Pub Date : 2024-10-16DOI: 10.3847/1538-4357/ad6eff
Richard Smith, Avi Patel, Monika D. Soraisam, Puragra Guhathakurta, Pranav Tadepalli, Sally Zhu, Joseph Liu, Léo Girardi, L. Clifton Johnson, Sagnick Mukherjee, Knut A. G. Olsen and Benjamin F. Williams
Variable stars in stellar clusters can offer key constraints on stellar evolution and pulsation models, utilizing estimates of host cluster properties to constrain stellar physical parameters. We present a catalog of 86 luminous (F814W < 19) variable stars in M31 clusters identified by mining the archival Panchromatic Hubble Andromeda Treasury (PHAT) survey using a combination of statistical analysis of sparse PHAT light curves and difference imaging. We determine the evolutionary phases and initial masses of these variable stars by matching them with theoretical isochrones generated using host cluster properties from the literature. We calculate the probability of PHAT photometry being blended due to the highly crowded nature of cluster environments for each cluster-variable star, using these probabilities to inform our level of confidence in the derived properties of each star. Our 86 cluster-variable stars have initial masses between 0.8 and 67 M⊙. Their evolutionary phases span the main sequence, more evolved hydrogen- and helium-burning phases, and the post–asymptotic giant branch. We identify numerous candidate variable star types: RV Tauri variables, red supergiants, and slowly pulsating B-type supergiants, along with Wolf–Rayet stars, α Cygni and Mira variables, a classical Cepheid, and a possible superasymptotic giant. We characterize 12 cluster-variable stars at higher confidence based on their difference image quality and lower blending probability. Ours is the first systematic study of variable stars in extragalactic stellar clusters leveraging the superior resolution of the Hubble Space Telescope and demonstrating the unique power of stellar clusters in constraining the fundamental properties of variable stars.
星团中的变星可以为恒星演化和脉动模型提供关键的约束条件，利用对宿主星团特性的估计来约束恒星的物理参数。我们利用对稀疏的哈勃仙女座宝库（PHAT）光曲的统计分析和差分成像相结合的方法，通过对档案全色哈勃仙女座宝库（PHAT）巡天的挖掘，发现了M31星团中的86颗发光变星（F814W < 19），并将其编入星表。我们将这些变星的演化阶段和初始质量与利用文献中的主星团属性生成的理论等时线进行匹配，从而确定这些变星的演化阶段和初始质量。我们计算了由于星团环境高度拥挤而导致每颗星团变星的PHAT光度被混合的概率，利用这些概率来确定我们对每颗恒星的推导性质的置信度。86颗星团变星的初始质量介于0.8到67 M⊙之间。它们的演化阶段跨越了主序、更演化的氢燃烧和氦燃烧阶段以及后渐变巨枝。我们确定了许多候选变星类型：金牛座 RV 变星、红超巨星、缓慢脉动的 B 型超巨星，还有天狼射线星、α Cygni 和米拉变星、一颗经典的蛇夫座变星和一颗可能的超巨星。我们根据其不同的图像质量和较低的混合概率，以较高的置信度描述了12颗星团变星。我们的研究是利用哈勃太空望远镜的高分辨率对河外星系恒星簇中的变星进行的首次系统研究，展示了恒星簇在制约变星基本性质方面的独特能力。
{"title":"Variable Stars in M31 Stellar Clusters from the Panchromatic Hubble Andromeda Treasury","authors":"Richard Smith, Avi Patel, Monika D. Soraisam, Puragra Guhathakurta, Pranav Tadepalli, Sally Zhu, Joseph Liu, Léo Girardi, L. Clifton Johnson, Sagnick Mukherjee, Knut A. G. Olsen and Benjamin F. Williams","doi":"10.3847/1538-4357/ad6eff","DOIUrl":"https://doi.org/10.3847/1538-4357/ad6eff","url":null,"abstract":"Variable stars in stellar clusters can offer key constraints on stellar evolution and pulsation models, utilizing estimates of host cluster properties to constrain stellar physical parameters. We present a catalog of 86 luminous (F814W < 19) variable stars in M31 clusters identified by mining the archival Panchromatic Hubble Andromeda Treasury (PHAT) survey using a combination of statistical analysis of sparse PHAT light curves and difference imaging. We determine the evolutionary phases and initial masses of these variable stars by matching them with theoretical isochrones generated using host cluster properties from the literature. We calculate the probability of PHAT photometry being blended due to the highly crowded nature of cluster environments for each cluster-variable star, using these probabilities to inform our level of confidence in the derived properties of each star. Our 86 cluster-variable stars have initial masses between 0.8 and 67 M⊙. Their evolutionary phases span the main sequence, more evolved hydrogen- and helium-burning phases, and the post–asymptotic giant branch. We identify numerous candidate variable star types: RV Tauri variables, red supergiants, and slowly pulsating B-type supergiants, along with Wolf–Rayet stars, α Cygni and Mira variables, a classical Cepheid, and a possible superasymptotic giant. We characterize 12 cluster-variable stars at higher confidence based on their difference image quality and lower blending probability. Ours is the first systematic study of variable stars in extragalactic stellar clusters leveraging the superior resolution of the Hubble Space Telescope and demonstrating the unique power of stellar clusters in constraining the fundamental properties of variable stars.