DSpace Collection:http://hdl.handle.net/2445/197032019-07-21T08:42:34Z2019-07-21T08:42:34ZThe cosmological bias factor of damped Lyman alpha systems: dependence on metal line strengthPérez Ràfols, IgnasiFont Ribera, AndreuMiralda Escudé, Jordi.Arinyo Prats, AndreuMas Ribas, Lluíshttp://hdl.handle.net/2445/1354592019-06-20T21:08:05Z2019-06-19T10:49:32ZTitle: The cosmological bias factor of damped Lyman alpha systems: dependence on metal line strength
Author: Pérez Ràfols, Ignasi; Font Ribera, Andreu; Miralda Escudé, Jordi.; Arinyo Prats, Andreu; Mas Ribas, Lluís
Abstract: We measure the cosmological bias factor of damped Ly α absorbers (DLAs) from their crosscorrelation with the Ly α forest absorption, as a function of the DLA metal strength, defined from an average of equivalent widths of the strongest detectable low-ionization metal lines. A clear increase of the bias factor with metal strength is detected, as expected from a relation of metallicity and velocity dispersion with host halo mass. The relation is stronger after the metal strength is corrected for the H I column density, to make it more related to metallicity instead of metal column density. After correcting for the effects of measurement errors of the metal strength parameter, we find that the bias factor of DLAs with the weakest metal lines is close to unity, consistent with an origin in dwarf galaxies with host halo masses ∼1010M , whereas the most metal rich DLAs have a bias factor as large as bDLA ∼ 3, indicative of massive galaxies or galaxy groups in host haloes with masses ∼1012M . Our result confirms the physical origin of the relation of bias factors measured from cross-correlation studies to the host haloes of the absorbers.2019-06-19T10:49:32ZOrigin of Metals around Galaxies. I. Catalogs of Metal-line Absorption Doublets from High-resolution Quasar SpectraMas Ribas, LluísRiemer Sørensen, SigneHennawi, Joseph F.Miralda Escudé, JordiO'Meara, John M.Pérez Ràfols, IgnasiMurphy, Michael T.Webb, John K.http://hdl.handle.net/2445/1350172019-06-13T21:07:04Z2019-06-13T09:22:45ZTitle: Origin of Metals around Galaxies. I. Catalogs of Metal-line Absorption Doublets from High-resolution Quasar Spectra
Author: Mas Ribas, Lluís; Riemer Sørensen, Signe; Hennawi, Joseph F.; Miralda Escudé, Jordi; O'Meara, John M.; Pérez Ràfols, Ignasi; Murphy, Michael T.; Webb, John K.
Abstract: We present the first paper of the series Origin of Metals around Galaxies, which aims to explore the origin of the metals observed in the circumgalactic and intergalactic media. In this work we extract and build catalogs of metal absorbers that will be used in future analyses, and make our results publicly available to the community. We design a fully automatic algorithm to search for absorption metal-line doublets of the species C IV, N V, Si IV, and Mg II in high-resolution (R >=30,000) quasar spectra without human intervention, and apply it to the high-resolution and signal-to-noise ratio spectra of 690 quasars, observed with the UVES and HIRES instruments. We obtain 5656 C IV doublets, 7919 doublets of Mg II, 2258 of Si IV, and 239 of N V, constituting the largest high-resolution metaldoublet samples to date, and estimate the dependence of their completeness and purity on various doublet parameters such as equivalent width and redshift, using real and artificial quasar spectra. The catalogs include doublets with rest-frame line-equivalent widths down to a few mÅ, all detected at a significance above 3σ, and covering the redshifts between 1 < z =<5, properties that make them useful for a wide range of chemical evolution studies.2019-06-13T09:22:45ZEnergy Loss of an Infinitely Massive Half-Bogomol'nyi-Prasad-Sommerfeld Particle by Radiation to All Orders in 1/NFiol Núñez, BartomeuGarolera Huguet, Blaihttp://hdl.handle.net/2445/1348242019-06-11T21:07:23Z2019-06-11T14:59:56ZTitle: Energy Loss of an Infinitely Massive Half-Bogomol'nyi-Prasad-Sommerfeld Particle by Radiation to All Orders in 1/N
Author: Fiol Núñez, Bartomeu; Garolera Huguet, Blai
Abstract: We use the AdS/CFT correspondence to compute the energy radiated by an infinitely massive half-Bogomol'nyi-Prasad-Sommerfeld particle charged under N = 4 super Yang-Mills theory, transforming in the symmetric or antisymmetric representation of the gauge group, and moving in the vacuum, to all orders in 1 / N and for large 't Hooft coupling. For the antisymmetric case we consider D 5 -branes reaching the boundary of five-dimensional anti-de Sitter space ( AdS 5 ) at arbitrary timelike trajectories, while for the symmetric case, we consider a D 3 -brane in AdS 5 that reaches the boundary at a hyperbola. We compare our results to the one obtained for the fundamental representation, deduced by considering a string in AdS 5 .2019-06-11T14:59:56ZYoung and Eccentric: The Quadruple System HD 86588Tokovinin, AndreiCorbett, HankFors Aldrich, OctaviHoward, WardLaw, Nicholas M.Moe, MaxwellRatzloff, JeffreyWalter, Frederick M.http://hdl.handle.net/2445/1345832019-06-06T21:07:32Z2019-06-06T11:27:11ZTitle: Young and Eccentric: The Quadruple System HD 86588
Author: Tokovinin, Andrei; Corbett, Hank; Fors Aldrich, Octavi; Howard, Ward; Law, Nicholas M.; Moe, Maxwell; Ratzloff, Jeffrey; Walter, Frederick M.
