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Hi everyone,
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<div>This week’s lunch talk will be given by Jesse Golden-Marx on Thursday at 1pm in A113. Here is the title and abstract:</div>
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<div><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 14px;"><b>The Hierarchical Growth of Bright Central Galaxies and Intracluster Light as
Traced by the Magnitude Gap</b></span></div>
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<span style="font-size: 14px;">Intracluster light (ICL) is known to surround bright central galaxies (BCGs). However, it remains unclear if the hierarchical growth processes that build the BCG are simultaneously building the ICL. We address this question using
2800 galaxy clusters identified in the Dark Energy Survey across the redshift range 0.20<z<0.60. To quantify hierarchical formation we use the stellar mass - halo mass (SMHM) relation for the BCG+ICL system and incorporate the magnitude gap (M14), the difference
in brightness between the BCG (measured within 30kpc) and 4th brightest cluster member galaxy within 0.5
</span><span style="font-size: 14px;">R200c, a parameter which traces BCG hierarchical growth. We find that the correlation with M14 decreases at large radii from the BCG's centre. However, the stellar light within the BCG+ICL transition region (30kpc - 80kpc)
most strongly correlates with the dark matter halo mass and has a statistically significant correlation with M14. As the light in this region and M14 are independent measurements, the transition region may grow as a result of the BCG's hierarchical two-phase
formation. Additionally, we use a stacked sample and find that clusters with large M14 values are characterized by larger ICL and BCG+ICL fractions, which illustrates that the merger processes that build the BCG stellar mass also grow the ICL and may suggest
that M14 combined with the ICL fraction can be used as a method to identify dynamically relaxed clusters.</span></div>
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<font size="2">See you all there!</font></div>
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Joe</div>
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