Constraints on (Fuzzy) Dark Matter Microphysics from Dwarf Galaxies - Ethan Nadler Less Travelled Path of Dark Matter (ICTS) 11/12/2020
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Constraints on (Fuzzy) Dark Matter
Microphysics from Dwarf Galaxies
Ethan Nadler
Less Travelled Path of Dark Matter (ICTS)
11/12/2020
Dark Matter and Structure Formation
Microphysical dark matter
properties affect structure
formation on small scales
Buckley & Peter 2018
Our Census of the Faintest Galaxies
MW halo virial radius
Ultra-faint Milky Way
satellite galaxies occupy
the smallest luminous
dark matter halos
Credit: J. Carlin
The Milky Way Satellite Population
Classical
CVn II
Boo III
Boo I Com SDSS
CVn I
Boo II Leo II
+60 PS1
Vir I Leo V
Wil 1
UMa I
Boo IV Leo IV Seg 1 DES
Leo I
UMi Dra II Crt II Sex DECam
Her
+30 UMa II Dra HSC
Hyd II
Cen I
ATLAS
Gaia
Ant II
0
Sgr Car III
Car II
Tri II Sgr II Car
LMC Pic II Col I
30 Hyi I
Seg 2 Peg III Pic I
SMC Ret III
Psc II
Ret II
Tuc II Tuc V Hor I
Aqr II Gru II Eri II
Tuc IV
Gru I Hor II
60 Cet III
Phe II
Tuc III
For
Cet II
Scl
Drlica-Wagner & Bechtol et al. 2020
Small Halos as Dark Matter Probes
CDM WDM
Lovell et al. 2011
Faint Galaxies as Dark Matter Probes
CDM WDM
There is No Missing Satellites Problem
• No missing satellites problem after correcting
for incomplete observations and extrapolating
standard stellar mass–halo mass relations
• Consistency has only been demonstrated at
fixed modeling assumptions, and only for the
brightest half of the Milky Way satellite population
Bullock & Boylan-Kolchin 2017
Wetzel et al. 2016
1. Resimulate Milky Way-
like halos from large
cosmological volume.
1.0
2. Paint satellite galaxies 100
↵
AAAB7XicbVBNS8NAEJ3Ur1q/qh69LBbBU0mqoMeiF48V7Ae0oUy2m3btZhN2N0IJ/Q9ePCji1f/jzX/jts1BWx8MPN6bYWZekAiujet+O4W19Y3NreJ2aWd3b/+gfHjU0nGqKGvSWMSqE6BmgkvWNNwI1kkUwygQrB2Mb2d++4kpzWP5YCYJ8yMcSh5yisZKrR6KZIT9csWtunOQVeLlpAI5Gv3yV28Q0zRi0lCBWnc9NzF+hspwKti01Es1S5COcci6lkqMmPaz+bVTcmaVAQljZUsaMld/T2QYaT2JAtsZoRnpZW8m/ud1UxNe+xmXSWqYpItFYSqIicnsdTLgilEjJpYgVdzeSugIFVJjAyrZELzll1dJq1b1Lqq1+8tK/SaPowgncArn4MEV1OEOGtAECo/wDK/w5sTOi/PufCxaC04+cwx/4Hz+AIzPjxw=
