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Register a new userPressure profiles and mass estimates using high-resolution Sunyaev-Zeldovich effect observations of Zwicky 3146 with MUSTANG-2
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The galaxy cluster Zwicky 3146 is a sloshing cool core cluster at $z=0.291$ that in X-ray imaging does not appear to exhibit significant pressure substructure in the intracluster medium (ICM). The published $M_{500}$ values range between $3.88^{+0.62}_{-0.58}$ to $22.50 pm 7.58 times 10^{14}$ M$_{odot}$, where ICM-based estimates with reported errors $<20$% suggest that we should expect to find a mass between $6.53^{+0.44}_{-0.44} times 10^{14}$ M$_{odot}$ (from Planck, with an $8.4sigma$ detection) and $8.52^{+1.77}_{-1.47} times 10^{14}$ M$_{odot}$ (from ACT, with a $14sigma$ detection). This broad range of masses is suggestive that there is ample room for improvement for all methods. Here, we investigate the ability to estimate the mass of Zwicky 3146 via the Sunyaev-Zeldovich (SZ) effect with data taken at 90 GHz by MUSTANG-2 to a noise level better than $15 mu$K at the center, and a cluster detection of $104sigma$. We derive a pressure profile from our SZ data which is in excellent agreement with that derived from X-ray data. From our SZ-derived pressure profiles, we infer $M_{500}$ and $M_{2500}$ via three methods -- $Y$-$M$ scaling relations, the virial theorem, and hydrostatic equilibrium -- where we employ X-ray constraints from emph{XMM-Newton} on the electron density profile when assuming hydrostatic equilibrium. Depending on the model and estimation method, our $M_{500}$ estimates range from $6.23 pm 0.59$ to $10.6 pm 0.95 times 10^{14}$ M$_{odot}$, where our estimate from hydrostatic equilibrium, is $8.29^{+1.93}_{-1.24}$ ($pm 19.1$% stat) ${}^{+0.74}_{-0.68}$ ($pm 8.6$% sys, calibration) $times 10^{14}$ M$_{odot}$. Our fiducial mass, derived from a $Y$-$M$ relation is $8.16^{+0.44}_{-0.54}$ ($pm 5.5$% stat) ${}^{+0.46}_{-0.43}$ ($pm 5.5$% sys, $Y$-$M$) ${}^{+0.59}_{-0.55}$ ($pm 7.0$% sys, cal.) $times 10^{14}$ M$_{odot}$.
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We present a technique to constrain galaxy cluster pressure profiles by jointly fitting Sunyaev-Zeldovich effect (SZE) data obtained with MUSTANG and Bolocam for the clusters Abell 1835 and MACS0647. Bolocam and MUSTANG probe different angular scales and are thus highly complementary. We find that the addition of the high resolution MUSTANG data can improve constraints on pressure profile parameters relative to those derived solely from Bolocam. In Abell 1835 and MACS0647, we find gNFW inner slopes of $gamma = 0.36_{-0.21}^{+0.33}$ and $gamma = 0.38_{-0.25}^{+0.20}$, respectively when $alpha$ and $beta$ are constrained to 0.86 and 4.67 respectively. The fitted SZE pressure profiles are in good agreement with X-ray derived pressure profiles.
We present pressure profiles of galaxy clusters determined from high resolution Sunyaev-Zeldovich (SZ) effect observations of fourteen clusters, which span the redshift range $ 0.25 < z < 0.89$. The procedure simultaneously fits spherical cluster models to MUSTANG and Bolocam data. In this analysis, we adopt the generalized NFW parameterization of pressure profiles to produce our models. Our constraints on ensemble-average pressure profile parameters, in this study $gamma$, $C_{500}$, and $P_0$, are consistent with those in previous studies, but for individual clusters we find discrepancies with the X-ray derived pressure profiles from the ACCEPT2 database. We investigate potential sources of these discrepancies, especially cluster geometry, electron temperature of the intracluster medium, and substructure. We find that the ensemble mean profile for all clusters in our sample is described by the parameters: $[gamma,C_{500},P_0] = [0.3_{-0.1}^{+0.1}, 1.3_{-0.1}^{+0.1}, 8.6_{-2.4}^{+2.4}]$, for cool core clusters: $[gamma,C_{500},P_0] = [0.6_{-0.1}^{+0.1}, 0.9_{-0.1}^{+0.1}, 3.6_{-1.5}^{+1.5}]$, and for disturbed clusters: $[gamma,C_{500},P_0] = [0.0_{-0.0}^{+0.1}, 1.5_{-0.2}^{+0.1},13.8_{-1.6}^{+1.6}]$. Four of the fourteen clusters have clear substructure in our SZ observations, while an additional two clusters exhibit potential substructure.
