Ludlam, R. M.R. M.LudlamMiller, J. M.J. M.MillerCackett, E. M.E. M.CackettFabian, A. C.A. C.FabianBACHETTI, MatteoMatteoBACHETTIParker, M. L.M. L.ParkerTomsick, J. A.J. A.TomsickBarret, D.D.BarretNATALUCCI, LORENZOLORENZONATALUCCIRana, V.V.RanaHarrison, F. A.F. A.Harrison2020-05-042020-05-0420160004-637Xhttp://hdl.handle.net/20.500.12386/24441We report on observations of the neutron star (NS) residing in the low-mass X-ray binary 1RXS J180408.9-34205 taken 2015 March by NuSTAR and XMM-Newton while the source was in the hard spectral state. We find multiple reflection features (Fe {{{K}}}<SUB>α </SUB> detected with NuSTAR; N vii, O vii, and O viii detected in the RGS) from different ionization zones. Through joint fits using the self-consistent relativistic reflection model relxill, we determine the inner radius to be ≤11.1 R <SUB> g </SUB>. For a 1.4 {M}<SUB>☉ </SUB> NS with a spin of {a}<SUB>\ast </SUB>=0, this is an inner disk radius of ≤slant 22.2 km. We find the inclination of the system to be between 18° and 29°. If the disk is truncated at a radius greater than the NS radius, it could be truncated by a boundary layer on the NS surface. It is also possible that the disk is truncated at the magnetospheric radius; conservative estimates would then imply B≤slant (0.3{--}1.0)× {10}<SUP>9</SUP> G at the magnetic poles, though coherent pulsations have not been detected and the source is not identified as a pulsar.STAMPAenArticle10.3847/0004-637X/824/1/372-s2.0-84976349102000377937300037https://iopscience.iop.org/article/10.3847/0004-637X/824/1/37/meta2016ApJ...824...37LFIS/05 - ASTRONOMIA E ASTROFISICAScienze Fisiche Settori ERC (ERC) di riferimento::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation