Three-dimensional MHD simulations of Radiatively cooling, Pulsed Jets

Abstract

(Abridged) We here investigate, by means of fully 3-D Smoothed Particle Magnetohydrodynamic numerical simulations, the effects of magnetic fields on overdense, radiatively cooling, pulsed jets, using different initial magnetic field topologies and strengths ($B\simeq 260\mu$G-0). The relative differences that have been previously detected in 2-D simulations involving distinct magnetic field configurations are diminished in the 3-D flows. While the presence of toroidal magnetic components can modify the morphology close to the jet head inhibiting its fragmentation in the early jet evolution, as previously reported in the literature, the impact of the pulsed-induced internal knots causes the appearance of a complex morphology at the jet head (as required by the observations of H-H jets) even in the MHD jet models with toroidal components. The detailed structure and emission properties of the internal working surfaces can be also significantly altered by the presence of magnetic fields. The increase of the magnetic field strength improves the jet collimation, and amplifies the density (by factors up to 1.4, and 4) and the Hα$intensity(byfactorsupto4,and5)behindtheknotsofjetswithhelicalfieldand$β\simeq 1-0.1$(respectively),relativetoanonmagneticjet.Asaconsequence,thecorresponding$I_{[SII]}}/I_{H}α}$ratio(whichisfrequentlyusedtodeterminetheexcitationlevelofHHobjects)canbedecreasedintheMHDmodelswithtoroidalcomponentsrelativetonon-magneticcalculations.WealsofindthatthehelicalmodeoftheK-HinstabilitycanbetriggeredinMHDmodelswithhelicalmagneticfields,causingsomejetwiggling.Noevidencefortheformationofthenoseconesisfoundinthe3-Dflows,noreveninthe$β\simeq 0.1$ case.

31 pages, 10 figures (see higher resolution figures in: http://www.iagusp.usp.br/~dalpino/mhd-jets/apj0301.tar.gz), ApJ in press

References in corpus (4)

• MHD Models of Axisymmetric Protostellar Jets
• On the Influence of Magnetic Fields on the Structure of Protostellar Jets
• The deceleration of Giant Herbig-Haro Flows
• The Magnetic Geometry of Pulsed Astrophysical Jets

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• JOYS: JWST MIRI/MRS spectra of the inner 500 au region of the L1527 IRS bipolar outflow