We report the discovery of four Fast Radio Bursts (FRBs) in the ongoing SUrvey for Pulsars and Extragalactic Radio Bursts (SUPERB) at the Parkes Radio Telescope: FRBs 150610, 151206, 151230 and 160102. Our real-time discoveries have enabled us to conduct extensive, rapid multi-messenger follow-up at 12 major facilities sensitive to radio, optical, X-ray, gamma-ray photons and neutrinos on time scales ranging from an hour to a few months post-burst. No counterparts to the FRBs were found and we provide upper limits on afterglow luminosities. None of the FRBs were seen to repeat. Formal fits to all FRBs show hints of scattering while their intrinsic widths are unresolved in time. FRB 151206 is at low Galactic latitude, FRB 151230 shows a sharp spectral cutoff, and FRB 160102 has the highest dispersion measure (DM = 2596.1±0.3 pc cm −3 ) detected to date. Three of the FRBs have high dispersion measures (DM >1500 pc cm −3 ), favouring a scenario where the DM is dominated by contributions from the Intergalactic Medium. The slope of the Parkes FRB source counts distribution with fluences > 2 Jy ms is α = −2.2 +0.6 −1.2 and still consistent with a Euclidean distribution (α = −3/2). We also find that the all-sky rate is 1.7 +1.5 −0.9 × 10 3 FRBs/(4π sr)/day above ∼ 2 Jy ms and there is currently no strong evidence for a latitude-dependent FRB sky-rate.

A deep survey of the Large Magellanic Cloud at ∼ 0.1−100 TeV photon energies with the Cherenkov Telescope Array is planned. We assess the detection prospects based on a model for the emission of the galaxy, comprising the four known TeV emitters, mock populations of sources, and interstellar emission on galactic scales. We also assess the detectability of 30 Doradus and SN 1987A, and the constraints that can be derived on the nature of dark matter. The survey will allow for fine spectral studies of N 157B, N 132D, LMC P3, and 30 Doradus C, and half a dozen other sources should be revealed, mainly pulsar-powered objects. The remnant from SN 1987A could be detected if it produces cosmic-ray nuclei with a flat power-law spectrum at high energies, or with a steeper index 2.3 − 2.4 pending a flux increase by a factor > 3 − 4 over ∼ 2015 − 2035. Large-scale interstellar emission remains mostly out of reach of the survey if its > 10 GeV spectrum has a soft photon index ∼ 2.7, but degree-scale 0.1 − 10 TeV pion-decay emission could be detected if the cosmic-ray spectrum hardens above >100 GeV. The 30 Doradus star-forming region is detectable if acceleration efficiency is on the order of 1 − 10% of the mechanical luminosity and diffusion is suppressed by two orders of magnitude within < 100 pc. Finally, the survey could probe the canonical velocity-averaged cross section for self-annihilation of weakly interacting massive particles for cuspy Navarro-Frenk-White profiles.

We present the angular correlation function measured from photometric samples comprising 1562 800 luminous red galaxies (LRGs). Three LRG samples were extracted from the Sloan Digital Sky Survey (SDSS) imaging data, based on colour‐cut selections at redshifts, z≈ 0.35, 0.55 and 0.7 as calibrated by the spectroscopic surveys, SDSS‐LRG, 2dF‐SDSS LRG and QSO (quasi‐stellar object) (2SLAQ) and the AAΩ‐LRG survey. The galaxy samples cover ≈7600 deg2 of sky, probing a total cosmic volume of ≈5.5 h−3 Gpc3. The small‐ and intermediate‐scale correlation functions generally show significant deviations from a single power‐law fit with a well‐detected break at ≈1 h−1 Mpc, consistent with the transition scale between the one‐ and two‐halo terms in halo occupation models. For galaxy separations 1–20 h−1 Mpc and at fixed luminosity, we see virtually no evolution of the clustering with redshift and the data are consistent with a simple high peaks biasing model where the comoving LRG space density is constant with z. At fixed z, the LRG clustering amplitude increases with luminosity in accordance with the simple high peaks model, with a typical LRG dark matter halo mass 1013–1014 h−1 M⊙. For r < 1 h−1 Mpc, the evolution is slightly faster and the clustering decreases towards high redshift consistent with a virialized clustering model. However, assuming the halo occupation distribution (HOD) and Λ cold dark matter (ΛCDM) halo merger frameworks, ∼2–3 per cent/Gyr of the LRGs are required to merge in order to explain the small scales clustering evolution, consistent with previous results. At large scales, our result shows good agreement with the SDSS‐LRG result of Eisenstein et al. but we find an apparent excess clustering signal beyond the baryon acoustic oscillations (BAO) scale. Angular power spectrum analyses of similar LRG samples also detect a similar apparent large‐scale clustering excess but more data are required to check for this feature in independent galaxy data sets. Certainly, if the ΛCDM model were correct then we would have to conclude that this excess was caused by systematics at the level of Δw≈ 0.001–0.0015 in the photometric AAΩ‐LRG sample.

