Rubin-LSST

Abstract:

As a prerequisite for cosmological studies using adaptive optics techniques, we have begun to identify and characterize faint sources in the vicinity of bright stars at high Galactic latitudes. The initial phase of this work has been a program of Ks imaging conducted with SOFI at the ESO NTT. From observations of 42 southern fields evenly divided between the spring and autumn skies, we have identified 391 additional stars and 1589 galaxies lying at separations Δθ ≤ 60″ from candidate guide stars in the magnitude range 9.0 ≤ R ≤ 12.4. When analyzed as a "discrete deep field" with 131 arcmin² area, our dataset gives galaxy number counts that agree with those derived previously over the range 16 ≤ Ks < 20.5. This consistency indicates that in the aggregate, our fields should be suitable for future statistical studies. We provide our source catalogue as a resource for users of large telescopes in the southern hemisphere.

Abstract:

We present 7-180μm photometry of a sample of hyperluminous infrared galaxies (HyLIGs) obtained with the photometer and camera mounted on the Infrared Space Observatory (ISO). We have used state-of-the-art' radiative transfer models of obscured starbursts and dusty tori to model their broadband spectral energy distributions (SEDs). We find that IRAS F00235+1024, IRAS F14218+3845 and IRAS F15307+3252 require a combination of starburst and AGN components to explain their mid to far-infrared emission, while for TXS0052+471 a dust torus model alone is sufficient. For IRAS F00235+1024 and IRAS F14218+3845 the starburst component is the predominant contributor whereas for IRAS F15307+3252 the dust torus component dominates. The implied star formation rates (SFR) estimated from the starburst infrared luminosities are dM*,all/dt > 1000M⊙yr^-1h50^-2 and are amongst the highest SFRs estimated to date. We also demonstrate that the well-known radio-FIR correlation observed for extragalactic sources extends into both higher radio and infrared power than previously investigated. The relation for HyLIGs has a mean q value of 1.94. The results of this study imply that better sampling of the IR SEDs of HyLIGs may reveal that both AGN and starburst components are required to explain their emission from the NIR to the sub-millimetre.

Abstract:

Inclusive momentum distributions of charged particles in restricted cones around jet axes were measured in dijet events with invariant dijet masses in the range 80 to 600 GeV/c2. Events were produced at the Fermilab Tevatron in pp collisions with a center of mass energy of 1.8 TeV and recorded by the Collider Detector at Fermilab. The results were compared to perturbative QCD calculations carried out in the framework of the modified leading log approximation (MLLA) and assuming local parton-hadron duality. It was shown that the data follow theoretical predictions quite well over the whole range of the jet energies included in this analysis. We extracted the MLLA cutoff scale Qe f f and found a value of 230±40 MeV. The theoretical prediction of Ejetsin θc scaling, where u c is the cone opening angle, was experimentally observed for the first time. From the MLLA fits to the data, two more parameters were extracted: the ratio of parton multiplicities in gluon and quark jets, r = Npartonsg-jet /Npartonsq-jet = 1.9±0.5, and the ratio of the number of charged hadrons to the number of predicted partons in a jet, KLPHDcharged=Nhadronscharged/Npartons=0.56±0.10.