Using long-term millisecond pulsar timing to obtain physical characteristics of the bulge globular cluster Terzan 5

Over the past decade the discovery of three unique stellar populations and a large number of confirmed pulsars within the globular cluster Terzan 5 has raised questions over its classification. Using the long-term radio pulsar timing of 36 millisecond pulsars in the cluster core, we provide new measurements of key physical properties of the system. As Terzan 5 is located within the galactic bulge, stellar crowding and reddening make optical and near infrared observations difficult. Pulsar accelerations, however, allow us to study the intrinsic characteristics of the cluster independent of reddening and stellar crowding and probe the mass density profile without needing to quantify the mass to light ratio. Relating the spin and orbital periods of each pulsar to the acceleration predicted by a King model, we find a core density of $1.58\times$10$^6$ M$_\odot$ pc$^{-3}$, a core radius of 0.16 pc, a pulsar density profile $n\propto r^{-3.14}$, and a total mass of M$_{\rm T}$($R_\perp<$1.0 pc)$\simeq3.0\times$10$^5$ M$_\odot$ assuming a cluster distance of 5.9 kpc. Using this information we argue against Terzan 5 being a disrupted dwarf galaxy and discuss the possibility of Terzan 5 being a fragment of the Milky Way's proto-bulge. We also discuss whether low-mass pulsars were formed via electron capture supernovae or exist in a core full of heavy white dwarfs and hard binaries. Finally we provide an upper limit for the mass of a possible black hole at the core of the cluster of 3.0$\times$10$^4$ M$_\odot$.Comment: 27 pages, 20 figures, 5 tables, thesis research, accepte

Toward an Empirical Theory of Pulsar Emission XII: Exploring the Physical Conditions in Millisecond Pulsar Emission Regions

The five-component profile of the 2.7-ms pulsar J0337+1715 appears to exhibit the best example to date of a core/double-cone emission-beam structure in a millisecond pulsar (MSP). Moreover, three other MSPs, the Binary Pulsar B1913+16, B1953+29 and J1022+1001, seem to exhibit core/single-cone profiles. These configurations are remarkable and important because it has not been clear whether MSPs and slow pulsars exhibit similar emission-beam configurations, given that they have considerably smaller magnetospheric sizes and magnetic field strengths. MSPs thus provide an extreme context for studying pulsar radio emission. Particle currents along the magnetic polar flux tube connect processes just above the polar cap through the radio-emission region to the light-cylinder and the external environment. In slow pulsars radio-emission heights are typically about 500 km around where the magnetic field is nearly dipolar, and estimates of the physical conditions there point to radiation below the plasma frequency and emission from charged solitons by the curvature process. We are able to estimate emission heights for the four MSPs and carry out a similar estimation of physical conditions in their much lower emission regions. We find strong evidence that MSPs also radiate by curvature emission from charged solitons.Comment: 14 pages, published in Ap

Twenty-One Millisecond Pulsars in Terzan 5 Using the Green Bank Telescope

We have discovered 21 millisecond pulsars (MSPs) in the globular cluster Terzan 5 using the Green Bank Telescope, bringing the total of known MSPs in Terzan 5 to 24. These discoveries confirm fundamental predictions of globular cluster and binary system evolution. Thirteen of the new MSPs are in binaries, of which two show eclipses and two have highly eccentric orbits. The relativistic periastron advance for the two eccentric systems indicates that at least one of these pulsars has a mass >1.68 Msun at 95% confidence. Such large neutron star masses constrain the equation of state of matter at or beyond the nuclear equilibrium density.Comment: 12 pages, 2 figures. Accepted by Science. Published electronically via Science Express 13 Jan 200

Técnica alternativa para reduzir a perda de medicação durante injeção intravítrea

PURPOSE: To describe an intravitreal injection technique using a commercially available 29-gauge insulin needle syringe (29GN syringe) and a 21-gauge (G) needle, comparing compound waste associated with this technique application and the one described in ranibizumab (Lucentis®) kit instructions. METHODS: Ten 0.3 ml doses of distilled water were aspirated using the 29GN syringe and 21G needle (PT technique), and another ten equal doses were aspirated employing the sterilized Lucentis® kit (LK technique), which contains a 1ml tuberculin syringe, a 18G needle for compound aspiration and a 30G needle for intravitreal injection. For aspiration using the PT technique, a 21G needle is attached over a 29GN syringe. After compound aspiration, the 21G needle is removed and intravitreal injection is performed using the 29G needle. Using a precision balance, the aspiration needles (21G for PT; 18G for LK) were weighed before and after water aspiration and the syringe-needle complexes for injection (29GN for PT; 30G for LK) were weighed before aspiration and after emptying them. The volumes left in the aspiration needles and needle-syringe complexes were estimated by the difference in weight in grams, which were converted to millilitres. RESULTS: The mean (±SD) residual volume (ml) of aspiration needles (21G for PT; 18G for LK) was significantly lower with PT technique (0.0034 ± 0.0016) when compared to LK tech nique (0.0579 ± 0.0011) (p<0.01). The mean (±SD) residual volume (ml) of syringe-needle complexes was significantly lower with PT technique (0.0056 ± 0.0011) than with LK (0.0906 ± 0.003 ml) (p<0.01). CONCLUSION: The proposed technique is a reasonable alternative for minimizing medication loss during intravitreal injection procedures.OBJETIVO: Descrever técnica de injeção intravítrea utilizando agulha-seringa de 29 gauge (seringa 29GN) e agulha 21 gauge (G) comercialmente disponíveis, comparando perda de composto associada à aplicação desta técnica com a descrita nas instruções do kit do ranibizumabe (Lucentis®). MÉTODOS: Dez doses de 0,3 ml de água destilada foram aspiradas com a seringa 29GN e a agulha 21G (técnica PT) e outras dez doses iguais foram aspiradas utilizando-se o kit do Lucentis® (técnica LK). Para aspiração com a técnica PT, a agulha 21G é colocada sobre a seringa 29GN. Depois da aspiração, a agulha 21G é removida e a injeção intravítrea é realizada com a agulha 29G. A técnica LK utiliza seringa de tuberculina de 1 ml acoplada a agulha 18G para aspiração e agulha 30G para injeção intravítrea. Usando balança de precisão, as agulhas de aspiração (21G para PT; 18G para LK) foram pesadas antes e depois da aspiração da água e os complexos agulha-seringa para injeção (29GN para PT; 30G para LK) foram pesados antes da aspiração e após serem esvaziados. Os volumes restantes nas agulhas de aspiração e complexos agulha-seringa foram estimados pela diferença dos pesos em gramas com conversão para mililitros. RESULTADOS: O volume (ml) residual médio (±DP) das agulhas de aspiração (21G para PT; 18G para LK) foi significativamente menor com a técnica PT (0,0034 ± 0,0016) quando comparado à técnica LK (0,0579 ± 0,0011) (p<0,01). O volume (ml) residual médio (±DP) dos complexos agulha-seringa foi significativamente menor com a técnica PT (0,0056 ± 0,0011) do que LK (0,0906 ± 0,003 ml) (p<0,01). CONCLUSÃO: A técnica de injeção proposta é uma alternativa razoável para minimizar perda de medicação durante aplicação de injeções intravítreas