Search

We present the serendipitous discovery of (1) a large double radio relic associated with the galaxy cluster PSZ2 G277.93 + 12.34 and (2) a new odd radio circle, ORC J1027–4422, both found in the same deep MeerKAT 1.3 GHz wide-band radio continuum image. The angular separation of the two arc-shaped cluster relics is ∼16 arcmin or ∼2.6 Mpc for a cluster redshift of z ≈ 0.158. The thin southern relic, which shows several ridges/shocks including one possibly moving inwards, has a linear extent of ∼1.64 Mpc. In contrast, the northern relic is about twice as wide, twice as bright, but only has a largest linear size of ∼0.66 Mpc. Complementary SRG/eROSITA X-ray images reveal extended emission from hot intracluster gas between the two relics and around the narrow-angle tail (NAT) radio galaxy PMN J1033–4335 (z ≈ 0.153) located just east of the northern relic. The radio morphologies of the NAT galaxy and the northern relic, which are also detected with the Australian Square Kilometer Array Pathfinder (ASKAP) at 888 MHz, suggest both are moving in the same outward direction. The discovery of ORC J1027–4422 in a different part of the same MeerKAT image makes it the fourth known single ORC. It has a diameter of ∼90 arcsec corresponding to 400 kpc at a tentative redshift of z ≈ 0.3 and remains undetected in X-ray emission. Supported by simulations, we discuss similarities between outward moving galaxy and cluster merger shocks as the formation mechanisms for ORCs and radio relics, respectively. [ABSTRACT FROM AUTHOR]

The INSPIRE project has built the largest sample of ultra-compact massive galaxies (UCMGs) at 0.1 < z < 0.4 and obtained their star formation histories (SFHs). Due to their preserved very old stellar populations, relics are the perfect systems to constrain the earliest epochs of mass assembly in the Universe and the formation of massive early-type galaxies. The goal of this work is to investigate whether a correlation exists between the degree of relicness (DoR), quantifying the fraction of stellar mass formed at z > 2, and the other stellar population parameters. We use the Full-Index-Fitting method to fit the INSPIRE spectra to single stellar population (SSP) models. This allows us to measure, for the first time, the slope of the IMF, as well as stellar metallicity [M/H], [Mg/Fe], [Ti/Fe], and [Na/Fe] ratios, and study correlations between them and the DoR. Similarly to normal-sized galaxies, UCMGs with larger stellar masses have overall higher metallicities. We found a correlation between the IMF slope and the DoR, that, however, breaks down for systems with a more extended SFH. An even stronger dependency is found between the IMF and the fraction of mass formed at high- z. At equal velocity dispersion and metallicity, galaxies with a higher DoR have a larger dwarf-to-giant ratio, i.e. a bottom heavy IMF, than that of low-DoR counterparts. This might indicate that the cosmic epoch and therefore different formation scenarios influence the fragmentation of the star formation cloud and hence might be the explanation for IMF variations detected in massive ETGs. [ABSTRACT FROM AUTHOR]

Compact massive relic galaxies are a class of galaxies that exhibit characteristics suggesting they have remained largely unchanged since their initial formation, making them 'relics' of the early Universe. These galaxies represent a distinct class characterized by strongly peaked high-velocity dispersion profiles with large rotational velocities. This study investigates the formation of such galaxies within the framework of Milgromian dynamics (MOND), offering a unique perspective on their origin without invoking the presence of cold or warm dark matter. Our analysis focuses on the collapse dynamics of isolated non-rotating post-big bang gas clouds, revealing kinematic and density profiles comparable to observed compact massive relic galaxies like NGC 1277, Mrk 1216, and PGC 032873. The findings underscore the natural emergence of compact massive relic galaxies within a MOND-based Universe, providing valuable insights into the interplay between gravitational dynamics and galaxy formation. [ABSTRACT FROM AUTHOR]

Relic galaxies are massive, compact, and quiescent objects observed in the local Universe that have not experienced any significant interaction episodes or merger events since about z  = 2, remaining relatively unaltered since their formation. On the other hand, massive and compact early-type galaxies (cETGs) in the local Universe appear to show similar properties to Relic galaxies, despite having substantial accretion history. Relic galaxies, with frozen history, can provide important clues about the intrinsic processes related to the evolutionary pathways of ETGs and the role that mergers play in their evolution. Using the high-resolution cosmological simulation TNG50-1 from IllustrisTNG project, we investigate the assembly history of a sample of massive, compact, old, and quiescent subhaloes split by satellite accretion fraction. We compare the evolutionary pathways at three cosmic epochs: z  = 2, z  = 1.5, and z  = 0, using the orbital decomposition numerical method to investigate the stellar dynamics of each galactic kinematical component and their environmental correlations. Our results point to a steady pathway across time that is not strongly dependent on the mergers or the environment. Relics and cETGs do not show a clear preference for high- or low-density environments within the volume explored at z  = 0, as they are found in both scenarios. However, the progenitors of Relic galaxies have consistently resided in high-density environments since z  = 2, while cETGs were shifted to such environments at a later stage. The merger history can be recovered from the stellar kinematics imprints in the local Universe. Relics and cETGs show consistently dynamical similarities at z  = 2 and differences at z  = 0 to disc, bulge, and hot inner stellar halo. In the current scenario, the mergers that drive the growth of cETGs do not give rise to a new and distinct evolutionary pathway when compared to Relics. [ABSTRACT FROM AUTHOR]

