Pub Date : 2025-03-04DOI: 10.3847/1538-4357/ad9d3e
Mick Wright, Justin Janquart and Nathan K. Johnson-McDaniel
As the gravitational-wave (GW) detector network is upgraded and the sensitivity of the detectors improves, novel scientific avenues open for exploration. For example, tests of general relativity (GR) will become more accurate as smaller deviations can be probed. Additionally, the detection of lensed GWs becomes more likely. However, these new avenues could also interact with each other, and a GW event presenting deviations from GR could be mistaken for a lensed one. Here, we explore how phenomenological deviations from GR or binaries of exotic compact objects could impact those lensing searches focusing on a single event. We consider strong lensing, millilensing, and microlensing, and find that certain phenomenological deviations from GR may be mistaken for all of these types of lensing. Therefore, our study shows that future candidate lensing events would need to be carefully examined to avoid a false claim of lensing where instead a deviation from GR has been seen.
{"title":"Effect of Deviations from General Relativity on Searches for Gravitational-wave Microlensing and Type II Strong Lensing","authors":"Mick Wright, Justin Janquart and Nathan K. Johnson-McDaniel","doi":"10.3847/1538-4357/ad9d3e","DOIUrl":"https://doi.org/10.3847/1538-4357/ad9d3e","url":null,"abstract":"As the gravitational-wave (GW) detector network is upgraded and the sensitivity of the detectors improves, novel scientific avenues open for exploration. For example, tests of general relativity (GR) will become more accurate as smaller deviations can be probed. Additionally, the detection of lensed GWs becomes more likely. However, these new avenues could also interact with each other, and a GW event presenting deviations from GR could be mistaken for a lensed one. Here, we explore how phenomenological deviations from GR or binaries of exotic compact objects could impact those lensing searches focusing on a single event. We consider strong lensing, millilensing, and microlensing, and find that certain phenomenological deviations from GR may be mistaken for all of these types of lensing. Therefore, our study shows that future candidate lensing events would need to be carefully examined to avoid a false claim of lensing where instead a deviation from GR has been seen.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538544","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 : 2025-03-04DOI: 10.3847/1538-4357/adae06
Saikhom Pravash, Archana Soam, Pham Ngoc Diep, Thiem Hoang, Nguyen Bich Ngoc and Le Ngoc Tram
Polarization of starlight and thermal dust emission due to aligned non-spherical grains helps us to trace magnetic field (B-field) morphology in molecular clouds and to study grain alignment mechanisms. In this work, we study grain alignment and disruption mechanisms in a filamentary infrared dark cloud G34.43+0.24 using thermal dust polarization observations from JCMT/POL-2 at 850 μm. We study three regions: the North harboring the MM3 core, the Center harboring the MM1 and MM2 cores, and the South harboring no core. We find the decrease in polarization fraction P with increasing total intensity and gas column density, known as polarization hole. To disentangle the effect of magnetic field tangling on the polarization hole, we estimate the polarization angle dispersion function. We find depolarizations in the North and Center regions are due to a decrease in the net alignment efficiency of grains, but in the South region, the effect of magnetic field tangling is significant to cause depolarization. To test whether the radiative torque (RAT) mechanism can reproduce the observational data, we calculate minimum alignment and disruption sizes of grains using RAT theory, and our study finds that the RAT alignment (RAT-A) mechanism can explain the depolarizations in the North and Center regions where the B-field tangling effect is less important, except for core regions. We find hints of RAT disruption (RAT-D) in the core regions of MM3 in the North, and MM1 and MM2 in the Center. We also find that the high P value of around 8%–20% in the outer regions of the filament can potentially be explained by the magnetically enhanced RAT alignment mechanism.
