Cosmicflows-3 Distance–Velocity Calculator(distances less than 400 Mpc)

Compute expectation distances or velocities based on smoothed velocity field from the Wiener filter model of Graziani et al. 2019.



*  Indicates required field
SGL [deg]
SGB [deg]
Cone [deg]


  Coordinate system
   equatorial
   galactic
   supergalactic

  Distance/Velocity
   distance
   velocity

  SGL= 102.0   SGB= -2.0

RA:

187.78917

  Dec:

13.33386

Glon:

282.96547

  Glat:

75.41360

SGL:

102.00000

  SGB:

-2.00000

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, Vls, vs. distance. Bottom panel: Cosmologically adjusted velocity, Vcls, vs. distance. The corrected velocity Vcls is related to the observed velocity Vls 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.