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142448754","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 : 2024-10-16DOI: 10.3847/1538-4357/ad73d6
Pradiphat Muangha, David Ruffolo, Alejandro Sáiz, Chanoknan Banglieng, Paul Evenson, Surujhdeo Seunarine, Suyeon Oh, Jongil Jung, Marc L. Duldig and John E. Humble
A technique has recently been developed for tracking short-term spectral variations in Galactic cosmic rays (GCRs) using data from a single neutron monitor (NM), by collecting histograms of the time delay between successive neutron counts and extracting the leader fraction L as a proxy of the spectral index. Here we analyze L from four Antarctic NMs from 2015 March to 2023 September. We have calibrated L from the South Pole NM with respect to a daily spectral index determined from published data of GCR proton fluxes during 2015–2019 from the Alpha Magnetic Spectrometer (AMS-02) on board the International Space Station. Our results demonstrate a robust correlation between the leader fraction and the spectral index fit over the rigidity range 2.97–16.6 GV for AMS-02 data, with uncertainty of 0.018 in the daily spectral index as inferred from L. In addition to the 11 yr solar activity cycle, a wavelet analysis confirms a 27 day periodicity in the GCR flux and spectral index corresponding to solar rotation, especially near sunspot minimum, while the flux occasionally exhibits a strong harmonic at 13.5 days. The magnetic field component along a nominal Parker spiral (i.e., the magnetic sector structure) is a strong determinant of such spectral and flux variations, with the solar wind speed exerting an additional, nearly rigidity-independent influence on flux variations. Our investigation affirms the capability of ground-based NM stations to accurately and continuously monitor cosmic-ray spectral variations over the long-term future.
{"title":"Variations in the Inferred Cosmic-Ray Spectral Index as Measured by Neutron Monitors in Antarctica","authors":"Pradiphat Muangha, David Ruffolo, Alejandro Sáiz, Chanoknan Banglieng, Paul Evenson, Surujhdeo Seunarine, Suyeon Oh, Jongil Jung, Marc L. Duldig and John E. Humble","doi":"10.3847/1538-4357/ad73d6","DOIUrl":"https://doi.org/10.3847/1538-4357/ad73d6","url":null,"abstract":"A technique has recently been developed for tracking short-term spectral variations in Galactic cosmic rays (GCRs) using data from a single neutron monitor (NM), by collecting histograms of the time delay between successive neutron counts and extracting the leader fraction L as a proxy of the spectral index. Here we analyze L from four Antarctic NMs from 2015 March to 2023 September. We have calibrated L from the South Pole NM with respect to a daily spectral index determined from published data of GCR proton fluxes during 2015–2019 from the Alpha Magnetic Spectrometer (AMS-02) on board the International Space Station. Our results demonstrate a robust correlation between the leader fraction and the spectral index fit over the rigidity range 2.97–16.6 GV for AMS-02 data, with uncertainty of 0.018 in the daily spectral index as inferred from L. In addition to the 11 yr solar activity cycle, a wavelet analysis confirms a 27 day periodicity in the GCR flux and spectral index corresponding to solar rotation, especially near sunspot minimum, while the flux occasionally exhibits a strong harmonic at 13.5 days. The magnetic field component along a nominal Parker spiral (i.e., the magnetic sector structure) is a strong determinant of such spectral and flux variations, with the solar wind speed exerting an additional, nearly rigidity-independent influence on flux variations. Our investigation affirms the capability of ground-based NM stations to accurately and continuously monitor cosmic-ray spectral variations over the long-term future.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443968","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 : 2024-10-16DOI: 10.3847/1538-4357/ad7259
