We present high angular resolution (∼80 mas) ALMA continuum images of the SN 1987A system, together with CO J=2→1, J=6 → 5, and SiO J=5→4 to J=7 → 6 images, which clearly resolve the ejecta (dust continuum and molecules) and ring (synchrotron continuum) components. Dust in the ejecta is asymmetric and clumpy, and overall the dust fills the spatial void seen in Hα images, filling that region with material from heavier elements. The dust clumps generally fill the space where CO J=6→5 is fainter, tentatively indicating that these dust clumps and CO are locationally and chemically linked. In these regions, carbonaceous dust grains might have formed after dissociation of CO. The dust grains would have cooled by radiation, and subsequent collisions of grains with gas would also cool the gas, suppressing the CO J=6→5 intensity. The data show a dust peak spatially coincident with the molecular hole seen in previous ALMA CO J=2→1 and SiO J=5→4 images. That dust peak, combined with CO and SiO line spectra, suggests that the dust and gas could be at higher temperatures than the surrounding material, though higher density cannot be totally excluded. One of the possibilities is that a compact source provides additional heat at that location. Fits to the far-infraredmillimeter spectral energy distribution give ejecta dust temperatures of 18-23K. We revise the ejecta dust mass to M dust = 0.2 − 0.4M for carbon or silicate grains, or a maximum of < 0.7M for a mixture of grain species, using the predicted nucleosynthesis yields as an upper limit. ciganp@cardiff.ac.uk

The nearby SN 1987A offers a spatially resolved view of the evolution of a young supernova (SN) remnant. Here we precent recent Hubble Space Telescope imaging observations of SN 1987A, which we use to study the evolution of the ejecta, the circumstellar equatorial ring (ER) and the increasing emission from material outside the ER. We find that the inner ejecta have been brightening at a gradually slower rate and that the western side has been brighter than the eastern side since ∼ 7000 days. This is expected given that the X-rays from the ER are most likely powering the ejecta emission. At the same time the optical emission from the ER continues to fade linearly with time. The ER is expanding at 680 ± 50 km s −1 , which reflects the typical velocity of transmitted shocks in the dense hotspots. A dozen spots and a rim of diffuse Hα emission have appeared outside the ER since 9500 days. The new spots are more than an order of magnitude fainter than the spots in the ER and also fade faster. We show that the spots and diffuse emission outside the ER may be explained by fast ejecta interacting with high-latitude material that extends from the ER toward the outer rings. Further observations of this emission will make it possible to determine the detailed geometry of the high-latitude material and provide insight into the formation of the rings and the mass-loss history of the progenitor.

Despite more than 30 years of searches, the compact object in Supernova (SN) 1987A has not yet been detected. We present new limits on the compact object in SN 1987A using millimeter, near-infrared, optical, ultraviolet, and X-ray observations from ALMA, VLT, HST, and Chandra. The limits are approximately 0.1 mJy (0.1×10 −26 erg s −1 cm −2 Hz −1 ) at 213 GHz, 1 L (6×10 −29 erg s −1 cm −2 Hz −1 ) in optical if our line-of-sight is free of ejecta dust, and 10 36 erg s −1 (2 × 10 −30 erg s −1 cm −2 Hz −1 ) in 2-10 keV X-rays. Our X-ray limits are an order of magnitude less constraining than previous limits because we use a more realistic ejecta absorption model based on three-dimensional neutrino-driven SN explosion models (Alp et al. 2018). The allowed bolometric luminosity of the compact object is 22 L Corresponding author: Dennis Alp dalp@kth.se arXiv:1805.04526v2 [astro-ph.HE] 30 Jul 2018 2 Alp et al.if our line-of-sight is free of ejecta dust, or 138 L if dust-obscured. Depending on assumptions, these values limit the effective temperature of a neutron star to < 4-8 MK and do not exclude models, which typically are in the range 3-4 MK. For the simplest accretion model, the accretion rate for an efficiency η is limited to < 10 −11 η −1 M yr −1 , which excludes most predictions. For pulsar activity modeled by a rotating magnetic dipole in vacuum, the limit on the magnetic field strength (B) for a given spin period (P ) is B 10 14 P 2 G s −2 , which firmly excludes pulsars comparable to the Crab. By combining information about radiation reprocessing and geometry, it is likely that the compact object is a dustobscured thermally-emitting neutron star, which may appear as a region of higher-temperature ejecta dust emission.