The changing milliarcsecond radio morphology of the gamma-ray binary LS 5039

LS 5039 is one of the few TeV emitting X-ray binaries detected so far. The powering source of its multiwavelength emission can be accretion in a microquasar scenario or wind interaction in a young nonaccreting pulsar scenario. Aims.To present new high-resolution radio images and compare them with the expected behavior in the different scenarios. Methods.We analyze Very Long Baseline Array (VLBA) radio observations that provide morphological and astrometric information at milliarcsecond scales. Results.We detect a changing morphology between two images obtained five days apart. In both runs there is a core component with a constant flux density, and an elongated emission with a position angle (PA) that changes by 12 $\pm$ $3\degr$ between both runs. The source is nearly symmetric in the first run and asymmetric in the second one. The astrometric results are not conclusive. Conclusions.A simple and shockless microquasar scenario cannot easily explain the observed changes in morphology. An interpretation within the young nonaccreting pulsar scenario requires the inclination of the binary system to be very close to the upper limit imposed by the absence of X-ray eclipses.

Confirmation of persistent radio jets in the microquasar LS 5039

We present here new observations conducted with the EVN and MERLIN of the persistent microquasar LS 5039 discovered by Paredes et al. (2000) with the VLBA. The new observations confirm the presence of an asymmetric two-sided jet reaching up to 1000 AU on the longest jet arm. The results suggest a bending of the jets with increasing distance from the core and/or precession. The origin and location of the high-energy gamma-ray emission associated with the system is discussed and an estimate of the magnetic field at the base of the jet given. Our results suggest a well collimated radio jet. We also comment on new observing strategies to be used with satellites and forthcoming detectors, since this persistent source appears to be a rather good laboratory to explore the accretion/ejection processes taking place near compact objects.

Kandidatbloggar i det finska presidentvalet 2006 : strategier och effekter

Abstract: Candidate blogs in the 2006 Finnish presidential elections : strategies and outcomes

Spectral energy distribution of the gamma-ray microquasar LS 5039

The microquasar LS 5039 has recently been detected as a source of very high energy (VHE) $\gamma$-rays. This detection, that confirms the previously proposed association of LS 5039 with the EGRET source 3EG~J1824$-$1514, makes of LS 5039 a special system with observational data covering nearly all the electromagnetic spectrum. In order to reproduce the observed spectrum of LS 5039, from radio to VHE $\gamma$-rays, we have applied a cold matter dominated jet model that takes into account accretion variability, the jet magnetic field, particle acceleration, adiabatic and radiative losses, microscopic energy conservation in the jet, and pair creation and absorption due to the external photon fields, as well as the emission from the first generation of secondaries. The radiative processes taken into account are synchrotron, relativistic Bremsstrahlung and inverse Compton (IC). The model is based on a scenario that has been characterized with recent observational results, concerning the orbital parameters, the orbital variability at X-rays and the nature of the compact object. The computed spectral energy distribution (SED) shows a good agreement with the available observational data.

LS 5039: A runaway microquasar ejected from the galactic plane

We have compiled optical and radio astrometric data of the microquasar LS 5039 and derived its proper motion. This, together with the distance and radial velocity of the system, allows us to state that this source is escaping from its own regional standard of rest, with a total systemic velocity of about 150 km/s and a component perpendicular to the galactic plane larger than 100 km/s. This is probably the result of an acceleration obtained during the supernova event that created the compact object in this binary system. We have computed the trajectory of LS 5039 in the past, and searched for OB associations and supernova remnants in its path. In particular, we have studied the possible association between LS 5039 and the supernova remnant G016.8-01.1, which, despite our efforts, remains dubious. We have also discovered and studied an HI cavity in the ISM, which could have been created by the stellar wind of LS 5039 or by the progenitor of the compact object in the system. Finally, in the symmetric supernova explosion scenario, we estimate that at least 17 solar masses were lost in order to produce the high eccentricity observed. Such a mass loss could also explain the observed runaway velocity of the microquasar.

Kvinnor och messiasgestalter i science fiction-film

Recension

Fången och Svalan

Simananniemen käsikirjoituskokoelma.

O källor, berg och lundar klagen [Stemmat]

Soitinnus: sekakuoro.

Planering av tidtabell, kostnader och arbetsplats för småhus

Det här examensarbete gjordes åt Seasong Travels Oy. I arbetet gjordes en kostnadsplan, tidtabell och dispositionsplan för en stugby på Norrkullalandet. Arbetet börjades med att bekanta sej med byggbranschens facklitteratur och ta reda på vilka faktorer som påverkar byggprojektets slutliga kostnader och tidtabell. På basen av områdets litteratur valdes kostnadsberäkningssättet att utföras med hjälp av Talo-80 nomenklatur och göra en byggnadsdelskalkyl. I arbetets undersökningsskede delades stugorna upp enligt Talo-80 nomenklatur i enskilda byggnadsdelar, varefter byggnadsdelarna prissattes. En tidtabell gjordes när alla byggnadsdelar var uppdelade och med hjälp av områdets litteratur räknades den effektiva byggtiden ut. Dispositionsplanen gjordes genom att studera områdets facklitteratur och själva byggplatsen.

Korta anmärckningar, wid inbyggarenas näringar och hushållning, uti Cala-Joki sochn

Huomautus: Inv.: I.G.N. - Ded.: Johan Calamnius. - Painovuosi nimekkeestä. - Arkit: A4 B2