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

Galactic dynamical structures are fossil records of the assembly histories ofgalaxies. By analyzing the cosmological hydrodynamical simulation TNG50, wefind that a dynamical structure that we call the "hot inner stellar halo,"defined by stars on dynamically hot orbits with circularity $\lambda_z < 0.5$at $3.5\,{\rm kpc}<r \lesssim 2\,R_e$, is a strong indicator of the mass ofaccreted satellite galaxies. We find a strong correlation between the mass ofthis hot inner stellar halo and the total ex situ stellar mass. There is asimilarly strong correlation with the stellar mass of the most massivesecondary galaxy ever merged. These TNG50 correlations are compatible withthose predicted by other simulations, for example by TNG100 across the wholemass range under study (galaxy stellar masses, $M_*$, in the$10^{10.3-11.6}$\,\Msun\, range) and by EAGLE for $M_* \gtrsim 10^{10.6}$\,\Msun\, galaxies.\ This shows that our predictions are robust acrossdifferent galaxy formation and feedback models and hold across a wide range ofnumerical resolution. The hot inner stellar halo is a product of massive andtypically ancient mergers, with inner-halo stars exhibiting three main physicalorigins: accreted and stripped from massive satellites, dynamically heated bymergers from the bulge and/or disk in the main progenitor, and formed from starformation triggered during mergers. The mass of the hot inner stellar halodefined in this paper is a quantity that can be robustly obtained for realgalaxies by applying a population-orbit superposition method tointegral-field-unit spectroscopy data, out to a distance of $\sim2\,R_e$, whichis possible with current observations. Hence, this paper shows thatintegral-field-unit observations and dynamical models of the inner regions ofgalaxies provide a way to quantitatively determine the mass of ancient accretedsatellites.

Mass of the dynamically hot inner stellar halo predicts the ancient accreted stellar mass