We present 10 to 18 images of four massive clusters of galaxies through the Sunyaev-Zeldovich Effect (SZE). These measurements, made at 90~GHz with the MUSTANG receiver on the Green Bank Telescope (GBT), reveal pressure sub-structure to the intra-cluster medium (ICM) in three of the four systems. We identify the likely presence of a previously unknown weak shock-front in MACS0744+3927. By fitting the Rankine-Hugoniot density jump conditions in a complementary SZE/X-ray analysis, we infer a Mach number of M = 1.2^{+0.2}_{-0.2} and a shock-velocity of 1827^{+267}_{-195}~km/s. In RXJ1347-1145, we present a new reduction of previously reported data and confirm the presence of a south-east SZE enhancement with a significance of 13.9 sigma when smoothed to 18 resolution. This too is likely caused by shock-heated gas produced in a recent merger. In our highest redshift system, CL1226+3332, we detect sub-structure at a peak significance of 4.6 sigma in the form of a ridge oriented orthogonally to the vector connecting the main mass peak and a sub-clump revealed by weak lensing. We also conclude that the gas distribution is elongated in a south-west direction, consistent with a previously proposed merger scenario. The SZE image of the cool core cluster Abell 1835 is, in contrast, consistent with azimuthally symmetric signal only. This pilot study demonstrates the potential of high-resolution SZE images to complement X-ray data and probe the dynamics of galaxy clusters
We present high resolution (9$^{prime prime}$) imaging of the Sunyaev-Zeldovich Effect (SZE) toward two massive galaxy clusters, MACS J0647.7+7015 ($z=0.591$) and MACS J1206.2-0847 ($z=0.439$). We compare these 90 GHz measurements, taken with the MUSTANG receiver on the Green Bank Telescope, with generalized Navarro-Frenk-White (gNFW) models derived from Bolocam 140 GHz SZE data as well as maps of the thermal gas derived from {it Chandra} X-ray observations. For MACS J0647.7+7015, we find a gNFW profile with core slope parameter $gamma= 0.9$ fits the MUSTANG image with $chi^{2}_{red}=1.005$ and probability to exceed (PTE) = 0.34. For MACS J1206.2-0847, we find $gamma=0.7$, $chi^{2}_{red}=0.993$, and PTE = 0.70. In addition, we find a significant ($>$3-$sigma$) residual SZE feature in MACS J1206.2-0847 coincident with a group of galaxies identified in VLT data and filamentary structure found in a weak-lensing mass reconstruction. We suggest the detected sub-structure may be the SZE decrement from a low mass foreground group or an infalling group. GMRT measurements at 610 MHz reveal diffuse extended radio emission to the west, which we posit is either an AGN-driven radio lobe, a bubble expanding away from disturbed gas associated with the SZE signal, or a bubble detached and perhaps re-accelerated by sloshing within the cluster. Using the spectroscopic redshifts available, we find evidence for a foreground ($z=0.423$) or infalling group, coincident with the residual SZE feature.
The Sunyaev-Zeldovich (SZ) effect is a powerful tool for studying clusters of galaxies and cosmology. Large mm-wave telescopes are now routinely detecting and mapping the SZ effect in a number of clusters, measure their comptonisation parameter and use them as probes of the large-scale structure and evolution of the universe. We show that estimates of the physical parameters of clusters (optical depth, plasma temperature, peculiar velocity, non-thermal components etc.) obtained from ground-based multi-band SZ photometry can be significantly biased, owing to the reduced frequency coverage, to the degeneracy between the parameters and to the presence of a number of independent components larger than the number of frequencies measured. We demonstrate that low-resolution spectroscopic measurements of the SZ effect that also cover frequencies $> 270$ GHz are effective in removing the degeneracy. We used accurate simulations of observations with lines-of-sight through clusters of galaxies with different experimental configurations (4-band photometers, 6-band photometer, multi-range differential spectrometer, full coverage spectrometers) and different intracluster plasma stratifications. We find that measurements carried out with ground-based few-band photometers are biased towards high electron temperatures and low optical depths, and require coverage of high frequency and/or independent complementary observations to produce unbiased information; a differential spectrometer that covers 4 bands with a resolution of $sim 6 GHz$ eliminates most if not all bias; full-range differential spectrometers are the ultimate resource that allows a full recovery of all parameters.
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