Dark Matter Density in Einstein Radius

JWST-ER1g Properties

• JWST-ER1g has a total mass of Mlens = 6.5-1.5 × 10^11 M⊙ within r = 6.6 kpc.
• Stellar mass within the Einstein radius is Mstars = (1.1-0.3 × 10^11) M⊙ for a Chabrier IMF.
• Lens mass is a factor of 5.9+4.1-1.6 higher than the stellar mass.

Possible Contributors to Lensing Mass

• Unlikely that significant fraction of lensing mass is in the form of gas.
• Observations of lensed quiescent galaxies and simulations find low gas masses.
• No hidden obscured starburst in JWST-ER1g, with an upper limit to the star formation rate of 63 M⊙ yr^-1.

Dark Matter Profile

• Dark matter density within the Einstein radius is a factor of ~2 higher than expected from scaling relations.
• Two possible options for the 'extra' dark matter:
  • Total halo mass could be higher than expected from the canonical stellar mass-halo mass relation.
  • Baryonic processes could lead to a dark matter profile that deviates from the NFW form.

Dark Matter within the Einstein Radius

• Dark matter mass within the Einstein radius is Mdm = 2.6+1.6-0.7 × 10^11 M⊙ for a NFW halo.
• Assumes a Navarro-Frenk-White (NFW) profile and the stellar mass-halo mass relation for z = 2.

Galaxy Properties

• JWST-ER1g is a quiescent galaxy, with an age of 1.9+0.3-0.6 Gyr and a low star formation rate of 4+19 M⊙ yr^-1.
• Galaxy is compact, with an observed effective radius of re = 1.9 ± 0.2 kpc.
• No obvious star-forming regions, tidal tails, or other irregularities in the residuals from the GALFIT fit.