S. Ferretti, S. Marrara, D. Bronte Ciriza, A. Magazzù, A. Foti, P. G. Gucciardi, A. Musolino, L. Folco, V. Della Corte, A. Rotundi, R. Saija, A. Mandanici, O. M. Maragò and M. G. Donato
Extraterrestrial material collected during space missions is highly exposed to contamination issues during on-Earth analysis. Although high-protection-level protocols were developed, to minimize the contamination due to sample manipulation and the substrate contribution an optimal strategy is to perform in situ analysis with contactless techniques. Optical and acoustic trapping represent ideal candidates for contactless manipulation and analysis of nanometer-to-millimeter-sized particles. Here, we show results of the manipulation of cometary analogs and micrometeorite samples using a single-axis acoustic levitator. The investigation of the particle dynamics in the trap allows the calculation of the trap spring constants that are found in the mN/m range. In addition, we collect the Raman spectra of two levitated fragments of Saratov meteorite, demonstrating that acoustic levitation can be effectively used for the contactless and low-contamination characterization of samples of interest in astrophysics.
{"title":"Contactless Manipulation and Raman Analysis of Cometary Analogs and Micrometeorites by Acoustic Levitation","authors":"S. Ferretti, S. Marrara, D. Bronte Ciriza, A. Magazzù, A. Foti, P. G. Gucciardi, A. Musolino, L. Folco, V. Della Corte, A. Rotundi, R. Saija, A. Mandanici, O. M. Maragò and M. G. Donato","doi":"10.3847/1538-4357/ad7259","DOIUrl":"https://doi.org/10.3847/1538-4357/ad7259","url":null,"abstract":"Extraterrestrial material collected during space missions is highly exposed to contamination issues during on-Earth analysis. Although high-protection-level protocols were developed, to minimize the contamination due to sample manipulation and the substrate contribution an optimal strategy is to perform in situ analysis with contactless techniques. Optical and acoustic trapping represent ideal candidates for contactless manipulation and analysis of nanometer-to-millimeter-sized particles. Here, we show results of the manipulation of cometary analogs and micrometeorite samples using a single-axis acoustic levitator. The investigation of the particle dynamics in the trap allows the calculation of the trap spring constants that are found in the mN/m range. In addition, we collect the Raman spectra of two levitated fragments of Saratov meteorite, demonstrating that acoustic levitation can be effectively used for the contactless and low-contamination characterization of samples of interest in astrophysics.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142448453","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 : 2024-10-16DOI: 10.3847/1538-4357/ad71c8
Valentin A. Skoutnev and Andrei M. Beloborodov
Tayler instability of toroidal magnetic fields Bϕ is broadly invoked as a trigger for turbulence and angular momentum transport in stars. This paper presents a systematic revision of the linear stability analysis for a rotating, magnetized, and stably stratified star. For plausible configurations of Bϕ, instability requires diffusive processes: viscosity, magnetic diffusivity, or thermal/compositional diffusion. Our results reveal a new physical picture, demonstrating how different diffusive effects independently trigger instability of two types of waves in the rotating star: magnetostrophic waves and inertial waves. It develops via overstability of the waves, whose growth rate sharply peaks at some characteristic wavenumbers. We determine instability conditions for each wave branch and find the characteristic wavenumbers. The results are qualitatively different for stars with magnetic Prandtl number Pm ≪ 1 (e.g., the Sun) and Pm ≫ 1 (e.g., protoneutron stars). The parameter dependence of unstable modes suggests a nonuniversal scaling of the possible Tayler–Spruit dynamo.