{"title":"B-fields and Dust in Interstellar Filaments Using Dust Polarization (BALLAD-POL). III. Grain Alignment and Disruption Mechanisms in G34.43+0.24 Using Polarization Observations from JCMT/POL-2","authors":"Saikhom Pravash, Archana Soam, Pham Ngoc Diep, Thiem Hoang, Nguyen Bich Ngoc and Le Ngoc Tram","doi":"10.3847/1538-4357/adae06","DOIUrl":"https://doi.org/10.3847/1538-4357/adae06","url":null,"abstract":"Polarization of starlight and thermal dust emission due to aligned non-spherical grains helps us to trace magnetic field (B-field) morphology in molecular clouds and to study grain alignment mechanisms. In this work, we study grain alignment and disruption mechanisms in a filamentary infrared dark cloud G34.43+0.24 using thermal dust polarization observations from JCMT/POL-2 at 850 μm. We study three regions: the North harboring the MM3 core, the Center harboring the MM1 and MM2 cores, and the South harboring no core. We find the decrease in polarization fraction P with increasing total intensity and gas column density, known as polarization hole. To disentangle the effect of magnetic field tangling on the polarization hole, we estimate the polarization angle dispersion function. We find depolarizations in the North and Center regions are due to a decrease in the net alignment efficiency of grains, but in the South region, the effect of magnetic field tangling is significant to cause depolarization. To test whether the radiative torque (RAT) mechanism can reproduce the observational data, we calculate minimum alignment and disruption sizes of grains using RAT theory, and our study finds that the RAT alignment (RAT-A) mechanism can explain the depolarizations in the North and Center regions where the B-field tangling effect is less important, except for core regions. We find hints of RAT disruption (RAT-D) in the core regions of MM3 in the North, and MM1 and MM2 in the Center. We also find that the high P value of around 8%–20% in the outer regions of the filament can potentially be explained by the magnetically enhanced RAT alignment mechanism.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538546","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 : 2025-03-04DOI: 10.3847/1538-4357/adaea0
Sibasish Laha, Eileen T. Meyer, Dev R. Sadaula, Ritesh Ghosh, Dhrubojyoti Sengupta, Megan Masterson, Onic I. Shuvo, Matteo Guainazzi, Claudio Ricci, Mitchell C. Begelman, Alexander Philippov, Rostom Mbarek, Amelia M. Hankla, Erin Kara, Francesca Panessa, Ehud Behar, Haocheng Zhang, Fabio Pacucci, Main Pal, Federica Ricci, Ilaria Villani, Susanna Bisogni, Fabio La Franca, Stefano Bianchi, Gabriele Bruni, Samantha Oates, Cameron Hahn, Matt Nicholl, S. Bradley Cenko, Sabyasachi Chattopadhyay, Josefa Becerra González, J. A. Acosta–Pulido, Suvendu Rakshit, Jiří Svoboda, Luigi Gallo, Adam Ingram and Darshan Kakkad
We present results from a high-cadence multiwavelength observational campaign of the enigmatic changing-look active galactic nucleus 1ES 1927+654 from 2022 May to 2024 April, coincident with an unprecedented radio flare (an increase in flux by a factor of ∼60 over a few months) and the emergence of a spatially resolved jet at 0.1–0.3 pc scales. Companion work has also detected a recurrent quasi-periodic oscillation (QPO) in the 2–10 keV band with an increasing frequency (1–2 mHz) over the same period. During this time, the soft X-rays (0.3–2 keV) monotonically increased by a factor of ∼8, while the UV emission remained nearly steady with <30% variation and the 2–10 keV flux showed variation by a factor ≲2. The weak variation of the 2–10 keV X-ray emission and the stability of the UV emission suggest that the magnetic energy density and accretion rate are relatively unchanged and that the jet could be launched owing to a reconfiguration of the magnetic field (toroidal to poloidal) close to the black hole. Advecting poloidal flux onto the event horizon would trigger the Blandford–Znajek mechanism, leading to the onset of the jet. The concurrent softening of the coronal slope (from Γ = 2.70 ± 0.04 to Γ = 3.27 ± 0.04), the appearance of a QPO, and the low coronal temperature ( ) during the radio outburst suggest that the poloidal field reconfiguration can significantly impact coronal properties and thus influence jet dynamics. These extraordinary findings in real time are crucial for coronal and jet plasma studies, particularly as our results are independent of coronal geometry.
