Pub Date : 2023-11-01DOI: 10.3847/1538-4357/ad0230
Zhizheng Pan, Xianzhong Zheng, Xu Kong
Abstract To understand in what mass regime star-forming galaxies (SFGs) build up central mass concentration most actively, we present a study on the luminosity-weighted stellar age radial gradient (∇ age ) distribution of ∼3600 low-redshift SFGs using the MaNGA Pipe3D data available in Data Release 17 from the Sloan Digital Sky Survey. The mean age gradient is negative, with ∇ age = −0.14 log Gyr/ R e , consistent with the inside-out disk formation scenario. Specifically, SFGs with positive ∇ age consist of ∼28% at log ( M * / M ⊙ ) < 9.5, while this fraction rises up to its peak (∼40%) near log ( M * / M ⊙ ) = 10 and then decreases to ∼15% at log ( M * / M ⊙ ) = 11. At fixed M * , SFGs with positive ∇ age typically have more compact sizes and more centrally concentrated star formation than their counterparts, indicative of recent central mass buildup events. These results suggest that the buildup of central stellar mass concentration in local SFGs is mostly active near M * = 10 10 M ⊙ . Our findings provide new insights into the origin of morphological differences between low-mass and high-mass SFGs.
{"title":"Local Star-forming Galaxies Build Up Central Mass Concentration Most Actively near M <sub>∗</sub> = 10<sup>10</sup> M <sub>⊙</sub>","authors":"Zhizheng Pan, Xianzhong Zheng, Xu Kong","doi":"10.3847/1538-4357/ad0230","DOIUrl":"https://doi.org/10.3847/1538-4357/ad0230","url":null,"abstract":"Abstract To understand in what mass regime star-forming galaxies (SFGs) build up central mass concentration most actively, we present a study on the luminosity-weighted stellar age radial gradient (∇ age ) distribution of ∼3600 low-redshift SFGs using the MaNGA Pipe3D data available in Data Release 17 from the Sloan Digital Sky Survey. The mean age gradient is negative, with ∇ age = −0.14 log Gyr/ R e , consistent with the inside-out disk formation scenario. Specifically, SFGs with positive ∇ age consist of ∼28% at log ( M * / M ⊙ ) < 9.5, while this fraction rises up to its peak (∼40%) near log ( M * / M ⊙ ) = 10 and then decreases to ∼15% at log ( M * / M ⊙ ) = 11. At fixed M * , SFGs with positive ∇ age typically have more compact sizes and more centrally concentrated star formation than their counterparts, indicative of recent central mass buildup events. These results suggest that the buildup of central stellar mass concentration in local SFGs is mostly active near M * = 10 10 M ⊙ . Our findings provide new insights into the origin of morphological differences between low-mass and high-mass SFGs.","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":"2 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135615168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.3847/1538-4357/ad02f1
K. Poopakun, W. Nuntiyakul, S. Khamphakdee, A. Seripienlert, D. Ruffolo, P. Evenson, P. Jiang, P. Chuanraksasat, K. Munakata, M. L. Duldig, J. E. Humble, J. Madsen, B. Soonthornthum, S. Komonjinda
Abstract The Galactic cosmic-ray spectrum manifests pronounced variations over the 11 yr sunspot cycle and more subtle variations over the 22 yr solar magnetic cycle. An important tool to study these variations is repeated latitude surveys with neutron monitors (NMs) on board icebreakers in conjunction with land-based references. We revisit 13 annual latitude surveys from 1994 to 2007 using reference data from the Mawson NM instead of McMurdo NM (which closed in 2017). We then consider two more latitude surveys (2018 and 2019) with a monitor similar to the 3NM64 in the previous surveys but without lead rings around the central tube, a so-called “semi-leaded neutron monitor.” The new surveys extend the linear relationship among data taken at different cutoff rigidity ranges. They also confirm the “crossover” measured near solar minima during epochs of opposite solar magnetic polarity and the absence of a crossover for epochs having the same solar magnetic polarity.