We report the discovery of a radio relic in the north-eastern periphery of the galaxy cluster Abell 2108 (A2108). A2108 is part of the uGMRT LOw-MAss Galaxy Cluster Survey (GLOMACS), where our main aim is to search for diffuse radio emission signatures in very sparsely explored low-mass galaxy clusters using uGMRT band-3 (central frequency 400 MHz). We used our uGMRT band-3 observations along with the existing archival band-3 uGMRT data to improve image sensitivity. Along with the previously reported south-western relic, the discovery of the new relic makes A2108 one of the few low-mass clusters hosting a double relic. The new relic spans over a region of 610 kpc × 310 kpc and, interestingly, differs considerably in size and morphology from the other relic. Using XMM–Newton science archive data, we also report the tentative detection of a mildly supersonic shock of Mach number |$\mathcal {M}_\mathrm{SB}=1.42$| and |$\mathcal {M}_\mathrm{T} = 1.43$| from the surface brightness and temperature discontinuities, respectively, near this newly found relic. Both the relics in A2108 are found to be significantly under-luminous compared with other double-relic systems in the mass–luminosity plane. Moreover, the north-eastern relic is remarkably under-luminous in the size–luminosity plane. Although mild supersonic shocks resulting from an off-axis merger could have influenced the origin of both relics, we hypothesize that local environments have played a crucial role in shaping their morphologies. [ABSTRACT FROM AUTHOR]

This paper presents the third data release of the INvestigating Stellar Population In RElics (INSPIRE) project, comprising 52 ultra-compact massive galaxies (UCMGs) observed with the X-Shooter spectrograph. We measure integrated stellar velocity dispersion, [Mg/Fe] abundances, ages, and metallicities for all the INSPIRE objects. We thus infer star formation histories and confirm the existence of a degree of relicness (DoR), defined in terms of the fraction of stellar mass formed by z  = 2, the time at which a galaxy has assembled 75 per cent of its mass, and the final assembly time. Objects with a high DoR assembled their stellar mass at early epochs, while low-DoR objects show a non-negligible fraction of later formed populations and hence a spread in ages and metallicities. A higher DoR correlates with larger [Mg/Fe], supersolar metallicity, and larger velocity dispersion values. The 52 UMCGs span a large range of DoR from 0.83 to 0.06, with 38 of them having formed more than 75  per cent of their mass by z  = 2. Of these, nine are extreme relics (DoR>0.7), since they formed the totality (⁠|$\gt 99~{{\ \rm per\ cent}}$|⁠) of their stellar mass by redshift z  = 2. The remaining 14 UCMGs cannot be considered relics, as they are characterized by more extended star formation histories. With INSPIRE  we built the first sizeable sample of relics outside the local Universe, up to z ∼ 0.4, increasing the number of confirmed relics by a factor of >10, and opening up an important window to explain the mass assembly of massive galaxies in the high- z Universe. [ABSTRACT FROM AUTHOR]

A joint hadronic model is shown to quantitatively explain the observations of diffuse radio emission from galaxy clusters in the form of minihaloes, giant haloes, relics, and their hybrid, transitional stages. Cosmic-ray diffusion of order D ∼ 1031–32 cm2 s−1, inferred independently from relic energies, the spatial variability of giant-halo spectra, and the spectral evolution of relics, reproduces the observed spatio-spectral distributions, explains the recently discovered mega-haloes as enhanced peripheral magnetization, and quenches electron (re)acceleration by weak shocks or turbulence. For instance, the hard-to-soft evolution along secondary-electron diffusion explains both the soft spectra in most halo peripheries and relic downstreams, and the hard spectra in most halo centres and relic edges, where the photon index can reach α ≃ −0.5 regardless of the Mach number |$\mathcal {M}$| of the coincident shock. Such spatio-spectral modelling, recent γ-ray observations, and additional accumulated evidence are thus shown to support a 2010 claim that the seamless transitions among minihaloes, giant haloes, and relics, their similar energetics, integrated spectra, and delineating discontinuities, the inconsistent |$\mathcal {M}$| inferred from radio versus X-rays in leptonic models, and additional observations, all indicate that these diffuse radio phenomena are manifestations of the same cosmic-ray ion population, with no need to invoke less natural alternatives. [ABSTRACT FROM AUTHOR]

The Main galaxy cluster in the Abell 781 system is undergoing a significant merger and accretion process with peripheral emission to the north and south-eastern flanks of the merging structure. Here we present a full polarimetric study of this field, using radio interferometric data taken at 21 and 92 cm with the Westerbork Synthesis Radio Telescope (WSRT), to a sensitivity better than any 21 cm (L band) observation to date. We detect evidence of extended low-level emission of 1.9 mJy associated with the Main cluster at 21 cm, although this detection necessitates further follow-up by modern instruments due to the limited resolution of the WSRT. Our polarimetric study indicates that, most likely, the peripheral emission associated with this cluster is not a radio relic. [ABSTRACT FROM AUTHOR]

Radio relics are giant sources of diffuse synchrotron radio emission in the outskirts of galaxy clusters that are associated with shocks in the intracluster medium. Still, the origin of relativistic particles that make up relics is not fully understood. For most relics, diffusive shock acceleration (DSA) of thermal electrons is not efficient enough to explain observed radio fluxes. In this paper, we use a magnetohydrodynamic simulation of galaxy clusters in combination with Lagrangian tracers to simulate the formation of radio relics. Using a Fokker–Planck solver to compute the energy spectra of relativistic electrons, we determine the synchrotron emission of the relic. We find that re-acceleration of fossil electrons plays a major role in explaining the synchrotron emission of radio relics. Particles that pass through multiple shocks contribute significantly to the overall luminosity of a radio relic and greatly boost the effective acceleration efficiency. Furthermore, we find that the assumption that the luminosity of a radio relic can be explained with DSA of thermal electrons leads to an overestimate of the acceleration efficiency by a factor of more than 103. [ABSTRACT FROM AUTHOR]