gal
50
B
onto subhalos using
AAAB/HicbVBNS8NAEN3Ur1q/oj16CRbBU0mqoMeiF48V7Ae0IWy2m3TpbhJ2J2II8a948aCIV3+IN/+N2zYHbX0w8Hhvhpl5fsKZAtv+Nipr6xubW9Xt2s7u3v6BeXjUU3EqCe2SmMdy4GNFOYtoFxhwOkgkxcLntO9Pb2Z+/4FKxeLoHrKEugKHEQsYwaAlz6yPFAsF9vIR0EfIQ8yLwjMbdtOew1olTkkaqETHM79G45ikgkZAOFZq6NgJuDmWwAinRW2UKppgMsUhHWoaYUGVm8+PL6xTrYytIJa6IrDm6u+JHAulMuHrToFhopa9mfifN0whuHJzFiUp0IgsFgUptyC2ZklYYyYpAZ5pgolk+laLTLDEBHReNR2Cs/zyKum1ms55s3V30Whfl3FU0TE6QWfIQZeojW5RB3URQRl6Rq/ozXgyXox342PRWjHKmTr6A+PzB8RalX4=
AAAB8nicbVDLSgMxFM3UV62vqks3wSK4KjNV0GWpG5cV7AOmQ8mkmTY0kwzJHaEM/Qw3LhRx69e482/MtLPQ1gOBwzn3knNPmAhuwHW/ndLG5tb2Tnm3srd/cHhUPT7pGpVqyjpUCaX7ITFMcMk6wEGwfqIZiUPBeuH0Lvd7T0wbruQjzBIWxGQsecQpASv5g5jAhBKRtebDas2tuwvgdeIVpIYKtIfVr8FI0TRmEqggxviem0CQEQ2cCjavDFLDEkKnZMx8SyWJmQmyReQ5vrDKCEdK2ycBL9TfGxmJjZnFoZ3MI5pVLxf/8/wUotsg4zJJgUm6/ChKBQaF8/vxiGtGQcwsIVRzmxXTCdGEgm2pYkvwVk9eJ91G3buqNx6ua81WUUcZnaFzdIk8dIOa6B61UQdRpNAzekVvDjgvzrvzsRwtOcXOKfoD5/MHcyGRXA==
0.75
N (< MV )
M50
galaxy—halo model.
10
fgal
AAAB+XicbVDLSsNAFL2pr1pfUZduBovgqiRV0WXRjRuhgn1AG8JkOm2HTiZhZlIoIX/ixoUibv0Td/6NkzYLbT0wcDjnXu6ZE8ScKe0431ZpbX1jc6u8XdnZ3ds/sA+P2ipKJKEtEvFIdgOsKGeCtjTTnHZjSXEYcNoJJne535lSqVgknvQspl6IR4INGcHaSL5t90OsxwTz9CHz0ysn8+2qU3PmQKvELUgVCjR9+6s/iEgSUqEJx0r1XCfWXoqlZoTTrNJPFI0xmeAR7RkqcEiVl86TZ+jMKAM0jKR5QqO5+nsjxaFSszAwk3lOtezl4n9eL9HDGy9lIk40FWRxaJhwpCOU14AGTFKi+cwQTCQzWREZY4mJNmVVTAnu8pdXSbtecy9q9cfLauO2qKMMJ3AK5+DCNTTgHprQAgJTeIZXeLNS68V6tz4WoyWr2DmGP7A+fwBvspOG
0.5
AAAB73icbVDLSgNBEOz1GeMr6tHLYBA8hd0o6DHoxYsQwTwgWcLsZDYZMo91ZlYIS37CiwdFvPo73vwbJ8keNLGgoajqprsrSjgz1ve/vZXVtfWNzcJWcXtnd2+/dHDYNCrVhDaI4kq3I2woZ5I2LLOcthNNsYg4bUWjm6nfeqLaMCUf7DihocADyWJGsHVSu2vYQODeXa9U9iv+DGiZBDkpQ456r/TV7SuSCiot4diYTuAnNsywtoxwOil2U0MTTEZ4QDuOSiyoCbPZvRN06pQ+ipV2JS2aqb8nMiyMGYvIdQpsh2bRm4r/eZ3UxldhxmSSWirJfFGccmQVmj6P+kxTYvnYEUw0c7ciMsQaE+siKroQgsWXl0mzWgnOK9X7i3LtOo+jAMdwAmcQwCXU4Bbq0AACHJ7hFd68R+/Fe/c+5q0rXj5zBH/gff4A8YOP5w==
M
Markov Chain Monte Carlo
0.25
1
0
0 -3 -6 -9 -12 -15 -18 7 7.5 8 8.5 9.0 9.5 10.0
MV [mag] log(Mpeak/M )
3. Apply observational
selection functions
based on imaging data.