{"title":"Solar Magnetic Polarity Effect on Neutron Monitor Count Rates: Comparing Latitude Surveys and Antarctic Stations","authors":"K. Poopakun, W. Nuntiyakul, S. Khamphakdee, A. Seripienlert, D. Ruffolo, P. Evenson, P. Jiang, P. Chuanraksasat, K. Munakata, M. L. Duldig, J. E. Humble, J. Madsen, B. Soonthornthum, S. Komonjinda","doi":"10.3847/1538-4357/ad02f1","DOIUrl":"https://doi.org/10.3847/1538-4357/ad02f1","url":null,"abstract":"Abstract The Galactic cosmic-ray spectrum manifests pronounced variations over the 11 yr sunspot cycle and more subtle variations over the 22 yr solar magnetic cycle. An important tool to study these variations is repeated latitude surveys with neutron monitors (NMs) on board icebreakers in conjunction with land-based references. We revisit 13 annual latitude surveys from 1994 to 2007 using reference data from the Mawson NM instead of McMurdo NM (which closed in 2017). We then consider two more latitude surveys (2018 and 2019) with a monitor similar to the 3NM64 in the previous surveys but without lead rings around the central tube, a so-called “semi-leaded neutron monitor.” The new surveys extend the linear relationship among data taken at different cutoff rigidity ranges. They also confirm the “crossover” measured near solar minima during epochs of opposite solar magnetic polarity and the absence of a crossover for epochs having the same solar magnetic polarity.","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":"141 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135714757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.3847/1538-4357/acfc4c
Z. Funda Bostancı, Tuğba Boztepe, Tolga Güver, Tod E. Strohmayer, Yuri Cavecchi, Ersin Göğüş, Diego Altamirano, Peter Bult, Deepto Chakrabarty, Sebastien Guillot, Gaurava K. Jaisawal, Christian Malacaria, Giulio C. Mancuso, Andrea Sanna, Jean H. Swank
Abstract We present temporal and time-resolved spectral analyses of all the thermonuclear X-ray bursts observed from the neutron star low-mass X-ray binary 4U 1728−34 with NICER from 2017 June to 2019 September. In total, we detected 11 X-ray bursts from the source and performed time-resolved spectroscopy. Unlike some of the earlier results for other bursting sources from NICER, our spectral results indicate that the use of a scaling factor for the persistent emission is not statistically necessary. This is primarily a result of the strong interstellar absorption in the line of sight toward 4U 1728−34, which causes the count rates to be significantly lower at low energies. We also searched for burst oscillations and detected modulations in six different bursts at around the previously known burst oscillation frequency of 363 Hz. Finally, we report the detection of oscillations prior to two bursts at 356 and 359 Hz, respectively. This is the first time in the literature where burst oscillations are detected before the rapid rise in X-ray flux, from any known burster. These oscillations disappear as soon as the burst starts to rise and occur at a somewhat lower frequency than the oscillations we detect during the bursts.