{"title":"Multiwavelength Observations of a Jet Launch in Real Time from the Post-changing-look Active Galaxy 1ES 1927+654","authors":"Sibasish Laha, Eileen T. Meyer, Dev R. Sadaula, Ritesh Ghosh, Dhrubojyoti Sengupta, Megan Masterson, Onic I. Shuvo, Matteo Guainazzi, Claudio Ricci, Mitchell C. Begelman, Alexander Philippov, Rostom Mbarek, Amelia M. Hankla, Erin Kara, Francesca Panessa, Ehud Behar, Haocheng Zhang, Fabio Pacucci, Main Pal, Federica Ricci, Ilaria Villani, Susanna Bisogni, Fabio La Franca, Stefano Bianchi, Gabriele Bruni, Samantha Oates, Cameron Hahn, Matt Nicholl, S. Bradley Cenko, Sabyasachi Chattopadhyay, Josefa Becerra González, J. A. Acosta–Pulido, Suvendu Rakshit, Jiří Svoboda, Luigi Gallo, Adam Ingram and Darshan Kakkad","doi":"10.3847/1538-4357/adaea0","DOIUrl":"https://doi.org/10.3847/1538-4357/adaea0","url":null,"abstract":"We present results from a high-cadence multiwavelength observational campaign of the enigmatic changing-look active galactic nucleus 1ES 1927+654 from 2022 May to 2024 April, coincident with an unprecedented radio flare (an increase in flux by a factor of ∼60 over a few months) and the emergence of a spatially resolved jet at 0.1–0.3 pc scales. Companion work has also detected a recurrent quasi-periodic oscillation (QPO) in the 2–10 keV band with an increasing frequency (1–2 mHz) over the same period. During this time, the soft X-rays (0.3–2 keV) monotonically increased by a factor of ∼8, while the UV emission remained nearly steady with <30% variation and the 2–10 keV flux showed variation by a factor ≲2. The weak variation of the 2–10 keV X-ray emission and the stability of the UV emission suggest that the magnetic energy density and accretion rate are relatively unchanged and that the jet could be launched owing to a reconfiguration of the magnetic field (toroidal to poloidal) close to the black hole. Advecting poloidal flux onto the event horizon would trigger the Blandford–Znajek mechanism, leading to the onset of the jet. The concurrent softening of the coronal slope (from Γ = 2.70 ± 0.04 to Γ = 3.27 ± 0.04), the appearance of a QPO, and the low coronal temperature ( ) during the radio outburst suggest that the poloidal field reconfiguration can significantly impact coronal properties and thus influence jet dynamics. These extraordinary findings in real time are crucial for coronal and jet plasma studies, particularly as our results are independent of coronal geometry.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538550","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 : 2025-03-04DOI: 10.3847/1538-4357/adae0b
Laura Duffy, Michael Eracleous, Jessie C. Runnoe, John J. Ruan, Scott F. Anderson, Sabrina Dimassimo, Paul Green and Stephanie LaMassa
Changing-look quasars (CLQs) exhibit dramatic variability in broad emission-line fluxes on short timescales. This behavior is challenging to many models of the quasar broad-line region, due in large part to the short transition times between high and low states. In order to constrain the cause of the dramatic variability, we obtained contemporaneous Hubble Space Telescope ultraviolet and Hobby Eberly Telescope optical spectra of three CLQs caught in their low state. We use these spectra, along with archival spectra taken during both the high and low states, to investigate potential scenarios for the change in state. Our data strongly disfavor a variable dust obscuration scenario for these three CLQs, and instead suggest that the observed transformation reflects a change in the intrinsic luminosity of the central engine. We also find that the low-state spectral energy distributions of all three quasars are reminiscent of those of low-luminosity active galactic nuclei, which suggests that the transition may result from a change in accretion flow structure caused by a reduced Eddington ratio.
