Abstract
We present a weak-lensing and dynamical study of the complex cluster Abell 1758 (A1758,
$\bar{z} = 0.278$
) supported by hydrodynamical simulations. This cluster is composed of two main ...structures called A1758N and A1758S. The northern structure is composed of A1758NW and A1758NE, with lensing determined masses of
$7.90_{-1.55}^{+1.89}$
× 1014 M⊙ and
$5.49_{-1.33}^{+1.67}$
× 1014 M⊙, respectively. They show a remarkable feature: while in A1758NW, there is a spatial agreement among weak-lensing mass distribution, intracluster medium and its brightest cluster galaxy (BCG), in A1758NE, the X-ray peak is located
$96_{-15}^{+14}$
arcsec away from the mass peak and BCG positions. Given the detachment between gas and mass, we could use the local surface mass density to estimate an upper limit for the dark matter self-interaction cross-section: σ/m < 5.83 cm2 g−1. Combining our velocity data with hydrodynamical simulations, we have shown that A1758 NW and NE had their closest approach 0.27 Gyr ago and their merger axis is 21° ± 12° from the plane of the sky. In the A1758S system, we have measured a total mass of
$4.96_{-1.19}^{+1.08} \times 10^{14}$
M⊙ and, using radial velocity data, we found that the main merger axis is located at 70° ± 4° from the plane of the sky, therefore closest to the line of sight.
Microgrids have emerged as a popular solution for electric energy distribution due to their reliability, sustainability, and growing accessibility. However, their implementation can be challenging, ...particularly due to regulatory and market issues. Building smaller-scale microgrids, also known as nanogrids, can present additional challenges, such as high investment costs that need to be justified by local demands. To address these challenges, this work proposes an economic feasibility assessment model that is applied to a real nanogrid under construction in the Brazilian electrical system, with electric vehicle charging stations as its main load. The model, which takes into account uncertainties, evaluates the economic viability of constructing a nanogrid using economic indicators estimated by the Monte Carlo simulation method, with the system operation represented by the OpenDSS software. The model also considers aspects of energy transactions within the net-metering paradigm, with energy compensation between the nanogrid and the main distribution network, and investigates how incentives can impact the viability of these microgrids.
We present a detailed strong-lensing, weak-lensing and X-ray analysis of Abell 2744 (z= 0.308), one of the most actively merging galaxy clusters known. It appears to have unleashed 'dark', 'ghost', ...'bullet' and 'stripped' substructures, each ∼1014 M⊙. The phenomenology is complex and will present a challenge for numerical simulations to reproduce. With new, multiband Hubble Space Telescope (HST) imaging, we identify 34 strongly lensed images of 11 galaxies around the massive Southern 'core'. Combining this with weak-lensing data from HST, VLT and Subaru, we produce the most detailed mass map of this cluster to date. We also perform an independent analysis of archival Chandra X-ray imaging. Our analyses support a recent claim that the Southern core and Northwestern substructure are post-merger and exhibit morphology similar to the Bullet Cluster viewed from an angle. From the separation between X-ray emitting gas and lensing mass in the Southern core, we derive a new and independent constraint on the self-interaction cross-section of dark matter particles σ/m < 3 ± 1 cm2 g−1. In the Northwestern substructure, the gas, dark matter and galaxy components have become separated by much larger distances. Most curiously, the 'ghost' clump (primarily gas) leads the 'dark' clump (primarily dark matter) by more than 150 kpc. We propose an enhanced 'ram-pressure slingshot' scenario which may have yielded this reversal of components with such a large separation, but needs further confirmation by follow-up observations and numerical simulations. A secondary merger involves a second 'bullet' clump in the North and an extremely 'stripped' clump to the West. The latter appears to exhibit the largest separation between dark matter and X-ray emitting baryons detected to date in our sky.
ABSTRACT
The galaxy cluster Abell 1644 ($\bar{z}=0.047$) is known for its remarkable spiral-like X-ray emission. It was previously identified as a bimodal system, comprising the subclusters, A1644S ...and A1644N, each one centred on a giant elliptical galaxy. In this work, we present a comprehensive study of this system, including new weak lensing and dynamical data and analysis plus a tailor-made hydrodynamical simulation. The lensing and galaxy density maps showed a structure in the North that could not be seen on the X-ray images. We, therefore, rename the previously known northern halo as A1644N1 and the new one as A1644N2. Our lensing data suggest that those have fairly similar masses: $M_{200}^{\rm N1}=0.90_{-0.85}^{+0.45} \times 10^{14}$ and $M_{200}^{\rm N2}=0.76_{-0.75}^{+0.37} \times 10^{14}$ M⊙, whereas the southern structure is the main one: $M_{200}^{\rm S}=1.90_{-1.28}^{+0.89}\times 10^{14}$ M⊙. Based on the simulations, fed by the observational data, we propose a scenario where the remarkable X-ray characteristics in the system are the result of a collision between A1644S and A1644N2 that happened ∼1.6 Gyr ago. Currently, those systems should be heading to a new encounter, after reaching their maximum separation.