Abstract: High-resolution spectroscopy and speckle interferometry reveal the young star HD 86588 as a quadruple system with a three-tier hierarchy. The 0 3 resolved binary A,B with an estimated period around 300 years contains the 8-yr pair Aa,Abc (also potentially resolvable), where Ab,Ac is a double-lined binary with equal components, for which we compute the spectroscopic orbit. Despite the short period of 2.4058 days, the orbit of Ab,Ac is eccentric (e=0.086±0.003)). It has a large inclination, but there are no eclipses; only a 4.4 mmag light modulation apparently caused by star spots on the components of this binary is detected with Evryscope. Assuming a moderate extinction of AV=0.5 mag and a parallax of 5.2 mas, we find that the stars are on or close to the main sequence (age >10 Myr) and their masses are from 1 to 1.3 solar. We measure the strength of the lithium line in the visual secondary B which, together with rotation, suggests that the system is younger than 150 Myr. This object is located behind the extension of the Chamaeleon I dark cloud (which explains extinction and interstellar sodium absorption), but apparently does not belong to it. We propose a scenario where the inner orbit has recently acquired its high eccentricity through dynamical interaction with the outer two components; it is now undergoing rapid tidal circularization on a timescale of ∼1 Myr. Alternatively, the eccentricity could be excited quasi-stationary by the outer component Aa.2019-06-06T11:27:11ZAnisotropic N=4 Super-Yang-Mills Plasma and Its InstabilitiesMateos, David (Mateos Solé)Trancanelli, Diegohttp://hdl.handle.net/2445/1344632019-06-04T21:07:18Z2019-06-04T09:15:02ZTitle: Anisotropic N=4 Super-Yang-Mills Plasma and Its Instabilities
Author: Mateos, David (Mateos Solé); Trancanelli, Diego
Abstract: We present a type-IIB supergravity solution dual to a spatially anisotropic finite-temperature N = 4 super-Yang-Mills plasma. The solution is static and completely regular. The full geometry can be viewed as a renormalization group flow from an ultraviolet anti-de Sitter geometry to an infrared Lifshitz-like geometry. The anisotropy can be equivalently understood as resulting from a position-dependent θ term or from a nonzero number density of dissolved D 7 -branes. The holographic stress tensor is conserved and anisotropic. The presence of a conformal anomaly plays an important role in the thermodynamics. The phase diagram exhibits homogeneous and inhomogeneous (i.e., mixed) phases. In some regions the homogeneous phase displays instabilities reminiscent of those of weakly coupled plasmas. We comment on similarities with QCD at finite baryon density and with the phenomenon of cavitation.2019-06-04T09:15:02ZEvidence for a Bound H-dibaryon from Lattice QCDBeane, Silas R.Chang, EmmanuelDetmold, WilliamJoo, B.Lin, H. W.Luu, Thomas C.Orginos, KostasParreño García, AssumptaSavage, Martin J.Torok, AaronWalker-Loud, AndréNPLQCD Collaborationhttp://hdl.handle.net/2445/1341632019-05-30T21:06:49Z2019-05-30T12:50:46ZTitle: Evidence for a Bound H-dibaryon from Lattice QCD
Author: Beane, Silas R.; Chang, Emmanuel; Detmold, William; Joo, B.; Lin, H. W.; Luu, Thomas C.; Orginos, Kostas; Parreño García, Assumpta; Savage, Martin J.; Torok, Aaron; Walker-Loud, André; NPLQCD Collaboration
Abstract: We present evidence for the existence of a bound H dibaryon, an I = 0 , J = 0 , s = − 2 state with valence quark structure u u d d s s , at a pion mass of m π ∼ 389 MeV . Using the results of lattice QCD calculations performed on four ensembles of anisotropic clover gauge-field configurations, with spatial extents of L ∼ 2.0 , 2.5, 3.0, and 3.9 fm at a spatial lattice spacing of b s ∼ 0.123 fm , we find an H dibaryon bound by B H ∞ = 16.6 ± 2.1 ± 4.6 MeV at a pion mass of m π ∼ 389 MeV .2019-05-30T12:50:46ZSuppression of Superfluidity upon Overflow of Trapped Fermions: Quantal and Thomas-Fermi StudiesSchuck, PeterViñas Gausí, Xavierhttp://hdl.handle.net/2445/1341612019-05-30T21:06:48Z2019-05-30T11:23:58ZTitle: Suppression of Superfluidity upon Overflow of Trapped Fermions: Quantal and Thomas-Fermi Studies