{"title":"NICER Observations of Thermonuclear Bursts from 4U 1728-34: Detection of Oscillations prior to the Onset of Two Bursts","authors":"Z. Funda Bostancı, Tuğba Boztepe, Tolga Güver, Tod E. Strohmayer, Yuri Cavecchi, Ersin Göğüş, Diego Altamirano, Peter Bult, Deepto Chakrabarty, Sebastien Guillot, Gaurava K. Jaisawal, Christian Malacaria, Giulio C. Mancuso, Andrea Sanna, Jean H. Swank","doi":"10.3847/1538-4357/acfc4c","DOIUrl":"https://doi.org/10.3847/1538-4357/acfc4c","url":null,"abstract":"Abstract We present temporal and time-resolved spectral analyses of all the thermonuclear X-ray bursts observed from the neutron star low-mass X-ray binary 4U 1728−34 with NICER from 2017 June to 2019 September. In total, we detected 11 X-ray bursts from the source and performed time-resolved spectroscopy. Unlike some of the earlier results for other bursting sources from NICER, our spectral results indicate that the use of a scaling factor for the persistent emission is not statistically necessary. This is primarily a result of the strong interstellar absorption in the line of sight toward 4U 1728−34, which causes the count rates to be significantly lower at low energies. We also searched for burst oscillations and detected modulations in six different bursts at around the previously known burst oscillation frequency of 363 Hz. Finally, we report the detection of oscillations prior to two bursts at 356 and 359 Hz, respectively. This is the first time in the literature where burst oscillations are detected before the rapid rise in X-ray flux, from any known burster. These oscillations disappear as soon as the burst starts to rise and occur at a somewhat lower frequency than the oscillations we detect during the bursts.","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":"17 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135714981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.3847/1538-4357/acfc21
Qirong Jiao, Wenlong Liu, Dianjun Zhang, Jinbin Cao
Abstract Solar wind is important for the space environment between the Sun and the Earth and varies with the sunspot cycle, which is influenced by solar internal dynamics. We study the impact of latitude-dependent sunspot data on solar wind speed using the Granger causality test method and a machine-learning prediction approach. The results show that the low-latitude sunspot number has a larger effect on the solar wind speed. The time delay between the annual average solar wind speed and sunspot number decreases as the latitude range decreases. A machine-learning model is developed for the prediction of solar wind speed considering latitude and time effects. It is found that the model performs differently with latitude-dependent sunspot data. It is revealed that the timescale of the solar wind speed is more strongly influenced by low-latitude sunspots and that sunspot data have a greater impact on the 30 day average solar wind speed than on a daily basis. With the addition of sunspot data below 7.°2 latitude, the prediction of the daily and 30 day averages is improved by 0.23% and 12%, respectively. The best correlation coefficient is 0.787 for the daily solar wind prediction model.
{"title":"Relation between Latitude-dependent Sunspot Data and Near-Earth Solar Wind Speed","authors":"Qirong Jiao, Wenlong Liu, Dianjun Zhang, Jinbin Cao","doi":"10.3847/1538-4357/acfc21","DOIUrl":"https://doi.org/10.3847/1538-4357/acfc21","url":null,"abstract":"Abstract Solar wind is important for the space environment between the Sun and the Earth and varies with the sunspot cycle, which is influenced by solar internal dynamics. We study the impact of latitude-dependent sunspot data on solar wind speed using the Granger causality test method and a machine-learning prediction approach. The results show that the low-latitude sunspot number has a larger effect on the solar wind speed. The time delay between the annual average solar wind speed and sunspot number decreases as the latitude range decreases. A machine-learning model is developed for the prediction of solar wind speed considering latitude and time effects. It is found that the model performs differently with latitude-dependent sunspot data. It is revealed that the timescale of the solar wind speed is more strongly influenced by low-latitude sunspots and that sunspot data have a greater impact on the 30 day average solar wind speed than on a daily basis. With the addition of sunspot data below 7.°2 latitude, the prediction of the daily and 30 day averages is improved by 0.23% and 12%, respectively. The best correlation coefficient is 0.787 for the daily solar wind prediction model.","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":"19 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135765575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.3847/1538-4357/acfa00
Salmoli Ghosh, P. Kharb, J. Baghel, S. Silpa
Abstract We present the polarization image of the hybrid morphology and broad absorption line quasar PG 1004+130 at 694 MHz obtained with the upgraded Giant Metrewave Radio Telescope. We detect linear polarization in this source’s core, jets, and lobes. The visible discontinuity in total intensity between the inner jets and the kiloparsec-scale lobes suggests that the source is restarted. The inferred poloidal magnetic ( B -) field structure in the inner jet is consistent with that observed in Fanaroff–Riley (FR) type II sources, as are the B -fields aligned with the lobe edges. Moreover, archival Chandra and XMM-Newton data indicate that PG 1004+130 displays several FRII-jetlike properties in X-rays. We conclude that PG 1004+130 is a restarted quasar, with both episodes of activity being FRII type. The spectral index images show the presence of an inverted spectrum core ( α = +0.30 ± 0.01) and a steep spectrum inner jet ( α = −0.62 ± 0.06) surrounded by much steeper lobe emission ( α ≈ −1.2 ± 0.1), consistent with the suggestion that the lobes are from a previous activity episode. The spectral age difference between the two activity episodes is likely to be small (<1.2 × 10 7 yr), in comparison to the lobe ages (∼3.3 × 10 7 yr). The inferred B -fields in the lobes are suggestive of turbulence and the mixing of plasma. This may account for the absence of X-ray cavities around this source, similar to what is observed in M87's radio halo region. The depolarization models reveal that thermal gas of mass ∼(2.4 ± 0.9) × 10 9 M ⊙ is mixed with the nonthermal plasma in the lobes of PG 1004+130.
