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 present new ALMA CO(2--1) observations of two well studied group-centeredelliptical galaxies: NGC~4636 and NGC~5846. In addition, we include a revisedanalysis of Cycle 0 ALMA observations of the central galaxy in the NGC~5044group that has been previously published. We find evidence that molecular gas,in the form of off-center orbiting clouds, is a common presence in brightgroup-centered galaxies (BGG). CO line widths are $\gtrsim 10$ times broaderthan Galactic molecular clouds, and using the reference Milky Way $X_{CO}$, thetotal molecular mass ranges from as low as $2.6\times 10^5 M_\odot$ in NGC~4636to $6.1\times 10^7 M_\odot$ in NGC~5044. With these parameters the virialparameters of the molecular structures is $\gg 1$. Complementary observationsof NGC~5846 and NGC~4636 using the ALMA Compact Array (ACA) do not exhibit anydetection of a CO diffuse component at the sensitivity level achieved bycurrent exposures. The origin of the detected molecular features is stilluncertain, but these ALMA observations suggest that they are the end product ofthe hot gas cooling process and not the result of merger events. Some of themolecular clouds are associated with dust features as revealed by HST dustextinction maps suggesting that these clouds formed from dust-enhanced cooling.The global nonlinear condensation may be triggered via the chaotic turbulentfield or buoyant uplift. The large virial parameter of the molecular structuresand correlation with the warm ($10^3 - 10^5 K$)/hot ($\ge10^6$) phase velocitydispersion provide evidence that they are unbound giant molecular associationsdrifting in the turbulent field, consistently with numerical predictions of thechaotic cold accretion process. Alternatively, the observed large CO linewidths may be generated by molecular gas flowing out from cloud surfaces due toheating by the local hot gas atmosphere.

ALMA observations of molecular clouds in three group centered elliptical galaxies: NGC 5846, NGC 4636, and NGC 5044