We present the cross-correlation of the density map of luminous red galaxies (LRGs) and the temperature fluctuation in the cosmic microwave background (CMB) as measured by the fiveyear Wilkinson Microwave Anisotropy Probe observations. The LRG samples were extracted from imaging data of the Sloan Digital Sky Survey (SDSS) Data Release 5 based on two previous spectroscopic redshift surveys, the SDSS LRG and the 2dF-SDSS LRG and QSO (2SLAQ) surveys designed to have average redshifts of z ≈ 0.35 and z ≈ 0.55. In addition, we have added a higher redshift photometric LRG sample based on the selection of the AAOmega LRG redshift survey at z ≈ 0.7. The total LRG sample thus comprises 1.5 million galaxies, sampling a redshift range of 0.2 < z < 0.9 over ≈7600 deg 2 of the sky, probing a total cosmic volume of ≈5.5 h −3 Gpc 3 .First, we find that the new LRG sample at z ≈ 0.7 shows very little positive evidence for the Integrated Sachs-Wolfe (ISW) effect. Indeed, the cross-correlation is negative out to ≈1 • . The standard cold dark matter ( CDM) model is rejected at ≈2-3 per cent significance by the new LRG data. We then analyse the previous samples at z ≈ 0.35 and z ≈ 0.55. As found by other authors, these results appear consistent with the standard ISW model, although the statistical significance remains marginal. We also reproduce the same result for the magnitudelimited SDSS galaxy samples of Giannantonio et al. Taking the z ≈ 0.35 and z ≈ 0.55 LRG results in combination with the new z ≈ 0.7 sample, the overall result is now more consistent with a null detection than with the standard CDM model prediction.We then performed a new test on the robustness of the LRG ISW detections at z ≈ 0.35 and z ≈ 0.55. We made eight rotations through 360 • of the CMB maps with respect to the LRG samples around the galactic pole. We find that in both cases, there are stronger effects at angles other than zero. This implies that the z ≈ 0.35 and z ≈ 0.55 ISW detections may still be subject to systematic errors which combined with the known sizeable statistical errors may leave the z ≈ 0.35 and z ≈ 0.55 ISW detections looking unreliable. We have further made the rotation test on several other samples where ISW detections have been claimed and find that they also show peaks when rotated. We conclude that in the samples we have tested, the ISW effect may be absent and we argue that this result may not be in contradiction with previous results.

Abstract We report the results of optical follow-up observations of 29 gravitational-wave triggers during the first half of the LIGO-Virgo Collaboration (LVC) O3 run with the Gravitational-wave Optical Transient Observer (GOTO) in its prototype 4-telescope configuration (GOTO-4). While no viable electromagnetic counterpart candidate was identified, we estimate our 3D (volumetric) coverage using test light curves of on- and off-axis gamma-ray bursts and kilonovae. In cases where the source region was observable immediately, GOTO-4 was able to respond to a GW alert in less than a minute. The average time of first observation was 8.79 hours after receiving an alert (9.90 hours after trigger). A mean of 732.3 square degrees were tiled per event, representing on average 45.3 per cent of the LVC probability map, or 70.3 per cent of the observable probability. This coverage will further improve as the facility scales up alongside the localisation performance of the evolving gravitational-wave detector network. Even in its 4-telescope prototype configuration, GOTO is capable of detecting AT2017gfo-like kilonovae beyond 200 Mpc in favourable observing conditions. We cannot currently place meaningful electromagnetic limits on the population of distant ($\hat{D}_L = 1.3$ Gpc) binary black hole mergers because our test models are too faint to recover at this distance. However, as GOTO is upgraded towards its full 32-telescope, 2 node (La Palma & Australia) configuration, it is expected to be sufficiently sensitive to cover the predicted O4 binary neutron star merger volume, and will be able to respond to both northern and southern triggers.