Pub Date : 2026-01-20DOI: 10.1051/0004-6361/202557602
Mats Ola Sand, Quentin Noraz, Guillaume Aulanier, Juan Martínez-Sykora, Mats Carlsson, Luc Rouppe van der Voort
Context. The formation mechanism for the dynamic type II spicules has remained elusive for many years. Their dynamical behaviour has long been linked to magnetic reconnection, yet no conclusive evidence has been provided. However, one recent observational study found signs of magnetic reconnection, as traced by Ellerman bombs (EBs), at the footpoints of many spicules. The triggering of EBs is generally linked to magnetic reconnection due to flux emergence and convective motions in the photosphere.Aims. We aim to explore whether we can connect EBs to type II spicules, and determine to what extent we can use EBs as an observational proxy to probe magnetic reconnection in this dynamic. We also aim to provide further insight into the mechanisms that trigger EBs.Methods. We used a simulation run with the radiative magnetohydrodynamics code Bifrost to track spicules and study the physical processes underlying their formation. To detect EBs and classify the spicules, we synthesised the chromospheric Hα spectral line using the multilevel radiative transfer code RH1.5D. We also traced shocks and current sheets to decipher the origin of EBs and spicules. We selected one type II spicule with a strong EB near its footpoint and studied their formation in detail.Results. A magnetoacoustic shock advects the magnetic field lines towards an oppositely directed ambient field, creating a current sheet. The current sheet accelerates dense plasma via a whiplash effect generated by magnetic reconnection into the inclined ambient field, launching the spicule. Several EB profiles trace shock- and magnetic-reconnection-induced dynamics during this process at the spicule footpoint.Conclusions. We present a new EB triggering mechanism in which a shock-induced current sheet reconnects, triggering an EB in the lower solar atmosphere. The shock-induced current sheet generates the upwards propagation of a type II spicule via reconnection outflows. These results provide a plausible physical origin for the recently observed connection between EBs and spicules.
{"title":"Shock-induced magnetic reconnection driving Ellerman bomb emission and a spicule","authors":"Mats Ola Sand, Quentin Noraz, Guillaume Aulanier, Juan Martínez-Sykora, Mats Carlsson, Luc Rouppe van der Voort","doi":"10.1051/0004-6361/202557602","DOIUrl":"https://doi.org/10.1051/0004-6361/202557602","url":null,"abstract":"<i>Context.<i/> The formation mechanism for the dynamic type II spicules has remained elusive for many years. Their dynamical behaviour has long been linked to magnetic reconnection, yet no conclusive evidence has been provided. However, one recent observational study found signs of magnetic reconnection, as traced by Ellerman bombs (EBs), at the footpoints of many spicules. The triggering of EBs is generally linked to magnetic reconnection due to flux emergence and convective motions in the photosphere.<i>Aims.<i/> We aim to explore whether we can connect EBs to type II spicules, and determine to what extent we can use EBs as an observational proxy to probe magnetic reconnection in this dynamic. We also aim to provide further insight into the mechanisms that trigger EBs.<i>Methods.<i/> We used a simulation run with the radiative magnetohydrodynamics code Bifrost to track spicules and study the physical processes underlying their formation. To detect EBs and classify the spicules, we synthesised the chromospheric H<i>α<i/> spectral line using the multilevel radiative transfer code RH1.5D. We also traced shocks and current sheets to decipher the origin of EBs and spicules. We selected one type II spicule with a strong EB near its footpoint and studied their formation in detail.<i>Results.<i/> A magnetoacoustic shock advects the magnetic field lines towards an oppositely directed ambient field, creating a current sheet. The current sheet accelerates dense plasma via a whiplash effect generated by magnetic reconnection into the inclined ambient field, launching the spicule. Several EB profiles trace shock- and magnetic-reconnection-induced dynamics during this process at the spicule footpoint.<i>Conclusions.<i/> We present a new EB triggering mechanism in which a shock-induced current sheet reconnects, triggering an EB in the lower solar atmosphere. The shock-induced current sheet generates the upwards propagation of a type II spicule via reconnection outflows. These results provide a plausible physical origin for the recently observed connection between EBs and spicules.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"187 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146006203","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 : 2026-01-15DOI: 10.1051/0004-6361/202557293
Angelos Nersesian, Yasha Kaushal, Marco Martorano, Arjen van der Wel, Po-Feng Wu, Rachel Bezanson, Eric F. Bell, Francesco D’Eugenio, Anna R. Gallazzi, Joel Leja, Stefano Zibetti, Sandro Tacchella
Aims. We analyzed the sizes and star formation histories (SFHs) of 2908 galaxies with M★ ≥ 109 M⊙ at 0.6 < z < 1.0, drawn from the Large Early Galaxy Astrophysics Census (LEGA-C) survey. The goal is to investigate the connection between galaxy sizes with SFH, stellar age, and metallicity.Methods. The SFHs were derived with Prospector by fitting the high signal-to-noise ratio, high spectral resolution spectroscopy drawn from the LEGA-C DR3 together with the broadband photometry from the UltraVISTA catalog. The galaxy sizes were measured by fitting a 2D Sérsic profile to the HST ACS F814W images.Results. We find diverse SFHs and quenching timescales (τq). The main quiescent population quenched over τq = 1.23 ± 0.04 Gyr, whereas the compact post-starburst galaxies (PSBs) quenched much faster, τq = 0.13 ± 0.03 Gyr. At fixed stellar mass, smaller quiescent galaxies quenched more rapidly than larger ones; at fixed size, the dependence on stellar mass is weak. Larger quiescent galaxies are marginally younger, quenched more slowly, and have near-solar metallicities, while compact quiescent galaxies are older, metal-rich, and quenched faster. PSBs formed half their mass later (zform ∼ 1.9) and quenched on the shortest timescales. The general trends with galaxy size, Z★, and zform for the quiescent populations remain consistent regardless of the method used to derive the stellar properties.Conclusions. We conclude that compact quiescent galaxies are consistent with both early moderately fast quenching and with more rapid late quenching. While this may suggest the existence of multiple quenching channels, our data are also compatible with a continuous distribution of quenching timescales. These findings suggest that different physical mechanisms may drive quenching across galaxy populations, potentially leading to similar morphological outcomes despite the differing evolutionary histories.
