A. W. Steiner - Institute for Nuclear Theory, University of Washington, United States

A. W. Steiner
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Name
A. W. Steiner
Affiliation
Institute for Nuclear Theory, University of Washington, United States
City
Seattle
Country
United States

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Nuclear Theory (41)
 
High Energy Astrophysical Phenomena (25)
 
Solar and Stellar Astrophysics (24)
 
Nuclear Experiment (11)
 
Astrophysics (3)
 
High Energy Physics - Phenomenology (3)
 
Computer Science - Information Theory (2)
 
Mathematics - Information Theory (2)
 
Instrumentation and Methods for Astrophysics (2)
 
Cosmology and Nongalactic Astrophysics (1)
 
General Relativity and Quantum Cosmology (1)
 
Earth and Planetary Astrophysics (1)
 
Physics - Superconductivity (1)

Publications Authored By A. W. Steiner

Thermal states of neutron stars in soft X-ray transients (SXRTs) are thought to be determined by "deep crustal heating" in the accreted matter that drives the quiescent luminosity and cooling via emission of photons and neutrinos from the interior. In this study, we assume a global thermal steady-state of the transient system and calculate the heating curves (quiescent surface luminosity as a function of mean accretion rate) predicted from theoretical models, taking into account variations in the equations of state, superfluidity gaps, thickness of the light element layer and a phenomenological description of the direct Urca threshold. We further provide a statistical analysis on the uncertainties in these parameters, and compare the overall results with observations of several SXRTs, in particular the two sources containing the coldest (SAX J1808. Read More

We present a quantitative analysis of superfluidity and superconductivity in dense matter from observations of isolated neutron stars in the context of the minimal cooling model. Our new approach produces the best fit neutron triplet superfluid critical temperature, the best fit proton singlet superconducting critical temperature, and their associated statistical uncertainties. We find that the neutron triplet critical temperature is $(1. Read More

Two low mass neutron stars, J0737-3039B and the companion to J1756-2251, show strong evidence of being formed from the collapse of an ONeMg core in an electron capture supernova (ECSN) or in an ultra-stripped iron core collapse supernova (FeCCSN). Using three different systematically generated sets of equations of state we explore the relationship between the moment of inertia of J0737-3039A and the binding energy of the two low mass neutron stars. We find this relationship, a less strict variant of the recently discovered I-Love-Q relations, is nevertheless more robust than a previously explored correlation between the binding energy and the slope of the nuclear symmetry energy L. Read More

The bulk of the rare earth elements are believed to be synthesized in the rapid neutron capture process or $r$ process of nucleosynthesis. The solar $r$-process residuals show a small peak in the rare earths around $A\sim 160$, which is proposed to be formed dynamically during the end phase of the $r$ process by a pileup of material. This abundance feature is of particular importance as it is sensitive to both the nuclear physics inputs and the astrophysical conditions of the main $r$ process. Read More

Background: The nuclear symmetry energy is a fundamental ingredient in determining the equation of state (EOS) of neutron stars (NS). Recent terrestrial experiments constrain both its value and slope at nuclear saturation density, however, its value at higher densities is unknown. Assuming a Free Fermi-gas (FFG) model for the kinetic symmetry energy, the high-density extrapolation depends on a single parameter, the density dependence of the potential symmetry energy. Read More

The primary astrophysical source of the rare earth elements is the rapid neutron capture process ($r$ process). The rare earth peak that is seen in the solar $r$-process residuals has been proposed to originate as a pile-up of nuclei during the end of the $r$ process. We introduce a new method utilizing Monte Carlo studies of nuclear masses in the rare earth region, that includes self-consistently adjusting $\beta$-decay rates and neutron capture rates, to find the mass surfaces necessary for the formation of the rare earth peak. Read More

This white paper informs the nuclear astrophysics community and funding agencies about the scientific directions and priorities of the field and provides input from this community for the 2015 Nuclear Science Long Range Plan. It summarizes the outcome of the nuclear astrophysics town meeting that was held on August 21-23, 2014 in College Station at the campus of Texas A&M University in preparation of the NSAC Nuclear Science Long Range Plan. It also reflects the outcome of an earlier town meeting of the nuclear astrophysics community organized by the Joint Institute for Nuclear Astrophysics (JINA) on October 9- 10, 2012 Detroit, Michigan, with the purpose of developing a vision for nuclear astrophysics in light of the recent NRC decadal surveys in nuclear physics (NP2010) and astronomy (ASTRO2010). Read More

One of the primary science goals of the next generation of hard X-ray timing instruments is to determine the equation of state of the matter at supranuclear densities inside neutron stars, by measuring the radius of neutron stars with different masses to accuracies of a few percent. Three main techniques can be used to achieve this goal. The first involves waveform modelling. Read More

We investigate constraints on neutron star structure arising from the assumptions that neutron stars have crusts, that recent calculations of pure neutron matter limit the equation of state of neutron star matter near the nuclear saturation density, that the high-density equation of state is limited by causality and the largest high-accuracy neutron star mass measurement, and that general relativity is the correct theory of gravity. We explore the role of prior assumptions by considering two classes of equation of state models. In a first, the intermediate- and high-density behavior of the equation of state is parameterized by piecewise polytropes. Read More

The cooling phase of thermonuclear (type-I) X-ray bursts can be used to constrain the neutron star (NS) compactness by comparing the observed cooling tracks of bursts to accurate theoretical atmosphere model calculations. By applying the so-called cooling tail method, where the information from the whole cooling track is used, we constrain the mass, radius, and distance for three different NSs in low-mass X-ray binaries 4U 1702-429, 4U 1724-307, and SAX J1810.8-260. Read More

Neutron star (binary neutron star and neutron star - black hole) mergers are believed to produce short-duration gamma-ray bursts. They are also believed to be the dominant source of gravitational waves to be detected by the advanced LIGO and the dominant source of the heavy r-process elements in the universe. Whether or not these mergers produce short-duration GRBs depends sensitively on the fate of the core of the remnant (whether, and how quickly, it forms a black hole). Read More

The likely presence of $\Lambda$ baryons in dense hadronic matter tends to soften the equation of state to an extend that the observed heaviest neutron stars are difficult to explain. We analyze this "hyperon problem" with a phenomenological approach. First, we review what can be learned about the interaction of $\Lambda$ particle with dense matter from the observed hypernuclei and extend this phenomenological analysis to asymmetric matter. Read More

