تقرير
Phase-space Properties and Chemistry of the Sagittarius Stellar Stream Down to the Extremely Metal-poor ($\rm[Fe/H] \lesssim -3$) Regime
| العنوان: | Phase-space Properties and Chemistry of the Sagittarius Stellar Stream Down to the Extremely Metal-poor ($\rm[Fe/H] \lesssim -3$) Regime |
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| المؤلفون: | Limberg, Guilherme, Queiroz, Anna B. A., Perottoni, Hélio D., Rossi, Silvia, Amarante, João A. S., Santucci, Rafael M., Chiappini, Cristina, Pérez-Villegas, Angeles, Lee, Young Sun |
| سنة النشر: | 2022 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Astrophysics of Galaxies |
| الوصف: | In this work, we study the phase-space and chemical properties of Sagittarius (Sgr) stream, the tidal tails produced by the ongoing destruction of Sgr dwarf spheroidal (dSph) galaxy, focusing on its very metal-poor (VMP; $\rm[Fe/H] < -2$) content. We combine spectroscopic and astrometric information from SEGUE and $Gaia$ EDR3, respectively, with data products from a new large-scale run of $\texttt{StarHorse}$ spectro-photometric code. Our selection criteria yields ${\sim}1600$ stream members, including ${>}200$ VMP stars. We find the leading arm ($b>0^\circ$) of Sgr stream to be more metal-poor, by ${\sim}0.2$ dex, than the trailing one ($b<0^\circ$). With a subsample of turnoff and subgiant stars, we estimate this substructure's stellar population to be ${\sim}1$ Gyr older than the thick disk's. With the aid of an $N$-body model of the Sgr system, we verify that simulated particles stripped earlier (${>}2$ Gyr ago) have present-day phase-space properties similar to lower-metallicity stream stars. Conversely, those stripped more recently (${<}2$ Gyr) are preferentially more akin to metal-rich ($\rm[Fe/H] > -1$) members of the stream. Such correlation between kinematics and chemistry can be explained by the existence of a dynamically hotter, less centrally-concentrated, and more metal-poor population in Sgr dSph prior to its disruption, implying that this galaxy was able to develop a metallicity gradient before its accretion. Finally, we discovered several carbon-enhanced metal-poor ($\rm[C/Fe] > +0.7$ and $\rm[Fe/H] \leq -1.5$) stars in Sgr stream, which is in tension with current observations of its remaining core where such objects are not found. Comment: Accepted for ApJ. The arXiv was updated to match the accepted version |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.3847/1538-4357/acb694 |
| URL الوصول: | http://arxiv.org/abs/2212.08249 |
| رقم الأكسشن: | edsarx.2212.08249 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.3847/1538-4357/acb694 |
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