{"title":"Tayler Instability Revisited","authors":"Valentin A. Skoutnev and Andrei M. Beloborodov","doi":"10.3847/1538-4357/ad71c8","DOIUrl":"https://doi.org/10.3847/1538-4357/ad71c8","url":null,"abstract":"Tayler instability of toroidal magnetic fields Bϕ is broadly invoked as a trigger for turbulence and angular momentum transport in stars. This paper presents a systematic revision of the linear stability analysis for a rotating, magnetized, and stably stratified star. For plausible configurations of Bϕ, instability requires diffusive processes: viscosity, magnetic diffusivity, or thermal/compositional diffusion. Our results reveal a new physical picture, demonstrating how different diffusive effects independently trigger instability of two types of waves in the rotating star: magnetostrophic waves and inertial waves. It develops via overstability of the waves, whose growth rate sharply peaks at some characteristic wavenumbers. We determine instability conditions for each wave branch and find the characteristic wavenumbers. The results are qualitatively different for stars with magnetic Prandtl number Pm ≪ 1 (e.g., the Sun) and Pm ≫ 1 (e.g., protoneutron stars). The parameter dependence of unstable modes suggests a nonuniversal scaling of the possible Tayler–Spruit dynamo.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443964","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 : 2024-10-16DOI: 10.3847/1538-4357/ad7467
Prahlad R. Epili and Wei Wang
We report the timing and spectral studies of the accreting X-ray pulsar 4U 2206+54 using AstroSat and Insight-HXMT observations taken in 2016 and 2020 respectively. X-ray pulsations from the system are detected by both missions. The AstroSat discovered a significant periodic signal at ∼5619 s in 2016, and Insight-HXMT found a pulsation period at ∼5291 s in 2020. A comparison of its spin-period evolution with the present spin-period estimates shows that the neutron star in 4U 2206+54 now has recently been undergoing a spin-up episode after attaining to its slow pulsations of 5750 s around 2015 from its prolonged spin-down phase. The present average spin-up rate of the pulsar is found to be at ∼1.2 × 10−13 Hz s−1. The phase-averaged spectra of the pulsar in 1–60 keV could be explained with a high-energy cutoff power-law continuum model; no evident line features are found with AstroSat. The application of Comptonization models such as comptt and compmag to the phase-averaged spectra of 4U 2206+54 reveals a hotter source photon region near the pulsar with an emission size extending to ∼2–2.8 km. Using the quasi-spherical settling accretion theory, we explain the present spin-up and the possibility of the strong magnetic field of the pulsar.
{"title":"AstroSat and Insight-HXMT Observations of the Long-period X-Ray Pulsar 4U 2206+54","authors":"Prahlad R. Epili and Wei Wang","doi":"10.3847/1538-4357/ad7467","DOIUrl":"https://doi.org/10.3847/1538-4357/ad7467","url":null,"abstract":"We report the timing and spectral studies of the accreting X-ray pulsar 4U 2206+54 using AstroSat and Insight-HXMT observations taken in 2016 and 2020 respectively. X-ray pulsations from the system are detected by both missions. The AstroSat discovered a significant periodic signal at ∼5619 s in 2016, and Insight-HXMT found a pulsation period at ∼5291 s in 2020. A comparison of its spin-period evolution with the present spin-period estimates shows that the neutron star in 4U 2206+54 now has recently been undergoing a spin-up episode after attaining to its slow pulsations of 5750 s around 2015 from its prolonged spin-down phase. The present average spin-up rate of the pulsar is found to be at ∼1.2 × 10−13 Hz s−1. The phase-averaged spectra of the pulsar in 1–60 keV could be explained with a high-energy cutoff power-law continuum model; no evident line features are found with AstroSat. The application of Comptonization models such as comptt and compmag to the phase-averaged spectra of 4U 2206+54 reveals a hotter source photon region near the pulsar with an emission size extending to ∼2–2.8 km. Using the quasi-spherical settling accretion theory, we explain the present spin-up and the possibility of the strong magnetic field of the pulsar.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443970","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 : 2024-10-16DOI: 10.3847/1538-4357/ad6f08
Yossi Oren, Amiel Sternberg, Christopher F. McKee, Yakov Faerman and Shy Genel
We analyze measurements of the thermal Sunyaev–Zeldovich (tSZ) effect arising in the circumgalactic medium (CGM) of L* galaxies, reported by J. N. Bregman et al. (B+22) and S. Das et al. (D+23). In our analysis, we use the Y. Faerman et al. CGM models, a new power-law model (PLM), and the TNG100 simulation. For a given Mvir, our PLM has four parameters: the fraction, fhCGM, of the halo baryon mass in hot CGM gas, the ratio, ϕT, of the actual gas temperature at the virial radius to the virial temperature, and the power-law indices, aP,th and an for the thermal electron pressure and the hydrogen nucleon density. The B+22 Compton-y profile implies steep electron pressure slopes (aP,th ≃ 2). For isothermal conditions, the temperature is at least 1.1 × 106 K, with a hot CGM gas mass of up to 3.5 × 1011M⊙ for a virial mass of 2.75 × 1012M⊙. However, if isothermal, the gas must be expanding out of the halos. An isentropic equation of state is favored for which hydrostatic equilibrium is possible. The B+22 and D+23 results are consistent with each other and with recent (0.5–2 keV) CGM X-ray observations of Milky Way mass systems. For Mvir ≃ 3 × 1012M⊙, the scaled Compton pressure integrals, , lie in the narrow range, 2.5 × 10−4–5.0 × 10−4 kpc2, for all three sets of observations. TNG100 underpredicts the tSZ parameters by factors ∼0.5 dex for the L* galaxies, suggesting that the feedback strengths and CGM gas losses are overestimated in the simulated halos at these mass scales.