2014Aug
Authors: M. Feroci1, J. W. den Herder2, E. Bozzo3, D. Barret4, S. Brandt5, M. Hernanz6, M. van der Klis7, M. Pohl8, A. Santangelo9, L. Stella10, A. Watts11, J. Wilms12, S. Zane13, M. Ahangarianabhari14, C. Albertus15, M. Alford16, A. Alpar17, D. Altamirano18, L. Alvarez19, L. Amati20, C. Amoros21, N. Andersson22, A. Antonelli23, A. Argan24, R. Artigue25, B. Artigues26, J. -L. Atteia27, P. Azzarello28, P. Bakala29, G. Baldazzi30, S. Balman31, M. Barbera32, C. van Baren33, S. Bhattacharyya34, A. Baykal35, T. Belloni36, F. Bernardini37, G. Bertuccio38, S. Bianchi39, A. Bianchini40, P. Binko41, P. Blay42, F. Bocchino43, P. Bodin44, I. Bombaci45, J. -M. Bonnet Bidaud46, S. Boutloukos47, L. Bradley48, J. Braga49, E. Brown50, N. Bucciantini51, L. Burderi52, M. Burgay53, M. Bursa54, C. Budtz-Jørgensen55, E. Cackett56, F. R. Cadoux57, P. Cais58, G. A. Caliandro59, R. Campana60, S. Campana61, F. Capitanio62, J. Casares63, P. Casella64, A. J. Castro-Tirado65, E. Cavazzuti66, P. Cerda-Duran67, D. Chakrabarty68, F. Château69, J. Chenevez70, J. Coker71, R. Cole72, A. Collura73, R. Cornelisse74, T. Courvoisier75, A. Cros76, A. Cumming77, G. Cusumano78, A. D'Aì79, V. D'Elia80, E. Del Monte81, A. De Luca82, D. De Martino83, J. P. C. Dercksen84, M. De Pasquale85, A. De Rosa86, M. Del Santo87, S. Di Cosimo88, S. Diebold89, T. Di Salvo90, I. Donnarumma91, A. Drago92, M. Durant93, D. Emmanoulopoulos94, M. H. Erkut95, P. Esposito96, Y. Evangelista97, A. Fabian98, M. Falanga99, Y. Favre100, C. Feldman101, V. Ferrari102, C. Ferrigno103, M. Finger104, M. H. Finger105, G. W. Fraser106, M. Frericks107, F. Fuschino108, M. Gabler109, D. K. Galloway110, J. L. Galvez Sanchez111, E. Garcia-Berro112, B. Gendre113, S. Gezari114, A. B. Giles115, M. Gilfanov116, P. Giommi117, G. Giovannini118, M. Giroletti119, E. Gogus120, A. Goldwurm121, K. Goluchová122, D. Götz123, C. Gouiffes124, M. Grassi125, P. Groot126, M. Gschwender127, L. Gualtieri128, C. Guidorzi129, L. Guy130, D. Haas131, P. Haensel132, M. Hailey133, F. Hansen134, D. H. Hartmann135, C. A. Haswell136, K. Hebeler137, A. Heger138, W. Hermsen139, J. Homan140, A. Hornstrup141, R. Hudec142, J. Huovelin143, A. Ingram144, J. J. M. in't Zand145, G. Israel146, K. Iwasawa147, L. Izzo148, H. M. Jacobs149, F. Jetter150, T. Johannsen151, H. M. Jacobs152, P. Jonker153, J. Josè154, P. Kaaret155, G. Kanbach156, V. Karas157, D. Karelin158, D. Kataria159, L. Keek160, T. Kennedy161, D. Klochkov162, W. Kluzniak163, K. Kokkotas164, S. Korpela165, C. Kouveliotou166, I. Kreykenbohm167, L. M. Kuiper168, I. Kuvvetli169, C. Labanti170, D. Lai171, F. K. Lamb172, P. P. Laubert173, F. Lebrun174, D. Lin175, D. Linder176, G. Lodato177, F. Longo178, N. Lund179, T. J. Maccarone180, D. Macera181, S. Maestre182, S. Mahmoodifar183, D. Maier184, P. Malcovati185, I. Mandel186, V. Mangano187, A. Manousakis188, M. Marisaldi189, A. Markowitz190, A. Martindale191, G. Matt192, I. M. McHardy193, A. Melatos194, M. Mendez195, S. Mereghetti196, M. Michalska197, S. Migliari198, R. Mignani199, M. C. Miller200, J. M. Miller201, T. Mineo202, G. Miniutti203, S. Morsink204, C. Motch205, S. Motta206, M. Mouchet207, G. Mouret208, J. Mulačová209, F. Muleri210, T. Muñoz-Darias211, I. Negueruela212, J. Neilsen213, A. J. Norton214, M. Nowak215, P. O'Brien216, P. E. H. Olsen217, M. Orienti218, M. Orio219, M. Orlandini220, P. Orleanski221, J. P. Osborne222, R. Osten223, F. Ozel224, L. Pacciani225, M. Paolillo226, A. Papitto227, J. M. Paredes228, A. Patruno229, B. Paul230, E. Perinati231, A. Pellizzoni232, A. V. Penacchioni233, M. A. Perez234, V. Petracek235, C. Pittori236, J. Pons237, J. Portell238, A. Possenti239, J. Poutanen240, M. Prakash241, P. Le Provost242, D. Psaltis243, D. Rambaud244, P. Ramon245, G. Ramsay246, M. Rapisarda247, A. Rachevski248, I. Rashevskaya249, P. S. Ray250, N. Rea251, S. Reddy252, P. Reig253, M. Reina Aranda254, R. Remillard255, C. Reynolds256, L. Rezzolla257, M. Ribo258, R. de la Rie259, A. Riggio260, A. Rios261, P. Rodríguez- Gil262, J. Rodriguez263, R. Rohlfs264, P. Romano265, E. M. R. Rossi266, A. Rozanska267, A. Rousseau268, F. Ryde269, L. Sabau-Graziati270, G. Sala271, R. Salvaterra272, A. Sanna273, J. Sandberg274, S. Scaringi275, S. Schanne276, J. Schee277, C. Schmid278, S. Shore279, R. Schneider280, A. Schwenk281, A. D. Schwope282, J. -Y. Seyler283, A. Shearer284, A. Smith285, D. M. Smith286, P. J. Smith287, V. Sochora288, P. Soffitta289, P. Soleri290, A. Spencer291, B. Stappers292, A. W. Steiner293, N. Stergioulas294, G. Stratta295, T. E. Strohmayer296, Z. Stuchlik297, S. Suchy298, V. Sulemainov299, T. Takahashi300, F. Tamburini301, T. Tauris302, C. Tenzer303, L. Tolos304, F. Tombesi305, J. Tomsick306, G. Torok307, J. M. Torrejon308, D. F. Torres309, A. Tramacere310, A. Trois311, R. Turolla312, S. Turriziani313, P. Uter314, P. Uttley315, A. Vacchi316, P. Varniere317, S. Vaughan318, S. Vercellone319, V. Vrba320, D. Walton321, S. Watanabe322, R. Wawrzaszek323, N. Webb324, N. Weinberg325, H. Wende326, P. Wheatley327, R. Wijers328, R. Wijnands329, M. Wille330, C. A. Wilson-Hodge331, B. Winter332, K. Wood333, G. Zampa334, N. Zampa335, L. Zampieri336, L. Zdunik337, A. Zdziarski338, B. Zhang339, F. Zwart340, M. Ayre341, T. Boenke342, C. Corral van Damme343, E. Kuulkers344, D. Lumb345
Affiliations: 11,1b, 2SRON, The Netherlands, 3ISDC, Geneve University, Switzerland, 4IRAP, Toulouse, France, 5National Space Institute, Lyngby, Denmark, 6IEEC-CSIC-UPC-UB, Barcelona, Spain, 7Astronomical Institute Anton Pannekoek, University of Amsterdam, The Netherlands, 8DPNC, Geneve University, Switzerland, 9IAAT Tuebingen, Germany, 10INAF-OA Rome, Italy, 11Astronomical Institute Anton Pannekoek, University of Amsterdam, The Netherlands, 12University of Erlangen-Nuremberg, Germany, 13MSSL, Surrey, United Kingdom, 14Politecnico Milano, Italy, 15Universidad de Granada, Spain, 16Washington University, United States, 17Sabanci University, Istanbul, Turkey, 18Astronomical Institute Anton Pannekoek, University of Amsterdam, The Netherlands, 19IEEC-CSIC-UPC-UB, Barcelona, Spain, 20INAF-IASF-Bologna, Italy, 21IRAP, Toulouse, France, 22Faculty of Physical and Applied Sciences, University of Southampton, United Kingdom, 23ASDC, Rome, Italy, 24IAPS-INAF, Rome, Italy, 25IRAP, Toulouse, France, 26IEEC-CSIC-UPC-UB, Barcelona, Spain, 27IRAP, Toulouse, France, 28ISDC, Geneve University, Switzerland, 29Silesian University in Opava, Czech Republic, 30University of Bologna, Italy, 31Middle East Technical University, Ankara, Turkey, 32Dipartimento di Chimica e