Bulletin of the American Physical Society
APS April Meeting 2022
Volume 67, Number 6
Saturday–Tuesday, April 9–12, 2022; New York
Session D14: Probing Dark Matter HalosRecordings Available
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Sponsoring Units: DAP Chair: Glennys Farrar, New York University (NYU) Room: Empire |
Saturday, April 9, 2022 1:30PM - 1:42PM |
D14.00001: Axionic Dark Matter Halos as Ground State Mean-Field Spherical Solutions Vladimir I Tsifrinovich, Gennady P Berman, Vyacheslav N Gorshkov We consider a dark matter halo (DMH) of a spherical galaxy as a Bose-Einstein condensate (BEC) of the ultra-light axions (ULA) with and without the interaction with the baryonic matter [1,2], and the two-component BEC [3]. In the mean-field (MF) limit, we derived the integro-differential equation of the Hartree-Fock type for the spherically symmetrical wave function of the DMH component. Typically, this equation includes two independent dimensionless parameters: (i) the ratio of baryon and axion total mases and (ii) the ratio of characteristic baryon and axion spatial parameters. For the two-component DMH, the number of parameters increases. We developed the “dissipation algorithm" for studying numerically the ground state of the axion halo. We estimated the characteristic mass of the axion in our model. |
Saturday, April 9, 2022 1:42PM - 1:54PM |
D14.00002: Gas-rich dwarf galaxies as powerful dark matter detectors Digvijay S Wadekar, Zihui Wang, Glennys R Farrar Gas-rich dwarf galaxies located outside the virial radius of their host are relatively pristine systems and have ultra-low gas cooling rates. This makes them very sensitive to heat injection by non-standard dark matter (DM). I will show that by requiring the gas heating rate by DM to not exceed the cooling rate of gas in the Leo T dwarf galaxy, one gets strong constraints on popular DM models like millicharged DM, axion like particles (ALPs) and primordial black holes (PBHs). For dark photon DM and for DM decay models, Leo T gives stronger constraints than all the previous literature. I will therefore show that observations of gas-rich dwarfs like Leo T from current and upcoming 21cm and optical surveys (e.g., Rubin observatory, Roman telescope) open a new way of probing DM. |
Saturday, April 9, 2022 1:54PM - 2:06PM |
D14.00003: Reconstructing the Subhalo Mass Function from Strong Gravitational Lensing Sebastian M Wagner-Carena, Risa Wechsler, Simon Birrer, Jelle Aalbers, Phil Marshall Constraining the distribution of small-scale structure in our universe will allow us to probe alternatives to the cold dark matter (CDM) paradigm. Strong gravitational lensing offers a unique window into small dark matter halos (109 Msun) because these halos impart a gravitational lensing signal even if they do not host luminous galaxies. However, the tens of thousands of free parameters in gravitational lensing by a substructure population makes directly evaluating the likelihood intractable. Simulation-based inference techniques can return posterior estimates without access to the likelihood, but they require a representative set of data simulations. To that end, we introduce the package paltas which builds on the lensing package lenstronomy to create large datasets of strong lensing images with realistic substructure, observational effects, and galaxy light pulled directly from the Hubble Space Telescope's COSMOS field. We use this simulation pipeline to train a neural posterior estimator of the subhalo mass function (SHMF) parameters and place constraints on populations of lenses generated using a disjoint set of galaxy sources. We find that by combining our networks with a hierarchical inference framework, we can both reliably infer the SHMF across a variety of configurations and scale efficiently to large lens populations. To our knowledge, our work is the first to constrain the SHMF on simulations with fully realistic sources and substructure, demonstrating the potential of strong-lens imaging to probe dark matter at small scales. |
Saturday, April 9, 2022 2:06PM - 2:18PM |
D14.00004: The Hidden Friend's Wake: Dark Matter and a Binary at the Galactic Center Samuel English, Benjamin Lehmann, Stefano Profumo Recent dynamical evidence suggests that Sgr A*, the massive object at the center of the Milky Way, may be a binary of two black holes rather than a single black hole. The existence of such a binary has dynamical consequences for the distribution of dark matter at the galactic center, with dramatic implications for dark matter annihilation signals. We show that the existence of a binary companion would significantly relax constraints on the dark matter annihilation cross-section from the galactic center, and would substantially weaken the case for dark matter annihilation as the origin of the claimed galactic center excess. |
Saturday, April 9, 2022 2:18PM - 2:30PM |
D14.00005: A gravitational-wave limit on the Chandrasekhar mass of dissipative dark matter: Constraining the abundance and mass spectrum of dark matter black holes using gravitational wave observations of binary black holes Divya Singh, Michael Ryan, RYAN MAGEE, Towsifa Akhter, Sarah E Shandera, Donghui Jeong, Chad R Hanna Dissipative dark matter models predict the formation of black holes through sufficient cooling and collapse of dark matter halos. In [1], Shandera et al. discuss the formation and expected mass distributions for such dark black holes(DBHs), and present expected event rates for dark black hole mergers that could be observed by Advanced LIGO and the Einstein Telescope for a range of dark black hole model parameters. Following the same dark atomic model and using LIGO and Virgo gravitational-wave observations of binary black-holes from GWTC-2 [2], we constrain the abundance and minimum mass of dark black holes in two cases - if GW190425 is a DBH binary or if none of the binary BHs from GWTC-2 are DBHs. Interpreting GW190425 as a dark matter black-hole binary limits the Chandrasekhar mass for dark matter to be below 1.4M⊙ at > 99.9% confidence implying that the dark proton is heavier than 0.95 GeV. Similarly, results from GWTC-3[4] and subsolar mass searches for compact objects in data from LIGO-Virgo’s third observing run[5] can further constrain the abundance of dissipative dark matter as a function of the minimum possible mass of DBHs, and provide an insight into the mass of the dark proton. |
Saturday, April 9, 2022 2:30PM - 2:42PM |
D14.00006: Astrometric weak lensing constraints on dark matter substructure with Gaia EDR3 Cristina Mondino, Anna-Maria Taki, Andreas Tsantilas, Ken Van Tilburg, Neal Weiner In this work, we present updated results on an ongoing dark matter search using astrometric weak gravitational lensing. Following the analysis in Mondino et al. (2020), results are reported on a dark matter search using proper motions on stars in the Magellanic Clouds from Gaia's most recent data release. Additionally, we assess our method on star-star lensing, and introduce a parallax template method to aid in the dark matter search. Finally, we provide preliminary sensitivity estimates for an acceleration-based search for compact dark matter structures. |
Saturday, April 9, 2022 2:42PM - 2:54PM |
D14.00007: Microlensing of extra-galactic sources by compact objects: modelling Víctor D Boscá Navarro, Pierre Fleury, Juan García-Bellido Needless to say that the nature of dark matter is one of the biggest questions of modern physics. The possibility that dark matter is (at least partially) made of compact objects is a very appealing idea. One way to probe compact objects, such as primordial black holes, beyond the Solar mass is via supernova lensing. In this project we model the probability density function of microlensing magnification P(A|f), given that a fraction f of dark matter is made of compact objects. We include many effects, such as the complex distribution of dark matter in haloes, the subtle effect of lens-lens coupling and the finite size of sources. |
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