{"title":"Sunyaev–Zeldovich Signals from L* Galaxies: Observations, Analytics, and Simulations","authors":"Yossi Oren, Amiel Sternberg, Christopher F. McKee, Yakov Faerman and Shy Genel","doi":"10.3847/1538-4357/ad6f08","DOIUrl":"https://doi.org/10.3847/1538-4357/ad6f08","url":null,"abstract":"We analyze measurements of the thermal Sunyaev–Zeldovich (tSZ) effect arising in the circumgalactic medium (CGM) of L* galaxies, reported by J. N. Bregman et al. (B+22) and S. Das et al. (D+23). In our analysis, we use the Y. Faerman et al. CGM models, a new power-law model (PLM), and the TNG100 simulation. For a given Mvir, our PLM has four parameters: the fraction, fhCGM, of the halo baryon mass in hot CGM gas, the ratio, ϕT, of the actual gas temperature at the virial radius to the virial temperature, and the power-law indices, aP,th and an for the thermal electron pressure and the hydrogen nucleon density. The B+22 Compton-y profile implies steep electron pressure slopes (aP,th ≃ 2). For isothermal conditions, the temperature is at least 1.1 × 106 K, with a hot CGM gas mass of up to 3.5 × 1011M⊙ for a virial mass of 2.75 × 1012M⊙. However, if isothermal, the gas must be expanding out of the halos. An isentropic equation of state is favored for which hydrostatic equilibrium is possible. The B+22 and D+23 results are consistent with each other and with recent (0.5–2 keV) CGM X-ray observations of Milky Way mass systems. For Mvir ≃ 3 × 1012M⊙, the scaled Compton pressure integrals, , lie in the narrow range, 2.5 × 10−4–5.0 × 10−4 kpc2, for all three sets of observations. TNG100 underpredicts the tSZ parameters by factors ∼0.5 dex for the L* galaxies, suggesting that the feedback strengths and CGM gas losses are overestimated in the simulated halos at these mass scales.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443963","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 : 2024-10-16DOI: 10.3847/1538-4357/ad79ff
Zhi-fu Chen, Zhe-Geng Chen, Xing-long Peng and Wei-rong Huang
Radio spectral shape of quasars can provide insight into the ages of quasars. We have compiled data for 1804 quasars with z ≲ 1 from the Sloan Digital Sky Survey (SDSS). Additionally, these quasars were also mapped by the Low-Frequency Array at 144 MHz and the Very Large Array Sky Survey at 3000 MHz. The radio spectral index, designated as (with S(ν) ∝ να), is analyzed between 144 and 3000 MHz as a proxy for the ages of quasars. We measure the [O III] λ5007 emission line in the SDSS spectra. A strong correlation was found between the equivalent width of the core component of the [O III] λ5007 emission line and . This relationship suggests that the core component of the [O III] λ5007 emission line could potentially serve as a surrogate for the evolutionary stage of a quasar. The quasars at an early stage of evolutions tend to show weaker [O III] λ5007 emission, while older quasars exhibit stronger [O III] λ5007 emission.
