2016/10/31 by Takahiro Morishita, Louis E. Abramson, Tommaso Treu +3 · 2 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Brightest cluster galaxy #Cluster (spacecraft) #Cosmology #Field (mathematics) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy cluster #Hubble space telescope #Intracluster medium #Space (punctuation) #Stellar mass #astro-ph.GA
paper · pdf · doi:10.3847/1538-4357/aa8403
Accepted for Publication in The Astrophysical Journal
arxiv created 2017/08/01 · openalex created_date 2017/08/17 · openalex publication_date 2017/09/10 · arxiv updated 2017/09/20 · openalex updated_date 2026/08/06
Abstract We investigate the intracluster light (ICL) in the six Hubble Frontier Field clusters at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>0.3</mml:mn> <mml:mo><</mml:mo> <mml:mi>z</mml:mi> <mml:mo><</mml:mo> <mml:mn>0.6</mml:mn> </mml:math> . We employ a new method, which is free from any functional form of the ICL profile, and exploit the unprecedented depth of this Hubble Space Telescope imaging to map the ICL’s diffuse light out to clustrocentric radii <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>R</mml:mi> <mml:mo>∼</mml:mo> <mml:mn>300</mml:mn> <mml:mspace width="0.25em"/> <mml:mi>kpc</mml:mi> </mml:math> ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>μ</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>ICL</mml:mi> </mml:mrow> </mml:msub> <mml:mo>∼</mml:mo> <mml:mn>27</mml:mn> </mml:math> mag arcsec −2 ). From these maps, we construct radial color and stellar mass profiles via SED fitting and find clear negative color gradients in all systems with increasing distance from the Brightest Cluster Galaxy (BCG). While this implies older/more metal-rich stellar components in the inner part of the ICL, we find that the ICL mostly consists of a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>≲</mml:mo> <mml:mn>2</mml:mn> <mml:mspace width="0.25em"/> <mml:mi>Gyr</mml:mi> </mml:math> population, and plausibly originated with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>*</mml:mo> </mml:mrow> </mml:msub> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> <mml:mo>≲</mml:mo> <mml:mn>10</mml:mn> </mml:math> cluster galaxies. Furthermore, we find that 10%–15% of the ICL’s mass at large radii ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>≳</mml:mo> <mml:mn>150</mml:mn> </mml:math> kpc) lies in a younger/bluer stellar population (∼1 Gyr), a phenomenon not seen in local samples. We attribute this light to the higher fraction of star-forming/(post-)starburst galaxies in clusters at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>z</mml:mi> <mml:mo>∼</mml:mo> <mml:mn>0.5</mml:mn> </mml:math> . Ultimately, we find the ICL’s total mass to be <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:msubsup> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>*</mml:mo> </mml:mrow> <mml:mrow> <mml:mi>ICL</mml:mi> </mml:mrow> </mml:msubsup> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> <mml:mo>∼</mml:mo> <mml:mn>11</mml:mn> </mml:math> –12, constituting 5%–20% of the clusters’ total stellar mass, or about half of the value at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>z</mml:mi> <mml:mo>∼</mml:mo> <mml:mn>0</mml:mn> </mml:math> . The above implies distinct formation histories for the ICL and BCGs/other massive cluster galaxies; i.e., the ICL at this epoch is still being constructed rapidly ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>∼</mml:mo> <mml:mn>40</mml:mn> <mml:mspace width="0.25em"/> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> </mml:math> yr −1 ), while the BCGs have mostly completed their evolution. To be consistent with the ICL measurements of local massive clusters, such as Virgo, our data suggest mass acquisition mainly from quiescent cluster galaxies is the principal source of ICL material in the subsequent ∼5 Gyr of cosmic time.