Post-Starbursts as Laboratories: Probing Star Formation Quenching and Late Phases of Stellar Evolution with NIRWALS

后星暴实验室：用 NIRWALS 探测恒星形成淬灭和恒星演化的后期阶段

• 批准号: 2307082
• 负责人: Christy Tremonti
• 金额: $ 65.51万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2307082&HistoricalAwards=false
• 关键词: Post; Starbursts; Laboratories; Probing; Star

Galaxies can be thought of as star forming "factories," where various processes (e.g., density waves, tidal forces, mergers, gas inflows) act to create regions of dense, gravitationally unstable gas, which subsequently fragment and collapse into stars. Depending on the specific process involved, this could result in a fairly constant star formation rate (SFR) or in an intense but short- lived episode, largely confined to the galaxy's nucleus and often accompanied by gas accreting onto a supermassive blackhole. Starburst galaxies are examples of the latter. In extreme cases the starburst is followed by a lengthy 'post-starburst' phase in which star formation is largely extinguished or 'quenched.' The principal investigator (PI) will lead a team investigating this quenching in a large sample of local post-starburst galaxies using a near-infrared (NIR) integral field spectrograph. Improved stellar evolution models will also be tested. The proposed work will also provide research experience and training for undergraduate students, provide material for a PhD thesis, and deliver a large astronomical dataset to the public domain. The team will observe a sample of 50 post-starburst galaxies using a new NIR integral-field spectrograph (NIRWALS) on the 11-meter Southern African Large Telescope (SALT). A key question is whether star formation quenching is caused by a lowered SFE or if it is caused by the violent blow-out of gas by supernova and/or or accreting supermassive blackholes. NIR hydrogen Paschen emission lines will be used to measure accurate star formation rates, with SFE estimated in combination with existing CO data. NIR emission lines of helium, sulfur, and iron will be used to reveal shocked gas and to determine if central supermassive blackholes actively inject energy into the gas. The team will compare post-starburst galaxies’ starlight to predictions of new stellar evolutionary synthesis models. These models include improved treatment of the late stages of stellar evolution that dominate the NIR emission of stellar populations between 0.5 to 2 billion years old (roughly the post-burst age of the observed galaxies). Correctly calibrating these models is critical for understanding the build-up of stellar mass in galaxies over cosmic time.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

可以将星系视为形成“工厂”的星系，其中各种过程（例如密度波，潮汐力，合并，气体流入）作用着建立致密的，重力不稳定的气体区域，随后碎片碎片并塌陷成恒星。根据所涉及的特定过程，这可能导致相当恒定的恒星形成率（SFR），也可能导致剧烈但短暂的发作，在很大程度上限于银河系的核，并且经常伴随着气体积聚到超大型黑洞上。 Starburst星系是后者的例子。在极端情况下，星爆之后是一个漫长的“恒星后”阶段，其中恒星形成在很大程度上被熄灭或“淬火”。首席研究员（PI）将领导一个团队，使用近红外（NIR）集成场光谱仪，在大量当地的季后星系中调查这一淬火。改进的恒星进化模型也将进行测试。拟议的工作还将为本科生提供研究经验和培训，为博士学位论文提供材料，并向公共领域提供大型的天文数据集。该团队将使用新的NIR Integrales-Field光谱仪（NIRWALS）在11米南部非洲大型望远镜（SALT）上观察50个恒星后星系。一个关键的问题是，恒星形成是否是由SFE降低的降低引起的，还是由超新星和/或接受超级质量黑洞的气体暴力吹出引起的。 NIR氢气发射线将用于测量准确的恒星形成速率，并估计SFE与现有的CO数据结合使用。 NIR发射线将使用氦，硫和铁的发射线来揭示震动的气体，并确定中央超级黑孔是否积极地注入气体中。该团队将将恒星后星系的星光与对新恒星进化合成模型的预测进行比较。这些模型包括改进了对恒星进化的晚期治疗，该阶段占主导地位的恒星种群在0.5至20亿年之间的NIR发射（大约是观察到的星系后的爆发后年龄）。正确校准这些模型对于理解宇宙时间内星系中恒星质量的积累至关重要。该奖项反映了NSF的法定任务，并通过使用基金会的知识分子优点和更广泛的影响评估标准来评估值得支持。