{"title":"Narrow [O iii] Emission Lines as a Potential Proxy for the Evolutionary Stage of Quasars","authors":"Zhi-fu Chen, Zhe-Geng Chen, Xing-long Peng and Wei-rong Huang","doi":"10.3847/1538-4357/ad79ff","DOIUrl":"https://doi.org/10.3847/1538-4357/ad79ff","url":null,"abstract":"Radio spectral shape of quasars can provide insight into the ages of quasars. We have compiled data for 1804 quasars with z ≲ 1 from the Sloan Digital Sky Survey (SDSS). Additionally, these quasars were also mapped by the Low-Frequency Array at 144 MHz and the Very Large Array Sky Survey at 3000 MHz. The radio spectral index, designated as (with S(ν) ∝ να), is analyzed between 144 and 3000 MHz as a proxy for the ages of quasars. We measure the [O III] λ5007 emission line in the SDSS spectra. A strong correlation was found between the equivalent width of the core component of the [O III] λ5007 emission line and . This relationship suggests that the core component of the [O III] λ5007 emission line could potentially serve as a surrogate for the evolutionary stage of a quasar. The quasars at an early stage of evolutions tend to show weaker [O III] λ5007 emission, while older quasars exhibit stronger [O III] λ5007 emission.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443976","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 : 2024-10-15DOI: 10.3847/1538-4357/ad6d5e
Rafael Ortiz III, Rogier A. Windhorst, Seth H. Cohen, Steven P. Willner, Rolf A. Jansen, Timothy Carleton, Patrick S. Kamieneski, Michael J. Rutkowski, Brent M. Smith, Jake Summers, Cheng Cheng, Dan Coe, Christopher J. Conselice, Jose M. Diego, Simon P. Driver, Jordan C. J. D’Silva, Brenda L. Frye, Hansung B. Gim, Norman A. Grogin, Heidi B. Hammel, Nimish P. Hathi, Benne W. Holwerda, Minhee Hyun, Myungshin Im, William C. Keel, Anton M. Koekemoer, Juno Li, Madeline A. Marshall, Tyler J. McCabe, Noah J. McLeod, Stefanie N. Milam, Rosalia O’Brien, Nor Pirzkal, Aaron S. G. Robotham, Russell E. Ryan, Christopher N. A. Willmer, Haojing Yan, Min S. Yun and Adi Zitrin
The first public 0.9–4.4 μm NIRCam images of the North Ecliptic Pole Time Domain Field uncovered galaxies displaying point-source features in their cores as seen in the longer-wavelength filters. We visually identified a sample of 66 galaxies (∼1 galaxy arcmin–2) with pointlike cores and have modeled their two-dimensional light profiles with GalFit, identifying 16 galactic nuclei with measurable point-source components. GalFit suggests that the visual sample is a mix of both compact stellar bulge and point-source galaxy cores. This core classification is complemented by spectral energy distribution modeling to infer the sample’s active galactic nucleus (AGN) and host-galaxy parameters. For galaxies with measurable point-source components, the median fractional AGN contribution to their 0.1–30.0 μm flux is 0.44, and 14/16 are color-classified AGN. We conclude that near-infrared point-source galaxy cores are signatures of AGN. In addition, we define an automated sample-selection criterion to identify these point-source features. This criterion can be used in other extant and future NIRCam images to streamline the search for galaxies with unresolved IR-luminous AGN. The James Webb Space Telescope’s superb angular resolution and sensitivity at infrared wavelengths are resurrecting the morphological identification of AGN.
