<p>Dark matter halo play a key role in many models of galaxies among which parametrized models of galaxy-halo relationship have a wide range of applications in astrophysics and cosmology. This paper investigates the in-plane and out-of-plane motion of a restricted mass in presence of dark matter halo, which is characterized by a dimensionless parameter <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\gamma \in [0,3)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>γ</mi> <mo>∈</mo> <mo stretchy="false">[</mo> <mn>0</mn> <mo>,</mo> <mn>3</mn> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> under the frame of restricted three body problem. First, the equations of motion are obtained and positions of all equilibrium points are computed followed by stability test is performed. It is observed that all collinear equilibrium points <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(L_1\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>L</mi> <mn>1</mn> </msub> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(L_2\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>L</mi> <mn>2</mn> </msub> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(L_3\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>L</mi> <mn>3</mn> </msub> </math></EquationSource> </InlineEquation> and out-of-plane equilibrium points <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(L_{6,7}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>L</mi> <mrow> <mn>6</mn> <mo>,</mo> <mn>7</mn> </mrow> </msub> </math></EquationSource> </InlineEquation> are unstable and change their individual positions within the range of <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(\gamma \in [0,\,3)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>γ</mi> <mo>∈</mo> <mo stretchy="false">[</mo> <mn>0</mn> <mo>,</mo> <mspace width="0.166667em" /> <mn>3</mn> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(\mu \in (0,\,1/2]\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>μ</mi> <mo>∈</mo> <mo stretchy="false">(</mo> <mn>0</mn> <mo>,</mo> <mspace width="0.166667em" /> <mn>1</mn> <mo stretchy="false">/</mo> <mn>2</mn> <mo stretchy="false">]</mo> </mrow> </math></EquationSource> </InlineEquation>, while non-collinear equilibrium points <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(L_{4,5}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>L</mi> <mrow> <mn>4</mn> <mo>,</mo> <mn>5</mn> </mrow> </msub> </math></EquationSource> </InlineEquation> are stable in linear sense within the range of stability as <InlineEquation ID="IEq9"> <EquationSource Format="TEX">\(\gamma \in [0,\,3)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>γ</mi> <mo>∈</mo> <mo stretchy="false">[</mo> <mn>0</mn> <mo>,</mo> <mspace width="0.166667em" /> <mn>3</mn> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq10"> <EquationSource Format="TEX">\(\mu \in (0,\,\mu _c]\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>μ</mi> <mo>∈</mo> <mo stretchy="false">(</mo> <mn>0</mn> <mo>,</mo> <mspace width="0.166667em" /> <msub> <mi>μ</mi> <mi>c</mi> </msub> <mo stretchy="false">]</mo> </mrow> </math></EquationSource> </InlineEquation> but varied their positions with <InlineEquation ID="IEq11"> <EquationSource Format="TEX">\(\gamma\)</EquationSource> <EquationSource Format="MATHML"><math> <mi>γ</mi> </math></EquationSource> </InlineEquation>. Additionally, the orbits in the vicinity of <InlineEquation ID="IEq12"> <EquationSource Format="TEX">\(L_4\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>L</mi> <mn>4</mn> </msub> </math></EquationSource> </InlineEquation> point are determined and it is found that amplitude, time-period and orientation change with respect to the dark matter halo parameter <InlineEquation ID="IEq13"> <EquationSource Format="TEX">\(\gamma\)</EquationSource> <EquationSource Format="MATHML"><math> <mi>γ</mi> </math></EquationSource> </InlineEquation>. Next, to visualize the prohibited zones for the motion of restricted mass, the zero-velocity curves are estimated at different values of <InlineEquation ID="IEq14"> <EquationSource Format="TEX">\(\gamma\)</EquationSource> <EquationSource Format="MATHML"><math> <mi>γ</mi> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq15"> <EquationSource Format="TEX">\(\mu\)</EquationSource> <EquationSource Format="MATHML"><math> <mi>μ</mi> </math></EquationSource> </InlineEquation> for both, in-plane and out-of-plane motion and it is seen that these are expanding with mass ratio <InlineEquation ID="IEq16"> <EquationSource Format="TEX">\(\mu\)</EquationSource> <EquationSource Format="MATHML"><math> <mi>μ</mi> </math></EquationSource> </InlineEquation> and dark matter halo parameter <InlineEquation ID="IEq17"> <EquationSource Format="TEX">\(\gamma\)</EquationSource> <EquationSource Format="MATHML"><math> <mi>γ</mi> </math></EquationSource> </InlineEquation>. The findings of this study are not only useful to enhance the mission design for space exploration but also helps to describe the perturbed motion in the different galactic systems.</p>

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On in-plane and out-of-plane motions under the influence of dark matter halo

  • Raj Mal Jat,
  • Ram Kishor

摘要

Dark matter halo play a key role in many models of galaxies among which parametrized models of galaxy-halo relationship have a wide range of applications in astrophysics and cosmology. This paper investigates the in-plane and out-of-plane motion of a restricted mass in presence of dark matter halo, which is characterized by a dimensionless parameter \(\gamma \in [0,3)\) γ [ 0 , 3 ) under the frame of restricted three body problem. First, the equations of motion are obtained and positions of all equilibrium points are computed followed by stability test is performed. It is observed that all collinear equilibrium points \(L_1\) L 1 , \(L_2\) L 2 , \(L_3\) L 3 and out-of-plane equilibrium points \(L_{6,7}\) L 6 , 7 are unstable and change their individual positions within the range of \(\gamma \in [0,\,3)\) γ [ 0 , 3 ) and \(\mu \in (0,\,1/2]\) μ ( 0 , 1 / 2 ] , while non-collinear equilibrium points \(L_{4,5}\) L 4 , 5 are stable in linear sense within the range of stability as \(\gamma \in [0,\,3)\) γ [ 0 , 3 ) and \(\mu \in (0,\,\mu _c]\) μ ( 0 , μ c ] but varied their positions with \(\gamma\) γ . Additionally, the orbits in the vicinity of \(L_4\) L 4 point are determined and it is found that amplitude, time-period and orientation change with respect to the dark matter halo parameter \(\gamma\) γ . Next, to visualize the prohibited zones for the motion of restricted mass, the zero-velocity curves are estimated at different values of \(\gamma\) γ and \(\mu\) μ for both, in-plane and out-of-plane motion and it is seen that these are expanding with mass ratio \(\mu\) μ and dark matter halo parameter \(\gamma\) γ . The findings of this study are not only useful to enhance the mission design for space exploration but also helps to describe the perturbed motion in the different galactic systems.