{"title":"The LEGA-C galaxy survey: Multiple quenching channels for quiescent galaxies at z ∼ 1","authors":"Angelos Nersesian, Yasha Kaushal, Marco Martorano, Arjen van der Wel, Po-Feng Wu, Rachel Bezanson, Eric F. Bell, Francesco D’Eugenio, Anna R. Gallazzi, Joel Leja, Stefano Zibetti, Sandro Tacchella","doi":"10.1051/0004-6361/202557293","DOIUrl":"https://doi.org/10.1051/0004-6361/202557293","url":null,"abstract":"<i>Aims.<i/> We analyzed the sizes and star formation histories (SFHs) of 2908 galaxies with <i>M<i/><sub>★<sub/> ≥ 10<sup>9<sup/> M<sub>⊙<sub/> at 0.6 < <i>z<i/> < 1.0, drawn from the Large Early Galaxy Astrophysics Census (LEGA-C) survey. The goal is to investigate the connection between galaxy sizes with SFH, stellar age, and metallicity.<i>Methods.<i/> The SFHs were derived with Prospector by fitting the high signal-to-noise ratio, high spectral resolution spectroscopy drawn from the LEGA-C DR3 together with the broadband photometry from the UltraVISTA catalog. The galaxy sizes were measured by fitting a 2D Sérsic profile to the <i>HST<i/> ACS F814W images.<i>Results.<i/> We find diverse SFHs and quenching timescales (<i>τ<i/><sub>q<sub/>). The main quiescent population quenched over <i>τ<i/><sub>q<sub/> = 1.23 ± 0.04 Gyr, whereas the compact post-starburst galaxies (PSBs) quenched much faster, <i>τ<i/><sub>q<sub/> = 0.13 ± 0.03 Gyr. At fixed stellar mass, smaller quiescent galaxies quenched more rapidly than larger ones; at fixed size, the dependence on stellar mass is weak. Larger quiescent galaxies are marginally younger, quenched more slowly, and have near-solar metallicities, while compact quiescent galaxies are older, metal-rich, and quenched faster. PSBs formed half their mass later (<i>z<i/><sub>form<sub/> ∼ 1.9) and quenched on the shortest timescales. The general trends with galaxy size, <i>Z<i/><sub>★<sub/>, and <i>z<i/><sub>form<sub/> for the quiescent populations remain consistent regardless of the method used to derive the stellar properties.<i>Conclusions.<i/> We conclude that compact quiescent galaxies are consistent with both early moderately fast quenching and with more rapid late quenching. While this may suggest the existence of multiple quenching channels, our data are also compatible with a continuous distribution of quenching timescales. These findings suggest that different physical mechanisms may drive quenching across galaxy populations, potentially leading to similar morphological outcomes despite the differing evolutionary histories.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"100 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145972362","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 : 2026-01-14DOI: 10.1051/0004-6361/202556907
Dan Hu, Shida Fan, Zhongsheng Yuan, Junjie Mao, Norbert Werner, Yuanyuan Su, François Mernier, Yuanyuan Zhao, Liyi Gu, Haiguang Xu
Context. Galaxy clusters trace the densest regions of the cosmic web and are crucial laboratories for studying the thermodynamic and chemical evolution of the intracluster medium (ICM). The massive galaxy cluster SPT-CL J0217−5014 (z ∼ 0.53; M500 ∼ 3 × 1014 M⊙) is one of the Swift X-Ray Telescope serendipitous galaxy clusters with the highest reported Fe abundance (∼1.3 ± 0.4 Z⊙ within ) and a potentially disturbed morphology.Aims. SPT-CL J0217−5014 presents an intriguing opportunity to investigate ICM chemical enrichment and cool-core survival. With this study, we aim to evaluate its chemical and thermodynamic properties with a dedicated Chandra observation.Methods. Using new Chandra observations, we derived surface brightness profiles and dynamical state parameters. We also performed spectral fitting using different backgrounds to constrain the Fe abundance. We performed joint analysis of the X-ray surface brightness, temperature, and integrated Sunyaev-Zel’dovich Compton parameter to constrain the density profile. The DESI optical galaxy cluster catalogue was examined to explore its large-scale environment.Results. The X-ray morphology reveals a disturbed ICM with a surface brightness edge at (∼100 kpc) to the west and a tail-like feature extending towards the east. The best-fit metal abundance within (∼0.7 R500) is Z⊙. The derived central electron number density, entropy, and cooling time classify this system as a non-cool-core cluster, suggesting that merger activity has likely disrupted the possible pre-existing cool core. At larger radii (∼1′−2′), we detected excess X-ray emission to the south spatially aligned with a filamentary distribution of red galaxies, indicating ongoing accretion along an intracluster filament. Based on the DESI DR9 cross-matched optical clusters and photometric redshifts, we identified three nearby lower-mass clusters that likely trace the large-scale structures, suggesting that SPT-CL J0217−5014 is the primary node of a dynamically active environment where past mergers and anisotropic accretion along cosmic filaments have shaped the present-day ICM.