{"title":"PG 1004+130: Hybrid Morphology Source or a Restarted FRII? A uGMRT Polarimetric Investigation","authors":"Salmoli Ghosh, P. Kharb, J. Baghel, S. Silpa","doi":"10.3847/1538-4357/acfa00","DOIUrl":"https://doi.org/10.3847/1538-4357/acfa00","url":null,"abstract":"Abstract We present the polarization image of the hybrid morphology and broad absorption line quasar PG 1004+130 at 694 MHz obtained with the upgraded Giant Metrewave Radio Telescope. We detect linear polarization in this source’s core, jets, and lobes. The visible discontinuity in total intensity between the inner jets and the kiloparsec-scale lobes suggests that the source is restarted. The inferred poloidal magnetic ( B -) field structure in the inner jet is consistent with that observed in Fanaroff–Riley (FR) type II sources, as are the B -fields aligned with the lobe edges. Moreover, archival Chandra and XMM-Newton data indicate that PG 1004+130 displays several FRII-jetlike properties in X-rays. We conclude that PG 1004+130 is a restarted quasar, with both episodes of activity being FRII type. The spectral index images show the presence of an inverted spectrum core ( α = +0.30 ± 0.01) and a steep spectrum inner jet ( α = −0.62 ± 0.06) surrounded by much steeper lobe emission ( α ≈ −1.2 ± 0.1), consistent with the suggestion that the lobes are from a previous activity episode. The spectral age difference between the two activity episodes is likely to be small (<1.2 × 10 7 yr), in comparison to the lobe ages (∼3.3 × 10 7 yr). The inferred B -fields in the lobes are suggestive of turbulence and the mixing of plasma. This may account for the absence of X-ray cavities around this source, similar to what is observed in M87's radio halo region. The depolarization models reveal that thermal gas of mass ∼(2.4 ± 0.9) × 10 9 M ⊙ is mixed with the nonthermal plasma in the lobes of PG 1004+130.","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":"18 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135765580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.3847/1538-4357/ad0374
Ryoji Iwashita, Jun Kataoka, Yoshiaki Sofue
Abstract The North Polar Spur (NPS) is a giant structure that is clearly visible in both radio and X-ray all-sky maps. We analyzed broadband radio observations covering a range between 22 MHz and 70 GHz to systematically analyze the thermal/nonthermal emissions associated with the NPS. We demonstrate that the radio emission of the NPS comprises synchrotron, free–free, and dust emission; however, synchrotron emissions dominate over other emissions, especially at high Galactic latitudes. Moreover, the synchrotron spectra exhibit a power-law behavior with N ( γ ) ∝ γ − s ( s ≃ 1.8–2.4) up to a few GHz moderated by a turnover at ν brk ≃ 1 GHz, above which the spectral index s decreases by one. Assuming that the turnover is due to the electrons being cooled by synchrotron radiation before escaping (or advecting) from the emission region, the magnetic field strength can be estimated to be B ∼ 8 μ G if the NPS is a distant structure that is near the Galactic center (GC). However, an unreasonably strong B ∼ 114 μ G is required if the NPS is near the local supernova remnant (SNR). The corresponding nonthermal energy stored in the NPS is E n/th ≃ 4.4 × 10 55 erg in the GC scenario, whereas E n/th ≃ 4.1 × 10 52 erg is difficult to explain with a single local SNR. We also estimated the gamma-ray emission associated with the NPS through inverse Comptonization of the cosmic microwave background, which peaks at 100–1000 keV with a flux of ν F ν ∼ 10 −9 erg cm −2 s −1 sr −1 in the GC model, and may be a good candidate for detection by future X-ray/gamma-ray observatories.