The Reionization Cluster Survey imaged 41 galaxy clusters with the Hubble Space Telescope (HST), in order to detect lensed and high-redshift galaxies. Each cluster was imaged to about 26.5 AB mag in three optical and four near-infrared bands, taken in two distinct visits separated by varying time intervals. We make use of the multiple near-infrared epochs to search for transient sources in the cluster fields, with the primary motivation of building statistics for bright caustic crossing events in gravitational arcs. Over the whole sample, we do not find any significant (≳5σ) caustic crossing events, in line with expectations from semi-analytical calculations but in contrast to what may be naively expected from previous detections of some bright events or from deeper transient surveys that do find high rates of such events. Nevertheless, we find six prominent supernova (SN) candidates over the 41 fields: three of them were previously reported and three are new ones reported here for the first time. Out of the six candidates, four are likely core-collapse SNe – three in cluster galaxies, and among which only one was known before, and one slightly behind the cluster at z ∼ 0.6–0.7. The other two are likely Ia – both of them previously known, one probably in a cluster galaxy and one behind it at z ≃ 2. Our study supplies empirical bounds for the rate of caustic crossing events in galaxy cluster fields to typical HST magnitudes, and lays the groundwork for a future SN rate study. [ABSTRACT FROM AUTHOR]

In the last decade, growing evidence has emerged supporting a non-universal stellar initial mass function (IMF) in massive galaxies, with a larger number of dwarf stars with respect to the Milky Way (bottom-heavy IMF). However, a consensus about the mechanisms that cause IMF variations is yet to be reached. Recently, it has been suggested that stars formed early-on in cosmic time, via a star formation burst, could be characterized by a bottom-heavy IMF. A promising way to confirm this is to use relics, ultra-compact massive galaxies, almost entirely composed by these 'pristine' stars. The INvestigating Stellar Population In RElics (INSPIRE) Project aims at assembling a large sample of confirmed relics, that can serve as laboratory to investigate on the conditions of star formation in the first 1–3 Gyr of the Universe. In this third INSPIRE paper, we build a high signal-to-noise spectrum from five relics, and one from five galaxies with similar sizes, masses, and kinematical properties, but characterized by a more extended star formation history (non-relics). Our detailed stellar population analysis suggests a systematically bottom-heavier IMF slope for relics than for non-relics, adding new observational evidence for the non-universality of the IMF at various redshifts and further supporting the above proposed physical scenario. [ABSTRACT FROM AUTHOR]

Gene loss is a prevalent source of genetic variation in genome evolution. Calling loss events effectively and efficiently is a critical step for systematically characterizing their functional and phylogenetic profiles genome wide. Here, we developed a novel pipeline integrating orthologous inference and genome alignment. Interestingly, we identified 33 gene loss events that give rise to evolutionarily novel long noncoding RNAs (lncRNAs) that show distinct expression features and could be associated with various functions related to growth, development, immunity, and reproduction, suggesting loss relics as a potential source of functional lncRNAs in humans. Our data also demonstrated that the rates of protein gene loss are variable among different lineages with distinct functional biases. [ABSTRACT FROM AUTHOR]

We present the initial results of our MeerKAT L-band observations of Abell 3376. We achieved higher (5″) angular resolution and better (∼4 μ Jy beam−1) sensitivity compared to the previous observations. Our achieved sensitivity is only a factor of 2 larger than the thermal noise of MeerKAT. Astrometric and flux comparison of discrete compact sources in the field between MeerKAT and the Very Large Array (VLA) indicated that our calibration procedures were successful. We detected West and East relics, and radio galaxies, which have been observed in previous works. With minimal missing flux problem in our MeerKAT observations, we derived the spectral indices of the West relic (−1.22 ± 0.05), East relic (−1.33 ± 0.08) and central radio galaxies (−0.94 ± 0.05). The improved images revealed faint, extending radio arcs for relics, and connection between the East relic and radio galaxies. It is probable that (at least some of) the re-accelerated electrons of the East relic are supplied by the jets of the radio galaxies. No significant diffuse radio emission was found in cluster central part, supporting previous works with a much better upper limit of radio flux of <1.8 × 1023 W Hz−1. [ABSTRACT FROM AUTHOR]

The short-lived buckling instability is responsible for the formation of at least some box/peanut (B/P) shaped bulges, which are observed in most massive, z  = 0, barred galaxies. Nevertheless, it has also been suggested that B/P bulges form via the slow trapping of stars on to vertically extended resonant orbits. The key difference between these two scenarios is that when the bar buckles, symmetry about the mid-plane is broken for a period of time. We use a suite of simulations (with and without gas) to show that when the buckling is sufficiently strong, a residual mid-plane asymmetry persists for several Gyrs after the end of the buckling phase, and is visible in simulation images. On the other hand, images of B/P bulges formed through resonant trapping and/or weak buckling remain symmetric about the mid-plane. We develop two related diagnostics to identify and quantify mid-plane asymmetry in simulation images of galaxies that are within 3° of edge-on orientation, allowing us to test whether the presence of a B/P-shaped bulge can be explained by a past buckling event. We apply our diagnostics to two nearly edge-on galaxies with B/P bulges from the Spitzer Survey of Stellar Structure in Galaxies, finding no mid-plane asymmetry, implying these galaxies formed their bulges either by resonant trapping or by buckling more than ∼5 Gyr ago. We conclude that the formation of B/P bulges through strong buckling may be a rare event in the past ∼5 Gyr. [ABSTRACT FROM AUTHOR]

In-field compositional analysis of large prehistoric relics, such as the Altar Stone at Stonehenge (England), is limited due to the size of the relics and difficulty in obtaining samples that can be analyzed in a laboratory. In this study, a portable Raman spectroscopy system was used to analyze the Altar Stone to help determine its origin and classification, which appears to differ from other bluestones at Stonehenge. While the study is ongoing and the definitive origin of the Altar Stone is not yet known, this study demonstrates the applicability of a portable Raman spectroscopy system in the compositional analysis of large samples in the field. [ABSTRACT FROM AUTHOR]