{"title":"A Chandra view of SPT-CL J0217–5014: A massive galaxy cluster at a cosmic intersection at z = 0.53","authors":"Dan Hu, Shida Fan, Zhongsheng Yuan, Junjie Mao, Norbert Werner, Yuanyuan Su, François Mernier, Yuanyuan Zhao, Liyi Gu, Haiguang Xu","doi":"10.1051/0004-6361/202556907","DOIUrl":"https://doi.org/10.1051/0004-6361/202556907","url":null,"abstract":"<i>Context.<i/> Galaxy clusters trace the densest regions of the cosmic web and are crucial laboratories for studying the thermodynamic and chemical evolution of the intracluster medium (ICM). The massive galaxy cluster SPT-CL J0217−5014 (<i>z<i/> ∼ 0.53; <i>M<i/><sub>500<sub/> ∼ 3 × 10<sup>14<sup/> M<sub>⊙<sub/>) is one of the <i>Swift<i/> X-Ray Telescope serendipitous galaxy clusters with the highest reported Fe abundance (∼1.3 ± 0.4 Z<sub>⊙<sub/> within ) and a potentially disturbed morphology.<i>Aims.<i/> SPT-CL J0217−5014 presents an intriguing opportunity to investigate ICM chemical enrichment and cool-core survival. With this study, we aim to evaluate its chemical and thermodynamic properties with a dedicated <i>Chandra<i/> observation.<i>Methods.<i/> Using new <i>Chandra<i/> observations, we derived surface brightness profiles and dynamical state parameters. We also performed spectral fitting using different backgrounds to constrain the Fe abundance. We performed joint analysis of the X-ray surface brightness, temperature, and integrated Sunyaev-Zel’dovich Compton parameter to constrain the density profile. The DESI optical galaxy cluster catalogue was examined to explore its large-scale environment.<i>Results.<i/> The X-ray morphology reveals a disturbed ICM with a surface brightness edge at (∼100 kpc) to the west and a tail-like feature extending towards the east. The best-fit metal abundance within (∼0.7 <i>R<i/><sub>500<sub/>) is Z<sub>⊙<sub/>. The derived central electron number density, entropy, and cooling time classify this system as a non-cool-core cluster, suggesting that merger activity has likely disrupted the possible pre-existing cool core. At larger radii (∼1′−2′), we detected excess X-ray emission to the south spatially aligned with a filamentary distribution of red galaxies, indicating ongoing accretion along an intracluster filament. Based on the DESI DR9 cross-matched optical clusters and photometric redshifts, we identified three nearby lower-mass clusters that likely trace the large-scale structures, suggesting that SPT-CL J0217−5014 is the primary node of a dynamically active environment where past mergers and anisotropic accretion along cosmic filaments have shaped the present-day ICM.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"45 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145968870","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 : 2026-01-14DOI: 10.1051/0004-6361/202554082
N. Cuello, E. Bianchi, F. Ménard, L. Loinard, R. Hernández Garnica, A. Durán, C. Ceccarelli, M. J. Maureira, C. J. Chandler, C. Codella, N. Sakai, L. Podio, G. Sabatini, L. Chahine, M. de Simone, D. Fedele, D. Johnstone, T. Hanawa, I. Jiménez-Serra, S. Yamamoto
Young binary stars with discs provide unique laboratories for studying the earliest stages of planet formation in star-forming environments. The detection of substructure in discs around Class I protostars challenges current models of disc evolution, and suggests that planets may form earlier than previously expected (< 1 Myr). In the context of the FAUST Large Program, we present observations of the circumbinary disc (CBD) around the young binary system L1551 IRS 5. The CBD exhibits two prominent over-densities in the continuum emission at the edge of the cavity, with the northern over-density being about 20% brighter than the southern one. By analysing the disc morphology and kinematics of L1551 IRS 5, we delineate dynamical constraints on the binary’s orbital parameters. Additionally, we present 3D hydrodynamical models of the CBD to predict both the dust and the gas surface densities. Then, we compare the resulting synthetic observations with ALMA observations of the continuum emission at 1.3 mm and the C18O line emission. Our analysis suggests that the density enhancements observed with ALMA in L1551 IRS 5 can be caused by interactions between the binary stars and the CBD, leading to dust concentration within the disc. We conclude that the observed over-density corresponds to a location where solids could potentially grow in size under favourable conditions.
