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

We used 87 high resolution hydrodynamical cosmological simulations from theNIHAO suite to investigate the relation between the maximum circular velocity(Vmax) of a dark matter halo in a collisionless simulation and the velocitywidth of the HI gas in the same halo in the hydrodynamical simulation. Thesetwo quantities are normally used to compare theoretical and observationalvelocity functions and have led to a possible discrepancy between observationsand predictions based on the Cold Dark Matter (CDM) model. We show that below100 km/s, there is clear bias between HI based velocities and Vmax, that leadsto an underestimation of the actual circular velocity of the halo. When thisbias is taken into account the CDM model has no trouble in reproducing theobserved velocity function and no lack of low velocity galaxies is actuallypresent. Our simulations also reproduce the linewidth - stellar mass(Tully-Fisher) relation and HI sizes, indicating that the HI gas in oursimulations is as extended as observed. The physical reason for the lower thanexpected linewidths is that, in contrast to high mass galaxies, low massgalaxies no longer have extended thin HI rotating disks, as is commonlyassumed.

NIHAO X: Reconciling the local galaxy velocity function with Cold Dark Matter via mock HI observations