Author: Schuck, Peter; Viñas Gausí, Xavier
Abstract: Two issues are treated in this work. (i) The generic fact that, if a fermionic superfluid in the BCS regime overflows from a narrow container into a much wider one, pairing is much suppressed at the overflow point. Physical examples where this feature may play an important role are discussed. (ii) A Thomas-Fermi approach to inhomogeneous superfluid Fermi systems is presented and shown to work well in cases where the local density approximation breaks down.2019-05-30T11:23:58ZStrong Coupling Isotropization of Non-Abelian Plasmas SimplifiedHeller, Michal P.Mateos, David (Mateos Solé)van der Schee, WilkeTrancanelli, Diegohttp://hdl.handle.net/2445/1341592019-05-30T21:06:48Z2019-05-30T11:04:50ZTitle: Strong Coupling Isotropization of Non-Abelian Plasmas Simplified
Author: Heller, Michal P.; Mateos, David (Mateos Solé); van der Schee, Wilke; Trancanelli, Diego
Abstract: We study the isotropization of a homogeneous, strongly coupled, non-Abelian plasma by means of its gravity dual. We compare the time evolution of a large number of initially anisotropic states as determined, on the one hand, by the full nonlinear Einstein's equations and, on the other, by the Einstein's equations linearized around the final equilibrium state. The linear approximation works remarkably well even for states that exhibit large anisotropies. For example, it predicts with a 20% accuracy the isotropization time, which is of the order of t iso ≲ 1 / T , with T the final equilibrium temperature. We comment on possible extensions to less symmetric situations.2019-05-30T11:04:50ZDisentangling the Dynamical Origin of P11 Nucleon ResonancesSuzuki, N.Juliá-Díaz, BrunoKamano, H.Lee, T. S. H.Matsuyama, A.Sato, T.http://hdl.handle.net/2445/1334432019-05-21T21:07:43Z2019-05-20T10:31:10ZTitle: Disentangling the Dynamical Origin of P11 Nucleon Resonances
Author: Suzuki, N.; Juliá-Díaz, Bruno; Kamano, H.; Lee, T. S. H.; Matsuyama, A.; Sato, T.
Abstract: We show that two almost degenerate poles near the π Δ threshold and the next higher mass pole in the P 11 partial wave of π N scattering evolve from a single bare state through its coupling with π N , η N , and π π N reaction channels. This finding provides new information on understanding the dynamical origins of the Roper N ∗ ( 1440 ) and N ∗ ( 1710 ) resonances listed by Particle Data Group. Our results for the resonance poles in other π N partial waves are also presented.2019-05-20T10:31:10ZHyperon-Nucleon Interactions from Quantum Chromodynamics and the Composition of Dense Nuclear MatterBeane, Silas R.Chang, EmmanuelCohen, S. D.Detmold, WilliamLin, H. W.Luu, Thomas C.Orginos, KostasParreño García, AssumptaSavage, Martin JWalker-Loud, AndréNPLQCD Collaborationhttp://hdl.handle.net/2445/1333552019-05-17T21:06:32Z2019-05-17T12:00:17ZTitle: Hyperon-Nucleon Interactions from Quantum Chromodynamics and the Composition of Dense Nuclear Matter
Author: Beane, Silas R.; Chang, Emmanuel; Cohen, S. D.; Detmold, William; Lin, H. W.; Luu, Thomas C.; Orginos, Kostas; Parreño García, Assumpta; Savage, Martin J; Walker-Loud, André; NPLQCD Collaboration
Abstract: The low-energy n Σ − interactions determine, in part, the role of the strange quark in dense matter, such as that found in astrophysical environments. The scattering phase shifts for this system are obtained from a numerical evaluation of the QCD path integral using the technique of lattice QCD. Our calculations, performed at a pion mass of m π ∼ 389 MeV in two large lattice volumes and at one lattice spacing, are extrapolated to the physical pion mass using effective field theory. The interactions determined from lattice QCD are consistent with those extracted from hyperon-nucleon experimental data within uncertainties and strengthen model-dependent theoretical arguments that the strange quark is a crucial component of dense nuclear matter.2019-05-17T12:00:17Z