Fisica, Palermo University, Italy, 33SRON, The Netherlands, 34Tata Institute of Fundamental Research, Mumbai, India, 35Middle East Technical University, Ankara, Turkey, 36INAF-OA Brera, Italy, 37Wayne State University, Detroit, United States, 38Politecnico Milano, Italy, 39University of Rome III, Italy, 40Dept. of Physics and Astronomy University of Padua, Italy, 41ISDC, Geneve University, Switzerland, 42University of Valencia, Spain, 43INAF-OA Padova, Padova, Italy, 44CNES, Toulouse, France, 45University of Pisa, Italy, 46CEA Saclay, DSM/IRFU/SAp, France, 47IAAT Tuebingen, Germany, 48MSSL, Surrey, United Kingdom, 49INPE, São José dos Campos, Brazil, 50Michigan state University, United States, 51Arcetri Observatory, INAF, Firenze, Italy, 52Cagliari University, Italy, 53INAF-OA Cagliari, Italy, 54Astronomical Institute of the Academy of Sciences of the Czech Republic, Czech Republic, 55National Space Institute, Lyngby, Denmark, 56Wayne State University, Detroit, United States, 57DPNC, Geneve University, Switzerland, 58Laboratoire d'Astrophysique de Bordeaux, France, 59IEEC-CSIC-UPC-UB, Barcelona, Spain, 601,1b, 61INAF-OA Brera, Italy, 62IAPS-INAF, Rome, Italy, 63Instituto de Astrofisica de Canarias, Tenerife, Spain, 64INAF-OA Rome, Italy, 65Instituto Astrofisica de Andalucia, Granada, Spain, 66ASDC, Rome, Italy, 67University of Valencia, Spain, 68MIT, Cambridge, United States, 69CEA Saclay, DSM/IRFU/SAp, France, 70National Space Institute, Lyngby, Denmark, 71MSSL, Surrey, United Kingdom, 72MSSL, Surrey, United Kingdom, 73INAF- Osservatorio Astronomico di Palermo, Italy, 74Instituto de Astrofisica de Canarias, Tenerife, Spain, 75ISDC, Geneve University, Switzerland, 76IRAP, Toulouse, France, 77INAF-OA Capodimonte, Napoli, Italy, 78INAF IFC, Palermo, Italy, 79Dipartimento di Chimica e Fisica, Palermo University, Italy, 80ASDC, Rome, Italy, 811,1b, 82INAF-IASF-Milano, Italy, 83INAF-OA Capodimonte, Napoli, Italy, 84SRON, The Netherlands, 85MSSL, Surrey, United Kingdom, 86IAPS-INAF, Rome, Italy, 87IAPS-INAF, Rome, Italy, 88IAPS-INAF, Rome, Italy, 89IAAT Tuebingen, Germany, 90Dipartimento di Chimica e Fisica, Palermo University, Italy, 91IAPS-INAF, Rome, Italy, 92Ferrara University, Ferrara, Italy, 93Department of Medical Biophysics, University of Toronto, Canada, 94School of Physics and Astronomy, University of Southampton, United Kingdom, 95Istanbul Kültür University, Turkey, 96INAF-IASF-Milano, Italy, 971,1b, 98Cambridge University, Cambridge, United Kingdom, 99ISSI Bern, Switzerland, 100DPNC, Geneve University, Switzerland, 101Leicester University, United Kingdom, 102Sapienza University, Rome, Italy, 103ISDC, Geneve University, Switzerland, 104Charles University in Prague, Czech Republic, 105Universities Space Research Association, Huntsville, United States, 106Leicester University, United Kingdom, 107SRON, The Netherlands, 108INAF-IASF-Bologna, Italy, 109University of Valencia, Spain, 110Monash Centre for Astrophysics, School of Physics and School of Mathematical Sciences, Monash University, Australia, 111IEEC-CSIC-UPC-UB, Barcelona, Spain, 112IEEC-CSIC-UPC-UB, Barcelona, Spain, 113ASDC, Rome, Italy, 114University of Maryland, United States, 115University of Tasmania, Australia, 116MPA Garching, Germany, 117ASDC, Rome, Italy, 118INAF-IRA-Bologna, Italy, 119INAF-IRA-Bologna, Italy, 120Sabanci University, Istanbul, Turkey, 121APC, Université Paris Diderot, CEA/Irfu, Observatoire de Paris, France, 122Silesian University in Opava, Czech Republic, 123CEA Saclay, DSM/IRFU/SAp, France, 124CEA Saclay, DSM/IRFU/SAp, France, 125Pavia University, Italy, 126Clemson University, United States, 127IAAT Tuebingen, Germany, 128Sapienza University, Rome, Italy, 129Ferrara University, Ferrara, Italy, 130ISDC, Geneve University, Switzerland, 131SRON, The Netherlands, 132Copernicus Astronomical Center, Warsaw, Poland, 133MSSL, Surrey, United Kingdom, 134National Space Institute, Lyngby, Denmark, 135Clemson University, United States, 136Open University, United Kingdom, 137Institut für Kernphysik, Technische Universität Darmstadt and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Germany, 138Monash Centre for Astrophysics, School of Physics and School of Mathematical Sciences, Monash University, Australia, 139SRON, The Netherlands, 140MIT, Cambridge, United States, 141National Space Institute, Lyngby, Denmark, 142Astronomical Institute of the Academy of Sciences of the Czech Republic, Czech Republic, 143University of Helsinki, Finland, 144Astronomical Institute Anton Pannekoek, University of Amsterdam, The Netherlands, 145SRON, The Netherlands, 146INAF-OA Rome, Italy, 147DAM and ICC-UB, Universitat de Barcelona, Spain, 148Sapienza University and ICRA, Rome, Italy, 149SRON, The Netherlands, 150IAAT Tuebingen, Germany, 151Perimeter Institute for Theoretical Physics, Waterloo, Canada, 152SRON, The Netherlands, 153SRON, The Netherlands, 154Technical University of Catalonia, Barcelona, Spain, 155Michigan state University, United States, 156Max-Planck-Institut fuer extraterrestrische Physik, Garching, Germany, 157Astronomical Institute of the Academy of Sciences of the Czech Republic, Czech Republic, 158IEEC-CSIC-UPC-UB, Barcelona, Spain, 159MSSL, Surrey, United Kingdom, 160Michigan state University, United States, 161MSSL, Surrey, United Kingdom, 162IAAT Tuebingen, Germany, 163Copernicus Astronomical Center, Warsaw, Poland, 164IAAT Tuebingen, Germany, 165University of Helsinki, Finland, 166NASA/Marshall Space Flight Center, United States, 167University of Erlangen-Nuremberg, Germany, 168SRON, The Netherlands, 169National Space Institute, Lyngby, Denmark, 170INAF-IASF-Bologna, Italy, 171Cornell University, Ithaca, United States, 172University of Illinois, United States, 173SRON, The Netherlands, 174APC, Université Paris Diderot, CEA/Irfu, Observatoire de Paris, France, 175IRAP, Toulouse, France, 176MSSL, Surrey, United Kingdom, 177Dipartimento di Fisica, Università degli Studi di Milano, Italy, 178University of Trieste, Italy, 179National Space Institute, Lyngby, Denmark, 180Texas Tech. University, United States, 181Politecnico Milano, Italy, 182IRAP, Toulouse, France, 183University of Maryland, United States, 184IAAT Tuebingen, Germany, 185Pavia University, Italy, 186School of Physics and Astronomy, University of Birmingham, United Kingdom, 187The Pennsylvania State University, United States, 188Copernicus Astronomical Center, Warsaw, Poland, 189INAF-IASF-Bologna, Italy, 190University of California, San Diego, United States, 191Leicester University, United