Cosmologies with Light Massive Relics (LiMRs) as a subdominant component of the dark sector are well-motivated from a particle physics perspective, and can also have implications for the σ8 tension between early and late time probes of clustering. The effects of LiMRs on the cosmic microwave background (CMB) and structure formation on large (linear) scales have been investigated extensively. In this paper, we initiate a systematic study of the effects of LiMRs on smaller, non-linear scales using cosmological N -body simulations; focusing on quantities relevant for photometric galaxy surveys. For most of our study, we use a particular model of non-thermal LiMRs but the methods developed generalizing to a large class of LiMR models – we explicitly demonstrate this by considering the Dodelson–Widrow velocity distribution. We find that, in general, the effects of LiMR on small scales are distinct from those of a ΛCDM universe, even when the value of σ8 is matched between the models. We show that weak lensing measurements around massive clusters, between ∼0.1  h −1Mpc and ∼10  h −1Mpc, should have sufficient signal-to-noise in future surveys to distinguish between ΛCDM and LiMR models that are tuned to fit both CMB data and linear scale clustering data at late times. Furthermore, we find that different LiMR cosmologies indistinguishable by conventional linear probes can be distinguished by non-linear probes if their velocity distributions are sufficiently different. LiMR models can, therefore, be best tested by jointly analyzing the CMB and late-time structure formation on both large and small scales. [ABSTRACT FROM AUTHOR]

Near-ultraviolet (NUV) spectroscopic studies have suggested that passively evolving massive, early-type galaxies host sub-one per cent fractions of young stars in their innermost regions. We shed light on the origin of these stars by analysing NGC 1277, a widely studied nearby prototypical massive compact relic galaxy. These are rare galaxies that have survived without experiencing significant size evolution via accretion and mergers since their formation at high redshift. We obtain a spectrum in the UV range within the central 1 kpc region of NGC 1277. We compare a carefully selected set of optical and NUV line-strengths to model predictions with star formation histories characteristic of massive galaxies. We find a 0.8 per cent mass fraction of young stars in the centre of NGC 1277, similar to that found in massive early-type galaxies. Given the limited accretion history of NGC 1277, these results favour an intrinsic, in situ , process triggering star formation at later epochs. Our results suggest a general constraint on the amount of young stars in the cores of massive early-type galaxies. This amount should be assumed as an upper limit for the young stellar contribution in massive galaxies, as there might be present other contributions from evolved stars. [ABSTRACT FROM AUTHOR]

Abell 3266 is a massive and complex merging galaxy cluster that exhibits significant substructure. We present new, highly sensitive radio continuum observations of Abell 3266 performed with the Australian Square Kilometre Array Pathfinder (0.8–1.1 GHz) and the Australia Telescope Compact Array (1.1–3.1 GHz). These deep observations provide new insights into recently reported diffuse non-thermal phenomena associated with the intracluster medium, including a 'wrong-way' relic, a fossil plasma source, and an as-yet unclassified central diffuse ridge, which we reveal comprises the brightest part of a large-scale radio halo detected here for the first time. The 'wrong-way' relic is highly atypical of its kind: it exhibits many classical signatures of a shock-related radio relic, while at the same time exhibiting strong spectral steepening. While radio relics are generally consistent with a quasi-stationary shock scenario, the 'wrong-way' relic is not. We study the spectral properties of the fossil plasma source; it exhibits an ultrasteep and highly curved radio spectrum, indicating an extremely aged electron population. The larger scale radio halo fills much of the cluster centre, and presents a strong connection between the thermal and non-thermal components of the intracluster medium, along with evidence of substructure. Whether the central diffuse ridge is simply a brighter component of the halo, or a mini-halo, remains an open question. Finally, we study the morphological and spectral properties of the multiple complex radio galaxies in this cluster in unprecedented detail, tracing their evolutionary history. [ABSTRACT FROM AUTHOR]

Massive early-type galaxies (ETGs) show several strong CO absorption features in their H - and K -band spectra that cannot be explained by state-of-the-art stellar population models. For many years, the disagreement has been attributed to the presence of intermediate-age stellar components that are dominated by stars in the asymptotic giant branch phase. However, no robust evidence of this scenario has been provided so far. One way to test this claim is by comparison of CO indices for ETGs and for relic galaxies. Lacking the intermediate-age stellar populations, relic galaxies provide us with a unique opportunity to address the origin of strong CO absorptions in ETGs. Here, we utilize the prototype relic galaxy NGC 1277 and compare the CO absorption features of this galaxy with the ones of a representative sample of massive ETGs. We show that the CO lines in both systems have similar strengths, significantly stronger than the predictions of stellar population synthesis models. We conclude that intermediate-age stellar populations in massive ETGs are not the culprit of the strong CO absorptions. [ABSTRACT FROM AUTHOR]

We aim to carry out a radio study of the SoUthern Cluster sCale Extended Source Survey (SUCCESS) sample consisting of 20 massive (M500 > 5 × 1014 M⊙), nearby (redshift <0.3) and southern (−50° < δ < −30°) galaxy clusters detected by the Planck satellite and the South Pole Telescope. Here, we report targeted GMRT observations (325/610 MHz) for a subsample of nine clusters. We also use the first data release of MeerKAT Galaxy Cluster Legacy Survey (1283 MHz) for five of these nine clusters. The properties of the mini-halo in RXC J0528.9-3927, a candidate mini-halo in A3322, the radio halo and candidate double relics in A3399, and the radio halo in RXC J0232.2-4420 are presented. We also report a detection of candidate radio relics at distances 1 and 1.9 Mpc from the centre of RXC J0232.2-4420. The southeast relic of A3399 is consistent with the radio power–mass scaling relation for radio relics, while the candidate relics around RXC J0232.2-4420 are outliers. This indicates an origin of the candidate relics near RXC J0232.2-4420 to be independent of this cluster and a cluster merger-shock origin for the relic in A3399. In this subsample of clusters, 1/9 hosts a radio halo and double relics, 1/9 hosts a radio halo and 2/9 host mini-haloes. The dynamical states based on X-ray morphology show that A3399 is a disturbed cluster; however, the radio halo cluster RXC J0232.2-4420 is relaxed, and the mini-halo clusters have intermediate morphologies, adding to the cases of the less commonly found associations. [ABSTRACT FROM AUTHOR]

