Daily Study Log (2019-02-13)

Research Mass-Radius Relation of Neutron Stars I have been reading the paper that my advisor recommended. I can understand the concept of the test after reading this. Maybe I can read it up and write a test code tomorrow. Study Astronomy & Astrophysics I have read the AAS Nova article. I have read the two…

Daily Study Log (2019-02-12)

 Research Mass-Radius Relation of Neutron Stars I have been reading the paper in order to check whether my code (TOV solver) follows the equation of state (EOS): Units in the EOS are used the geometrized( ) units, so I need to convert it into cgs units: I easily put this calculation in my TOV solver,…

Daily Study Log (2019-02-11)

Research Mass-Radius Relation of Neutron Stars I need to figure out why 1% of the difference occurs between the TOV solvers and RNS code. To do this, I’m studying another simple analytic solution in previous papers. Study Astronomy & Astrophysics I have read the AAS Nova article. English I have read the front page of…

Daily Study Log (2019-02-10)

Research Mass-Radius Relation of Neutron Stars I did a convergence study for three different codes (RNS v 2.0, my TOV solver, and my advisor’s TOV solver) to see they are converging to the same value. It is highly recommended that the results should be visualized for comparison. So I wrote a Python code for a…

Daily Study Log (2019-02-09)

Study English I have added 22 sentences, 1 TOEFL essay, and 1 GRE essay. I have studied 39 words, 28 sentences, 3 TOEFL essays, and 3 GRE essays using Anki. Math I have solved 6 GRE Quantitative problems. Physics I have solved 6 Physics GRE problems. I have updated 2 Physics GRE solutions in this…

Daily Study Log (2019-02-08)

Research Mass-Radius Relation of Neutron Stars I learned something important in dealing with numerical calculations. Whenever I do simulations, I should always do a convergence study to see how the grid resolution affects your results. I should try decreasing the radial grid cell size to see if the codes are converging to the same value. Study…

Physics GRE GR 1777, Problem 046 Solution

Physics GRE GR 1777 Problem 046 046. Classical Mechanics (Hooke’s law) You should know about Hooke’s law The potential energy stored in a spring Solution Extension The same external force is applied to both springs,   Stored Potential Energy Answer (A) References https://en.wikipedia.org/wiki/Hooke%27s_law

Daily Study Log (2019-02-07)

Research Mass-Radius Relation of Neutron Stars I have tested the RNS v2.0 code for the cases of two central mass densities, and , respectively. I have compared these results with my TOV solver’s results, and my advisor’s sample code results. They are similar but not the same. Study Astronomy & Astrophysics I have read the AAS…

Daily Study Log (2019-02-06)

Research Mass-Radius Relation of Neutron Stars I have tested the validity of the RNS v2.0 code for () polytropic case with the central mass density is . It turned out to be a good agreement with the Lane-Emden solution. Study English I have studied 29 words, 25 sentences, and 2 TOEFL essays using Anki. General…

Daily Study Log (2019-02-05)

Research Mass-Radius Relation of Neutron Stars I got the relation between the central energy density and central mass density. In the polytropic n = 1 () case, Using this relation, I put the central mass density into my TOV solver and compare with RNS result. The results are slightly different. Now I have to find…