Abstract
We present a stacked weak-lensing analysis of 27 richness selected galaxy clusters at 0.40 ≤ z ≤ 0.62 in the COnstrain Dark Energy with X-ray galaxy clusters (CODEX) survey. The fields were ...observed in five bands with the Canada–France–Hawaii Telescope (CFHT). We measure the stacked surface mass density profile with a 14σ significance in the radial range 0.1 < R Mpc h
−1 < 2.5. The profile is well described by the halo model, with the main halo term following a Navarro–Frenk–White profile (NFW) profile and including the off-centring effect. We select the background sample using a conservative colour–magnitude method to reduce the potential systematic errors and contamination by cluster member galaxies. We perform a Bayesian analysis for the stacked profile and constrain the best-fitting NFW parameters
$M_{200c} = 6.6^{+1.0}_{-0.8} \times 10^{14} \,h^{-1} \,\mathrm{M}_{{\odot }}$
and
$c_{200c} = 3.7^{+0.7}_{-0.6}$
. The off-centring effect was modelled based on previous observational results found for redMaPPer Sloan Digital Sky Survey clusters. Our constraints on M
200c
and c
200c
allow us to investigate the consistency with numerical predictions and select a concentration–mass relation to describe the high richness CODEX sample. Comparing our best-fitting values for M
200c
and c
200c
with other observational surveys at different redshifts, we find no evidence for evolution in the concentration–mass relation, though it could be mitigated by particular selection functions. Similar to previous studies investigating the X-ray luminosity–mass relation, our data suggest a lower evolution than expected from self-similarity.
The galaxy cluster Abell 3376 is a nearby ($$\bar{z}=0.046$$) dissociative merging cluster surrounded by two prominent radio relics and showing an X-ray comet-like morphology. The merger system is ...comprised of the subclusters A3376W and A3376E. Based on new deep multiwavelength large-field images and published redshifts, we bring new insights about the history of this merger. Despite the difficulty of applying the weak lensing technique at such low redshift, we successfully recovered the mass distribution in the cluster field. Moreover, with the application of a two-body model, we have addressed the dynamics of this merging system. We have found the individual masses of M$$_{200}^{\rm W}=3.0_{-1.7}^{+1.3}\times 10^{14}$$ M_⊙ and M$$_{200}^{\rm E}=0.9_{-0.8}^{+0.5}\times 10^{14}$$ M_⊙. The cometary-shaped X-ray distribution shows only one peak spatially coincident with both eastern BCG and the A3376E mass peak whereas the gas content of A3376W seems to be stripped out. Our data allowed us to confirm the existence of a third subcluster located at the north, 1147 ± 62 kpc apart from the neighbour subcluster A3376E and having a mass M$$_{200}^{\rm N}=1.4_{-1.0}^{+0.7}\times 10^{14}$$ M_⊙. From our dynamical analysis, we found the merging is taking place very close to the plane of the sky, with the merger axis just 10° ± 11° from it. The application of a two-body analysis code showed that the merging cluster is seen $$0.9_{-0.3}^{+0.2}$$ Gyr after the pericentric passage and it is currently going to the point of maximum separation between the subclusters.
ABSTRACT
The COnstrain Dark Energy with X-ray clusters (CODEX) sample contains the largest flux limited sample of X-ray clusters at 0.35 < z < 0.65. It was selected from ROSAT data in the 10 000 ...square degrees of overlap with BOSS, mapping a total number of 2770 high-z galaxy clusters. We present here the full results of the CFHT CODEX programme on cluster mass measurement, including a reanalysis of CFHTLS Wide data, with 25 individual lensing-constrained cluster masses. We employ lensfit shape measurement and perform a conservative colour–space selection and weighting of background galaxies. Using the combination of shape noise and an analytic covariance for intrinsic variations of cluster profiles at fixed mass due to large-scale structure, miscentring, and variations in concentration and ellipticity, we determine the likelihood of the observed shear signal as a function of true mass for each cluster. We combine 25 individual cluster mass likelihoods in a Bayesian hierarchical scheme with the inclusion of optical and X-ray selection functions to derive constraints on the slope α, normalization β, and scatter σln λ|μ of our richness–mass scaling relation model in log-space: ${\langle {\rm In}\,\, \lambda\!\!\mid\!\!\mu\rangle = \alpha\mu + \beta,}
$ with μ = ln (M200c/Mpiv), and Mpiv = 1014.81M⊙. We find a slope $\alpha = 0.49^{+0.20}_{-0.15}$, normalization $\exp (\beta) = 84.0^{+9.2}_{-14.8}$, and $\sigma _{\ln \lambda | \mu } = 0.17^{+0.13}_{-0.09}$ using CFHT richness estimates. In comparison to other weak lensing richness–mass relations, we find the normalization of the richness statistically agreeing with the normalization of other scaling relations from a broad redshift range (0.0 < z < 0.65) and with different cluster selection (X-ray, Sunyaev–Zeldovich, and optical).