{"title":"PEARLS: Discovery of Point-source Features within Galaxies in the North Ecliptic Pole Time Domain Field","authors":"Rafael Ortiz III, Rogier A. Windhorst, Seth H. Cohen, Steven P. Willner, Rolf A. Jansen, Timothy Carleton, Patrick S. Kamieneski, Michael J. Rutkowski, Brent M. Smith, Jake Summers, Cheng Cheng, Dan Coe, Christopher J. Conselice, Jose M. Diego, Simon P. Driver, Jordan C. J. D’Silva, Brenda L. Frye, Hansung B. Gim, Norman A. Grogin, Heidi B. Hammel, Nimish P. Hathi, Benne W. Holwerda, Minhee Hyun, Myungshin Im, William C. Keel, Anton M. Koekemoer, Juno Li, Madeline A. Marshall, Tyler J. McCabe, Noah J. McLeod, Stefanie N. Milam, Rosalia O’Brien, Nor Pirzkal, Aaron S. G. Robotham, Russell E. Ryan, Christopher N. A. Willmer, Haojing Yan, Min S. Yun and Adi Zitrin","doi":"10.3847/1538-4357/ad6d5e","DOIUrl":"https://doi.org/10.3847/1538-4357/ad6d5e","url":null,"abstract":"The first public 0.9–4.4 μm NIRCam images of the North Ecliptic Pole Time Domain Field uncovered galaxies displaying point-source features in their cores as seen in the longer-wavelength filters. We visually identified a sample of 66 galaxies (∼1 galaxy arcmin–2) with pointlike cores and have modeled their two-dimensional light profiles with GalFit, identifying 16 galactic nuclei with measurable point-source components. GalFit suggests that the visual sample is a mix of both compact stellar bulge and point-source galaxy cores. This core classification is complemented by spectral energy distribution modeling to infer the sample’s active galactic nucleus (AGN) and host-galaxy parameters. For galaxies with measurable point-source components, the median fractional AGN contribution to their 0.1–30.0 μm flux is 0.44, and 14/16 are color-classified AGN. We conclude that near-infrared point-source galaxy cores are signatures of AGN. In addition, we define an automated sample-selection criterion to identify these point-source features. This criterion can be used in other extant and future NIRCam images to streamline the search for galaxies with unresolved IR-luminous AGN. The James Webb Space Telescope’s superb angular resolution and sensitivity at infrared wavelengths are resurrecting the morphological identification of AGN.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142440565","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 : 2024-10-15DOI: 10.3847/1538-4357/ad77c9
B. Karimi, P. Barmby and S. Abbassi
This study investigates the detectability of intermediate-mass black holes (IMBHs) within the mass range 102M⊙ ≤ MBH ≤ 105M⊙ in the globular star clusters of NGC 1399 at a frequency of 300.00 MHz. Employing the theoretical Bondi accretion model and the empirical fundamental plane (FP) of black hole accretion, we estimate IMBH masses based on bolometric luminosity and X-ray/radio luminosities, respectively. By simulating a 3 hr observation of 77 globular cluster (GC) candidates using the Square Kilometre Array, we identify radio detection benchmarks indicative of accretion onto IMBHs. Our results show that IMBHs inside the globular star clusters located in NGC 1399 are indeed detectable, with the Bondi accretion model providing IMBH mass estimates ranging from 2.93 × 103.0±0.39M⊙ to 7.43 × 104.0±0.39M⊙ and the empirical FP relation suggesting IMBH mass estimation with 3.41 × 105.0±0.96M⊙. These findings highlight the presence and detectability of IMBHs in GCs, offering insights into their role as precursors to supermassive black holes and enriching our understanding of black hole formation and evolution in astrophysical environments.
{"title":"Prospects for Revealing Intermediate-mass Black Holes in NGC 1399 Using SKA","authors":"B. Karimi, P. Barmby and S. Abbassi","doi":"10.3847/1538-4357/ad77c9","DOIUrl":"https://doi.org/10.3847/1538-4357/ad77c9","url":null,"abstract":"This study investigates the detectability of intermediate-mass black holes (IMBHs) within the mass range 102M⊙ ≤ MBH ≤ 105M⊙ in the globular star clusters of NGC 1399 at a frequency of 300.00 MHz. Employing the theoretical Bondi accretion model and the empirical fundamental plane (FP) of black hole accretion, we estimate IMBH masses based on bolometric luminosity and X-ray/radio luminosities, respectively. By simulating a 3 hr observation of 77 globular cluster (GC) candidates using the Square Kilometre Array, we identify radio detection benchmarks indicative of accretion onto IMBHs. Our results show that IMBHs inside the globular star clusters located in NGC 1399 are indeed detectable, with the Bondi accretion model providing IMBH mass estimates ranging from 2.93 × 103.0±0.39M⊙ to 7.43 × 104.0±0.39M⊙ and the empirical FP relation suggesting IMBH mass estimation with 3.41 × 105.0±0.96M⊙. These findings highlight the presence and detectability of IMBHs in GCs, offering insights into their role as precursors to supermassive black holes and enriching our understanding of black hole formation and evolution in astrophysical environments.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142440574","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 : 2024-10-15DOI: 10.3847/1538-4357/ad59aa