Kingdom, 192University of Rome III, Italy, 193School of Physics and Astronomy, University of Southampton, United Kingdom, 194University of Melbourne, Australia, 195Kapteyn Astronomical Institute, University of Groningen, The Netherlands, 196INAF-IASF-Milano, Italy, 197Space Research Centre, Warsaw, Poland, 198DAM and ICC-UB, Universitat de Barcelona, Spain, 199INAF-IASF-Milano, Italy, 200University of Maryland, United States, 201Michigan state University, United States, 202INAF IFC, Palermo, Italy, 203Centro de Astrobiologia, 204University of Alberta, Canada, 205Observatoire Astronomique de Strasbourg, France, 206INAF-OA Brera, Italy, 207Université Paris Diderot France, 208IRAP, Toulouse, France, 209National Space Institute, Lyngby, Denmark, 2101,1b, 211Oxford University, United Kingdom, 212University of Alicante, Spain, 213MIT, Cambridge, United States, 214Open University, United Kingdom, 215MIT, Cambridge, United States, 216Leicester University, United Kingdom, 217National Space Institute, Lyngby, Denmark, 218INAF-IRA-Bologna, Italy, 219INAF-OA Padova, Padova, Italy, 220INAF-IASF-Bologna, Italy, 221Space Research Centre, Warsaw, Poland, 222Leicester University, United Kingdom, 223Space Telescope Institute, United States, 224University of Arizona, United States, 2251,1b, 226Università di Napoli Fedelico II, Italy, 227IEEC-CSIC-UPC-UB, Barcelona, Spain, 228DAM and ICC-UB, Universitat de Barcelona, Spain, 229Leiden Observatory, The Netherlands, 230Raman Research Institute, India, 231IAAT Tuebingen, Germany, 232INAF-OA Cagliari, Italy, 233Sapienza University and ICRA, Rome, Italy, 234Facultad de Ciencias-Trilingüe University of Salamanca, Spain, 235Czech Technical University in Prague, Czech Republic, 236ASDC, Rome, Italy, 237University of Alicante, Spain, 238IEEC-CSIC-UPC-UB, Barcelona, Spain, 239INAF-OA Cagliari, Italy, 240Tuorla Observatory, University of Turku, Finland, 241Ohio University, United States, 242CEA Saclay, DSM/IRFU/SAp, France, 243University of Arizona, United States, 244IRAP, Toulouse, France, 245IRAP, Toulouse, France, 246Armagh Observatory, United Kingdom, 2471,1b, 248INFN, Trieste, Italy, 249INFN, Trieste, Italy, 250NRL, Washington, United States, 251IEEC-CSIC-UPC-UB, Barcelona, Spain, 252Institute for Nuclear Theory, University of Washington, United States, 253Foundation for Research and Technology, Heraklion, Greece, 254National Institute of Aerospace Technology, 255MIT, Cambridge, United States, 256University of Maryland, United States, 257Max Planck Institute for Gravitational Physics, Germany, 258DAM and ICC-UB, Universitat de Barcelona, Spain, 259SRON, The Netherlands, 260INAF-OA Cagliari, Italy, 261University of Surrey, United Kingdom, 262Instituto de Astrofisica de Canarias, Tenerife, Spain, 263CEA Saclay, DSM/IRFU/SAp, France, 264ISDC, Geneve University, Switzerland, 265INAF IFC, Palermo, Italy, 266Leiden Observatory, The Netherlands, 267Copernicus Astronomical Center, Warsaw, Poland, 268MSSL, Surrey, United Kingdom, 269KTH Royal Institute of Technology, Stockholm, Sweden, 270National Institute of Aerospace Technology, 271IEEC-CSIC-UPC-UB, Barcelona, Spain, 272INAF-IASF-Milano, Italy, 273Kapteyn Astronomical Institute, University of Groningen, The Netherlands, 274Jorgen Sandberg Consulting, Denmark, 275Institute for Astronomy K.U. Leuven, Leuven, Belgium, 276CEA Saclay, DSM/IRFU/SAp, France, 277Silesian University in Opava, Czech Republic, 278University of Erlangen-Nuremberg, Germany, 279University of Pisa, Italy, 280INAF-OA Rome, Italy, 281Institut für Kernphysik, Technische Universität Darmstadt and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Germany, 282Leibniz-Institut fuer Astrophysik Potsdam, Germany, 283CNES, Toulouse, France, 284National University of Ireland, Ireland, 285MSSL, Surrey, United Kingdom, 286University of California, United States, 287MSSL, Surrey, United Kingdom, 288Astronomical Institute of the Academy of Sciences of the Czech Republic, Czech Republic, 289IAPS-INAF, Rome, Italy, 290Kapteyn Astronomical Institute, University of Groningen, The Netherlands, 291MSSL, Surrey, United Kingdom, 292University of Manchester, United Kingdom, 293Institute for Nuclear Theory, University of Washington, United States, 294Aristotle University of Thessaloniki, Greece, 295ASDC, Rome, Italy, 296Goddard Space Flight Center, Greenbelt, United States, 297Silesian University in Opava, Czech Republic, 298IAAT Tuebingen, Germany, 299IAAT Tuebingen, Germany, 300ISAS, Kanagawa, Japan, 301Dept. of Physics and Astronomy University of Padua, Italy, 302Argelander-Institut für Astronomie, Bonn, Germany, 303IAAT Tuebingen, Germany, 304IEEC-CSIC-UPC-UB, Barcelona, Spain, 305University of Maryland, United States, 306University of California, Berkeley, Space Sciences Laboratory, United States, 307Silesian University in Opava, Czech Republic, 308University of Alicante, Spain, 309ICREA, Barcelona, Spain, 310ISDC, Geneve University, Switzerland, 311IAPS-INAF, Rome, Italy, 312Dept. of Physics and Astronomy University of Padua, Italy, 313University of Rome Tor Vergata, Italy, 314IAAT Tuebingen, Germany, 315Astronomical Institute Anton Pannekoek, University of Amsterdam, The Netherlands, 316INFN, Trieste, Italy, 317APC, Université Paris Diderot, CEA/Irfu, Observatoire de Paris, France, 318Leicester University, United Kingdom, 319INAF IFC, Palermo, Italy, 320Physical Institute of the Academy of Sciences of the Czech Republic, Czech Republic, 321MSSL, Surrey, United Kingdom, 322ISAS, Kanagawa, Japan, 323Space Research Centre, Warsaw, Poland, 324IRAP, Toulouse, France, 325MIT, Cambridge, United States, 326IAAT Tuebingen, Germany, 327University of Warwick, United Kingdom, 328Astronomical Institute Anton Pannekoek, University of Amsterdam, The Netherlands, 329Astronomical Institute Anton Pannekoek, University of Amsterdam, The Netherlands, 330University of Erlangen-Nuremberg, Germany, 331NASA/Marshall Space Flight Center, Huntsville, United States, 332MSSL, Surrey, United Kingdom, 333NRL, Washington, United States, 334INFN, Trieste, Italy, 335INFN, Trieste, Italy, 336INAF-OA Padova, Padova, Italy, 337Copernicus Astronomical Center, Warsaw, Poland, 338Copernicus Astronomical Center, Warsaw, Poland, 339University of Nevada, Las Vegas, United States, 340SRON, The Netherlands, 341European Space Agency, ESTEC, The Netherlands, 342European Space Agency, ESTEC, The Netherlands, 343European Space Agency, ESTEC, The Netherlands, 344European Space Astronomy Centre, Madrid, Spain, 345European Space Agency, ESTEC, The Netherlands