{"title":"Broadband Radio Study of the North Polar Spur: Origin of the Spectral Turnover with Insights into the X-Ray and Gamma-Ray Spectra","authors":"Ryoji Iwashita, Jun Kataoka, Yoshiaki Sofue","doi":"10.3847/1538-4357/ad0374","DOIUrl":"https://doi.org/10.3847/1538-4357/ad0374","url":null,"abstract":"Abstract The North Polar Spur (NPS) is a giant structure that is clearly visible in both radio and X-ray all-sky maps. We analyzed broadband radio observations covering a range between 22 MHz and 70 GHz to systematically analyze the thermal/nonthermal emissions associated with the NPS. We demonstrate that the radio emission of the NPS comprises synchrotron, free–free, and dust emission; however, synchrotron emissions dominate over other emissions, especially at high Galactic latitudes. Moreover, the synchrotron spectra exhibit a power-law behavior with N ( γ ) ∝ γ − s ( s ≃ 1.8–2.4) up to a few GHz moderated by a turnover at ν brk ≃ 1 GHz, above which the spectral index s decreases by one. Assuming that the turnover is due to the electrons being cooled by synchrotron radiation before escaping (or advecting) from the emission region, the magnetic field strength can be estimated to be B ∼ 8 μ G if the NPS is a distant structure that is near the Galactic center (GC). However, an unreasonably strong B ∼ 114 μ G is required if the NPS is near the local supernova remnant (SNR). The corresponding nonthermal energy stored in the NPS is E n/th ≃ 4.4 × 10 55 erg in the GC scenario, whereas E n/th ≃ 4.1 × 10 52 erg is difficult to explain with a single local SNR. We also estimated the gamma-ray emission associated with the NPS through inverse Comptonization of the cosmic microwave background, which peaks at 100–1000 keV with a flux of ν F ν ∼ 10 −9 erg cm −2 s −1 sr −1 in the GC model, and may be a good candidate for detection by future X-ray/gamma-ray observatories.","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":"26 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135765726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.3847/1538-4357/acf75c
Massimo Pascale, Liang Dai, Christopher F. McKee, Benny T.-H. Tsang
Abstract Strong lensing offers a precious opportunity for studying the formation and early evolution of super star clusters that are rare in our cosmic backyard. The Sunburst Arc, a lensed Cosmic Noon galaxy, hosts a young super star cluster with escaping Lyman continuum radiation. Analyzing archival Hubble Space Telescope images and emission line data from Very Large Telescope/MUSE and X-shooter, we construct a physical model for the cluster and its surrounding photoionized nebula. We confirm that the cluster is ≲4 Myr old, is extremely massive M ⋆ ∼ 10 7 M ⊙ , and yet has a central component as compact as several parsecs, and we find a gas-phase metallicity Z = (0.22 ± 0.03) Z ⊙ . The cluster is surrounded by ≳10 5 M ⊙ of dense clouds that have been pressurized to P ∼ 10 9 K cm −3 by perhaps stellar radiation at within 10 pc. These should have large neutral columns N HI > 10 22.8 cm −2 to survive rapid ejection by radiation pressure. The clouds are likely dusty as they show gas-phase depletion of silicon, and may be conducive to secondary star formation if N HI > 10 24 cm −2 or if they sink farther toward the cluster center. Detecting strong [N iii ] λ λ 1750,1752, we infer heavy nitrogen enrichment log(N/O)=−0.21−0.11+0.10 . This requires efficiently retaining ≳500 M ⊙ of nitrogen in the high-pressure clouds from massive stars heavier than 60 M ⊙ up to 4 Myr. We suggest a physical origin of the high-pressure clouds from partial or complete condensation of slow massive star ejecta, which may have an important implication for the puzzle of multiple stellar populations in globular clusters.