Jakob T. Faber, Daniele Michilli, Ryan Mckinven, Jianing Su, Aaron B. Pearlman, Kenzie Nimmo, Robert A. Main, Victoria Kaspi, Mohit Bhardwaj, Shami Chatterjee, Alice P. Curtin, Matt Dobbs, Gwendolyn Eadie, B. M. Gaensler, Zarif Kader, Calvin Leung, Kiyoshi W. Masui, Ayush Pandhi, Emily Petroff, Ziggy Pleunis, Masoud Rafiei-Ravandi, Ketan R. Sand, Paul Scholz, Kaitlyn Shin, Kendrick Smith and Ingrid Stairs
We present the discovery of 12 apparently nonrepeating fast radio burst (FRB) sources, detected by the Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope. These sources, only one of which has been presented previously in the first CHIME/FRB catalog, were selected from a database comprising CHIME/FRB full-array raw voltage data recordings, based on their large signal-to-noise ratios and complex morphologies. Our study examines the time-frequency characteristics of these bursts, including drifting, microstructure, and periodicities. The events in this sample display a variety of unique drifting phenomenologies that deviate from the linear negative drifting phenomenon seen in many repeating FRBs, and motivate a possible new framework for classifying drifting archetypes. Additionally, we detect microstructure features of duration ≲50 μs in seven events, with some as narrow as ≃7 μs. We find no evidence of significant periodicities between subburst components. Furthermore, we report the polarization characteristics of seven events, including their polarization fractions and Faraday rotation measures (RMs). The observed ∣RM∣ values span a wide range of 17.24(2)–328.06(2) rad m−2, with apparent linear polarization fractions between 0.340(1) and 0.946(3). The morphological properties of the bursts in our sample appear broadly consistent with predictions from both relativistic shock and magnetospheric models of FRB emission, as well as propagation through discrete ionized plasma structures. We address these models and discuss how they can be tested using our improved understanding of morphological archetypes.
{"title":"Morphologies of Bright Complex Fast Radio Bursts with CHIME/FRB Voltage Data","authors":"Jakob T. Faber, Daniele Michilli, Ryan Mckinven, Jianing Su, Aaron B. Pearlman, Kenzie Nimmo, Robert A. Main, Victoria Kaspi, Mohit Bhardwaj, Shami Chatterjee, Alice P. Curtin, Matt Dobbs, Gwendolyn Eadie, B. M. Gaensler, Zarif Kader, Calvin Leung, Kiyoshi W. Masui, Ayush Pandhi, Emily Petroff, Ziggy Pleunis, Masoud Rafiei-Ravandi, Ketan R. Sand, Paul Scholz, Kaitlyn Shin, Kendrick Smith and Ingrid Stairs","doi":"10.3847/1538-4357/ad59aa","DOIUrl":"https://doi.org/10.3847/1538-4357/ad59aa","url":null,"abstract":"We present the discovery of 12 apparently nonrepeating fast radio burst (FRB) sources, detected by the Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope. These sources, only one of which has been presented previously in the first CHIME/FRB catalog, were selected from a database comprising CHIME/FRB full-array raw voltage data recordings, based on their large signal-to-noise ratios and complex morphologies. Our study examines the time-frequency characteristics of these bursts, including drifting, microstructure, and periodicities. The events in this sample display a variety of unique drifting phenomenologies that deviate from the linear negative drifting phenomenon seen in many repeating FRBs, and motivate a possible new framework for classifying drifting archetypes. Additionally, we detect microstructure features of duration ≲50 μs in seven events, with some as narrow as ≃7 μs. We find no evidence of significant periodicities between subburst components. Furthermore, we report the polarization characteristics of seven events, including their polarization fractions and Faraday rotation measures (RMs). The observed ∣RM∣ values span a wide range of 17.24(2)–328.06(2) rad m−2, with apparent linear polarization fractions between 0.340(1) and 0.946(3). The morphological properties of the bursts in our sample appear broadly consistent with predictions from both relativistic shock and magnetospheric models of FRB emission, as well as propagation through discrete ionized plasma structures. We address these models and discuss how they can be tested using our improved understanding of morphological archetypes.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142440511","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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