The missing metals problem. III How many metals are expelled from galaxies?

[Abridged] We revisit the metal budget at z~2. In the first two papers of this series, we already showed that ~30% (to <60% if extrapolating the LF) of the metals are observed in all z~2.5 galaxies detected in current surveys. Here, we extend our analysis to the metals outside galaxies, i.e. in intergalactic medium (IGM), using observational data and analytical calculations. Our results for the two are strikingly similar: (1) Observationally, we find that, besides the small (5%) contribution of DLAs, the forest and sub-DLAs contribute subtantially to make <30--45% of the metal budget, but neither of these appear to be sufficient to close the metal budget. The forest accounts for 15--30% depending on the UV background, and sub-DLAs for >2% to <17% depending on the ionization fraction. Together, the `missing metals' problem is substantially eased. (2) We perform analytical calculations based on the effective yield--mass relation. At z=2, we find that the method predicts that 2$--50% of the metals have been ejected from galaxies into the IGM, consistent with the observations. The metal ejection is predominantly by L<1/3L_B^*(z=2) galaxies, which are responsible for 90% the metal enrichment, while the 50 percentile is at L~1/10L^*_B(z=2). As a consequence, if indeed 50% of the metals have been ejected from galaxies, 3--5 bursts of star formation are required per galaxy prior to z=2. The ratio between the mass of metals outside galaxies to those in stars has changed from z=2 to z=0: it was 2:1 or 1:1 and is now 1:8 or 1:9. This evolution implies that a significant fraction of the IGM metals will cool and fall back into galaxies.Comment: 18pages, MNRAS, in press; small changes to match proofs; extended version with summary tabl

Cosmic Needles versus Cosmic Microwave Background Radiation

It has been suggested by a number of authors that the 2.7K cosmic microwave background (CMB) radiation might have arisen from the radiation from Population III objects thermalized by conducting cosmic graphite/iron needle-shaped dust. Due to lack of an accurate solution to the absorption properties of exceedingly elongated grains, in existing literature which studies the CMB thermalizing process they are generally modelled as (1) needle-like spheroids in terms of the Rayleigh approximation; (2) infinite cylinders; and (3) the antenna theory. We show here that the Rayleigh approximation is not valid since the Rayleigh criterion is not satisfied for highly conducting needles. We also show that the available intergalactic iron dust, if modelled as infinite cylinders, is not sufficient to supply the required opacity at long wavelengths to obtain the observed isotropy and Planckian nature of the CMB. If appealing to the antenna theory, conducting iron needles with exceedingly large elongations (10^4) appear able to provide sufficient opacity to thermalize the CMB within the iron density limit. But the applicability of the antenna theory to exceedingly thin needles of nanometer/micrometer in thickness needs to be justified.Comment: 13 pages, 4 figures; submitted to ApJ

Stars In Other Universes: Stellar structure with different fundamental constants

Motivated by the possible existence of other universes, with possible variations in the laws of physics, this paper explores the parameter space of fundamental constants that allows for the existence of stars. To make this problem tractable, we develop a semi-analytical stellar structure model that allows for physical understanding of these stars with unconventional parameters, as well as a means to survey the relevant parameter space. In this work, the most important quantities that determine stellar properties -- and are allowed to vary -- are the gravitational constant $G$, the fine structure constant $\alpha$, and a composite parameter $C$ that determines nuclear reaction rates. Working within this model, we delineate the portion of parameter space that allows for the existence of stars. Our main finding is that a sizable fraction of the parameter space (roughly one fourth) provides the values necessary for stellar objects to operate through sustained nuclear fusion. As a result, the set of parameters necessary to support stars are not particularly rare. In addition, we briefly consider the possibility that unconventional stars (e.g., black holes, dark matter stars) play the role filled by stars in our universe and constrain the allowed parameter space.Comment: accepted to JCAP, 29 pages, 6 figure

Additional femoral catheter in combination with popliteal catheter for analgesia after major ankle surgery

