Massimo Pascale, Liang Dai, Christopher F. McKee, Benny T.-H. Tsang
{"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":null,"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":4.8000,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Astrophysical Journal","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.3847/1538-4357/acf75c","RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
引用次数: 1
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 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.
期刊介绍:
The Astrophysical Journal is the foremost research journal in the world devoted to recent developments, discoveries, and theories in astronomy and astrophysics.