Parameters

Required

• Sky position, galactic, supergalactic, or equatorial (J2000 as 360° decimal) in degrees.

Optional

• Cone (degrees) [default 10°]; plot data points within this cone angle.
• Distance (Mpc); returns model velocity in km/s.
• Velocity (km/s); returns model distance(s) in Mpc – potentially more than one value.

Features

• Model distance – velocity curve (blue) is derived from interpolation of velocities on a grid of distances with grid intervals of 6.25 Mpc. The value at each point is averaged over the 8 nearest grid points weighted by the inverse square of separation.
• Pause cursor over blue curve for distance and velocity information at chosen location.
• Pause cursor over data points for extra information.

Details

• Top panel: Observed velocity, V_ls, vs. distance. Bottom panel: Cosmologically adjusted velocity, V^c_ls, vs. distance. The corrected velocity V^c_ls is related to the observed velocity V_ls by:

V_{ls}^c = f(z)V_{ls}  where f(z) = 1+1/2(1-q_0)z-1/6(2-q_0-3q_0^2)z^2 q_0 = 1/2(\Omega_m-2\Omega_{\Lambda}) = -0.595  when\Omega_m=0.27 and \Omega_{\Lambda}=0.73 and z=V_{ls}/c.



• In both panels, symbols of differing sizes correspond to different masses of the associated elements: large brown circles if mass greater than 10¹⁴M_☉, smaller red circles if mass is between 10¹³ and 10¹⁴M_☉, and black plus signs if mass is below 10¹³M_☉.
• PGC1 is the Principal Galaxies Catalog identification of the brightest member of the group contributing to the data point
• The H₀=75 dashed line is only for reference.

How to acknowledge this work

• If you use the results of this work in your research or other applications, please cite Kourkchi et al. 2020, AJ, 159, 67 (arXiv:1912.07214).
• This application is based on the velocity field reconstruction from the Wiener filter model of Graziani et al., 2019, MNRAS, 488, 5438.