{"title":"Nitrogen-enriched, Highly Pressurized Nebular Clouds Surrounding a Super Star Cluster at Cosmic Noon","authors":"Massimo Pascale, Liang Dai, Christopher F. McKee, Benny T.-H. Tsang","doi":"10.3847/1538-4357/acf75c","DOIUrl":"https://doi.org/10.3847/1538-4357/acf75c","url":null,"abstract":"Abstract Strong lensing offers a precious opportunity for studying the formation and early evolution of super star clusters that are rare in our cosmic backyard. The Sunburst Arc, a lensed Cosmic Noon galaxy, hosts a young super star cluster with escaping Lyman continuum radiation. Analyzing archival Hubble Space Telescope images and emission line data from Very Large Telescope/MUSE and X-shooter, we construct a physical model for the cluster and its surrounding photoionized nebula. We confirm that the cluster is ≲4 Myr old, is extremely massive M ⋆ ∼ 10 7 M ⊙ , and yet has a central component as compact as several parsecs, and we find a gas-phase metallicity Z = (0.22 ± 0.03) Z ⊙ . The cluster is surrounded by ≳10 5 M ⊙ of dense clouds that have been pressurized to P ∼ 10 9 K cm −3 by perhaps stellar radiation at within 10 pc. These should have large neutral columns N HI > 10 22.8 cm −2 to survive rapid ejection by radiation pressure. The clouds are likely dusty as they show gas-phase depletion of silicon, and may be conducive to secondary star formation if N HI > 10 24 cm −2 or if they sink farther toward the cluster center. Detecting strong [N iii ] λ λ 1750,1752, we infer heavy nitrogen enrichment <?CDATA $mathrm{log}({rm{N}}/{rm{O}})=-{0.21}_{-0.11}^{+0.10}$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:mi>log</mml:mi> <mml:mo stretchy=\"false\">(</mml:mo> <mml:mi mathvariant=\"normal\">N</mml:mi> <mml:mrow> <mml:mo stretchy=\"true\">/</mml:mo> </mml:mrow> <mml:mi mathvariant=\"normal\">O</mml:mi> <mml:mo stretchy=\"false\">)</mml:mo> <mml:mo>=</mml:mo> <mml:mo>−</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>0.21</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.11</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.10</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> . This requires efficiently retaining ≳500 M ⊙ of nitrogen in the high-pressure clouds from massive stars heavier than 60 M ⊙ up to 4 Myr. We suggest a physical origin of the high-pressure clouds from partial or complete condensation of slow massive star ejecta, which may have an important implication for the puzzle of multiple stellar populations in globular clusters.","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":"240 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135372183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.3847/1538-4357/acf6c0
Angeli Sandoval, Allison Youngblood, R. O. Parke Loyd, Kevin France
The Lyα emission line is the brightest UV emission line in M and K dwarf spectra and serves as an important tool for studies of stellar chromospheres, the interstellar medium, and exoplanet atmospheres. However, Lyα observations have proven difficult due to the strong absorption by the interstellar medium, necessitating a reconstruction of the intrinsic stellar line from the observed spectrum. We have performed new Lyα reconstructions on the MUSCLES Treasury Survey stars, incorporating improved parameterizations for the intrinsic line wings and line core. We present an analysis of how the updated Lyα fluxes could impact photochemical and atmospheric escape studies and flux–flux scaling relations with other chromospheric emission lines such as Ca ii H and K. We find the overall intrinsic Lyα flux of our star sample decreases by as little as 10% to as much as ∼5× fainter compared to previous findings. The exception to this flux decrease is the M dwarf GJ 581, whose Lyα flux increased by 4%. These results will likely have a limited impact on the aforementioned studies that rely on Lyα fluxes.
