Out of sight, out of mind? The impact of correlated clustering in substructure lensing
ABSTRACT A promising route for revealing the existence of dark matter structures on mass scales smaller than the faintest galaxies is through their effect on strong gravitational lenses. We examine the role of local, lens-proximate clustering in boosting the lensing probability relative to contributions from substructure and unclustered line-of-sight (LOS) haloes. Using two cosmological simulations that can resolve halo masses of Mhalo ≃ 109 M⊙ (in a simulation box of length $L_{\rm box}{\sim }100\, {\rm Mpc}$) and 107 M⊙ ($L_{\rm box}\sim 20\, {\rm Mpc}$), we demonstrate that clustering in the vicinity of the lens host produces a clear enhancement relative to an assumption of unclustered haloes that persists to $\gt 20\, R_{\rm vir}$. This enhancement exceeds estimates that use a two-halo term to account for clustering, particularly within $2-5\, R_{\rm vir}$. We provide an analytic expression for this excess, clustered contribution. We find that local clustering boosts the expected count of 109 M⊙ perturbing haloes by $\sim \! 35{{\ \rm per\ cent}}$ compared to substructure alone, a result that will significantly enhance expected signals for low-redshift (zl ≃ 0.2) lenses, where substructure contributes substantially compared to LOS haloes. We also find that the orientation of the lens with respect to the line of more »
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Publication Date:
NSF-PAR ID:
10258062
Journal Name:
Monthly Notices of the Royal Astronomical Society
Volume:
502
Issue:
4
Page Range or eLocation-ID:
6064 to 6079
ISSN:
0035-8711
4. ABSTRACT We compare predictions for galaxy–galaxy lensing profiles and clustering from the Henriques et al. public version of the Munich semi-analytical model (SAM) of galaxy formation and the IllustrisTNG suite, primarily TNG300, with observations from KiDS + GAMA and SDSS-DR7 using four different selection functions for the lenses (stellar mass, stellar mass and group membership, stellar mass and isolation criteria, and stellar mass and colour). We find that this version of the SAM does not agree well with the current data for stellar mass-only lenses with $M_\ast \gt 10^{11}\, \mathrm{ M}_\odot$. By decreasing the merger time for satellite galaxies as well as reducingmore »