Simulated LMC
4. Calculate likelihood of
DES PS1
5 5
Observed Observed
observed satellites
4 Predicted 4 Predicted
given galaxy—halo
3 3
dN/dMV
dN/dMV
2 2
connection parameters. 1 1
0 0
-12 -9 -6 -3 0 -12 -9 -6 -3 0
MV [mag] MV [mag]
EN & Wechsler et al. 2020
Transfer function
Fit the Milky Way satellite population with subhalo
mass function suppression, marginalizing over
galaxy–halo connection and MW halo properties:
Subhalo mass function
Satellite luminosity function
Current satellite observations are sensitive to ~25%
suppression in subhalo abundance relative to CDM
EN & Drlica-Wagner et al. 2020
Fuzzy Dark Matter Subhalo Mass Function interference due to macroscopic de Broglie wavelength → cutoff in abundance of low-mass halos
Fuzzy Dark Matter Subhalo Mass Function
Order of magnitude uncertainty in FDM SHMF!Fuzzy Dark Matter Constraints
• Fuzzy dark matter lighter than
10-21 eV is robustly ruled out by
MW satellite observations
• Strongly disfavors FDM models
that solve the core/cusp problem
• Sets a lower limit on ULA mass
for negligible self-interactions
EN & Drlica-Wagner et al. 2020Fuzzy Dark Matter Constraints
• Fuzzy dark matter lighter than
10-21 eV is robustly ruled out by
MW satellite observations
• Strongly disfavors FDM models
that solve the core/cusp problem
• Subhalo evolution with ULA-like
self-interactions is an important
area for simulation work!
EN & Drlica-Wagner et al. 2020Late-Forming Dark Matter Constraints
• Dark radiation that transitions to
CDM (“late-forming dark matter”)
suppresses power on small scales
• Cutoff in halo abundance is set by
the LFDM transition redshift
• From MW satellites, dark radiation
can transition to CDM no later
than 1 week after the Big Bang:
Das & EN 2020Combining Small-Scale Structure Probes
• Lyman-α forest, strong gravitational
lensing, and stellar streams yield Preliminary
similar dark matter constraints
• Joint models of small-scale probes
are key to break degeneracies and
robustly detect non-CDM physics
• In progress: combined constraints
using MW satellite abundances
and strong gravitational lensing
EN, S. Birrer, D. Gilman et al. in prep.Outlook
• The lack of a cutoff in the abundance of Milky Way satellites down to halo
masses of ~108 M☉ yields stringent constraints on dark matter physics
• These constraints will continue to improve with next-generation data
from the Vera C. Rubin Observatory (LSST) and simulation advances
• Fuzzy dark mater lighter than 10 eV
-21 is robustly ruled out despite SHMF
uncertainty (for ULAs, simulations with self-interactions are crucial)
• Joint modeling of small-scale structure probes is an important area for
future work, starting with satellites, stellar streams, and strong lensesThanks! Susmita Adhikari, Arka Banerjee, Keith Bechtol, Kimberly Boddy, Subinoy Das, Alex Drlica-Wagner, Vera Gluscevic, Greg Green, Yao-Yuan Mao, Sidney Mau, Mitch McNanna, Risa Wechsler
Galaxy–Halo Connection Model
Empirical modeling allows us to marginalize over theoretical uncertainties
EN, Y.-Y. Mao, G. Green, R. Wechsler 2019Dark Matter Constraints
cutoff in galaxy occupation
mass scale of suppression
due to dark matter physics
EN & Drlica-Wagner et al. 2020Warm Dark Matter Constraints
• Nearly all viable parameter space
for resonantly-produced sterile
neutrino dark matter is ruled out
• The sterile neutrino interpretation
of the 3.5 keV X-ray line is ruled
out at >> 99% confidence
• The dark matter free-streaming
length must be smaller than the
sizes of the halos that host ultra-
faint dwarf galaxies (~10 kpc)
EN & Drlica-Wagner et al. 2020Interacting Dark Matter Constraints
• Collisional damping due to DM–
baryon scattering at early times
suppresses power on small scales
• Mass of the smallest halo allowed
to form corresponds to the size of
the horizon when
Momentum Hubble rate
transfer rate
• Minimum observed halo mass
sets cross section limit
EN, V. Gluscevic, K. Boddy, R. Wechsler 2019Interacting Dark Matter Constraints
EN & Drlica-Wagner et al. 2020You can also read