{"title":"A Detailed Look at a Trio of Changing-look Quasars: Spectral Energy Distributions and the Dust Extinction Test* †","authors":"Laura Duffy, Michael Eracleous, Jessie C. Runnoe, John J. Ruan, Scott F. Anderson, Sabrina Dimassimo, Paul Green and Stephanie LaMassa","doi":"10.3847/1538-4357/adae0b","DOIUrl":"https://doi.org/10.3847/1538-4357/adae0b","url":null,"abstract":"Changing-look quasars (CLQs) exhibit dramatic variability in broad emission-line fluxes on short timescales. This behavior is challenging to many models of the quasar broad-line region, due in large part to the short transition times between high and low states. In order to constrain the cause of the dramatic variability, we obtained contemporaneous Hubble Space Telescope ultraviolet and Hobby Eberly Telescope optical spectra of three CLQs caught in their low state. We use these spectra, along with archival spectra taken during both the high and low states, to investigate potential scenarios for the change in state. Our data strongly disfavor a variable dust obscuration scenario for these three CLQs, and instead suggest that the observed transformation reflects a change in the intrinsic luminosity of the central engine. We also find that the low-state spectral energy distributions of all three quasars are reminiscent of those of low-luminosity active galactic nuclei, which suggests that the transition may result from a change in accretion flow structure caused by a reduced Eddington ratio.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"57 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538547","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 : 2025-03-04DOI: 10.3847/1538-4357/adb1bc
Jaclyn B. Champagne, Feige Wang, Jinyi Yang, Xiaohui Fan, Joseph F. Hennawi, Fengwu Sun, Eduardo Bañados, Sarah E. I. Bosman, Tiago Costa, Melanie Habouzit, Xiangyu Jin, Hyunsung D. Jun, Mingyu Li, Weizhe Liu, Federica Loiacono, Alessandro Lupi, Chiara Mazzucchelli, Maria Pudoka, Sofía Rojas-Ruiz, Wei Leong Tee, Maxime Trebitsch, Haowen Zhang, 昊 文 张, Ming-Yang Zhuang, 明阳 庄 and Siwei Zou
We present in this paper (Paper II of the series) a 35 arcmin2 JWST/NIRCam imaging and wide-field slitless spectroscopy mosaic centered on J0305–3150, a luminous quasar at z = 6.61. The F356W grism data reveal 124 [O iii]+Hβ emitters at 5.3 < z < 7, 53 of which constitute a protocluster spanning (10 cMpc)2 across 6.5 < z < 6.8. We find no evidence of any broad-line active galactic nucleus (AGN) in individual galaxies or stacking, reporting a median Hβ FWHM of 585 ± 152 km s−1; however, the mass–excitation diagram and “little red dot” color and compactness criteria suggest that there are a few AGN candidates on the outskirts of the protocluster. We fit the spectral energy distributions (SEDs) of the [O iii] emitters with Prospector and Bagpipes and find that none of the SED-derived properties (stellar mass, age, or star formation rate) correlate with proximity to the quasar. While there is no correlation between galaxy age and local galaxy density, we find modest correlations of local galaxy density with increasing stellar mass, decreasing 10–100 Myr star formation rate ratios, and decreasing nebular line equivalent widths. We further find that the protocluster galaxies are consistent with being more massive, being older, and hosting higher star formation rates than the field sample at the 3σ level, distributed in a filamentary structure that supports inside-out formation of the protocluster. There is modest evidence that galaxy evolution proceeds differently as a function of the density of local environment within protoclusters during the epoch of reionization, and the central quasar has little effect on the galaxy properties of the surrounding structure.
{"title":"A Quasar-anchored Protocluster at z = 6.6 in the ASPIRE Survey. II. An Environmental Analysis of Galaxy Properties in an Overdense Structure","authors":"Jaclyn B. Champagne, Feige Wang, Jinyi Yang, Xiaohui Fan, Joseph F. Hennawi, Fengwu Sun, Eduardo Bañados, Sarah E. I. Bosman, Tiago Costa, Melanie Habouzit, Xiangyu Jin, Hyunsung D. Jun, Mingyu Li, Weizhe Liu, Federica Loiacono, Alessandro Lupi, Chiara Mazzucchelli, Maria Pudoka, Sofía Rojas-Ruiz, Wei Leong Tee, Maxime Trebitsch, Haowen Zhang, 昊 文 张, Ming-Yang Zhuang, 明阳 庄 and Siwei Zou","doi":"10.3847/1538-4357/adb1bc","DOIUrl":"https://doi.org/10.3847/1538-4357/adb1bc","url":null,"abstract":"We present in this paper (Paper II of the series) a 35 arcmin2 JWST/NIRCam imaging and wide-field slitless spectroscopy mosaic centered on J0305–3150, a luminous quasar at z = 6.61. The F356W grism data reveal 124 [O iii]+Hβ emitters at 5.3 < z < 7, 53 of which constitute a protocluster spanning (10 cMpc)2 across 6.5 < z < 6.8. We find no evidence of any broad-line active galactic nucleus (AGN) in individual galaxies or stacking, reporting a median Hβ FWHM of 585 ± 152 km s−1; however, the mass–excitation diagram and “little red dot” color and compactness criteria suggest that there are a few AGN candidates on the outskirts of the protocluster. We fit the spectral energy distributions (SEDs) of the [O iii] emitters with Prospector and Bagpipes and find