{"title":"FAUST","authors":"N. Cuello, E. Bianchi, F. Ménard, L. Loinard, R. Hernández Garnica, A. Durán, C. Ceccarelli, M. J. Maureira, C. J. Chandler, C. Codella, N. Sakai, L. Podio, G. Sabatini, L. Chahine, M. de Simone, D. Fedele, D. Johnstone, T. Hanawa, I. Jiménez-Serra, S. Yamamoto","doi":"10.1051/0004-6361/202554082","DOIUrl":"https://doi.org/10.1051/0004-6361/202554082","url":null,"abstract":"Young binary stars with discs provide unique laboratories for studying the earliest stages of planet formation in star-forming environments. The detection of substructure in discs around Class I protostars challenges current models of disc evolution, and suggests that planets may form earlier than previously expected (< 1 Myr). In the context of the FAUST Large Program, we present observations of the circumbinary disc (CBD) around the young binary system L1551 IRS 5. The CBD exhibits two prominent over-densities in the continuum emission at the edge of the cavity, with the northern over-density being about 20% brighter than the southern one. By analysing the disc morphology and kinematics of L1551 IRS 5, we delineate dynamical constraints on the binary’s orbital parameters. Additionally, we present 3D hydrodynamical models of the CBD to predict both the dust and the gas surface densities. Then, we compare the resulting synthetic observations with ALMA observations of the continuum emission at 1.3 mm and the C<sup>18<sup/>O line emission. Our analysis suggests that the density enhancements observed with ALMA in L1551 IRS 5 can be caused by interactions between the binary stars and the CBD, leading to dust concentration within the disc. We conclude that the observed over-density corresponds to a location where solids could potentially grow in size under favourable conditions.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"30 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145968869","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 : 2026-01-13DOI: 10.1051/0004-6361/202557595
Jaroslav Haas, Pavel Kroupa, Sergij Mazurenko
Context. The stellar dynamical evolution of massive star clusters formed during starburst periods leads to the segregation of ≳104M⊙ stellar-mass black hole sub-clusters in their centres. In gas-rich environments, such as galactic central molecular zones, these black hole clusters are likely to accrete large amounts of the gas from their surroundings, which in turn affects their internal dynamics.Aims. In this Letter we estimated the corresponding accretion rate onto the black hole cluster and its radiative feedback. We assessed whether such an accretion flow can lead to the collapse of the black hole cluster into an intermediate-mass black hole.Methods. The estimates were obtained analytically, considering the astrophysical conditions and star formation history reported for the central molecular zone of our Galaxy.Results. We find that a stellar black hole cluster with mass ≳104M⊙ located in the twisted ring of molecular clouds with radius ≈100 pc that is observed in the central molecular zone of our Galaxy can accrete about the same mass in gas on a timescale of a few million years. We suggest that this is sufficient for its subsequent collapse into an intermediate-mass black hole. Based on an estimate of the dynamical friction inspiral time, we further argue that the locations of the intermediate-mass black hole candidates recently observed in the central molecular zone are compatible with their formation therein during the last starburst period reported to have occurred ≈1 Gyr ago.
{"title":"Intermediate-mass black hole incubators","authors":"Jaroslav Haas, Pavel Kroupa, Sergij Mazurenko","doi":"10.1051/0004-6361/202557595","DOIUrl":"https://doi.org/10.1051/0004-6361/202557595","url":null,"abstract":"<i>Context.<i/> The stellar dynamical evolution of massive star clusters formed during starburst periods leads to the segregation of ≳10<sup>4<sup/> <i>M<i/><sub>⊙<sub/> stellar-mass black hole sub-clusters in their centres. In gas-rich environments, such as galactic central molecular zones, these black hole clusters are likely to accrete large amounts of the gas from their surroundings, which in turn affects their internal dynamics.<i>Aims.<i/> In this Letter we estimated the corresponding accretion rate onto the black hole cluster and its radiative feedback. We assessed whether such an accretion flow can lead to the collapse of the black hole cluster into an intermediate-mass black hole.<i>Methods.<i/> The estimates were obtained analytically, considering the astrophysical conditions and star formation history reported for the central molecular zone of our Galaxy.<i>Results.<i/> We find that a stellar black hole cluster with mass ≳10<sup>4<sup/> <i>M<i/><sub>⊙<sub/> located in the twisted ring of molecular clouds with radius ≈100 pc that is observed in the central molecular zone of our Galaxy can accrete about the same mass in gas on a timescale of a few million years. We suggest that this is sufficient for its subsequent collapse into an intermediate-mass black hole. Based on an estimate of the dynamical friction inspiral time, we further argue that the locations of the intermediate-mass black hole candidates recently observed in the central molecular zone are compatible with their formation therein during the last starburst period reported to have occurred ≈1 Gyr ago.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"40 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145968856","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 : 2026-01-12DOI: 10.1051/0004-6361/202557333
Sergio Martínez-González, Santiago Jiménez, Casiana Muñoz-Tuñón
Context. A subset of very young super-early galaxies at z ≳ 10, often called blue monsters, shows extremely blue UV continua and faint far-IR emission. This might imply much less dust than expected from standard enrichment scenarios.Aims. We wish to understand the reason for the apparent absence of dust in the blue monsters. To do this, we show by combining full 3D hydrodynamical dust-survival yields with 3D thin-shell scalings that clustered supernovae drive a mechanical blowout in stratified self-gravitating clouds, and we predict the retained dust-to-stellar mass ratio at the cluster scale and the corresponding galaxy-integrated value.Methods. We took the net dust yield per unit stellar mass from existing 3D hydrodynamical studies of young stellar clusters with sequential supernovae, and we set the blowout radius as a function of gas concentration using established 3D thin-shell scalings. For an assumed gas–dust coupling across the blowout boundary, the retained dust-to-stellar ratio accounts for the fraction of supernovae that remain confined versus those that vent mechanically.Results. For all typical cluster masses, sizes, and cloud-scale star formation efficiencies, mechanical venting removes a large part of gas and dust. The retained dust-to-stellar mass ratio is lowered by about one-half to two orders of magnitude relative to the supernova net dust yield. The outcome mainly depends on the gas concentration and only weakly on metallicity, and it therefore remains effective at low Z. After weighting by a Schechter cluster mass function and a Weibull core–radius distribution, the galaxy-integrated value falls in the same range inferred for spectroscopically confirmed blue monsters.Conclusions. Mechanical venting at the cluster scale can account for the very low dust fractions inferred for blue monsters without requiring extreme in situ destruction and without fine-tuning.
