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arXiv 2407.01685astro-ph.GA
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在宇宙正午强透镜星系SDSS J0901+1814中分辨恒星形成率与气体示踪剂的比较

Comparisons Between Resolved Star Formation Rate and Gas Tracers in the Strongly Lensed Galaxy SDSS J0901+1814 at Cosmic Noon

Qingxiang Chen, Chelsea E. Sharon, Hiddo S. Algera, Andrew J. Baker, Charles R. Keeton, Dieter Lutz, Daizhong Liu, Anthony J. Young, Amit Tagore, Jesus Rivera, … 展开作者

Qingxiang Chen, Chelsea E. Sharon, Hiddo S. Algera, Andrew J. Baker, Charles R. Keeton, Dieter Lutz, Daizhong Liu, Anthony J. Young, Amit Tagore, Jesus Rivera, Erin K. Hicks, Sahar S. Allam, Douglas L. Tucker

AI总结:

本文通过对宇宙正午强透镜星系SDSS J0901+1814的多波段观测,比较了不同恒星形成率和气体示踪剂在千秒差距尺度上的Schmidt-Kennicutt关系,发现红外示踪SFR斜率最陡,而CO(7-6)和CI跃迁不适合示踪主体分子气体。

摘要:

我们报告了对SDSS J090122.37+181432.3的新射电观测,这是一个位于z=2.26的强透镜恒星形成星系。我们使用VLA对1.4 GHz(L波段)和3 GHz(S波段)连续谱进行成像,并使用ALMA对1.2 mm(波段6)连续谱进行成像,此外还观测了CO(7-6)和CI(3P2→3P1)谱线,所有观测的分辨率均优于约1.7角秒。基于VLA的积分流量密度,我们将射电谱分解为自由-自由(FF)辐射和非热辐射成分。红外-射电相关(IRRC)参数qTIR=2.65_{-0.31}^{+0.24}与恒星形成星系的预期一致。我们获得了不受尘埃消光影响的射电连续谱恒星形成率(SFR),从FF辐射、非热辐射以及同时考虑两种辐射过程得到的值分别为620_{-220}^{+280} M⊙ yr^{-1}、230_{-160}^{+570} M⊙ yr^{-1}和280_{-120}^{+460} M⊙ yr^{-1},与之前的结果一致。我们根据CI(3P2→3P1)谱线估计气体质量为M_gas=(1.2±0.2)×10^{11} M⊙,与先前由CO(1-0)导出的气体质量一致。利用我们新的红外和射电连续谱数据绘制SFR图,我们评估了在约千秒差距尺度上Schmidt-Kennicutt关系对SFR和气体示踪剂选择的依赖性。不同的SFR示踪剂产生不同的斜率,其中红外斜率最陡,这可能是由于J0901中存在高度遮蔽的恒星形成。射电连续谱图在绘制SFR时具有最低的斜率和整体保真度,尽管其产生的总SFR是一致的。我们还发现,当使用CO(7-6)或CI(3P2→3P1)来示踪气体质量时,Schmidt-Kennicutt关系的斜率最平坦,这表明这些跃迁不适合用于示踪像J0901这样的星系中的主体分子气体。

英文摘要:

We report new radio observations of SDSS J090122.37+181432.3, a strongly lensed star-forming galaxy at $z=2.26$. We image 1.4 GHz (L-band) and 3 GHz (S-band) continuum using the VLA and 1.2 mm (band 6) continuum with ALMA, in addition to the CO(7-6) and CI(${\rm ^3P_2\rightarrow ^3\!P_1}$) lines, all at $\lesssim1.^{\prime\prime}7$ resolution. Based on the VLA integrated flux densities, we decompose the radio spectrum into its free-free (FF) and non-thermal components. The infrared-radio correlation (IRRC) parameter $q_{\rm TIR}=2.65_{-0.31}^{+0.24}$ is consistent with expectations for star forming galaxies. We obtain radio continuum-derived SFRs that are free of dust extinction, finding $\rm {620}_{-220}^{+280}\,M_\odot\,yr^{-1}$, $\rm {230}_{-160}^{+570}\,M_\odot\,yr^{-1}$, and $\rm {280}_{-120}^{+460}\,M_\odot\,yr^{-1}$ from the FF emission, non-thermal emission, and when accounting for both emission processes, respectively, in agreement with previous results. We estimate the gas mass from the CI(${\rm ^3P_2\rightarrow ^3\!P_1}$) line as $M_{\rm gas}=(1.2\pm0.2)\times10^{11}\,M_\odot$, which is consistent with prior CO(1-0)-derived gas masses. Using our new IR and radio continuum data to map the SFR, we assess the dependence of the Schmidt-Kennicutt relation on choices of SFR and gas tracer for $\sim{\rm kpc}$ scales. The different SFR tracers yield different slopes, with the IR being the steepest, potentially due to highly obscured star formation in J0901. The radio continuum maps have the lowest slopes and overall fidelity for mapping the SFR, despite producing consistent total SFRs. We also find that the Schmidt-Kennicutt relation slope is flattest when using CO(7-6) or CI(${\rm ^3P_2\rightarrow ^3\!P_1}$) to trace gas mass, suggesting that those transitions are not suitable for tracing the bulk molecular gas in galaxies like J0901.

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