Ly α发射线是M和K矮星光谱中最亮的紫外发射线，是研究恒星色球、星际介质和系外行星大气的重要工具。然而，由于星际介质的强烈吸收，观测Ly α已被证明是困难的，需要从观测到的光谱中重建本征恒星线。我们对muscle国库调查的恒星进行了新的Ly α重建，包括改进的本征线翼和线核参数化。我们分析了更新的Ly α通量如何影响光化学和大气逃逸研究，以及与其他色球发射谱线(如Ca ii H和k)的通量通量缩放关系。我们发现，与以前的发现相比，我们的恒星样本的整体本征Ly α通量减少了10%，暗了约5倍。但M矮星gj581的Ly α通量增加了4%。这些结果可能对上述依赖于Ly α通量的研究影响有限。
{"title":"New and Improved Lyα Reconstructions for M and K Dwarfs","authors":"Angeli Sandoval, Allison Youngblood, R. O. Parke Loyd, Kevin France","doi":"10.3847/1538-4357/acf6c0","DOIUrl":"https://doi.org/10.3847/1538-4357/acf6c0","url":null,"abstract":"The Lyα emission line is the brightest UV emission line in M and K dwarf spectra and serves as an important tool for studies of stellar chromospheres, the interstellar medium, and exoplanet atmospheres. However, Lyα observations have proven difficult due to the strong absorption by the interstellar medium, necessitating a reconstruction of the intrinsic stellar line from the observed spectrum. We have performed new Lyα reconstructions on the MUSCLES Treasury Survey stars, incorporating improved parameterizations for the intrinsic line wings and line core. We present an analysis of how the updated Lyα fluxes could impact photochemical and atmospheric escape studies and flux–flux scaling relations with other chromospheric emission lines such as Ca ii H and K. We find the overall intrinsic Lyα flux of our star sample decreases by as little as 10% to as much as ∼5× fainter compared to previous findings. The exception to this flux decrease is the M dwarf GJ 581, whose Lyα flux increased by 4%. These results will likely have a limited impact on the aforementioned studies that rely on Lyα fluxes.","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":"42 5-6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135372419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract This study examines the impact of cluster environments on galaxy properties using data from the Hyper Suprime-Cam Subaru Strategic Program and an optically selected CAMIRA cluster sample. Specifically, the study analyzes the fractions of quiescent and green valley galaxies with stellar masses above 10 8.6 M ⊙ at z ∼ 0.2 and 10 9.8 M ⊙ at z ∼ 1.1, investigating their trends in radius and density. The results indicate that a slow quenching mechanism is at work, as evidenced by a radially independent specific star formation rate reduction of 0.1 dex for star-forming galaxies in a cluster environment. The study also finds that slow quenching dominates fast quenching only for low-mass galaxies (<10 9.2 M ⊙ ) near the cluster edge, based on their contributions to the quiescent fraction. After controlling for M * , z , and local overdensity, the study still finds a significant radial gradient in the quiescent fraction, indicating active ram pressure stripping in dense environments. That said, analyzing the density trend of the quiescent fraction with other fixed parameters suggests that radial and density-related quenching processes are equally crucial for low-mass cluster galaxies. The study concludes that ram pressure stripping is the primary environmental quenching mechanism for high stellar mass galaxies in clusters. By contrast, ram pressure stripping and density-related quenching processes act comparably for low-mass cluster galaxies around the center. Near the cluster boundary, starvation and harassment become the leading quenching processes for low stellar mass galaxies.