Relic galaxies are massive compact quiescent galaxies that formed at high-redshift and remained almost unchanged since then. In this work, we search for analogues to relic galaxies in the TNG50 cosmological simulations to understand relic formation and test the ability of TNG50 to reproduce such rare objects. Using stellar mass, age, radius, quiescence, and stellar assembly criteria, we find five subhaloes in TNG50 that could be potential relic analogues. We compare their properties with other constraints imposed by a sample of 13 observed relic galaxies. We find one analogue in TNG50 that simultaneously satisfies most of the available observational constraints, such as metallicity and morphology. It also shows similarities to the confirmed relic NGC 1277, regarding environment and dark matter fraction. By taking into account a degree of relicness, a second relic analogue may also be considered. However, the central parts of the brightness and density profiles of the analogues are less steep than that of real relic galaxies, possibly due to limited numerical resolution. We identify two formation pathways of relic analogues in TNG50 depending on their environment: they either have their remaining gas stripped during the infall into a cluster at z ≲ 1.2 or consume it before z > 1.5. They are then deprived of significant star formation, leaving their stellar populations almost unaltered during the last 9 Gyr. We also find that the analogue progenitors at z ∼ 4 inhabit more massive haloes than progenitors of quiescent galaxies with similar stellar mass at z ∼ 0. [ABSTRACT FROM AUTHOR]

Superclusters are the largest objects in the Universe, and they provide a unique opportunity to study how galaxy clusters are born at the junction of the cosmic web as well as the distribution of magnetic fields and relativistic particles beyond cluster volume. The field of radio astronomy is going through an exciting and important era of the Square Kilometer Array (SKA). We now have the most sensitive functional radio telescopes, such as the MeerKAT, which offers high angular resolution and sensitivity towards diffuse and faint radio sources. To study the radio environments around supercluster, we observed the (core part of) Saraswati supercluster with the MeerKAT. From our MeerKAT Observation of the Saraswati Supercluster (MOSS) project, the initial results of the pilot observations of two massive galaxy clusters, A2631 and ZwCl2341.1+0000, which are located around the dense central part of the Saraswati supercluster, were discussed. In this paper, we describe the observations and data analysis details, including direction-dependent calibration. In particular, we focus on the ZwCl2341.1+0000 galaxy cluster, which hosts double radio relics and puzzling diffuse radio source in the filamentary network. We have imaged these double radio relics in our high resolution and sensitive L -band MeerKAT observation and a puzzling radio source, located between relics, in the low-resolution image. We also derived the spectra of double radio relics using MeerKAT and archival GMRT observations. The following papers will focus on the formation of radio relics and halo, as well as radio galaxy properties in a supercluster core environment. [ABSTRACT FROM AUTHOR]

Radio relics are giant (∼Mpc) synchrotron sources that are believed to be produced by the (re)acceleration of cosmic ray electrons (CRe) by shocks in the intracluster medium. In this numerical study, we focus on the possibility that some radio relics may arise when electrons undergo diffusive shock acceleration at multishocks in the outskirts of merging galaxy clusters. This multishock (MS) scenario appears viable to produce CRe that emit visible synchrotron emission. We show that electrons that have been shocked multiple times develop an energy spectrum that significantly differs from the power-law spectrum expected in the case of a single shock scenario. As a consequence, the radio emission generated by CRe that shocked multiple times is higher than the emission produced by CRe that are shocked only once. In the case explored in this paper, the radio emission produced in the two scenarios differ by one order of magnitude. In particular in the MS scenario, the simulated relic follows a KGJP spectral shape, consistent with observation. Furthermore, the produced radio emission is large enough to be detectable with current radio telescopes (e.g. LOFAR, JVLA). [ABSTRACT FROM AUTHOR]

Radio relics are the manifestation of electrons presumably being shock (re-)accelerated to high energies in the outskirts of galaxy clusters. However, estimates of the shocks' strength yield different results when measured with radio or X-ray observations. In general, Mach numbers obtained from radio observations are larger than the corresponding X-ray measurements. In this work, we investigate this Mach number discrepancy. For this purpose, we used the cosmological code enzo to simulate a sample of galaxy clusters that host bright radio relics. For each relic, we computed the radio Mach number from the integrated radio spectrum and the X-ray Mach number from the X-ray surface brightness and temperature jumps. Our analysis suggests that the differences in the Mach number estimates follow from the way in which different observables are related to different parts of the underlying Mach number distribution: radio observations are more sensistive to the high Mach numbers present only in a small fraction of a shock's surface, while X-ray measurements reflect the average of the Mach number distribution. Moreover, X-ray measurements are very sensitive to the relic's orientation. If the same relic is observed from different sides, the measured X-ray Mach number varies significantly. On the other hand, the radio measurements are more robust, as they are unaffected by the relic's orientation. [ABSTRACT FROM AUTHOR]

Giant radio relics are arc-like structures of diffuse, non-thermal synchrotron radiation that trace shock waves induced by galaxy cluster mergers. The particle (re-)acceleration mechanism producing such radio relics is unclear. One major open question is whether relics can be formed directly from a population of thermal seed electrons, or if pre-existing relativistic seed electrons are required. In some cases, active galactic nuclei (AGNs) can provide such a population of sub-GeV electrons. However, it is unclear how common this connection is. In this paper, we present LOFAR 140 MHz and Very Large Array L -band radio observations, as well as Chandra data of PSZ2 G096.88+24.18, a merging galaxy cluster system hosting a pair of radio relics. A large patch of diffuse emission connects a bright radio galaxy with one of the relics, likely affecting the properties of the relic. We find that the most plausible explanation for the connection is that the merger shock wave has passed over an AGN lobe. The shock passing over this seed population of electrons has led to an increased brightness in the relic only in the region filled with seed electrons. [ABSTRACT FROM AUTHOR]

