Difference: TheGalacticBar (6 vs. 7)

Revision 72009-06-23 - MerceRomero

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META TOPICPARENT name="POstDocMerce"
-- MerceRomero - 15 Jan 2009
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  In the next step I proceeded the same way as with the bar potential. Here I consider the potential resulting from the superposition of the axisymmetric component and the spiral arms. I analysed each component of the model to check which one has an effect to the outer parts of the galaxy and, again, the spiral mass and its pattern speed are the two parameters with a major influence. I make families of models by fixing the rest of the parameters and varying "alfa2b" and "omegs" within a range of values. For each model, I compute the invariant manifolds and I plot the resulting morphology in a 2D grid. Analogously to that of the bar potential, I decrease on the x-axis the spiral pattern speed from left to right and, in the y-axis I decrease the spiral mass from top to bottom. The results are in the file: plot2dsp.pdf, attached below. Again, the locus of the spiral is plotted in red lines. There are some models, were self-consistency is achieved.
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The next step is performing the same study when we consider the axisymmetric + bar + spiral, i.e. the total potential, with the bar and spirals rotating at the same pattern speed. The results are shown in the last next two plots of the table below. In the first case, I fixed the value of alfa2b=0.05 and I vary the bar mass and the pattern speed (plot2dbarsp.pdf). In the second case, I increase the spiral mass to alfa2b=0.1 (plot2dbarsp2.pdf). The plot plot2dbar.pdf represents the case when alfa2b=0.
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The next step is performing the same study when we consider the axisymmetric + bar + spiral, i.e. the total potential, with the bar and spirals rotating at the same pattern speed. The results are shown in the next two plots of the table below. In the first case, I fixed the value of alfa2b=0.05 and I vary the bar mass and the pattern speed (plot2dbarsp05.pdf). In the second case, I increase the spiral mass to alfa2b=0.1 (plot2dbarsp1.pdf). The plot plot2dbar.pdf represents the case when alfa2b=0.
  In this last case, we obtain some nice self-consistent spiral arms corresponding to realistic values for the bar mass and the pattern speed. So we will study them in detail.
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META FILEATTACHMENT attr="" comment="2D grid varying the pattern speed and the Bar mass" date="1236952927" name="plot2dbar.pdf" path="plot2dbar.pdf" size="6163638" user="MerceRomero" version="1.1"
META FILEATTACHMENT attr="" comment="2D grid varying the pattern speed and the Spiral mass" date="1236952951" name="plot2dsp.pdf" path="plot2dsp.pdf" size="5701286" user="MerceRomero" version="1.1"
META FILEATTACHMENT attr="" comment="2D grid with the total potential varying the bar mass and the pattern speed. alfa2b=0.05" date="1236952977" name="plot2dbarsp.pdf" path="plot2dbarsp.pdf" size="5835526" user="MerceRomero" version="1.1"
META FILEATTACHMENT attr="" comment="2D grid with the total potential varying the bar mass and the pattern speed. alfa2b=0.1" date="1236953018" name="plot2dbarsp2.pdf" path="plot2dbarsp2.pdf" size="7138445" user="MerceRomero" version="1.1"
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Finally, I change the bar model to that used by Dehnen in his paper of 2000 AJ 119, 800-812: "The effect of the OLR of the galactic bar on the local stellar velocity distribution". So I take the power-law to model the axisymmetric component and the cos(2theta) potential of the bar. There I include another free parameter, namely the exponent in the A(r) function. He sets it to 3, and I will change it in other cases (as I do in our papers with Lia). The last figure in the table is the 2D grid for a flat rotation curve (beta=0) and the same potential he uses (expb=3). There I vary the bar strength characterized by the parameter alpha (close related to the amplitude of the bar) in the same range he uses in the paper, and in the x-axis, I vary the pattern speed as usual, also in the same ranges as he uses. Note that here the model is the superposition of an axisymmetric component plus a bar. So NO spiral potential is included. The results are as expected. No clear spiral arms are present. And the shape of the manifolds delineate approximately the shape of the OLR closed orbits, with an R1 shape.

Now I'm planning to change the shape of the rotation curve (by varying beta) and the shape of the force curve (by varying expb).

I also include in each panel a circle of radius 8.5 to show the solar radius, and as before, the locus of the spiral.

META FILEATTACHMENT attr="" comment="2D grid varying the pattern speed and the Bar mass. Barbara's models" date="1236952927" name="plot2dbar.pdf" path="plot2dbar.pdf" size="6163638" user="MerceRomero" version="1.1"
 
META FILEATTACHMENT attr="" comment="Talk at a conference, with a summary of the dynamics" date="1236953865" name="Romero.pdf" path="Romero.pdf" size="7141911" user="MerceRomero" version="1.1"
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META FILEATTACHMENT attr="" comment="2D grid varyind the pattern speed and the spiral mass. Barbara's models" date="1245747855" name="plot2dsp.pdf" path="plot2dsp.pdf" size="7859867" user="MerceRomero" version="1.1"
META FILEATTACHMENT attr="" comment="2D grid varying the pattern speed and the Bar mass. Spiral mass=0.05. Barbara's models" date="1245749763" name="plot2dbarsp05.pdf" path="plot2dbarsp05.pdf" size="7994077" user="MerceRomero" version="1.1"
META FILEATTACHMENT attr="" comment="2D grid varying the pattern speed and the Bar mass. Spiral mass=0.1. Barbara's models" date="1245750049" name="plot2dbarsp1.pdf" path="plot2dbarsp1.pdf" size="7416859" user="MerceRomero" version="1.1"
META FILEATTACHMENT attr="" comment="2D grid varying the pattern speed and bar strength (alpha). Beta=0 and exp=3. Dehnen00 model" date="1245751183" name="plot2Dbeta0exp3.pdf" path="plot2Dbeta0exp3.pdf" size="8538293" user="MerceRomero" version="1.1"
 
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