The Large Observatory For x-ray Timing (LOFT) was studied within ESA M3 Cosmic Vision framework and participated in the final down-selection for a launch slot in 2022-2024. Thanks to the unprecedented combination of effective area and spectral resolution of its main instrument, LOFT will study the behaviour of matter under extreme conditions, such as the strong gravitational field in the innermost regions of accretion flows close to black holes and neutron stars, and the supra-nuclear densities in the interior of neutron stars. The science payload is based on a Large Area Detector (LAD, 10 m 2 effective area, 2-30 keV, 240 eV spectral resolution, 1 deg collimated field of view) and a WideField Monitor (WFM, 2-50 keV, 4 steradian field of view, 1 arcmin source location accuracy, 300 eV spectral resolution). Read More

It has been conjectured that the velocity of sound in any medium is smaller than the velocity of light in vacuum divided by $\sqrt{3}$. Simple arguments support this bound in non-relativistic and/or weakly coupled theories. The bound has been demonstrated in several classes of strongly coupled theories with gravity duals and is saturated only in conformal theories. Read More

2014Jul
Affiliations: 1Institute for Nuclear Theory, University of Washington

There are several assumptions made in a standard $\chi^2$ analysis of data, including the frequent assumption that the likelihood function is well approximated by a multivariate Gaussian distribution. This article briefly reviews the standard approach and describes how Bayesian inference can be used to go beyond the assumption that the likelihood is Gaussian. Two separate types of analysis relevant to nuclear physics are used as test cases. Read More

We perform a systematic assessment of models for the equation of state (EOS) of dense matter in the context of recent neutron star mass and radius measurements to obtain a broad picture of the structure of neutron stars. We demonstrate that currently available neutron star mass and radius measurements provide strong constraints on moments of inertia, tidal deformabilities, and crust thicknesses. A measurement of the moment of inertia of PSR J0737-3039A with 10% error, without any other information from observations, will constrain the EOS over a range of densities to within 50%$-$60%. Read More

2014Mar
Affiliations: 1Department of Physics and Astronomy, State University of New York at Stony Brook, 2Institute for Nuclear Theory, University of Washington

The nuclear symmetry energy is intimately connected with nuclear astrophysics. This contribution focuses on the estimation of the symmetry energy from experiment and how it is related to the structure of neutron stars. The most important connection is between the radii of neutron stars and the pressure of neutron star matter in the vicinity of the nuclear saturation density $n_s$. Read More

The temperature in the crust of an accreting neutron star, which comprises its outermost kilometer, is set by heating from nuclear reactions at large densities, neutrino cooling, and heat transport from the interior. The heated crust has been thought to affect observable phenomena at shallower depths, such as thermonuclear bursts in the accreted envelope. Here we report that cycles of electron capture and its inverse, $\beta^-$ decay, involving neutron-rich nuclei at a typical depth of about 150 m, cool the outer neutron star crust by emitting neutrinos while also thermally decoupling the surface layers from the deeper crust. Read More

Recent progress in quantum Monte Carlo with modern nucleon-nucleon interactions have enabled the successful description of properties of light nuclei and neutron-rich matter. As a demonstration, we show that the agreement between theoretical calculations of the charge form factor of 12C and the experimental data is excellent. Applying similar methods to isospin-asymmetric systems allows one to describe neutrons confined in an external potential and homogeneous neutron-rich matter. Read More

We review the calculation of the equation of state of pure neutron matter using quantum Monte Carlo (QMC) methods. QMC algorithms permit the study of many-body nuclear systems using realistic two- and three-body forces in a nonperturbative framework. We present the results for the equation of state of neutron matter, and focus on the role of three-neutron forces at supranuclear density. Read More