This article unpacks the connections between empire, piety, and pilgrimage in the early modern western Indian Ocean world by examining the history of a reliquary shrine dedicated to a qadam, or footprint relic of the Prophet Muḥammad located in Ahmedabad, Gujarat. Classified by the Archeological Survey of India as the 'Tomb of Mir Abu Turab' (ASI Monument no. N - GJ - 44), the site was a qadamgāh in the Mughal period and from the late - sixteenth to the early - eighteenth centuries functioned as a place of visitation (mazār) for pilgrims eager to see the naqsh - i qadam - i sharīf (the impression of the noble foot), whose white appearance stood in stark contrast against the black stone. By examining Persian historical narratives, including one authored by the man responsible for the relic's arrival to South Asia, this article demonstrates how relics mediated Mughal imperium, devotion to the Prophet Muḥammad, and sayyid identity in early modern Gujarat. [ABSTRACT FROM AUTHOR]

We analyse the globular cluster (GC) systems of a sample of 15 massive, compact early-type galaxies (ETGs), 13 of which have already been identified as good relic galaxy candidates on the basis of their compact morphologies, old stellar populations and stellar kinematics. These relic galaxy candidates are likely the nearby counterparts of high-redshift red nugget galaxies. Using F814W (≈ I) and F160W (≈ H) data from the WFC3 camara onboard the Hubble Space Telescope , we determine the total number, luminosity function, specific frequency, colour, and spatial distribution of the GC systems (GCSs). We find lower specific frequencies (SN < 2.5 with a median of SN = 1) than ETGs of comparable mass. This is consistent with a scenario of rapid, early dissipative formation, with relatively low levels of accretion of low-mass, high- SN satellites. The GC half-number radii are compact, but follow the relations found in normal ETGs. We identify an anticorrelation between the specific angular momentum (λ R) of the host galaxy and the (I − H) colour distribution width of their GCSs. Assuming that λ R provides a measure of the degree of dissipation in massive ETGs, we suggest that the (I − H) colour distribution width can be used as a proxy for the degree of complexity of the accretion histories in these systems. [ABSTRACT FROM AUTHOR]

A Hindu samādhi is a shrine that marks the final resting - place of a realised guru's body and reflects the traditional understanding that the realised sage's perfected body should not be cremated but rather should be preserved as a localised instantiation of sacred power. While some scholars speculate that the Hindu samādhi shrine tradition is borrowed from the Sufi dargāh (tomb - shrine) tradition, I argue that the Hindu samādhi burial practice has pre - dargāh roots resonant with the Buddhist stūpa and relic worship tradition. This article charts the development of this samādhi burial practice in regard to three important considerations: the act of taking samādhi , burying the body, and marking the burial site. It is this long - established burial practice that eventually blossoms into a full - fledged worship tradition in part by coming into contact with the Sufi dargāh tradition. [ABSTRACT FROM AUTHOR]

In April 2017, a group of mannequins was removed during renovation of the Hiroshima Peace Memorial Museum. The new exhibit instead focuses on objects left by the dead (ihin) as well as survivor testimonies, representing the latest change in a seventy-year controversy regarding museal representations of the devastation wrought by the atomic bomb. Controversies paralleled debates over Holocaust memorialization and the treatment of objects left by victims. The following examines the history of A-bomb objects in the Hiroshima museum, most importantly, the way relics have been discussed, exhibited, and debated. This evolution has elevated relics to the status of sacred objects, central to commemoration and memorialization. [ABSTRACT FROM AUTHOR]

In the long sixteenth century, knowledge about the saints was disseminated not only through hagiographical texts, be they in Latin or the vernacular, but also through visual images, both in churches and in (urban) secular public spaces, through souvenirs such as pilgrims' badges, ephemeral printed texts in the vernacular, and printed images. Examples from the northern Low Countries of the various media that played a role in the veneration of the saints, more particularly those that were to be encountered by pilgrims at the feasts of these holy men and women, are presented, and, whenever possible, descriptions by contemporaries will be used. This allows the links between hagiography, via sermons and miracles, with the festive occasions on which saints and believers met, to be established. [ABSTRACT FROM AUTHOR]

This article discusses Yossi Maurey's study of the liturgy and prosae (sung poems) of the Sainte-Chapelle in Paris. Maurey examines the music in relation to the political and theological symbolism of the place, which was built as a reliquary for important Christian relics and served to reinforce the power of the city and the Capetian dynasty. The study focuses on the prosae for the feasts of the relics, particularly the Feast of the Crown of Thorns and the Feast of the Reception of Relics. Maurey also explores the use of contrafactum, where melodies from other prosae were borrowed, and the Marian themes present in the liturgy. The main source for this study is a prosary manuscript preserved in Bari, Italy, which was copied for the Sainte-Chapelle in Bari and reflects the liturgy of the Parisian Sainte-Chapelle. The book provides in-depth textual and musical analysis of the prosae, along with translations and musical transcriptions. While there are some errors in the transcriptions, the book offers valuable editions for further research. Overall, the study sheds light on the role of plainchant in political programs during the Middle Ages. [Extracted from the article]