Major mergers between massive clusters have a profound effect in the intracluster gas, which may be used as a probe of the dynamics of structure formation at the high end of the mass function. An ...example of such a merger is observed at the northern component of Abell 1758, comprising two massive sub-clusters separated by approximately 750 kpc. One of the clusters exhibits an offset between the dark matter and the intracluster gas. We aim to determine whether it is possible to reproduce the specific morphological features of this cluster by means of a major merger. We perform dedicated SPH (smoothed particle hydrodynamics) N-body simulations in an attempt to simultaneously recover several observed features of Abell 1758, such as the X-ray morphology and the separation between the two peaks in the projected galaxy luminosity map. We propose a specific scenario for the off-axis collision of two massive clusters. This model adequately reproduces several observed features and suggests that Abell 1758 is seen approximately 0.4 Gyr after the first pericentric passage, and that the clusters are already approaching their maximum separation. This means that their relative velocity is as low as 380 km s... At the same time, the simulated model entails shock waves of ~4500 km s..., which are currently undetected presumably due to the low-density medium. We explain the difference between these velocities and argue that the predicted shock fronts, while plausible, cannot be detected from currently available data. (ProQuest: ... denotes formulae/symbols omitted.)
ABSTRACT
Collision events lead to peculiar morphologies in the intracluster gas of galaxies clusters. That seems to be the case of Abell 1644, a nearby galaxy cluster, composed of three main ...structures: the southern cluster that exhibits a spiral-like morphology, A1644S; the northern cluster seen in X-ray observations, A1644N1; and the recently discovered substructure, A1644N2. By means of N-body hydrodynamical simulations, we attempt to reconstruct the dynamical history of this system. These simulations resulted in two specific scenarios: (i) The collision between A1644S and A1644N2. Our best model has an inclination between the merger plane and the plane of the sky of 30°, and reaches the best morphology 1.6 Gyr after the pericentric passage. At this instant A1644N2 is gas poor, becoming nearly undetectable in X-ray emission. This model shows a good agreement with observations; (ii) The collision between A1644S and A1644N1. This approach did not give rise to results as satisfactory as the first scenario, due to great disturbances in density and mismatching temperature maps. As a complementary study, we perform a three-cluster simulation using as base the best-fitting model to reproduce the current state of A1644 with the three main structures. This scenario presented a good agreement to the global morphology of the observations. Thus, we find that the more likely scenario is a collision between A1644S and the newly discovered A1644N2, where A1644N1 may be present as long as it does not greatly interfere in the formation of the spiral feature.
MiniJPAS is a ∼1 deg
2
imaging survey of the AEGIS field in 60 bands, performed to demonstrate the scientific potential of the upcoming Javalambre-Physics of the Accelerating Universe Astrophysical ...Survey (J-PAS). Full coverage of the 3800–9100 Å range with 54 narrow-band filters, in combination with 6 optical broad-band filters, allows for extremely accurate photometric redshifts (photo-
z
), which, applied over areas of thousands of square degrees, will enable new applications of the photo-
z
technique, such as measurement of baryonic acoustic oscillations. In this paper we describe the method we used to obtain the photo-
z
that is included in the publicly available miniJPAS catalogue, and characterise the photo-
z
performance. We built photo-spectra with 100 Å resolution based on forced-aperture photometry corrected for point spread function. Systematic offsets in the photometry were corrected by applying magnitude shifts obtained through iterative fitting with stellar population synthesis models. We computed photo-
z
with a customised version of L
E
P
HARE
, using a set of templates that is optimised for the J-PAS filter-set. We analysed the accuracy of miniJPAS photo-
z
and their dependence on multiple quantities using a subsample of 5266 galaxies with spectroscopic redshifts from SDSS and DEEP, which we find to be representative of the whole
r
< 23 miniJPAS sample. Formal 1
σ
uncertainties for the photo-
z
that are calculated with the Δ
χ
2
method underestimate the actual redshift errors. The
o
d
d
s
parameter has a stronger correlation with |Δ
z
| and accurately reproduces the probability of a redshift outlier (|Δ
z
| > 0.03), regardless of the magnitude, redshift, or spectral type of the sources. We show that the two main summary statistics characterising the photo-
z
accuracy for a population of galaxies (
σ
NMAD
and
η
) can be predicted by the distribution of
o
d
d
s
in this population, and we use this to estimate the statistics for the whole miniJPAS sample. At
r
< 23, there are ∼17 500 galaxies per deg
2
with valid photo-
z
estimates, ∼4200 of which are expected to have |Δ
z
| < 0.003. The typical error is
σ
NMAD
= 0.013 with an outlier rate
η
= 0.39. The target photo-
z
accuracy
σ
NMAD
= 0.003 is achieved for
o
d
d
s
> 0.82 with
η
= 0.05, at the cost of decreasing the density of selected galaxies to
n
∼ 5200 deg
−2
(∼2600 of which have |Δ
z
| < 0.003).
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