ABSTRACT
We estimate the intracluster light (ICL) component within a sample of 18 clusters detected in the XMM Cluster Survey (XCS) data using the deep (∼26.8 mag) Hyper Suprime-Cam Subaru Strategic ...Programme data release 1 i-band data. We apply a rest-frame μB = 25 mag arcsec−2 isophotal threshold to our clusters, below which we define light as the ICL within an aperture of RX,500 (X-ray estimate of R500) centred on the brightest cluster galaxy (BCG). After applying careful masking and corrections for flux losses from background subtraction, we recover ∼20 per cent of the ICL flux, approximately four times our estimate of the typical background at the same isophotal level (${\sim}5{{\ \rm per\ cent}}$). We find that the ICL makes up about ${\sim}24{{\ \rm per\ cent}}$ of the total cluster stellar mass on average (∼41 per cent including the flux contained in the BCG within 50 kpc); this value is well matched with other observational studies and semi-analytic/numerical simulations, but is significantly smaller than results from recent hydrodynamical simulations (even when measured in an observationally consistent way). We find no evidence for any links between the amount of ICL flux with cluster mass, but find a growth rate of 2–4 for the ICL between 0.1 < z < 0.5. We conclude that the ICL is the dominant evolutionary component of stellar mass in clusters from z ∼ 1. Our work highlights the need for a consistent approach when measuring ICL alongside the need for deeper imaging, in order to unambiguously measure the ICL across as broad a redshift range as possible (e.g. 10-yr stacked imaging from the Vera C. Rubin Observatory).
ABSTRACT
We present a sample of 329 low-to intermediate-redshift (0.05 <z< 0.3) brightest cluster galaxies (BCGs) in X-ray-selected clusters from the SPectroscopic IDentification of eRosita Sources ...survey, a spectroscopic survey within Sloan Digital Sky Survey-IV (SDSS-IV). We define our BCGs by simultaneous consideration of legacy X-ray data from ROSAT, maximum-likelihood outputs from an optical cluster-finder algorithm and visual inspection. Using SDSS imaging data, we fit Sérsic profiles to our BCGs in three bands (g, r, i) with sigma a galfit-based software wrapper. We examine the reliability of our fits by running our pipeline on ∼104 point spread function-convolved model profiles injected into eight random cluster fields; we then use the results of this analysis to create a robust subsample of 198 BCGs. We outline three cluster properties of interest: overall cluster X-ray luminosity (LX), cluster richness as estimated by redMaPPer (λ),and cluster halo mass (M200), which is estimated via velocity dispersion. In general, there are significant correlations with BCG stellar mass between all three environmental properties, but no significant trends arise with either Sérsic index or effective radius. There is no major environmental dependence on the strength of the relation between effective radius and BCG stellar mass. Stellar mass therefore arises as the most important factor governing BCG morphology. Our results indicate that our sample consists of a large number of relaxed, mature clusters containing broadly homogeneous BCGs up to z ∼ 0.3, suggesting that there is little evidence for much ongoing structural evolution for BCGs in these systems.
We estimate the Intracluster Light (ICL) component within a sample of 18
clusters detected in XMM Cluster Survey (XCS) data using deep ($\sim$ 26.8 mag)
Hyper Suprime Cam Subaru Strategic Program DR1 ...(HSC-SSP DR1) $i$-band data. We
apply a rest-frame ${\mu}_{B} = 25 \ \mathrm{mag/arcsec^{2}}$ isophotal
threshold to our clusters, below which we define light as the ICL within an
aperture of $R_{X,500}$ (X-ray estimate of $R_{500}$) centered on the Brightest
Cluster Galaxy (BCG). After applying careful masking and corrections for flux
losses from background subtraction, we recover $\sim$20% of the ICL flux,
approximately four times our estimate of the typical background at the same
isophotal level ($\sim$ 5%). We find that the ICL makes up about $\sim$ 24% of
the total cluster stellar mass on average ($\sim$ 41% including the flux
contained in the BCG within 50 kpc); this value is well-matched with other
observational studies and semi-analytic/numerical simulations, but is
significantly smaller than results from recent hydrodynamical simulations (even
when measured in an observationally consistent way). We find no evidence for
any links between the amount of ICL flux with cluster mass, but find a growth
rate of $2-4$ for the ICL between $0.1 < z < 0.5$. We conclude that the ICL is
the dominant evolutionary component of stellar mass in clusters from $z \sim
1$. Our work highlights the need for a consistent approach when measuring ICL
alongside the need for deeper imaging, in order to unambiguously measure the
ICL across as broad a redshift range as possible (e.g. 10-year stacked imaging
from the Vera C. Rubin Observatory).