that none of the SED-derived properties (stellar mass, age, or star formation rate) correlate with proximity to the quasar. While there is no correlation between galaxy age and local galaxy density, we find modest correlations of local galaxy density with increasing stellar mass, decreasing 10–100 Myr star formation rate ratios, and decreasing nebular line equivalent widths. We further find that the protocluster galaxies are consistent with being more massive, being older, and hosting higher star formation rates than the field sample at the 3σ level, distributed in a filamentary structure that supports inside-out formation of the protocluster. There is modest evidence that galaxy evolution proceeds differently as a function of the density of local environment within protoclusters during the epoch of reionization, and the central quasar has little effect on the galaxy properties of the surrounding structure.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538610","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 : 2025-03-04DOI: 10.3847/1538-4357/adafa2
Cainã de Oliveira, Rodrigo Guedes Lang and Pedro Batista
Active galactic nuclei (AGN) are among the main candidates for ultra-high-energy cosmic-ray (UHECR) sources. However, while some theoretical and phenomenological works favor AGNs as the main sources, recent works have shown that using the very-high-energy γ-ray flux as a proxy for the UHECR flux leads to a bad agreement with data. In this context, the energy spectrum and composition data are hardly fitted. At the same time, the arrival directions map is badly described and a spurious dipole direction is produced. In this work, we propose a possible solution to these contradictions. Using the observed γ-ray flux as a proxy may carry the implicit assumption of beamed UHECR emission and, consequently, its beam will remain collimated up to its detection on Earth. We show that assuming an isotropic UHECR emission and correcting the γ-ray emission proxy by Doppler boosting can overcome the problem. The combined fit of the spectrum and composition is improved, with a change of reduced χ2 from 4.6 to 3.1. In particular, the tension between the observed and modeled dipole directions can be reduced from 5.9 (2.1)σ away from the data to 3.5 (1.1)σ for E > 8 EeV (E > 32 EeV). We also show that this effect is particularly important when including AGNs of different classes in the same analysis, such as radio galaxies and blazars.
{"title":"On Gamma Rays as Predictors of Ultra-high-energy Cosmic-Ray Flux in Active Galactic Nuclei","authors":"Cainã de Oliveira, Rodrigo Guedes Lang and Pedro Batista","doi":"10.3847/1538-4357/adafa2","DOIUrl":"https://doi.org/10.3847/1538-4357/adafa2","url":null,"abstract":"Active galactic nuclei (AGN) are among the main candidates for ultra-high-energy cosmic-ray (UHECR) sources. However, while some theoretical and phenomenological works favor AGNs as the main sources, recent works have shown that using the very-high-energy γ-ray flux as a proxy for the UHECR flux leads to a bad agreement with data. In this context, the energy spectrum and composition data are hardly fitted. At the same time, the arrival directions map is badly described and a spurious dipole direction is produced. In this work, we propose a possible solution to these contradictions. Using the observed γ-ray flux as a proxy may carry the implicit assumption of beamed UHECR emission and, consequently, its beam will remain collimated up to its detection on Earth. We show that assuming an isotropic UHECR emission and correcting the γ-ray emission proxy by Doppler boosting can overcome the problem. The combined fit of the spectrum and composition is improved, with a change of reduced χ2 from 4.6 to 3.1. In particular, the tension between the observed and modeled dipole directions can be reduced from 5.9 (2.1)σ away from the data to 3.5 (1.1)σ for E > 8 EeV (E > 32 EeV). We also show that this effect is particularly important when including AGNs of different classes in the same analysis, such as radio galaxies and blazars.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538551","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 : 2025-03-04DOI: 10.3847/1538-4357/adaeac
Tomer D. Yavetz
Many of the stars in the Galaxy are members of binary systems, the widest of which can eventually become disrupted due to a combination of kicks from passing objects and the Galactic tidal field. If the Galactic disk were purely axisymmetric, the stars from a disrupted binary system would slowly drift apart on nearly identical orbits. We study how the existence of nonaxisymmetric structures, such as a rigidly rotating bar, can greatly alter this picture. In particular, we show how the orbital dynamics near the resonances sourced by these nonaxisymmetric perturbations create local fluctuations in the distribution of disrupted binary separations. We simulate the evolution of wide binary systems embedded in a gravitational potential with a rotating galactic bar, and show how features and fluctuations in the distribution of disrupted binaries can be used to locate bar resonances and constrain the bar’s pattern speed and amplitude.