{"title":"Missing dust of super-early galaxies","authors":"Sergio Martínez-González, Santiago Jiménez, Casiana Muñoz-Tuñón","doi":"10.1051/0004-6361/202557333","DOIUrl":"https://doi.org/10.1051/0004-6361/202557333","url":null,"abstract":"<i>Context.<i/> A subset of very young super-early galaxies at <i>z<i/> ≳ 10, often called blue monsters, shows extremely blue UV continua and faint far-IR emission. This might imply much less dust than expected from standard enrichment scenarios.<i>Aims.<i/> We wish to understand the reason for the apparent absence of dust in the blue monsters. To do this, we show by combining full 3D hydrodynamical dust-survival yields with 3D thin-shell scalings that clustered supernovae drive a mechanical blowout in stratified self-gravitating clouds, and we predict the retained dust-to-stellar mass ratio at the cluster scale and the corresponding galaxy-integrated value.<i>Methods.<i/> We took the net dust yield per unit stellar mass from existing 3D hydrodynamical studies of young stellar clusters with sequential supernovae, and we set the blowout radius as a function of gas concentration using established 3D thin-shell scalings. For an assumed gas–dust coupling across the blowout boundary, the retained dust-to-stellar ratio accounts for the fraction of supernovae that remain confined versus those that vent mechanically.<i>Results.<i/> For all typical cluster masses, sizes, and cloud-scale star formation efficiencies, mechanical venting removes a large part of gas and dust. The retained dust-to-stellar mass ratio is lowered by about one-half to two orders of magnitude relative to the supernova net dust yield. The outcome mainly depends on the gas concentration and only weakly on metallicity, and it therefore remains effective at low <i>Z<i/>. After weighting by a Schechter cluster mass function and a Weibull core–radius distribution, the galaxy-integrated value falls in the same range inferred for spectroscopically confirmed blue monsters.<i>Conclusions.<i/> Mechanical venting at the cluster scale can account for the very low dust fractions inferred for blue monsters without requiring extreme in situ destruction and without fine-tuning.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"4 1","pages":"L10"},"PeriodicalIF":6.5,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145956524","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 : 2026-01-12DOI: 10.1051/0004-6361/202557325
N.-E. Nèmec, Ò. Porqueras-León, I. Ribas, A. I. Shapiro
Aims. Transmission spectroscopy allows to measure the wavelength dependence of the transit signal of an exoplanet, thus enabling probing of its atmospheric composition. However, the transmission spectrum also carries information of the host star, generally referred to as ‘contamination‘. Stellar activity leads to an apparent change in the stellar radius, directly impacting the transit depth. This contamination is regarded as the major hurdle in discovering and characterising the atmospheres of exoplanets.Methods. The objective is to understand how the chromatic effect (i.e. the wavelength dependence) of the stellar activity-induced transit depth depends on the surface distribution of magnetic features. The surface distribution of other stars generally is unknown, with the exception of our very own star, the Sun. We therefore investigate the solar paradigm as ‘ground truth’ to explore how much the chromatic effects depends on the distribution of magnetic features. In particular, we explored the impact of centre-to-limb variations (CLV) of the magnetic features and their resulting chromatic effect. Specifically, we investigated the solar paradigm as the ‘ground truth’.Results. We utilised spot and faculae masks obtained from SDO/HMI magnetograms and intensitygrams together with the SATIRE approach of calculating solar variability to calculate the chromatic dependence of the apparent radius of the Sun for the last solar cycle. We tested several approaches to convolving the area coverage with the spectra to uncover the potential biases and we investigated the drivers responsible for the chromatic effect.Conclusions. We find that using a simplified approach that only relies on the disc area coverage and neglects CLV in the spectra to calculate the chromatic effects lead to an underestimation of the apparent radius. In particular, for the faculae component, the CLV need to be taken into account accordingly, especially since the facular area coverage is by far larger than that of spots for stars with near-solar activity level. We report that this chromatic dependence can be detected in transits of an Earth-sized and a Jupiter-sized planet. Additionally, we assessed the amplitude of this effect between solar minimum and solar maximum. We found that for a Jupiter-like transit this amplitude is at the level of 40 ppm, well above the 10 ppm noise floor of JWST. However, this effect is only on the level of 0.4 ppm for the Earth-like transit.
