English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The expected gamma-ray flux coming from dark matter annihilation in dwarfspheroidal (dSph) galaxies depends on the so-called `J-factor', the integral ofthe squared dark matter density along the line-of-sight. We examine the degreeto which estimates of J are sensitive to contamination (by foreground Milky Waystars and stellar streams) of the stellar-kinematic samples that are used toinfer dark matter densities in `ultrafaint' dSphs. Applying standard kinematicanalyses to hundreds of mock data sets that include varying levels ofcontamination, we find that mis-classified contaminants can cause J-factors tobe overestimated by orders of magnitude. Stellar-kinematic data sets for whichwe obtain such biased estimates tend 1) to include relatively large fractionsof stars with ambiguous membership status, and 2) to give estimates for J thatare sensitive to specific choices about how to weight and/or to exclude starswith ambiguous status. Comparing publicly-available stellar-kinematic samplesfor the nearby dSphs Reticulum~II and Segue~I, we find that only the latterdisplays both of these characteristics. Estimates of Segue~I's J-factor shouldtherefore be regarded with a larger degree of caution when planning andinterpreting gamma-ray observations. Moreover, robust interpretations regardingdark matter annihilation in dSph galaxies in general will require explicitexamination of how interlopers might affect the inferred dark matter densityprofile.

monthly notices of the royal astronomical society

Contamination of stellar-kinematic samples and uncertainty about dark  matter annihilation profiles in ultrafaint dwarf galaxies: the example of  Segue I