{"title":"Disrupted Wide Binaries as Dynamical Probes of Galactic Structure","authors":"Tomer D. Yavetz","doi":"10.3847/1538-4357/adaeac","DOIUrl":"https://doi.org/10.3847/1538-4357/adaeac","url":null,"abstract":"Many of the stars in the Galaxy are members of binary systems, the widest of which can eventually become disrupted due to a combination of kicks from passing objects and the Galactic tidal field. If the Galactic disk were purely axisymmetric, the stars from a disrupted binary system would slowly drift apart on nearly identical orbits. We study how the existence of nonaxisymmetric structures, such as a rigidly rotating bar, can greatly alter this picture. In particular, we show how the orbital dynamics near the resonances sourced by these nonaxisymmetric perturbations create local fluctuations in the distribution of disrupted binary separations. We simulate the evolution of wide binary systems embedded in a gravitational potential with a rotating galactic bar, and show how features and fluctuations in the distribution of disrupted binaries can be used to locate bar resonances and constrain the bar’s pattern speed and amplitude.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"67 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538549","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}
We perform new general relativistic hydrodynamics simulations for collapses of rotating supermassive star cores with an approximate nuclear burning up to carbon and a detailed equation of state. For all the models we investigate, the energy generation by nuclear burning plays only a minor role, leading to the formation of a black hole without a nuclear-powered explosion. For rotating models, however, the stellar explosion associated with shock heating is driven from a torus, which forms after the black hole formation. The explosion energy is up to 10−4 of the mass energy of the supermassive star cores (∼1055–1056 erg). We find that, even if we increase the rotational angular momentum of the progenitor, the ejecta mass saturates at ∼1% of the total mass of the initial stellar core. The average ejecta velocity also saturates at ≈20% of the speed of light. As a result, the ejecta kinetic energy is approximately proportional to the initial mass of the supermassive star core for the rapidly rotating case. We also perform viscous hydrodynamics simulations to explore the evolution of the remnant torus. Although the viscous heating drives an outflow from the torus, we find that its effect is subdominant in terms of the kinetic energy because of the small velocity (≈0.07c) of the ejecta component.
{"title":"Powerful Explosions from the Collapse of Rotating Supermassive Stars","authors":"Sho Fujibayashi, Cédric Jockel, Kyohei Kawaguchi, Yuichiro Sekiguchi and Masaru Shibata","doi":"10.3847/1538-4357/adb0b8","DOIUrl":"https://doi.org/10.3847/1538-4357/adb0b8","url":null,"abstract":"We perform new general relativistic hydrodynamics simulations for collapses of rotating supermassive star cores with an approximate nuclear burning up to carbon and a detailed equation of state. For all the models we investigate, the energy generation by nuclear burning plays only a minor role, leading to the formation of a black hole without a nuclear-powered explosion. For rotating models, however, the stellar explosion associated with shock heating is driven from a torus, which forms after the black hole formation. The explosion energy is up to 10−4 of the mass energy of the supermassive star cores (∼1055–1056 erg). We find that, even if we increase the rotational angular momentum of the progenitor, the ejecta mass saturates at ∼1% of the total mass of the initial stellar core. The average ejecta velocity also saturates at ≈20% of the speed of light. As a result, the ejecta kinetic energy is approximately proportional to the initial mass of the supermassive star core for the rapidly rotating case. We also perform viscous hydrodynamics simulations to explore the evolution of the remnant torus. Although the viscous heating drives an outflow from the torus, we find that its effect is subdominant in terms of the kinetic energy because of the small velocity (≈0.07c) of the ejecta component.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"12 3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538553","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 : 2025-03-04DOI: 10.3847/1538-4357/adb1b3
Jason C. Speights, Virginia Aust and Qinyan Lu
Radial profiles of pattern speeds are measured at subkiloparsec resolution for NGC 628. The radial profiles are directly measured using a general form of the Tremaine–Weinberg method that allows for the pattern speed to vary with radius. The method is applied to both stars and CO, H i, and Hα spectral lines. The trends in the results are consistent for all of the data, showing that sources and sinks in the interstellar medium have a negligible effect when applying the integrated continuity equation. The spiral pattern rotates at a greater angular frequency in the inner region of the disks than in their outer region. Most of the measured values of the pattern speed are less than the material speed. The results for the inner disk show an approximately constant trend, consistent with rigidly rotating density waves. The offsets in stellar photometric and spectral line intensity data corroborate this result. There are radially decreasing trends in the results for the outer region of the disks that are similar to the material speed, consistent with shearing patterns or what is expected for overlapping wave modes of decreasing pattern speed. There is no single theory for the origin of the spiral patterns that can explain all of the results, but the results fail to provide evidence for a single global wave mode.