{"title":"Deciphering transmission spectra by exploring the solar paradigm","authors":"N.-E. Nèmec, Ò. Porqueras-León, I. Ribas, A. I. Shapiro","doi":"10.1051/0004-6361/202557325","DOIUrl":"https://doi.org/10.1051/0004-6361/202557325","url":null,"abstract":"<i>Aims<i/>. Transmission spectroscopy allows to measure the wavelength dependence of the transit signal of an exoplanet, thus enabling probing of its atmospheric composition. However, the transmission spectrum also carries information of the host star, generally referred to as ‘contamination‘. Stellar activity leads to an apparent change in the stellar radius, directly impacting the transit depth. This contamination is regarded as the major hurdle in discovering and characterising the atmospheres of exoplanets.<i>Methods<i/>. The objective is to understand how the chromatic effect (i.e. the wavelength dependence) of the stellar activity-induced transit depth depends on the surface distribution of magnetic features. The surface distribution of other stars generally is unknown, with the exception of our very own star, the Sun. We therefore investigate the solar paradigm as ‘ground truth’ to explore how much the chromatic effects depends on the distribution of magnetic features. In particular, we explored the impact of centre-to-limb variations (CLV) of the magnetic features and their resulting chromatic effect. Specifically, we investigated the solar paradigm as the ‘ground truth’.<i>Results<i/>. We utilised spot and faculae masks obtained from SDO/HMI magnetograms and intensitygrams together with the SATIRE approach of calculating solar variability to calculate the chromatic dependence of the apparent radius of the Sun for the last solar cycle. We tested several approaches to convolving the area coverage with the spectra to uncover the potential biases and we investigated the drivers responsible for the chromatic effect.<i>Conclusions<i/>. We find that using a simplified approach that only relies on the disc area coverage and neglects CLV in the spectra to calculate the chromatic effects lead to an underestimation of the apparent radius. In particular, for the faculae component, the CLV need to be taken into account accordingly, especially since the facular area coverage is by far larger than that of spots for stars with near-solar activity level. We report that this chromatic dependence can be detected in transits of an Earth-sized and a Jupiter-sized planet. Additionally, we assessed the amplitude of this effect between solar minimum and solar maximum. We found that for a Jupiter-like transit this amplitude is at the level of 40 ppm, well above the 10 ppm noise floor of JWST. However, this effect is only on the level of 0.4 ppm for the Earth-like transit.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"38 1","pages":"A111"},"PeriodicalIF":6.5,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145956556","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 : 2026-01-12DOI: 10.1051/0004-6361/202557177
Emmanuel Dartois, Jennifer A. Noble, Jennifer B. Bergner, Klaus M. Pontoppidan, Korash Assani, Daniel Harsono, Melissa K. McClure, Julia C. Santos, Will E. Thompson, Lukas Welzel, Nicole Arulanantham, Alice S. Booth, Maria N. Drozdovskaya, Zhi-Yun Li, Jie Ma, Laurine Martinien, François Ménard, Karin Oberg, Karl Stapelfeldt, Yao-Lun Yang
Aims. Edge-on discs offer a unique opportunity to probe radial and vertical dust and gas distributions in the protoplanetary phase. This study aims to investigate the distribution of micron-sized dust particles in the Flying Saucer in Rho Ophiuchi by leveraging the unique observational conditions of a bright infrared background that enables the edge-on disc to be seen in both silhouette and scattered light at specific wavelengths.Methods. We used NIRSpec IFU observations from the JWST Edge-on Disc Ice program (JEDIce) of the Flying Saucer serendipitously observed against a Polycyclic Aromatic Hydrocarbons-emitting background to constrain the dust distribution and grain sizes via radiative transfer modelling.Results. The observation of the Flying Saucer in silhouette at 3.29 μm reveals that the midplane radial extent of small dust grains is ∼235 au, i.e. larger than the large-grain disc extent previously determined to be 190 au from millimetre data. The scattered light observed in emission probes micron-sized icy grains at large vertical distances above the midplane. The vertical extent of the disc silhouette is similar at visible, near-IR, and mid-IR wavelengths, corroborating the conclusion that dust settling is inefficient for grains as large as tens of microns, both vertically and radially.
