

{"title":"An In-depth Analysis of Quiet-Sun IRIS Brightenings","authors":"Llŷr Dafydd Humphries, Huw Morgan and David Kuridze","doi":"10.3847/1538-4357/ad8576","DOIUrl":"https://doi.org/10.3847/1538-4357/ad8576","url":null,"abstract":"Small-scale brightenings are ubiquitous, dynamic, and energetic phenomena found in the chromosphere. An advanced filter-detection algorithm applied to high-resolution observations from the Interface Region Imaging Spectrograph enables the detection of these brightenings close to the noise level. This algorithm also tracks the movement of these brightenings and extracts their characteristics. This work outlines the results of an in-depth analysis of a quiet-Sun data set including a comparison of a brighter domain—associated with a supergranular boundary—to the quiescent internetwork domains. Several characteristics of brightenings from both domains are extracted and analysed, providing a range of sizes, durations, brightness values, travel distances, and speeds. The “active” quiet-Sun events tend to travel shorter distances and at slower speeds across the plane of the sky than their “true” quiet-Sun counterparts. These results are consistent with the magnetic field model of supergranular photospheric structures and the magnetic canopy model of the chromosphere above. Spectroscopic analyses reveal that bright points demonstrate blueshift (as well as some bidirectionality) and that they may rise from the chromosphere into the transition region. We believe that these bright points are magnetic in nature, are likely the result of magnetic reconnection, and follow current sheets between magnetic field gradients, rather than travel along magnetic field lines themselves.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"71 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142684471","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}

{"title":"How Do the Velocity Anisotropies of Halo Stars, Dark Matter, and Satellite Galaxies Depend on Host Halo Properties?","authors":"Jiaxin He, Wenting Wang, Zhaozhou Li, Jiaxin Han, Vicente Rodriguez-Gomez, Donghai Zhao, Xianguang Meng, Yipeng Jing, Shi Shao, Rui Shi and Zhenlin Tan","doi":"10.3847/1538-4357/ad8882","DOIUrl":"https://doi.org/10.3847/1538-4357/ad8882","url":null,"abstract":"We investigate the mass (M200) and concentration (c200) dependencies of the velocity anisotropy (β) profiles for different components in the dark matter halo—including halo stars, dark matter, and subhalos—using systems from the IllustrisTNG simulations. Beyond a critical radius, β becomes more radial with the increase of M200, reflecting more prominent radial accretion around massive halos. The critical radius is r ∼ rs, 0.3 rs, and rs for halo stars, dark matter, and subhalos, with rs being the scale radius of the host halos. This dependence on M200 is the strongest for subhalos and the weakest for halo stars. In central regions, the β of halo stars and dark matter particles get more isotropic with the increase of M200 in TNG300 due to baryons. By contrast, the β of dark matter from the dark-matter-only TNG300-Dark run shows much weaker dependence on M200 within rs. Dark matter in TNG300 is slightly more isotropic than in TNG300-Dark at 0.2 rs < r < 10 rs and . Halo stars and dark matter also become more radial with the increase in c200, at fixed M200. Halo stars are more radial than the β profile of dark matter by approximately a constant beyond rs. Dark matter particles are more radial than subhalos. The differences can be understood, as subhalos on more radial orbits are more easily stripped, contributing more stars and dark matter to the diffuse components. We provide the fitting formula for the differences between the β of halo stars and dark matter at rs < r < 3 rs as for and as βstar − βDM = 0.328 for .","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"61 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142684477","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}