2013Jun
Authors: Kirpal Nandra1, Didier Barret2, Xavier Barcons3, Andy Fabian4, Jan-Willem den Herder5, Luigi Piro6, Mike Watson7, Christophe Adami8, James Aird9, Jose Manuel Afonso10, Dave Alexander11, Costanza Argiroffi12, Lorenzo Amati13, Monique Arnaud14, Jean-Luc Atteia15, Marc Audard16, Carles Badenes17, Jean Ballet18, Lucia Ballo19, Aya Bamba20, Anil Bhardwaj21, Elia Stefano Battistelli22, Werner Becker23, Michaël De Becker24, Ehud Behar25, Stefano Bianchi26, Veronica Biffi27, Laura Bîrzan28, Fabrizio Bocchino29, Slavko Bogdanov30, Laurence Boirin31, Thomas Boller32, Stefano Borgani33, Katharina Borm34, Nicolas Bouché35, Hervé Bourdin36, Richard Bower37, Valentina Braito38, Enzo Branchini39, Graziella Branduardi-Raymont40, Joel Bregman41, Laura Brenneman42, Murray Brightman43, Marcus Brüggen44, Johannes Buchner45, Esra Bulbul46, Marcella Brusa47, Michal Bursa48, Alessandro Caccianiga49, Ed Cackett50, Sergio Campana51, Nico Cappelluti52, Massimo Cappi53, Francisco Carrera54, Maite Ceballos55, Finn Christensen56, You-Hua Chu57, Eugene Churazov58, Nicolas Clerc59, Stephane Corbel60, Amalia Corral61, Andrea Comastri62, Elisa Costantini63, Judith Croston64, Mauro Dadina65, Antonino D'Ai66, Anne Decourchelle67, Roberto Della Ceca68, Konrad Dennerl69, Klaus Dolag70, Chris Done71, Michal Dovciak72, Jeremy Drake73, Dominique Eckert74, Alastair Edge75, Stefano Ettori76, Yuichiro Ezoe77, Eric Feigelson78, Rob Fender79, Chiara Feruglio80, Alexis Finoguenov81, Fabrizio Fiore82, Massimiliano Galeazzi83, Sarah Gallagher84, Poshak Gandhi85, Massimo Gaspari86, Fabio Gastaldello87, Antonis Georgakakis88, Ioannis Georgantopoulos89, Marat Gilfanov90, Myriam Gitti91, Randy Gladstone92, Rene Goosmann93, Eric Gosset94, Nicolas Grosso95, Manuel Guedel96, Martin Guerrero97, Frank Haberl98, Martin Hardcastle99, Sebastian Heinz100, Almudena Alonso Herrero101, Anthony Hervé102, Mats Holmstrom103, Kazushi Iwasawa104, Peter Jonker105, Jelle Kaastra106, Erin Kara107, Vladimir Karas108, Joel Kastner109, Andrew King110, Daria Kosenko111, Dimita Koutroumpa112, Ralph Kraft113, Ingo Kreykenbohm114, Rosine Lallement115, Giorgio Lanzuisi116, J. Lee117, Marianne Lemoine-Goumard118, Andrew Lobban119, Giuseppe Lodato120, Lorenzo Lovisari121, Simone Lotti122, Ian McCharthy123, Brian McNamara124, Antonio Maggio125, Roberto Maiolino126, Barbara De Marco127, Domitilla de Martino128, Silvia Mateos129, Giorgio Matt130, Ben Maughan131, Pasquale Mazzotta132, Mariano Mendez133, Andrea Merloni134, Giuseppina Micela135, Marco Miceli136, Robert Mignani137, Jon Miller138, Giovanni Miniutti139, Silvano Molendi140, Rodolfo Montez141, Alberto Moretti142, Christian Motch143, Yaël Nazé144, Jukka Nevalainen145, Fabrizio Nicastro146, Paul Nulsen147, Takaya Ohashi148, Paul O'Brien149, Julian Osborne150, Lida Oskinova151, Florian Pacaud152, Frederik Paerels153, Mat Page154, Iossif Papadakis155, Giovanni Pareschi156, Robert Petre157, Pierre-Olivier Petrucci158, Enrico Piconcelli159, Ignazio Pillitteri160, C. Pinto161, Jelle de Plaa162, Etienne Pointecouteau163, Trevor Ponman164, Gabriele Ponti165, Delphine Porquet166, Ken Pounds167, Gabriel Pratt168, Peter Predehl169, Daniel Proga170, Dimitrios Psaltis171, David Rafferty172, Miriam Ramos-Ceja173, Piero Ranalli174, Elena Rasia175, Arne Rau176, Gregor Rauw177, Nanda Rea178, Andy Read179, James Reeves180, Thomas Reiprich181, Matthieu Renaud182, Chris Reynolds183, Guido Risaliti184, Jerome Rodriguez185, Paola Rodriguez Hidalgo186, Mauro Roncarelli187, David Rosario188, Mariachiara Rossetti189, Agata Rozanska190, Emmanouil Rovilos191, Ruben Salvaterra192, Mara Salvato193, Tiziana Di Salvo194, Jeremy Sanders195, Jorge Sanz-Forcada196, Kevin Schawinski197, Joop Schaye198, Axel Schwope199, Salvatore Sciortino200, Paola Severgnini201, Francesco Shankar202, Debora Sijacki203, Stuart Sim204, Christian Schmid205, Randall Smith206, Andrew Steiner207, Beate Stelzer208, Gordon Stewart209, Tod Strohmayer210, Lothar Strüder211, Ming Sun212, Yoh Takei213, V. Tatischeff214, Andreas Tiengo215, Francesco Tombesi216, Ginevra Trinchieri217, T. G. Tsuru218, Asif Ud-Doula219, Eugenio Ursino220, Lynne Valencic221, Eros Vanzella222, Simon Vaughan223, Cristian Vignali224, Jacco Vink225, Fabio Vito226, Marta Volonteri227, Daniel Wang228, Natalie Webb229, Richard Willingale230, Joern Wilms231, Michael Wise232, Diana Worrall233, Andrew Young234, Luca Zampieri235, Jean In't Zand236, Silvia Zane237, Andreas Zezas238, Yuying Zhang239, Irina Zhuravleva240
Affiliations: 1DE, 2FR, 3ES, 4UK, 5NL, 6IT, 7UK, 8FR, 9UK, 10PT, 11UK, 12IT, 13IT, 14FR, 15FR, 16CH, 17US, 18FR, 19IT, 20JP, 21IN, 22IT, 23DE, 24BE, 25IL, 26IT, 27IT, 28NL, 29IT, 30US, 31FR, 32DE, 33IT, 34DE, 35FR, 36IT, 37UK, 38IT, 39IT, 40UK, 41US, 42US, 43DE, 44DE, 45DE, 46US, 47IT, 48CZ, 49IT, 50US, 51IT, 52IT, 53IT, 54ES, 55ES, 56DK, 57US, 58DE, 59DE, 60FR, 61GR, 62IT, 63NL, 64UK, 65IT, 66IT, 67FR, 68IT, 69DE, 70DE, 71UK, 72CZ, 73US, 74CH, 75UK, 76IT, 77JP, 78US, 79UK, 80FR, 81FI, 82IT, 83IT, 84CA, 85UK, 86IT, 87IT, 88DE, 89GR, 90DE, 91IT, 92US, 93FR, 94BE, 95FR, 96AT, 97ES, 98DE, 99UK, 100US, 101ES, 102FR, 103SE, 104ES, 105NL, 106NL, 107UK, 108CZ, 109US, 110UK, 111FR, 112FR, 113US, 114D, 115FR, 116GR, 117US, 118FR, 119UK, 120IT, 121DE, 122IT, 123UK, 124CA, 125IT, 126UK, 127DE, 128IT, 129ES, 130IT, 131UK, 132IT, 133NL, 134DE, 135IT, 136IT, 137IT, 138US, 139ES, 140IT, 141ES, 142IT, 143FR, 144BE, 145FI, 146IT, 147US, 148JP, 149UK, 150UK, 151DE, 152DE, 153US, 154UK, 155GR, 156IT, 157US, 158FR, 159IT, 160IT, 161UK, 162NL, 163FR, 164UK, 165DE, 166FR, 167UK, 168FR, 169DE, 170US, 171US, 172NL, 173DE, 174IT, 175US, 176DE, 177BE, 178IT, 179UK, 180UK, 181DE, 182FR, 183US, 184IT, 185FR, 186CA, 187IT, 188DE, 189IT, 190PL, 191UK, 192IT, 193DE, 194IT, 195DE, 196ES, 197CH, 198NL, 199D, 200IT, 201IT, 202FR, 203UK, 204IE, 205DE, 206US, 207US, 208IT, 209UK, 210US, 211DE, 212US, 213JP, 214FR, 215IT, 216US, 217IT, 218JP, 219US, 220NL, 221US, 222IT, 223UK, 224IT, 225NL, 226IT, 227FR, 228US, 229FR, 230UK, 231DE, 232NL, 233UK, 234UK, 235IT, 236NL, 237UK, 238GR, 239DE, 240US