{"title":"The near-infrared silhouette of the Flying Saucer edge-on disc revealed by the JWST JEDIce program","authors":"Emmanuel Dartois, Jennifer A. Noble, Jennifer B. Bergner, Klaus M. Pontoppidan, Korash Assani, Daniel Harsono, Melissa K. McClure, Julia C. Santos, Will E. Thompson, Lukas Welzel, Nicole Arulanantham, Alice S. Booth, Maria N. Drozdovskaya, Zhi-Yun Li, Jie Ma, Laurine Martinien, François Ménard, Karin Oberg, Karl Stapelfeldt, Yao-Lun Yang","doi":"10.1051/0004-6361/202557177","DOIUrl":"https://doi.org/10.1051/0004-6361/202557177","url":null,"abstract":"<i>Aims.<i/> Edge-on discs offer a unique opportunity to probe radial and vertical dust and gas distributions in the protoplanetary phase. This study aims to investigate the distribution of micron-sized dust particles in the Flying Saucer in Rho Ophiuchi by leveraging the unique observational conditions of a bright infrared background that enables the edge-on disc to be seen in both silhouette and scattered light at specific wavelengths.<i>Methods.<i/> We used NIRSpec IFU observations from the JWST Edge-on Disc Ice program (JEDIce) of the Flying Saucer serendipitously observed against a Polycyclic Aromatic Hydrocarbons-emitting background to constrain the dust distribution and grain sizes via radiative transfer modelling.<i>Results.<i/> The observation of the Flying Saucer in silhouette at 3.29 μm reveals that the midplane radial extent of small dust grains is ∼235 au, i.e. larger than the large-grain disc extent previously determined to be 190 au from millimetre data. The scattered light observed in emission probes micron-sized icy grains at large vertical distances above the midplane. The vertical extent of the disc silhouette is similar at visible, near-IR, and mid-IR wavelengths, corroborating the conclusion that dust settling is inefficient for grains as large as tens of microns, both vertically and radially.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"250 1","pages":"L14"},"PeriodicalIF":6.5,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145956554","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 : 2026-01-12DOI: 10.1051/0004-6361/202557153
E. Vanzella, M. Messa, A. Zanella, A. Bolamperti, M. Castellano, F. Loiacono, P. Bergamini, G. Roberts Borsani, A. Adamo, A. Fontana, T. Treu, F. Calura, C. Grillo, M. Lombardi, P. Rosati, R. Gilli, M. Meneghetti
We report the discovery of a faint (M1700 ≃ −12.2), oxygen-deficient, strongly lensed ionizing source – dubbed Lensed And Pristine 2 (LAP2) – at a spectroscopic redshift of z = 4.19. LAP2 appears to be isolated and lies very close to the caustic produced by the lensing galaxy cluster Abell 2744. It was observed with the James Webb Space Telescope (JWST) NIRSpec MSA in prism mode as part of the UNCOVER program. The NIRSpec spectrum reveals prominent Lyα (7.1σ), clear Hα (6.2σ), tentative Hβ (≃2.8σ) emissions and no detectable [O/III]λλ4959,5007 (∼7 times fainter than Hα). The inferred [O III] 2σ upper limit corresponds to an R3 index < 0.85 (assuming the Hα/Hβ = 2.86 case B recombination ratio), which, under high-ionization conditions, implies a metallicity of Z < 6 × 10−3Z⊙. The combination of faint ultraviolet luminosity, a large rest-frame Hα equivalent width (≃650 Å), and an extremely compact size (< 10 pc) suggests that LAP2 is being caught in an early, pristine formation phase consistent with an instantaneous-burst scenario, with an estimated stellar mass of at most a few ×104 M⊙. Deep VLT/MUSE observations further reveal copious Lyα emission forming an arclet that straddles the critical line. LAP2 joins the rare class of extremely metal-poor star-forming complexes that the JWST has started to unveil at redshifts 3–7, and it provides a glimpse into a still very poorly explored low-luminosity regime.
{"title":"A pristine, star-forming complex at z = 4.19★","authors":"E. Vanzella, M. Messa, A. Zanella, A. Bolamperti, M. Castellano, F. Loiacono, P. Bergamini, G. Roberts Borsani, A. Adamo, A. Fontana, T. Treu, F. Calura, C. Grillo, M. Lombardi, P. Rosati, R. Gilli, M. Meneghetti","doi":"10.1051/0004-6361/202557153","DOIUrl":"https://doi.org/10.1051/0004-6361/202557153","url":null,"abstract":"We report the discovery of a faint (M<sub>1700<sub/> ≃ −12.2), oxygen-deficient, strongly lensed ionizing source – dubbed Lensed And Pristine 2 (LAP2) – at a spectroscopic redshift of <i>z<i/> = 4.19. LAP2 appears to be isolated and lies very close to the caustic produced by the lensing galaxy cluster Abell 2744. It was observed with the <i>James Webb Space Telescope<i/> (JWST) NIRSpec MSA in prism mode as part of the UNCOVER program. The NIRSpec spectrum reveals prominent Ly<i>α<i/> (7.1<i>σ<i/>), clear H<i>α<i/> (6.2<i>σ<i/>), tentative H<i>β<i/> (≃2.8<i>σ<i/>) emissions and no detectable [O/III]<i>λλ<i/>4959,5007 (∼7 times fainter than H<i>α<i/>). The inferred [O III] 2<i>σ<i/> upper limit corresponds to an R3 index < 0.85 (assuming the H<i>α<i/>/H<i>β<i/> = 2.86 case B recombination ratio), which, under high-ionization conditions, implies a metallicity of <i>Z<i/> < 6 × 10<sup>−3<sup/> <i>Z<i/><sub>⊙<sub/>. The combination of faint ultraviolet luminosity, a large rest-frame H<i>α<i/> equivalent width (≃650 Å), and an extremely compact size (< 10 pc) suggests that LAP2 is being caught in an early, pristine formation phase consistent with an instantaneous-burst scenario, with an estimated stellar mass of at most a few ×10<sup>4<sup/> M<sub>⊙<sub/>. Deep VLT/MUSE observations further reveal copious Ly<i>α<i/> emission forming an arclet that straddles the critical line. LAP2 joins the rare class of extremely metal-poor star-forming complexes that the JWST has started to unveil at redshifts 3–7, and it provides a glimpse into a still very poorly explored low-luminosity regime.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"266 1","pages":"L12"},"PeriodicalIF":6.5,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145956553","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 : 2026-01-12DOI: 10.1051/0004-6361/202557342
B. Agís-González, D. Hutsemékers, I. Liodakis, S. Cazzoli, D. Sluse, G. Miniutti, I. Márquez, J. Masegosa, F. Marin, J. A. Acosta-Pulido, C. Ramos Almeida
Context. X-ray quasi-periodic eruptions (QPEs) are repeating, high-amplitude, soft X-ray bursts observed from the nuclei of a dozen nearby low-mass galaxies. Their origin remains a major puzzle in the physics of accretion variability. Observational data indicate that X-ray and/or optical tidal disruption events (TDEs) may precede QPE detections. Although both kinds of outburst are driven by supermassive black holes, they are more frequently detected in faded active galactic nuclei (AGNs), when the TDE is not happening in a dormant galaxy. In the case of the QPE discovery source, GSN 069, observations and simulations have revealed evidence of past nuclear activity, although it remains debated whether this activity arose from a past AGN phase or from an enhanced TDE rate.Aims. We investigated the origin of the past nuclear activity in GSN 069.Methods. Past AGN activity imprints detectable polarization in optical light, due to the expected delay between direct and scattered light. On 6 September 2019, we targeted GSN 069 with VLT/FORS2 in both imaging polarimetry and spectropolarimetry modes so that its optical polarization could be investigated while the first detected QPE phase was still active.Results. We measured a rising polarization, from ∼0% to ∼1.5%, as moving away from the nucleus of GSN 069. This rise is probed to be intrinsic to the central engine, confirming the already detected extended emission line region (EELR) by integral field unit data.Conclusions. The increasing radial polarization demonstrates a switched-off nucleus. The polarization angle traces an axis aligned with elongated [OIII], [NII], and Hα gas distributions, revealing an EELR that may be consistent with relic polarization cones, therefore suggesting the presence of a torus-like structure in the past. Thus, optical polarization echoes geometrically favor a faded AGN as the origin of the EELR rather than a past elevated TDE rate, although the latter cannot be excluded.
{"title":"Polarization echoes from past nuclear activity in the quasi-periodic eruption source GSN 069","authors":"B. Agís-González, D. Hutsemékers, I. Liodakis, S. Cazzoli, D. Sluse, G. Miniutti, I. Márquez, J. Masegosa, F. Marin, J. A. Acosta-Pulido, C. Ramos Almeida","doi":"10.1051/0004-6361/202557342","DOIUrl":"https://doi.org/10.1051/0004-6361/202557342","url":null,"abstract":"<i>Context.<i/> X-ray quasi-periodic eruptions (QPEs) are repeating, high-amplitude, soft X-ray bursts observed from the nuclei of a dozen nearby low-mass galaxies. Their origin remains a major puzzle in the physics of accretion variability. Observational data indicate that X-ray and/or optical tidal disruption events (TDEs) may precede QPE detections. Although both kinds of outburst are driven by supermassive black holes, they are more frequently detected in faded active galactic nuclei (AGNs), when the TDE is not happening in a dormant galaxy. In the case of the QPE discovery source, GSN 069, observations and simulations have revealed evidence of past nuclear activity, although it remains debated whether this activity arose from a past AGN phase or from an enhanced TDE rate.<i>Aims.<i/> We investigated the origin of the past nuclear activity in GSN 069.<i>Methods.<i/> Past AGN activity imprints detectable polarization in optical light, due to the expected delay between direct and scattered light. On 6 September 2019, we targeted GSN 069 with VLT/FORS2 in both imaging polarimetry and spectropolarimetry modes so that its optical polarization could be investigated while the first detected QPE phase was still active.<i>Results.<i/> We measured a rising polarization, from ∼0% to ∼1.5%, as moving away from the nucleus of GSN 069. This rise is probed to be intrinsic to the central engine, confirming the already detected extended emission line region (EELR) by integral field unit data.<i>Conclusions.<i/> The increasing radial polarization demonstrates a switched-off nucleus. The polarization angle traces an axis aligned with elongated [OIII], [NII], and H<i>α<i/> gas distributions, revealing an EELR that may be consistent with relic polarization cones, therefore suggesting the presence of a torus-like structure in the past. Thus, optical polarization echoes geometrically favor a faded AGN as the origin of the EELR rather than a past elevated TDE rate, although the latter cannot be excluded.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"96 1","pages":"L13"},"PeriodicalIF":6.5,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145956526","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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