TY - JOUR
T1 - Improved halo model calibrations for mixed dark matter models of ultralight axions
AU - Dome, Tibor
AU - May, Simon
AU - Laguë, Alex
AU - Marsh, David J E
AU - Johnston, Sarah
AU - Bose, Sownak
AU - Tocher, Alex
AU - Fialkov, Anastasia
N1 - Publisher Copyright:
© 2025 The Author(s).
PY - 2025/2
Y1 - 2025/2
N2 - We study the implications of relaxing the requirement for ultralight axions to account for all dark matter in the Universe by examining mixed dark matter (MDM) cosmologies with axion fractions f ≤ 0.3 within the fuzzy dark matter window 10−25 eV ≤ m ≤ 10−23 eV. Our simulations, using a new MDM gravity solver implemented in AXIREPO, capture wave dynamics across various scales with high accuracy down to redshifts z ≈ 1. We identify haloes with ROCKSTAR using the cold dark matter component and find good agreement of inferred halo mass functions and concentration–mass relations with theoretical models across redshifts z = 1–10. This justifies our halo finder approach a posteriori as well as the assumptions underlying the MDM halo model AXIONHMCODE. Using the inferred axion halo mass–cold halo mass relation Ma(Mc) and calibrating a generalized smoothing parameter α to our MDM simulations, we present a new version of AXIONHMCODE. The code exhibits excellent agreement with simulations on scales k < 20 hcMpc−1 at redshifts z = 1–3.5 for f ≤ 0.1 around the fiducial axion mass m = 10−24.5 eV = 3.16 × 10−25 eV, with maximum deviations remaining below 10 per cent. For axion fractions f ≤ 0.3, the model maintains accuracy with deviations under 20 per cent at redshifts z ≈ 1 and scales k < 10 hcMpc−1, though deviations can reach up to 30 per cent for higher redshifts when f = 0.3. Reducing the run-time for a single evaluation of AXIONHMCODE to below 1 min, these results highlight the potential of AXIONHMCODE to provide a robust framework for parameter sampling across MDM cosmologies in Bayesian constraint and forecast analyses.
AB - We study the implications of relaxing the requirement for ultralight axions to account for all dark matter in the Universe by examining mixed dark matter (MDM) cosmologies with axion fractions f ≤ 0.3 within the fuzzy dark matter window 10−25 eV ≤ m ≤ 10−23 eV. Our simulations, using a new MDM gravity solver implemented in AXIREPO, capture wave dynamics across various scales with high accuracy down to redshifts z ≈ 1. We identify haloes with ROCKSTAR using the cold dark matter component and find good agreement of inferred halo mass functions and concentration–mass relations with theoretical models across redshifts z = 1–10. This justifies our halo finder approach a posteriori as well as the assumptions underlying the MDM halo model AXIONHMCODE. Using the inferred axion halo mass–cold halo mass relation Ma(Mc) and calibrating a generalized smoothing parameter α to our MDM simulations, we present a new version of AXIONHMCODE. The code exhibits excellent agreement with simulations on scales k < 20 hcMpc−1 at redshifts z = 1–3.5 for f ≤ 0.1 around the fiducial axion mass m = 10−24.5 eV = 3.16 × 10−25 eV, with maximum deviations remaining below 10 per cent. For axion fractions f ≤ 0.3, the model maintains accuracy with deviations under 20 per cent at redshifts z ≈ 1 and scales k < 10 hcMpc−1, though deviations can reach up to 30 per cent for higher redshifts when f = 0.3. Reducing the run-time for a single evaluation of AXIONHMCODE to below 1 min, these results highlight the potential of AXIONHMCODE to provide a robust framework for parameter sampling across MDM cosmologies in Bayesian constraint and forecast analyses.
UR - http://www.scopus.com/inward/record.url?scp=85215754450&partnerID=8YFLogxK
U2 - 10.1093/mnras/staf005
DO - 10.1093/mnras/staf005
M3 - Article
SN - 0035-8711
VL - 537
SP - 252
EP - 271
JO - MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
JF - MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
IS - 1
ER -