This White Paper, submitted to the recent ESA call for science themes to define its future large missions, advocates the need for a transformational leap in our understanding of two key questions in astrophysics: 1) How does ordinary matter assemble into the large scale structures that we see today? 2) How do black holes grow and shape the Universe? Hot gas in clusters, groups and the intergalactic medium dominates the baryonic content of the local Universe. To understand the astrophysical processes responsible for the formation and assembly of these large structures, it is necessary to measure their physical properties and evolution. This requires spatially resolved X-ray spectroscopy with a factor 10 increase in both telescope throughput and spatial resolving power compared to currently planned facilities. Read More

White dwarfs, neutron stars and stellar mass black holes are key laboratories to study matter in most extreme conditions of gravity and magnetic field. The unprecedented effective area of Athena+ will allow us to advance our understanding of emission mechanisms and accretion physics over a wide range of mass accretion rates, starting from lower and sub-luminous quiescent X-ray binaries up to super-Eddington ultra-luminous sources. Athena+ will measure stellar black hole spins in a much higher number of binaries than achievable now, opening the possibility to study how spin varies with black hole history. Read More

2013May
Affiliations: 1Department of Physics and Astronomy, State University of New York at Stony Brook, 2Institute for Nuclear Theory, University of Washington

We perform a systematic analysis of neutron star radius constraints from five quiescent low-mass X-ray binaries and examine how they depend on measurements of their distances and amounts of intervening absorbing material, as well as their assumed atmospheric compositions. We construct and calibrate to published results a semi-analytic model of the neutron star atmosphere which approximates these effects for the predicted masses and radii. Starting from mass and radius probability distributions established from hydrogen-atmosphere spectral fits of quiescent sources, we apply this model to compute alternate sets of probability distributions. Read More

If the observed quasi-periodic oscillations in magnetar flares are partially confined to the crust, then the oscillation frequencies are unique probes of the nuclear physics of the neutron star crust. We study crustal oscillations in magnetars including corrections for a finite Alfven velocity. Our crust model uses a new nuclear mass formula that predicts nuclear masses with an accuracy very close to that of the finite range droplet model. Read More

2013Feb
Affiliations: 1Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Mexico, 2Department of Physics and Astronomy, State University of New York at Stony Brook, Stony Brook, USA, 3Department of Physics and Astronomy, Ohio University, Athens, USA, 4Institute for Nuclear Theory, University of Washington, Seattle, USA

Neutron stars provide a fertile environment for exploring superfluidity under extreme conditions. It is not surprising that Cooper pairing occurs in dense matter since nucleon pairing is observed in nuclei as energy differences between even-even and odd-even nuclei. Since superfluids and superconductors in neutron stars profoundly affect neutrino emissivities and specific heats, their presence can be observed in the thermal evolution of neutron stars. Read More

Many of the currently available equations of state for core-collapse supernova simulations give large neutron star radii and do not provide large enough neutron star masses, both of which are inconsistent with some recent neutron star observations. In addition, one of the critical uncertainties in the nucleon-nucleon interaction, the nuclear symmetry energy, is not fully explored by the currently available equations of state. In this article, we construct two new equations of state which match recent neutron star observations and provide more flexibility in studying the dependence on nuclear matter properties. Read More

The equation of state (EOS) of dense matter has been a long-sought goal of nuclear physics. Equations of state generate unique mass versus radius (M-R) relations for neutron stars, the ultra-dense remnants of stellar evolution. In this work, we determine the neutron star mass-radius relation and, based on recent observations of both transiently accreting and bursting sources, we show that the radius of a 1. Read More

The symmetry energy contribution to the nuclear Equation of State (EoS) impacts various phenomena in nuclear astrophysics, nuclear structure, and nuclear reactions. Its determination is a key objective of contemporary nuclear physics with consequences for the understanding of dense matter within neutron stars. We examine the results of laboratory experiments that have provided initial constraints on the nuclear symmetry energy and its density dependence at and somewhat below normal nuclear matter density. Read More

A quasi-statistical equilibrium model is constructed to simulate the multicomponent composition of the crust of an accreting neutron star. The ashes of rp-process nucleosynthesis are driven by accretion through a series of electron captures, neutron emissions, and pycnonuclear fusions up to densities near the transition between the neutron star crust and core. A liquid droplet model which includes nuclear shell effects is used to provide nuclear masses far from stability. Read More

2011Oct
Affiliations: 1Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, 2Department of Physics and Astronomy, Ohio University, 3Department of Physics and Astronomy, State University of New York at Stony Brook, 4Institute for Nuclear Theory, University of Washington

The supernova remnant Cassiopeia A contains the youngest known neutron star which is also the first one for which real time cooling has ever been observed. In order to explain the rapid cooling of this neutron star, we first present the fundamental properties of neutron stars that control their thermal evolution with emphasis on the neutrino emission processes and neutron/proton superfluidity/superconductivity. Equipped with these results, we present a scenario in which the observed cooling of the neutron star in Cassiopeia A is interpreted as being due to the recent onset of neutron superfluidity in the core of the star. Read More

Using a phenomenological form of the equation of state of neutron matter near the saturation density which has been previously demonstrated to be a good characterization of quantum Monte Carlo simulations, we show that currently available neutron star mass and radius measurements provide a significant constraint on the equation of state of neutron matter. At higher densities we model the equation of state using polytropes and a quark matter model, and we show that our results do not change strongly upon variation of the lower boundary density where these polytropes begin. Neutron star observations offer an important constraint on a coefficient which is directly connected to the strength of the three-body force in neutron matter, and thus some theoretical models of the three-body may be ruled out by currently available astrophysical data. Read More

2010Nov
Affiliations: 1Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, 2Department of Physics and Astrononmy, Ohio University, 3Department of Physics and Astronomy, State University of New York at Stony Brook, 4Joint Institute for Nuclear Astrophysics, National Superconducting Cyclotron Laboratory and Department of Physics and Astrononmy, Michigan State University

We propose that the observed cooling of the neutron star in Cassiopeia A is due to enhanced neutrino emission from the recent onset of the breaking and formation of neutron Cooper pairs in the 3P2 channel. We find that the critical temperature for this superfluid transition is ~0.5x10^9 K. Read More

In this two part paper we consider a wireless network in which a source terminal communicates with a destination and a relay terminal is occasionally present in close proximity to the source without source's knowledge, suggesting oblivious protocols. The source-relay channel is assumed to be a fixed gain AWGN due to the proximity while the source-destination and the relay-destination channels are subject to a block flat Rayleigh fading. A perfect CSI at the respective receivers only is assumed. Read More

This is the second in a two part series of papers on incorporation of the broadcast approach into oblivious protocols for the relay channel where the source and the relay are collocated. Part I described the broadcast approach and its benefits in terms of achievable rates when used with the sequential decode- and-forward (SDF) scheme. Part II investigates yet another oblivious scheme, the Block-Markov decode- and-forward (BMDF) under the single and two-layered transmissions. Read More