We present a sample of 329 low to intermediate redshift ($0.05 < z < 0.3$)
brightest cluster galaxies (BCGs) in X-ray selected clusters from the
SPectroscopic IDentification of eRosita Sources ...(SPIDERS) survey, a
spectroscopic survey within Sloan Digital Sky Survey-IV (SDSS-IV). We define
our BCGs by simultaneous consideration of legacy X-ray data from ROSAT, maximum
likelihood outputs from an optical cluster-finder algorithm and visual
inspection. Using SDSS imaging data, we fit S\'ersic profiles to our BCGs in
three bands (\textit{g}, \textit{r}, \textit{i}) with \textsc{SIGMA}, a
\textsc{GALFIT}-based software wrapper. We examine the reliability of our fits
by running our pipeline on ${\sim}10^{4}$ psf-convolved model profiles injected
into 8 random cluster fields, we then use the results of this analysis to
create a robust subsample of 198 BCGs. We outline three cluster properties of
interest: overall cluster X-ray luminosity ($L_{X}$), cluster richness as
estimated by \textsc{redMaPPer} ($ \lambda $) and cluster halo mass
($M_{200}$), which is estimated via velocity dispersion. In general, there are
significant correlations with BCG stellar mass between all three environmental
properties, but no significant trends arise with either S\'ersic index or
effective radius. There is no major environmental dependence on the strength of
the relation between effective radius and BCG stellar mass. Stellar mass
therefore arises as the most important factor governing BCG morphology. Our
results indicate that our sample consists of a large number of relaxed, mature
clusters containing broadly homogeneous BCGs up to $z \sim 0.3$, suggesting
that there is little evidence for much ongoing structural evolution for BCGs in
these systems.
We estimate the Intracluster Light (ICL) component within a sample of 18 clusters detected in XMM Cluster Survey (XCS) data using deep (\(\sim\) 26.8 mag) Hyper Suprime Cam Subaru Strategic Program ...DR1 (HSC-SSP DR1) \(i\)-band data. We apply a rest-frame \({\mu}_{B} = 25 \ \mathrm{mag/arcsec^{2}}\) isophotal threshold to our clusters, below which we define light as the ICL within an aperture of \(R_{X,500}\) (X-ray estimate of \(R_{500}\)) centered on the Brightest Cluster Galaxy (BCG). After applying careful masking and corrections for flux losses from background subtraction, we recover \(\sim\)20% of the ICL flux, approximately four times our estimate of the typical background at the same isophotal level (\(\sim\) 5%). We find that the ICL makes up about \(\sim\) 24% of the total cluster stellar mass on average (\(\sim\) 41% including the flux contained in the BCG within 50 kpc); this value is well-matched with other observational studies and semi-analytic/numerical simulations, but is significantly smaller than results from recent hydrodynamical simulations (even when measured in an observationally consistent way). We find no evidence for any links between the amount of ICL flux with cluster mass, but find a growth rate of \(2-4\) for the ICL between \(0.1 < z < 0.5\). We conclude that the ICL is the dominant evolutionary component of stellar mass in clusters from \(z \sim 1\). Our work highlights the need for a consistent approach when measuring ICL alongside the need for deeper imaging, in order to unambiguously measure the ICL across as broad a redshift range as possible (e.g. 10-year stacked imaging from the Vera C. Rubin Observatory).
We present a sample of 329 low to intermediate redshift (\(0.05 < z < 0.3\)) brightest cluster galaxies (BCGs) in X-ray selected clusters from the SPectroscopic IDentification of eRosita Sources ...(SPIDERS) survey, a spectroscopic survey within Sloan Digital Sky Survey-IV (SDSS-IV). We define our BCGs by simultaneous consideration of legacy X-ray data from ROSAT, maximum likelihood outputs from an optical cluster-finder algorithm and visual inspection. Using SDSS imaging data, we fit Sérsic profiles to our BCGs in three bands (\textit{g}, \textit{r}, \textit{i}) with \textsc{SIGMA}, a \textsc{GALFIT}-based software wrapper. We examine the reliability of our fits by running our pipeline on \({\sim}10^{4}\) psf-convolved model profiles injected into 8 random cluster fields, we then use the results of this analysis to create a robust subsample of 198 BCGs. We outline three cluster properties of interest: overall cluster X-ray luminosity (\(L_{X}\)), cluster richness as estimated by \textsc{redMaPPer} (\( \lambda \)) and cluster halo mass (\(M_{200}\)), which is estimated via velocity dispersion. In general, there are significant correlations with BCG stellar mass between all three environmental properties, but no significant trends arise with either Sérsic index or effective radius. There is no major environmental dependence on the strength of the relation between effective radius and BCG stellar mass. Stellar mass therefore arises as the most important factor governing BCG morphology. Our results indicate that our sample consists of a large number of relaxed, mature clusters containing broadly homogeneous BCGs up to \(z \sim 0.3\), suggesting that there is little evidence for much ongoing structural evolution for BCGs in these systems.
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