A Hierarchical Framework for explaining the Cosmic Ray Spectrum using Diffusive Shock Acceleration

The hypothesis that the entire cosmic ray spectrum, from $\lesssim1\,{\rm GeV}$ to $\gtrsim100\,{\rm EeV}$ energy, can be accounted for by diffusive shock acceleration on increasingly large scales is critically examined. Specifically, it is conjectured that Galactic cosmic rays, up to $\sim3\,{\rm PeV}$, are mostly produced by local supernova remnants, from which they escape upstream. These cosmic rays initiate a powerful magnetocentrifugal wind, removing disk mass and angular momentum before passing through the Galactic Wind Termination Shock at a radius $\sim200\,{\rm kpc}$, where they can be re-accelerated to account for observed cosmic rays up to $\sim30\,{\rm PeV}$. The cosmic rays transmitted downstream from more powerful termination shocks associated with other galaxies can be further accelerated at Intergalactic Accretion Shocks to the highest energies observed. In this interpretation, the highest rigidity observed particles are protons; the highest energy particles are heavy nuclei, such as iron. A universal "bootstrap" prescription, coupling the energy density of the magnetic turbulence to that of the resonant cosmic rays, is proposed, initially for the highest energy particles escaping far ahead of the shock front and then scattering, successively, lower energy particles downstream. Observable implications of this general scheme relate to the spectrum, composition and sky distribution of Ultra-High-Energy Cosmic Rays, the extragalactic radio background, the Galactic halo magnetic field and Pevatrons.Comment: accepted for publication on Proceedings of Science for the 38th International Cosmic Ray Conference (ICRC2023

JWST Reveals a Possible z ∼ 11 Galaxy Merger in Triply Lensed MACS0647-JD

MACS0647–JD is a triply lensed z ∼ 11 galaxy originally discovered with the Hubble Space Telescope. The three lensed images are magnified by factors of ∼8, 5, and 2 to AB mag 25.1, 25.6, and 26.6 at 3.5 μm. The brightest is over a magnitude brighter than other galaxies recently discovered at similar redshifts z > 10 with JWST. Here, we report new JWST imaging that clearly resolves MACS0647–JD as having two components that are either merging galaxies or stellar complexes within a single galaxy. The brighter larger component “A” is intrinsically very blue (β ∼ −2.6 ± 0.1), likely due to very recent star formation and no dust, and is spatially extended with an effective radius ∼70 ± 24 pc. The smaller component “B” (r ∼ 20-+58 pc) appears redder (β ∼ −2 ± 0.2), likely because it is older (100–200 Myr) with mild dust extinction (AV ∼ 0.1 mag). With an estimated stellar mass ratio of roughly 2:1 and physical projected separation ∼400 pc, we may be witnessing a galaxy merger 430 million years after the Big Bang. We identify galaxies with similar colors in a high-redshift simulation, finding their star formation histories to be dissimilar, which is also suggested by the spectral energy distribution fitting, suggesting they formed further apart. We also identify a candidate companion galaxy “C” ∼3 kpc away, likely destined to merge with A and B. Upcoming JWST Near Infrared Spectrograph observations planned for 2023 January will deliver spectroscopic redshifts and more physical properties for these tiny magnified distant galaxies observed in the early universe.We are grateful and indebted to all 20,000 people who worked to make JWST an incredible discovery machine. We dedicate these JWST observations to Rob Hawkins, former lead developer of the Astronomer’s Proposal Tool (APT). Rob lost his life in 2020 November while astronomers around the world were using APT to prepare observations we proposed for JWST Cycle 1. This work is based on observations made with the NASA/ESA/CSA James Webb Space Telescope (JWST) and Hubble Space Telescope (HST). The data were obtained from theMikulski Archive for Space Telescopes (MAST) at the Space Telescope Science Institute (STScI), which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with programs JWST-GO1433 and HST-GO 9722, 10493, 10793, and 12101. T.H. and A. were funded by a grant for JWST-GO-01433 provided by STScI under NASA contract NAS 5-03127. L.W. acknowledges support from the National Science Foundation Graduate Research Fellowship under grant No. DGE-2137419. A.A. acknowledges support from the Swedish Research Council (Vetenskapsrådet project grant No. 2021-05559). P. D. acknowledges support from the NWO grant 016. VIDI.189.162 (“ODIN”) and the European Commission’s and University of Groningen’s CO-FUND Rosalind Franklin program and warmly thanks the Institute for Advanced Study (IAS) Princeton, where a part of this work was carried out, for their generous hospitality and support through the Bershadsky Fund. The Cosmic Dawn Center is funded by the Danish National Research Foundation (DNRF) under grant #140. E.Z. and A.V. ackowledge support from the Swedish National Space Agency. M.B. acknowledges support from the Slovenian national research agency ARRS through grant No. N1-0238. M.O. acknowledges support from JSPS KAKENHI grant Nos. JP22H01260, JP20H05856, JP20H00181, and JP22K21349. A. Z., A.K.M., and L.J.F. acknowledge support by grant No. 2020750 from the United States-Israel Binational Science Foundation (BSF) and grant No. 2109066 from the United States National Science Foundation (NSF), and by the Ministry of Science & Technology, Israel. E.V. and M.N. acknowledge financial support through grant Nos. PRIN-MIUR 2017WSCC32 and 2020SKSTHZ and INAF “main-stream” grant Nos. 1.05.01.86.20 and 1.05.01.86.31. Y.J.-T. acknowl edges financial support from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No. 898633, the MSCA IF Extensions Program of the Spanish National Research Council (CSIC), and the State Agency for Research of the Spanish MCIU through the Center of Excellence Severo Ochoa award to the Instituto de Astrofísica de Andalucía (SEV-2017- 0709). A.C.C. thanks the Leverhulme Trust for their support via a Leverhulme Early Career Fellowshi