We present the discovery of a single radio relic located at the edge of the galaxy cluster A2384, using the MeerKAT radio telescope. A2384 is a nearby (z = 0.092), low-mass, complex bimodal, merging galaxy cluster that displays a dense X-ray filament (∼700 kpc in length) between A2384(N; northern cluster) and A2384(S; southern cluster). The origin of the radio relic is puzzling. Using the MeerKAT observation of A2384, we estimate that the physical size of the radio relic is 824 × 264 kpc2 and that it is a steep spectrum source. The radio power of the relic is |$P_{1.4\mathrm{GHz}}\, \sim$| (3.87 ± 0.40) × 1023 W Hz−1. This radio relic could be the result of shock wave propagation during the passage of the low-mass A2384(S) cluster through the massive A2384(N) cluster, creating a trail appearing as a hot X-ray filament. In the previous GMRT 325 MHz observation, we detected a peculiar FR I radio galaxy interacting with the hot X-ray filament of A2384, but the extended radio relic was not detected; it was confused with the southern lobe of the FR I galaxy. This newly detected radio relic is elongated and perpendicular to the merger axis, as seen in other relic clusters. In addition to the relic, we notice a candidate radio ridge in the hot X-ray filament. The physical size of the radio ridge source is ∼182 × 129 kpc2. Detection of the diffuse radio sources in the X-ray filament is a rare phenomenon, and could be a new class of radio source found between the two merging clusters of A2384(N) and A2384(S). [ABSTRACT FROM AUTHOR]

Observations of radio relics at very high frequency (>10 GHz) can help to understand how particles age and are (re-)accelerated in galaxy cluster outskirts and how magnetic fields are amplified in these environments. In this work, we present new single-dish 18.6 GHz Sardinia Radio Telescope and 14.25 GHz Effelsberg observations of the well-known northern radio relic of CIZA J2242.8+5301. We detected the relic which shows a length of ∼1.8 Mpc and a flux density equal to |$S_{14.25\, \mathrm{ GHz}}=(9.5\pm 3.9)\, \mathrm{ mJy}$| and |$S_{18.6\, \mathrm{ GHz}}=(7.67\pm 0.90)\, \mathrm{ mJy}$| at 14.25 and 18.6 GHz, respectively. The resulting best-fitting model of the relic spectrum from 145 MHz to 18.6 GHz is a power-law spectrum with spectral index α = 1.12 ± 0.03: no evidence of steepening has been found in the new data presented in this work. For the first time, polarization properties have been derived at 18.6 GHz, revealing an averaged polarization fraction of |$\sim\! 40{{\ \rm per\ cent}}$| and a magnetic field aligned with the 'filaments' or 'sheets' of the relic. [ABSTRACT FROM AUTHOR]

The origin of radio relics is usually explained via diffusive shock acceleration (DSA) or re-acceleration of electrons at/from merger shocks in galaxy clusters. The case of acceleration is challenged by the low predicted efficiency of low Mach number merger shocks, unable to explain the power observed in most radio relics. In this letter, we present the discovery of a new giant radio relic around the galaxy cluster Abell 2249 (⁠|$z$|  = 0.0838) using Low-Frequency Array (LOFAR). It is special since it has the lowest surface brightness of all known radio relics. We study its radio and X-ray properties combining LOFAR data with uGMRT, JVLA, and XMM. This object has a total power of |$L_{1.4\rm\, GHz}=4.1\pm 0.8 \times 10^{23}$| W Hz−1 and integrated spectral index α = 1.15 ± 0.23. We infer for this radio relic a lower bound on the magnetization of |$B\ge 0.4\, \mu$| G, a shock Mach number of |$\mathcal {M}\approx 3.79$|⁠ , and a low acceleration efficiency consistent with DSA. This result suggests that a missing population of relics may become visible, thanks to the unprecedented sensitivity of the new generation of radio telescopes. [ABSTRACT FROM AUTHOR]

Radio relics are vast synchrotron sources that sit on the outskirts of merging galaxy clusters. In this work we model their formation using a Press–Schechter formalism to simulate merger rates, analytical models for the intracluster medium and the shock dynamics, as well as a simple model for the cosmic ray electrons at the merger shocks. We show that the statistical properties of the population of radio relics are strongly dependent on key physical parameters, such as the acceleration efficiency, the magnetic field strength at the relic, the geometry of the relic and the duration of the electron acceleration at merger shocks. It turns out that the flux distribution as well as the power–mass relation can constrain key parameters of the intracluster medium. With the advent of new large-area radio surveys, statistical analyses of radio relics will complement what we have learned from observations of individual objects. [ABSTRACT FROM AUTHOR]

We report the discovery of the oldest stellar substructure in the Orion star-forming region (OSFR), the Orion relic filament. The relic filament is physically associated with the OSFR, as demonstrated by Gaia DR2 photometry and astrometry, as well as by targeted radial velocity follow-up observations of a bright subsample of proper motion-selected candidate members. Gaia DR2 parallaxes place the Orion relic filament in the more distant part of the OSFR, ∼430 pc from the Sun. Given its age, velocity dispersion, spatial extent, and shape, it is not possible for the Orion relic filament to have formed as a single stellar cluster, even taking into account residual gas expulsion. The relic filament is also too young to be a tidal stream, because Galactic tides act on much longer time-scales, of the order of 100 Myr. It therefore appears likely that the structure formed from a molecular cloud filament similar to Orion A in the OSFR and retained its morphology despite decoupling from its natal gas. Hence, the Orion relic filament bears witness to the short-lived evolutionary phase between gas removal and dispersion owing to shears and tides, and provides crucial new insights into how stars are formed in molecular clouds. [ABSTRACT FROM AUTHOR]

Despite the age and prestige of the Royal Society of London, the history of its collections of scientific instruments and apparatus has largely been one of accidental accumulation and neglect. This article tracks their movements and the processes by which objects came to be recognized as possessing value beyond reuse or sale. From at least the mid-nineteenth century, the few surviving objects with links to the society's early history and its most illustrious Fellows came to be termed 'relics', were treated with suitable reverence, put on display and made part of the society's public self-presentation. If the more quotidian objects survived into the later 1800s, when their potential as objects for collection, research, display, reproduction and loan began to be appreciated, they are likely to have survived to the present day. [ABSTRACT FROM AUTHOR]