以亚千亿帕秒的分辨率测量了 NGC 628 的图案速度径向剖面图。径向剖面是利用特里梅因-温伯格方法的一般形式直接测量的，该方法允许图案速度随半径变化。该方法既适用于恒星，也适用于 CO、H i 和 Hα 光谱线。所有数据的结果趋势都是一致的，表明在应用综合连续性方程时，星际介质中的源和汇的影响可以忽略不计。星盘内部区域的螺旋图案旋转角频率比星盘外部区域大。大部分图案速度的测量值都小于物质速度。内盘的结果显示出近似恒定的趋势，与刚性旋转的密度波一致。恒星光度和光谱线强度数据的偏移也证实了这一结果。磁盘外部区域的结果呈径向递减趋势，与物质速度相似，与剪切模式或模式速度递减的重叠波模式的预期一致。对于螺旋模式的起源，没有一种单一的理论可以解释所有的结果，但这些结果未能为单一的全局波模式提供证据。
{"title":"Spiral Density Waves in the Multiple-armed Galaxy NGC 628","authors":"Jason C. Speights, Virginia Aust and Qinyan Lu","doi":"10.3847/1538-4357/adb1b3","DOIUrl":"https://doi.org/10.3847/1538-4357/adb1b3","url":null,"abstract":"Radial profiles of pattern speeds are measured at subkiloparsec resolution for NGC 628. The radial profiles are directly measured using a general form of the Tremaine–Weinberg method that allows for the pattern speed to vary with radius. The method is applied to both stars and CO, H i, and Hα spectral lines. The trends in the results are consistent for all of the data, showing that sources and sinks in the interstellar medium have a negligible effect when applying the integrated continuity equation. The spiral pattern rotates at a greater angular frequency in the inner region of the disks than in their outer region. Most of the measured values of the pattern speed are less than the material speed. The results for the inner disk show an approximately constant trend, consistent with rigidly rotating density waves. The offsets in stellar photometric and spectral line intensity data corroborate this result. There are radially decreasing trends in the results for the outer region of the disks that are similar to the material speed, consistent with shearing patterns or what is expected for overlapping wave modes of decreasing pattern speed. There is no single theory for the origin of the spiral patterns that can explain all of the results, but the results fail to provide evidence for a single global wave mode.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538520","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 : 2025-03-04DOI: 10.3847/1538-4357/adb310
Blake Ledger, Christine D. Wilson, Osvald Klimi, Núria Torres-Albà and Toshiki Saito
We use the CN/CO intensity ratio to obtain the dense gas fraction, fdense, for a sample of 16 ultraluminous and luminous infrared (IR) galaxies and compare fdense with a suite of global galaxy properties. We find a significant correlation between fdense and star formation rate calculated using both IR luminosities and radio continuum, although there is significant scatter in each relation. We find no trend between global or peak fdense and merger stage. We find no correlation between global fdense and X-ray luminosity; however, the correlation becomes significant when we measure fdense at the location of peak X-ray emission. Our interpretation is that the dense gas is co-localized with strong X-ray emission from active galactic nuclei or strong central star formation.
{"title":"Building on the Archives: Connecting the CN/CO Intensity Ratio with Global Galaxy Properties in Nearby U/LIRGs","authors":"Blake Ledger, Christine D. Wilson, Osvald Klimi, Núria Torres-Albà and Toshiki Saito","doi":"10.3847/1538-4357/adb310","DOIUrl":"https://doi.org/10.3847/1538-4357/adb310","url":null,"abstract":"We use the CN/CO intensity ratio to obtain the dense gas fraction, fdense, for a sample of 16 ultraluminous and luminous infrared (IR) galaxies and compare fdense with a suite of global galaxy properties. We find a significant correlation between fdense and star formation rate calculated using both IR luminosities and radio continuum, although there is significant scatter in each relation. We find no trend between global or peak fdense and merger stage. We find no correlation between global fdense and X-ray luminosity; however, the correlation becomes significant when we measure fdense at the location of peak X-ray emission. Our interpretation is that the dense gas is co-localized with strong X-ray emission from active galactic nuclei or strong central star formation.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"211 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538613","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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