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 Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Due to the peculiar properties of ultra-diffuse galaxies (UDGs),understanding their origin presents a major challenge. Previous X-ray studiesdemonstrated that the bulk of UDGs lack substantial X-ray emission, implyingthat they reside in low-mass dark matter halos. This result, in concert withother observational and theoretical studies, pointed out that most UDGs belongto the class of dwarf galaxies. However, a subset of UDGs is believed to host alarge population of globular clusters (GCs), which is indicative of massivedark matter halos. This, in turn, hints that some UDGs may be failed$L_{\star}$ galaxies. In this work, I present Chandra and XMM-Newtonobservations of two archetypal UDGs, Dragonfly 44 and DF X1, and I constraintheir dark matter halo mass based on the X-ray emission originating from hotgaseous emission and from the population of low-mass X-ray binaries residing inGCs. Both Dragonfly 44 and DF X1 remain undetected in X-rays. The upper limitson the X-ray emission exclude the possibility that these galaxies reside inmassive ($M_{\rm vir} \gtrsim 5\times10^{11} \ \rm{M_{\odot}}$) dark matterhalos, suggesting that they are not failed $L_{\star}$ galaxies. These resultsdemonstrate that even these iconic UDGs resemble to dwarf galaxies with $M_{\rmvir} \lesssim 10^{11} \ \rm{M_{\odot}}$, implying that UDGs represent a singlegalaxy population.

The Archetypal Ultra-Diffuse Galaxy, Dragonfly 44, is not a Dark Milky Way