Direct Detection of Cold Dark Matter Substructure

By N. Dalal, C. D. O. Physics, Ucsd, Center for Computational Astrophysics. 2001

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We devise a method to measure the abundance of satellite halos in gravitational lens galaxies and apply our method to a sample of seven lens systems. After using Monte Carlo simulations to verify the method, we find that substructure comprises fsat = 0.02 (median, 0.006 < fsat < 0.07 at 90% confidence) of the mass of typical lens galaxies, in excellent agreement with predictions of cold dark matter (CDM) simulations. We estimate a characteristic critical radius for the satellites of 0.″0001 < b < 0.″006 (90% confidence). For a dn/dM ∝ M-1.8 (Mlow < M < Mhigh) satellite mass function, the critical radius provides an estimate for the upper mass limit of 106 M☉ ≲ Mhigh ≲ 109 M☉. Our measurement confirms a generic prediction of CDM models and may obviate the need to invoke alternatives to CDM such as warm dark matter or self-interacting dark matter.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/0e0d264e3e4d89562d14d9ca5521999fbcc6308e

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Citations in the corpus

Detection of a dark substructure through gravitational imaging (2009, methodology): “(iii) The substructure masses and positions are then more precisely quantified by assuming a tidally truncated pseudo-Jaffe (PJ) profile (Dalal & Kochanek 2002) and by simultaneously optimising for the main lens galaxy and substr cture parameters, i.e. its massMsub and position on the lens plane…”
The mass function and average mass-loss rate of dark matter subhaloes (2004, background): “…substructure crisis (Klypin et al. 1999b; Moore et al. 1999; D’onghia & Lake 2004), for the flux-ratio statistics of multiply lensed quasars (e.g. Metcalf & Madau 2001; Bradač et al. 2002; Chiba 2002; Dalal & Kochanek 2002), and for the build-up of the galactic halo (Helmi, White & Springel 2003).”
Gravitational probes of dark matter physics (2017, background): “Currently, the best constraints on the substructure mass function come from flux ratio anomalies and gravitational imaging studies [308, 309, 310, 311, 312].”
Mining for Dark Matter Substructure: Inferring Subhalo Population Properties from Strong Lenses with Machine Learning (2019, background): “01 M 200 (Despali & Vegetti 2017; Hiroshima et al. 2018) respectively, and corresponding ﬁducial substructure mass fraction in this range of 5%, roughly consistent with observations in Dalal & Kochanek (2002); Hi-roshima et al. (2018); Hsueh et al. (2019).”
Orbital parameters of infalling dark matter substructures (2004, result): “Observational tests for its presence, though not yet conclusive, are in good agreement with the theoretical expectations (Metcalf & Madau 2001; Chiba 2002; Dalal & Kochanek 2002).”
SIZES AND TEMPERATURE PROFILES OF QUASAR ACCRETION DISKS FROM CHROMATIC MICROLENSING (2010, background): “Dalal & Kochanek (2002) suggest error bars of 10%; Keeton et al. (2003) call this “quite conservative.””
Galaxy Masses: A Review (2013, result): “The first lensing studies of this topic, based on the so-called flux-ratio anomalies Mao & Schneider (1998); Metcalf & Madau (2001) of radio-loud lenses quasars from the CLASS survey (Dalal & Kochanek 2002) indicated a level of substructure broadly consistent with the expectations of CDM cosmology.”
Inference of the cold dark matter substructure mass function at z = 0.2 using strong gravitational lenses (2014, background): “Our current results imply a fraction which is consistent within the error with the mass fraction derived by Dalal & Kochanek (2002) (0.006 f 0.07) using measurements of flux-ratio anomalies in multiply imaged quasars.”
Numerical simulations of the dark universe: State of the art and the next decade (2012, background): “of individual halos through cluster and galaxy-galaxy lensing [75, 76], and strong lensing, which can probe the central slope of DM density profiles [77] and is sensitive, through flux ratio anomalies [78] and potentially time-delay perturbations [79], to the amount of DM substructure present in clu”
HerMES: CANDIDATE GRAVITATIONALLY LENSED GALAXIES AND LENSING STATISTICS AT SUBMILLIMETER WAVELENGTHS (2012, background): “In combination with dynamical studies, lensing mass reconstruction allows one to obtain the density profile of the dark matter in individual lensing galaxies down to ∼ 10 kpc scales (e.g. Miralda-Escude 1995; Dalal & Kochanek 2002; Metcalf & Zhao 2002; Rusin & Kochanek 2005; Treu & Koopmans 2004).”
The number and size of subhalo-induced gaps in stellar streams (2016, background): “…so-called DM subhaloes may be betrayed by small perturbations in the images of cosmological gravitational lenses (see e.g. Mao & Schneider 1998; Dalal & Kochanek 2002; Hezaveh et al. 2013), or, alternatively, be revealed by gaps in the stellar streams around the Milky Way (MW) galaxy (see e.g.…”