{"title":"Radial and Local Density Dependence of Star Formation Properties in Galaxy Clusters from the Hyper Suprime-Cam Survey","authors":"Hung-Yu Jian, Lihwai Lin, Bau-Ching Hsieh, Keiichi Umetsu, Carlos Lopez-Coba, Masamune Oguri, Connor Bottrell, Yoshiki Toba, Yusei Koyama, Yu-Yen Chang, Tadayuki Kodama, Yutaka Komiyama, Surhud More, Kai-Yang Lin, Atsushi J. Nishizawa, Ichi Tanaka","doi":"10.3847/1538-4357/acfc22","DOIUrl":"https://doi.org/10.3847/1538-4357/acfc22","url":null,"abstract":"Abstract This study examines the impact of cluster environments on galaxy properties using data from the Hyper Suprime-Cam Subaru Strategic Program and an optically selected CAMIRA cluster sample. Specifically, the study analyzes the fractions of quiescent and green valley galaxies with stellar masses above 10 8.6 M ⊙ at z ∼ 0.2 and 10 9.8 M ⊙ at z ∼ 1.1, investigating their trends in radius and density. The results indicate that a slow quenching mechanism is at work, as evidenced by a radially independent specific star formation rate reduction of 0.1 dex for star-forming galaxies in a cluster environment. The study also finds that slow quenching dominates fast quenching only for low-mass galaxies (<10 9.2 M ⊙ ) near the cluster edge, based on their contributions to the quiescent fraction. After controlling for M * , z , and local overdensity, the study still finds a significant radial gradient in the quiescent fraction, indicating active ram pressure stripping in dense environments. That said, analyzing the density trend of the quiescent fraction with other fixed parameters suggests that radial and density-related quenching processes are equally crucial for low-mass cluster galaxies. The study concludes that ram pressure stripping is the primary environmental quenching mechanism for high stellar mass galaxies in clusters. By contrast, ram pressure stripping and density-related quenching processes act comparably for low-mass cluster galaxies around the center. Near the cluster boundary, starvation and harassment become the leading quenching processes for low stellar mass galaxies.","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":"46 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135372613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.3847/1538-4357/acfa78
Ephim Golbraikh, Yuri Lyubarsky
Abstract We study the nonlinear decay of the fast magnetosonic (fms) into the Alfvén waves in relativistic force-free magnetohydrodynamics. The work has been motivated by models of pulsar radio emission and fast radio bursts (FRBs), in which the emission is generated in neutron star magnetospheres at conditions when not only the Larmor but also the plasma frequencies significantly exceed the radiation frequency. The decay process places limits on the source luminosity in these models. We estimated the decay rate and showed that the phase volume of Alfvén waves available for the decay of an fms wave is infinite. Therefore, the energy of fms waves could be completely transferred to the small-scale Alfvén waves not via a cascade, as in the Kolmogorov turbulence, but directly. Our results explain the anomalously low radio efficiency of the Crab pulsar and show that FRBs could not be produced well within magnetar magnetospheres.
{"title":"On the Escape of Low-frequency Waves from Magnetospheres of Neutron Stars","authors":"Ephim Golbraikh, Yuri Lyubarsky","doi":"10.3847/1538-4357/acfa78","DOIUrl":"https://doi.org/10.3847/1538-4357/acfa78","url":null,"abstract":"Abstract We study the nonlinear decay of the fast magnetosonic (fms) into the Alfvén waves in relativistic force-free magnetohydrodynamics. The work has been motivated by models of pulsar radio emission and fast radio bursts (FRBs), in which the emission is generated in neutron star magnetospheres at conditions when not only the Larmor but also the plasma frequencies significantly exceed the radiation frequency. The decay process places limits on the source luminosity in these models. We estimated the decay rate and showed that the phase volume of Alfvén waves available for the decay of an fms wave is infinite. Therefore, the energy of fms waves could be completely transferred to the small-scale Alfvén waves not via a cascade, as in the Kolmogorov turbulence, but directly. Our results explain the anomalously low radio efficiency of the Crab pulsar and show that FRBs could not be produced well within magnetar magnetospheres.","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":"9 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135410171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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