Background The contribution of the saphenous nerve in pain after major ankle surgery is unknown. The aim of this study was to evaluate its contribution in this context. Methods Fifty patients were included in this prospective, randomized, controlled study. In all patients [Group P (popliteal) and Group F (popliteal+femoral)], a popliteal catheter was placed before operation and ropivacaine 0.5% (30 ml) administered via this catheter; major ankle surgery was then performed under spinal anaesthesia. In Group PF patients, an additional femoral catheter was sited before operation and ropivacaine 0.5% (10 ml) administered. Six hours after spinal anaesthesia (defined as T0), a continuous infusion of ropivacaine 0.3% (14 ml h−1) was started through the popliteal catheter until T24. Then, the concentration was reduced to 0.2% until T48. Patients in Group PF received continuous ropivacaine 0.2% (5 ml h−1) through the femoral catheter from T0 to T48. I.V. morphine patient-controlled analgesia was used as a rescue analgesia. Pain at rest, pain with movement, adverse effects, and i.v. morphine consumption were assessed. Pain at rest and on movement was evaluated 6 months after operation. Results Pain at rest was comparable in the two groups. In Group PF, patients had significantly reduced pain during movement in the postoperative period (P=0.01) and 6 months after operation (P=0.03). Morphine consumption was significantly reduced in Group PF at T0-T24 and T24-T48 (P=0.01). Adverse effects were comparable in both groups. Conclusions The addition of continuous femoral catheter infusion of ropivacaine to a continuous popliteal catheter infusion improved postoperative analgesia during movement after major ankle surgery. This effect was still present 6 months after surger

Impacto social de las radiaciones no ionizantes y las políticas públicas

El objetivo del presente trabajo es fundamentar los beneficios de la contribución del asesoramiento profesional en la generación y transferencia del conocimiento, para la toma de decisiones en las políticas públicas que permita apropiarse de los avances y aplicaciones resultantes del trabajo científico desarrollado.Las Radiaciones No Ionizantes (RNI) son aquellas que no poseen la energía suficiente para ionizar la materia, pero que producen otro tipo de efectos, especialmente de tipo térmico. Sus efectos a largo plazo sobre la salud de los seres humanos aún es materia de discusión y es por esto que se genera en la ciudadanía una honda preocupación por el desconocimiento y falta de normativas a nivel municipal. El Grupo ITMA reúne un grupo interdisciplinario de profesionales con el objetivo de investigar el impacto de las RNI sobre el medio ambiente y los sistemas biológicos. Una de sus actividades es el asesoramiento a municipios y organismos públicos respecto de las RNI, en particular, el despliegue de antenas de telefonía móvil para generar ordenanzas municipales que contribuyan a la tranquilidad y mejora de la calidad de vida de la comunidad y contemplen los controles necesarios para preservar estas condiciones en el tiempo

Network Synchronization, Diffusion, and the Paradox of Heterogeneity

Many complex networks display strong heterogeneity in the degree (connectivity) distribution. Heterogeneity in the degree distribution often reduces the average distance between nodes but, paradoxically, may suppress synchronization in networks of oscillators coupled symmetrically with uniform coupling strength. Here we offer a solution to this apparent paradox. Our analysis is partially based on the identification of a diffusive process underlying the communication between oscillators and reveals a striking relation between this process and the condition for the linear stability of the synchronized states. We show that, for a given degree distribution, the maximum synchronizability is achieved when the network of couplings is weighted and directed, and the overall cost involved in the couplings is minimum. This enhanced synchronizability is solely determined by the mean degree and does not depend on the degree distribution and system size. Numerical verification of the main results is provided for representative classes of small-world and scale-free networks.Comment: Synchronization in Weighted Network

Scalar fields in an anisotropic closed universe

We study in this article a class of homogeneous, but anisotropic cosmological models in which shear viscosity is included. Within the matter content we consider a component (the quintessence component) determined by the barotropic equations of state, $p=\alpha \rho$, with $\alpha < 0$. We establish conditions under which a closed axisymmetrical cosmological model may look flat al low redshift.Comment: 6 pages, Latex, 2 figures, accepted in Phys. Rev.

Gravitational hydrodynamics of large scale structure formation

The gravitational hydrodynamics of the primordial plasma with neutrino hot dark matter is considered as a challenge to the bottom-up cold dark matter paradigm. Viscosity and turbulence induce a top-down fragmentation scenario before and at decoupling. The first step is the creation of voids in the plasma, which expand to 37 Mpc on the average now. The remaining matter clumps turn into galaxy clusters. Turbulence produced at expanding void boundaries causes a linear morphology of 3 kpc fragmenting protogalaxies along vortex lines. At decoupling galaxies and proto-globular star clusters arise; the latter constitute the galactic dark matter halos and consist themselves of earth-mass H-He planets. Frozen planets are observed in microlensing and white-dwarf-heated ones in planetary nebulae. The approach also explains the Tully-Fisher and Faber-Jackson relations, and cosmic microwave temperature fluctuations of micro-Kelvins.Comment: 6 pages, no figure