SMA outflow/disk studies in the massive star-forming region IRAS18089-1732

SMA observations of the massive star-forming region IRAS 18089-1732 in the 1mm and 850mu band reveal outflow and disk signatures in different molecular lines. The SiO(5--4) data show a collimated outflow in the northern direction. In contrast, the HCOOCH3(20--19) line, which traces high-density gas, is confined to the very center of the region and shows a velocity gradient across the core. The HCOOCH3 velocity gradient is not exactly perpendicular to the outflow axis but between an assumed disk plane and the outflow axis. We interpret these HCOOCH3 features as originating from a rotating disk that is influenced by the outflow and infall. Based on the (sub-)mm continuum emission, the mass of the central core is estimated to be around 38M_sun. The dynamical mass derived from the HCOOCH3 data is 22Msun, of about the same order as the core mass. Thus, the mass of the protostar/disk/envelope system is dominated by its disk and envelope. The two frequency continuum data of the core indicate a low dust opacity index beta ~ 1.2 in the outer part, decreasing to beta ~ 0.5 on shorter spatial scales.Comment: 7 pages of text, 1 table, 3 figures, accepted for ApJ Letter

Submillimeter Array multiline observations of the massive star-forming region IRAS 18089-1732

Submillimeter Array (SMA) observations of the high-mass star-forming region IRAS 18089-1732 in the 1 mm and 850 $\mu$m band with 1 GHz bandwidth reveal a wealth of information. We present the observations of 34 lines from 16 different molecular species. Most molecular line maps show significant contributions from the outflow, and only few molecules are confined to the inner core. We present and discuss the molecular line observations and outline the unique capabilities of the SMA for future imaging line surveys at high spatial resolution.Comment: Accepted for ApJ Letters, SMA special volum

Supergravity with a Gravitino LSP

We investigate supergravity models in which the lightest supersymmetric particle (LSP) is a stable gravitino. We assume that the next-lightest supersymmetric particle (NLSP) freezes out with its thermal relic density before decaying to the gravitino at time t ~ 10^4 s - 10^8 s. In contrast to studies that assume a fixed gravitino relic density, the thermal relic density assumption implies upper, not lower, bounds on superpartner masses, with important implications for particle colliders. We consider slepton, sneutrino, and neutralino NLSPs, and determine what superpartner masses are viable in all of these cases, applying CMB and electromagnetic and hadronic BBN constraints to the leading two- and three-body NLSP decays. Hadronic constraints have been neglected previously, but we find that they provide the most stringent constraints in much of the natural parameter space. We then discuss the collider phenomenology of supergravity with a gravitino LSP. We find that colliders may provide important insights to clarify BBN and the thermal history of the Universe below temperatures around 10 GeV and may even provide precise measurements of the gravitino's mass and couplings.Comment: 24 pages, updated figures and minor changes, version to appear in Phys.Rev.

Dirac Cosmology and the Acceleration of the Contemporary Universe

A model is suggested to unify the Einstein GR and Dirac Cosmology. There is one adjusted parameter $b_2$ in our model. After adjusting the parameter $b_2$ in the model by using the supernova data, we have calculated the gravitational constant $\bar G$ and the physical quantities of $a(t)$, $q(t)$ and $\rho_r(t)/ \rho_b(t)$ by using the present day quantities as the initial conditions and found that the equation of state parameter $w_{\theta}$ equals to -0.83, the ratio of the density of the addition creation $\Omega_{\Lambda}=0.8$ and the ratio of the density of the matter including multiplication creation, radiation and normal matter $\Omega_m =0.2$ at present. The results are self-consistent and in good agreement with present knowledge in cosmology. These results suggest that the addition creation and multiplication creation in Dirac cosmology play the role of the dark energy and dark matter.Comment: 13 pages, 8 figure

Magnetic structure of the Eu2+ moments in superconducting EuFe2(As1-xPx)2 with x = 0.19

The magnetic structure of the Eu2+ moments in the superconducting EuFe2(As1-xPx)2 sample with x = 0.19 has been determined using neutron scattering. We conclude that the Eu2+ moments are aligned along the c direction below T_C = 19.0(1) K with an ordered moment of 6.6(2) mu_B in the superconducting state. An impurity phase similar to the underdoped phase exists within the bulk sample which orders antiferromagnetically below T_N = 17.0(2) K. We found no indication of iron magnetic order, nor any incommensurate magnetic order of the Eu2+ moments in the sample.Comment: Accepted for publication in Phys. Rev. B (regular article