# An Assessment of the In-Situ Growth of the Intracluster Light in the High Redshift Galaxy Cluster SpARCS1049+56

**Authors:** Capucine Barfety, Félix-Antoine Valin, Tracy M. A. Webb, Min Yun, Heath Shipley, Kyle Boone, Brian Hayden, Julie Hlavacek-Larrondo, Adam Muzzin, Allison G. Noble, Saul Perlmutter, Carter Rhea, Gillian Wilson, H. K. C Yee  
**arXiv:** [2203.13764](https://arxiv.org/abs/2203.13764)  
**Date:** 2022-03-25  
**Summary page:** https://www.summarizepaper.com/en/paper/2203.13764v1/

## Key points

- Recent study focused on stellar mass formation in galaxy cluster cores, specifically the Brightest Cluster Galaxy (BCG) in high-redshift cluster SpARCS1049+56
- Insights gained through reanalyzed HST imaging, previous star formation rate measurements, and new radio molecular gas spectroscopy
- Clustered stellar mass found approximately 12 kpc away from BCG in a long, clumpy structure
- Mass spatially aligned with substantial reservoir of molecular gas likely fueling star formation rate of $860 \pm 130 M_\odot/yr
- Intense star-forming activity proposed to be driven by massive cooling flows from hot intracluster X-ray gas, not previously observed at such high redshifts
- Estimated contribution of event to Intracluster Light (ICL) mass between 15% and 21% in one instance
- Investigation sheds light on galactic evolution and complex interplay of physical processes shaping stellar growth within galaxy clusters
- Findings deepen understanding of star formation mechanisms in distant clusters and raise questions about broader implications for cosmic evolution

## Summary

A recent study delved into the complex process of stellar mass formation within galaxy cluster cores, specifically focusing on the Brightest Cluster Galaxy (BCG) in the high-redshift cluster SpARCS1049+56. By combining reanalyzed HST imaging, previous star formation rate measurements, and new radio molecular gas spectroscopy, researchers gained insights into the past, present, and future of star formation in this system. The analysis revealed a significant amount of clustered stellar mass ranging from $(2.2 \pm 0.5) \times 10^{10} M_\odot$ to $(6.6 \pm 1.2) \times 10^{10} M_\odot$, located approximately 12 kpc away from the BCG in a long, clumpy structure. This mass was found to be spatially aligned with a substantial reservoir of molecular gas totaling $(1.0 \pm 0.7) \times 10^{11} M_\odot$, likely fueling the remarkable star formation rate of $860 \pm 130 M_\odot/yr as observed through infrared studies. The researchers proposed that this intense star-forming activity was driven by massive cooling flows originating from hot intracluster X-ray gas—a phenomenon not previously observed at such high redshifts. This event was estimated to contribute between 15% and 21% of the Intracluster Light (ICL) mass in one instance, suggesting it may be rare within a cluster's lifespan but potentially common across galaxy clusters. This comprehensive investigation sheds light on an intriguing aspect of galactic evolution and highlights the complex interplay between various physical processes shaping stellar growth within galaxy cluster environments. The findings not only deepen our understanding of star formation mechanisms at play in distant clusters but also raise intriguing questions about the broader implications for cosmic evolution and intergalactic star formation dynamics.