JWST reveals a possible z∼11z \sim 11 galaxy merger in triply-lensed MACS0647−-JD

MACS0647$-$JD is a triply-lensed $z\sim11$ galaxy originally discovered with the Hubble Space Telescope. Here we report new JWST imaging, which clearly resolves MACS0647$-$JD as having two components that are either merging galaxies or stellar complexes within a single galaxy. Both are very small, with stellar masses $\sim10^8\,M_\odot$ and radii $r<100\,\rm pc$. The brighter larger component "A" is intrinsically very blue ($\beta\sim-2.6$), likely due to very recent star formation and no dust, and is spatially extended with an effective radius $\sim70\,\rm pc$. The smaller component "B" appears redder ($\beta\sim-2$), likely because it is older ($100-200\,\rm Myr$) with mild dust extinction ($A_V\sim0.1\,\rm mag$), and a smaller radius $\sim20\,\rm pc$. We identify galaxies with similar colors in a high-redshift simulation, finding their star formation histories to be out of phase. With an estimated stellar mass ratio of roughly 2:1 and physical projected separation $\sim400\,\rm pc$, we may be witnessing a galaxy merger 400 million years after the Big Bang. We also identify a candidate companion galaxy C $\sim3\,{\rm kpc}$ away, likely destined to merge with galaxies A and B. The combined light from galaxies A+B is magnified by factors of $\sim$8, 5, and 2 in three lensed images JD1, 2, and 3 with F356W fluxes $\sim322$, $203$, $86\,\rm nJy$ (AB mag 25.1, 25.6, 26.6). MACS0647$-$JD is significantly brighter than other galaxies recently discovered at similar redshifts with JWST. Without magnification, it would have AB mag 27.3 ($M_{UV}=-20.4$). With a high confidence level, we obtain a photometric redshift of $z=10.6\pm0.3$ based on photometry measured in 6 NIRCam filters spanning $1-5\rm\mu m$, out to $4300\,\r{A}$ rest-frame. JWST NIRSpec observations planned for January 2023 will deliver a spectroscopic redshift and a more detailed study of the physical properties of MACS0647$-$JD.Comment: 27 pages, 14 figures, submitted to Natur

The impact of viral mutations on recognition by SARS-CoV-2 specific T cells.

We identify amino acid variants within dominant SARS-CoV-2 T cell epitopes by interrogating global sequence data. Several variants within nucleocapsid and ORF3a epitopes have arisen independently in multiple lineages and result in loss of recognition by epitope-specific T cells assessed by IFN-γ and cytotoxic killing assays. Complete loss of T cell responsiveness was seen due to Q213K in the A∗01:01-restricted CD8+ ORF3a epitope FTSDYYQLY207-215; due to P13L, P13S, and P13T in the B∗27:05-restricted CD8+ nucleocapsid epitope QRNAPRITF9-17; and due to T362I and P365S in the A∗03:01/A∗11:01-restricted CD8+ nucleocapsid epitope KTFPPTEPK361-369. CD8+ T cell lines unable to recognize variant epitopes have diverse T cell receptor repertoires. These data demonstrate the potential for T cell evasion and highlight the need for ongoing surveillance for variants capable of escaping T cell as well as humoral immunity.This work is supported by the UK Medical Research Council (MRC); Chinese Academy of Medical Sciences(CAMS) Innovation Fund for Medical Sciences (CIFMS), China; National Institute for Health Research (NIHR)Oxford Biomedical Research Centre, and UK Researchand Innovation (UKRI)/NIHR through the UK Coro-navirus Immunology Consortium (UK-CIC). Sequencing of SARS-CoV-2 samples and collation of data wasundertaken by the COG-UK CONSORTIUM. COG-UK is supported by funding from the Medical ResearchCouncil (MRC) part of UK Research & Innovation (UKRI),the National Institute of Health Research (NIHR),and Genome Research Limited, operating as the Wellcome Sanger Institute. T.I.d.S. is supported by a Well-come Trust Intermediate Clinical Fellowship (110058/Z/15/Z). L.T. is supported by the Wellcome Trust(grant number 205228/Z/16/Z) and by theUniversity of Liverpool Centre for Excellence in Infectious DiseaseResearch (CEIDR). S.D. is funded by an NIHR GlobalResearch Professorship (NIHR300791). L.T. and S.C.M.are also supported by the U.S. Food and Drug Administration Medical Countermeasures Initiative contract75F40120C00085 and the National Institute for Health Research Health Protection Research Unit (HPRU) inEmerging and Zoonotic Infections (NIHR200907) at University of Liverpool inpartnership with Public HealthEngland (PHE), in collaboration with Liverpool School of Tropical Medicine and the University of Oxford.L.T. is based at the University of Liverpool. M.D.P. is funded by the NIHR Sheffield Biomedical ResearchCentre (BRC – IS-BRC-1215-20017). ISARIC4C is supported by the MRC (grant no MC_PC_19059). J.C.K.is a Wellcome Investigator (WT204969/Z/16/Z) and supported by NIHR Oxford Biomedical Research Centreand CIFMS. The views expressed are those of the authors and not necessarily those of the NIHR or MRC