We determine an empirical dense matter equation of state from a heterogeneous dataset of six neutron stars: three type I X-ray bursters with photospheric radius expansion, studied by Ozel et al., and three transient low-mass X-ray binaries. We critically assess the mass and radius determinations from the X-ray burst sources and show explicitly how systematic uncertainties, such as the photospheric radius at touchdown, affect the most probable masses and radii. Read More

We demonstrate the close similarity of a generalized Fermi breakup model, in which densities of excited states are taken into account, to the microcanonical statistical multifragmentation model used to describe the desintegration of highly excited fragments of nuclear reactions. Read More

The density dependence of the nuclear symmetry energy is inspected using the Statistical Multifragmentation Model with Skyrme effective interactions. The model consistently considers the expansion of the fragments' volumes at finite temperature at the freeze-out stage. By selecting parameterizations of the Skyrme force that lead to very different equations of state for the symmetry energy, we investigate the sensitivity of different observables to the properties of the effective forces. Read More

The properties of the nuclear isoscaling at finite temperature are investigated and the extent to which its parameter $\alpha$ holds information on the symmetry energy is examined. We show that, although finite temperature effects invalidate the analytical formulas that relate the isoscaling parameter $\alpha$ to those of the mass formula, the symmetry energy remains the main ingredient that dictates the behavior of $\alpha$ at finite temperatures, even for very different sources. This conclusion is not obvious as it is not true in the vanishing temperature limit, where analytical formulas are available. Read More

2009Jun
Affiliations: 1Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Mexico D.F., Mexico, 2Department of Physics and Astronomy, State University of New York at Stony Brook, Stony Brook, NY, USA, 3Department of Physics and Astrononmy, Ohio University, Athens, OH, USA, 4Joint Institute for Nuclear Astrophysics, National Superconducting Cyclotron Laboratory and Department of Physics and Astrononmy, Michigan State University, East Lansing, MI, USA

The minimal cooling paradigm for neutron star cooling assumes that enhanced cooling due to neutrino emission from any direct Urca process, due either to nucleons or to exotica such as hyperons, Bose condensates, or deconfined quarks, does not occur. This scenario was developed to replace and extend the so-called standard cooling scenario to include neutrino emission from the Cooper pair breaking and formation processes that occur near the critical temperature for superfluid/superconductor pairing. Recently, it has been found that Cooper-pair neutrino emission from the vector channel is suppressed by a large factor compared to the original estimates that violated vector current conservation. Read More

Observationally inferred superburst ignition depths are shallower than models predict. We address this discrepancy by reexamining the superburst trigger mechanism. We first explore the hypothesis of Kuulkers et al. Read More

This white paper, directed to the Stars and Stellar Evolution panel, has three objectives: 1) to provide the Astro2010 Decadal Survey with a vista into the goals of the nuclear physics and nuclear astrophysics community; 2) to alert the astronomical community of joint opportunities for discoveries at the interface between nuclear physics and astronomy; and 3) to delineate efforts in nuclear physics and describe the observational and theoretical advances in astrophysics necessary to make progress towards answering the following questions in the Nuclear Science 2007 Long Range Plan: 1) What is the origin and distribution of the elements? 2) What are the nuclear reactions that power stars and stellar explosions? 3) What is the nature of dense matter? The scope of this white paper concerns the specific area of "low energy" nuclear astrophysics. We define this as the area of overlap between astrophysics and the study of nuclear structure and reactions. Of the questions listed above, two -- What is the origin of the elements? and What is the nature of dense matter? -- were specifically listed in the National Academies Study, "Connecting Quarks with the Cosmos". Read More

We show that the fundamental seismic shear mode, observed as a quasi-periodic oscillation in giant flares emitted by highly-magnetized neutron stars, is particularly sensitive to the nuclear physics of the crust. The identification of an oscillation at ~ 30 Hz as the fundamental crustal shear mode requires a nuclear symmetry energy that depends very weakly on density near saturation. If the nuclear symmetry energy varies more strongly with density, then lower frequency oscillations, previously identified as torsional Alfven modes of the fluid core, could instead be associated with the crust. Read More

The Statistical Multifragmentation Model is modified to incorporate the Helmholtz free energies calculated in the finite temperature Thomas-Fermi approximation using Skyrme effective interactions. In this formulation, the density of the fragments at the freeze-out configuration corresponds to the equilibrium value obtained in the Thomas-Fermi approximation at the given temperature. The behavior of the nuclear caloric curve at constant volume is investigated in the micro-canonical ensemble and a plateau is observed for excitation energies between 8 and 10 MeV per nucleon. Read More

Constraints on the EoS for symmetric matter (equal neutron and proton numbers) at supra-saturation densities have been extracted from energetic collisions of heavy ions. Collisions of neutron-deficient and neutron-rich heavy ions now provide initial constraints on the EoS of neutron-rich matter at sub-saturation densities. Comparisons are made to other available constraints. Read More

Collisions involving 112Sn and 124Sn nuclei have been simulated with the improved Quantum Molecular Dynamics transport model. The results of the calculations reproduce isospin diffusion data from two different observables and the ratios of neutron and proton spectra. By comparing these data to calculations performed over a range of symmetry energies at saturation density and different representations of the density dependence of the symmetry energy, constraints on the density dependence of the symmetry energy at sub-normal density are obtained. Read More

Neutrinos emitted during the collapse, bounce and subsequent explosion provide information about supernova dynamics. The neutrino spectra are determined by weak interactions with nuclei and nucleons in the inner regions of the star, and thus the neutrino spectra are determined by the composition of matter. The composition of stellar matter at temperature ranging from $T=1-3$ MeV and densities ranging from $10^{-5}$ to 0. Read More

We determine characteristic timescales for the viscous damping of r-mode oscillations in rapidly rotating compact stars that contain quark matter. We present results for the color-flavor-locked (CFL) phase of dense quark matter, in which the up, down and strange quarks are gapped, as well as the normal (ungapped) quark phase. While the ungapped quark phase supports a temperature window between 10^8 K and 5x10^9 K where the r-mode is damped even for rapid rotation, the r-mode in a rapidly rotating pure CFL star is not damped in the temperature range 10^10 K - 10^11 K. Read More

Using different parameterizations of the nuclear mass formula, we study the sensitivity of the isoscaling parameters to the mass formula employed in grand-canonical calculations. Previous works on isoscaling have suggested that the symmetry energy implied in such calculations is anomalously smaller than that suggested by fits to nuclear masses. We show that surface corrections to the symmetry energy naturally broadens the isotopic distribution thus allowing for values of the symmetry energy which more closely match those obtained from nuclear masses. Read More

{We calculate the neutrino emissivity of superfluid neutron matter in the inner crust of neutron stars. We find that neutrino emission due to fluctuations resulting from the formation of Cooper pairs at finite temperature is highly suppressed in non-relativistic systems. This suppression of the pair breaking emissivity in a simplified model of neutron matter with interactions that conserve spin is of the order of $v_F^4$ for density fluctuations and $v_F^2$ for spin fluctuations, where $v_F$ is the Fermi velocity of neutrons. Read More

The pervasive role of the nuclear symmetry energy in establishing some nuclear static and dynamical properties, and in governing some attributes of neutron star properties is highlighted. Read More