3 research outputs found
A New Galaxy Cluster Merger Capable of Probing Dark Matter: Abell 56
We report the discovery of a binary galaxy cluster merger via a search of the
redMaPPer optical cluster catalog, with a projected separation of 535 kpc
between the BCGs. Archival XMM-Newton spectro-imaging reveals a gas peak
between the BCGs, suggesting a recent pericenter passage. We conduct a galaxy
redshift survey to quantify the line-of-sight velocity difference (
km/s) between the two subclusters. We present weak lensing mass maps from
archival HST/ACS imaging, revealing masses of
and M associated with the southern and
northern galaxy subclusters respectively. We also present deep GMRT 650 MHz
data revealing extended emission, 420 kpc long, which may be an AGN tail but is
potentially also a candidate radio relic. We draw from cosmological n-body
simulations to find analog systems, which imply that this system is observed
fairly soon (60-271 Myr) after pericenter, and that the subcluster separation
vector is within 22 of the plane of the sky, making it suitable for an
estimate of the dark matter scattering cross section. We find cm/g, suggesting that further study of this system could
support interestingly tight constraints.Comment: accepted to Ap
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A New Dissociative Galaxy Cluster Merger: RM J150822.0+575515.2
Abstract:
Galaxy cluster mergers that exhibit clear dissociation between their dark matter, intracluster gas, and stellar components are great laboratories for probing dark matter properties. Mergers that are binary and in the plane of the sky have the additional advantage of being simpler to model, allowing for a better understanding of the merger dynamics. We report the discovery of a galaxy cluster merger with all these characteristics and present a multiwavelength analysis of the system, which was found via a search in the redMaPPer optical cluster catalog. We perform a galaxy redshift survey to confirm the two subclusters are at the same redshift (0.541, with 368 ± 519 km s−1 line-of-sight velocity difference between them). The X-ray morphology shows two surface brightness peaks between the brightest cluster galaxies (BCGs). We construct weak-lensing mass maps that reveal a mass peak associated with each subcluster. Fitting Navarro–Frenk–White profiles to the lensing data, we find masses of M
200c = 36 ± 11 × 1013 and 38 ± 11 × 1013
M
⊙
h
−1 for the southern and northern subclusters, respectively. From the mass maps, we infer that the two mass peaks are separated by
520
−
125
+
162
kpc along the merger axis, whereas the two BCGs are separated by 697 kpc. We also present deep GMRT 650 MHz data to search for a radio relic or halo and find none. Using the observed merger parameters, we find analog systems in cosmological n-body simulations and infer that this system is observed between 96 and 236 Myr after pericenter, with the merger axis within 28° of the plane of the sky
Recommended from our members
A New Galaxy Cluster Merger Capable of Probing Dark Matter: A56
We report the discovery of a binary galaxy cluster merger via a search of the redMaPPer optical cluster catalog, with a projected separation of 535 kpc between the brightest cluster galaxies (BCGs). Archival XMM-Newton spectro-imaging reveals a gas peak between the BCGs, suggesting a recent pericenter passage. We conduct a galaxy redshift survey to quantify the line-of-sight velocity difference (153 ± 281 km s−1) between the two subclusters. We present weak-lensing mass maps from archival Hubble Space Telescope Advanced Camera for Surveys (HST/ACS) imaging, revealing masses of M 200 = 4.5 ± 0.8 × 1014 and 2.8 ± 0.7 × 1014 M ⊙ associated with the southern and northern galaxy subclusters, respectively. We also present deep GMRT 650 MHz data revealing extended emission, 420 kpc long, which may be an active galactic nucleus (AGN) tail but is potentially also a candidate radio relic. We draw from cosmological n-body simulations to find analog systems, which imply that this system is observed fairly soon (60-271 Myr) after pericenter, and that the subcluster separation vector is within 22° of the plane of the sky, making it suitable for an estimate of the dark matter scattering cross section. We find σ DM m = 1.1 ± 0.6 cm2 g−1, suggesting that further study of this system could support interestingly tight constraints