The Colegio Mayor de San Ildefonso and University of Alcalá was an important cultural institution in the Hispanic world of the early modern era. Founded by Cardinal Ximénez de Cisneros (1436–1517), it assembled an important group of symbolic objects, amongst them trophies, relics, images and mirabilia. The beatification of the founder led not only to a corresponding increase in the numbers of those objects, seen as relics, but also to their display in particular places, with the creation of a number of proto-museums. With the coming of the Enlightenment, a number of veritable museums were formed, with consequent changes in the values attributed to the symbolic items. From that time until the creation in 1836 of the University of Madrid, by making use of the assets and professorships of the University of Alcalá, the remaining symbolic objects were considered primarily as illustrating the history of the institution. [ABSTRACT FROM AUTHOR]

This article explores the place of miracle mediators in the spectrum of fourteenth-century healing practitioners. Using the canonisation inquest testimony for Lady Delphine de Pui Michel, collected in Provence in 1363, the article identifies the kinds of healing practitioners available to sufferers and then looks at three miracle mediators in particular. These three miracle mediators show that all of the people making relics available to others for healing purposes had knowledge about how to produce, distribute and use relics. But some also had significant knowledge of health and medicine. This article places miracle mediators in the spectrum of healing practitioners and offers a way to study non-titled female healing practitioners in the later Middle Ages. [ABSTRACT FROM AUTHOR]

In both J.K. Rowling's Harry Potter series (1997-2007) and Merrie Haskell's The Castle Behind Thorns (2014), relics destabilise the distinctions between bodies and objects, as a way of questioning bodily limits and limitations-- ultimately, the limitation of death. In Rowling's framework, bodily relics are inhuman monstrosities. The Castle Behind Thorns, however, explores other possibilities of relic discourse--options in which the fragmented, dispersed body still contains agency--and sanctity. This view of relics resonates with post-humanist feminist theory and theology's exploration of intersubjectivity, and thus Haskell's text suggests new alternatives in children's literature for portraying the body as holy, even if it is not 'wholly' one's own. [ABSTRACT FROM AUTHOR]

The article discusses the history of translation, also considering its broader definitions throughout historical periods including the Middle Ages, Renaissance, and Early Modern period. It compares a number of case studies on subjects including the Medieval translation of relics and the Eucharist, Renaissance translators of pagan literature, and coin specie.

This article examines a cup looted during the Second China War of 1860, as it moved through the hands of different collectors and as it changed its identity and physical form. Identified as the ‘Skull of Confucius’ when it was first exhibited at the London International Exhibition of 1862, the cup, made from the calvaria of a human skull, was richly mounted in gold and jewels. Following its exhibition it quickly changed owners, but soon lost its identity with Confucius; eventually stripped of its mounts, it reverted to being merely a fragment of skull. As such it then became a craniological specimen, examined by those interested in its racial and cultural origins. Pieced together from a variety of sources, the skull-cup’s collecting history provides an interesting example of the many ways in which objects can change materially as well as in meaning. [ABSTRACT FROM PUBLISHER]

New Barnet's Abbey Folk Park embodied the unique sensibilities of its director, the antiquary, occult scholar and ‘irregular bishop’ Father J. S. M. Ward. A populist ‘open air’ museum on a pattern that proliferated across Britain after World War II, Ward's museum was also a vehicle for the pentecostal millennialism of his Confraternity of the Kingdom of Christ. The museum, its collection and the manner of its display demonstrates an unusual confluence between occult Christianity and more familiar themes of national heritage and Spenglerian notions of decline in inter-war Britain. [ABSTRACT FROM PUBLISHER]

The article presents an examination into the history of the relic tooth of Buddha, seized by the Portuguese in 1561 from an invasion of Sri Lanka and allegedly destroyed by Don Constantino da Bragança, Viceroy of Goa. Introductory details are given outlining the various historical claims of the events, noting the divergent accounts of the tooth's survival or reproduction. Analysis is then given regarding the religious-cultural aspects behind the destruction of the item through the lens of Catholic-Buddhist comparative views on relics and their importance.

The article discusses ancient Egyptian practices such as mummification, drawing connections to the veneration of relics in other cultures. The example of the cult of Osiris is cited, as the dismembered god's remains were believed to be kept in sanctuaries. It is noted that the housing and display of mummies in modern museums is very similar to the traditional western treatment of relics, and not at all representative of ancient Egyptian belief. Egyptian theories about the afterlife are described, and the practice of mummifying animals is also discussed in this context.

The article presents an exploration into the history of relics and Church history in Bohemia during the Reformation and Counter-Reformation in the 16th and 17th centuries. Details are given highlighting the intersection between the political and religious spheres during the conflicted era, noting ways in which relics and reliquaries were used by national leaders to bolster their political aspirations in the region. Particular analysis is then offered describing and evaluating this phenomenon in Bohemia.

The article examines the worship and respect accorded certain relics in medieval Islam. Scholar Lionel Rothkrug has observed that Islam seems to have had relatively few relics. However, the author identifies and discusses several including the human remains of holy figures, rocks, sacred footprints, prophets, saints, and more. He lists four functions that relics served in medieval Islam. Relics acted as metonymies of holy people, they defined sacred spaces, they represented piety and learning, and they gave legitimacy to a ruler's reign.

The article presents discussion concerning the historical and religious veneration of the Mexican president and hero José Antonio López de Santa Anna. Details are given outlining the career of Santa Anna from his early military career to his military defeat by the United States, noting a battle injury he sustained and his use of a prosthetic leg. Details are then given tracking the continued history of Santa Anna's prosthetic leg after his defeat and the pseudo-cult surrounding his memory throughout the 19th century. Analysis is also given describing the cultural significance and religious interpretation of the phenomenon.

An index of relics and remains is presented for the January 2010 issue of the journal “Past & Present."