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AGN Feedback and the Development of Dusty Multiphase Gas in X-ray Emitting Elliptical Galaxies

Pasquale Temi, Francesco Ubertosi, Fabrizio Brighenti, Alexandros Maragkoudakis, Valeria Olivares, Alexandre Amblard, Massimo Gaspari, Myriam Gitti, Pamela M. Marcum, Kevin Fogarty, Alejandro S. Borlaff, William G. Mathews

Abstract

This paper investigates the physical and kinematic properties of dust-rich regions in a small sample of group-centered elliptical galaxies, emphasizing their connection with the hot X-ray emitting gas and detailed dust grain characteristics. Comprehensive multi-wavelength data, including H-alpha and CO emission detected by MUSE and ALMA, demonstrate the presence of dust clouds embedded within complex, hot X-ray atmospheres shaped by AGN feedback. X-ray images show bubbles and cavities surrounded by bright rims. We find that dust regions containing molecular gas traced by CO are preferentially located at the rims of these X-ray cavities, suggesting that AGN-driven outflows enhance the condensation of cold, dusty gas at these compressive interfaces. Kinematic measurements indicate that molecular and ionized gas phases are dynamically and spatially linked, supporting the framework of a multiphase medium arising from the top-down condensation rain in the hot plasma and related chaotic cold accretion. Crucially, spatial variations in the total-to-selective extinction ratio Rv show that regions where dust, CO, and H-alpha emission coincide exhibit notably smaller Rv values, implying steeper extinction curves and the predominance of smaller or less evolved dust grains within these mixed-phase environments. This contrasts with larger Rv values found elsewhere in the dust clouds, suggesting grain growth or survival mechanisms within shielded cold gas.

AGN Feedback and the Development of Dusty Multiphase Gas in X-ray Emitting Elliptical Galaxies

Abstract

This paper investigates the physical and kinematic properties of dust-rich regions in a small sample of group-centered elliptical galaxies, emphasizing their connection with the hot X-ray emitting gas and detailed dust grain characteristics. Comprehensive multi-wavelength data, including H-alpha and CO emission detected by MUSE and ALMA, demonstrate the presence of dust clouds embedded within complex, hot X-ray atmospheres shaped by AGN feedback. X-ray images show bubbles and cavities surrounded by bright rims. We find that dust regions containing molecular gas traced by CO are preferentially located at the rims of these X-ray cavities, suggesting that AGN-driven outflows enhance the condensation of cold, dusty gas at these compressive interfaces. Kinematic measurements indicate that molecular and ionized gas phases are dynamically and spatially linked, supporting the framework of a multiphase medium arising from the top-down condensation rain in the hot plasma and related chaotic cold accretion. Crucially, spatial variations in the total-to-selective extinction ratio Rv show that regions where dust, CO, and H-alpha emission coincide exhibit notably smaller Rv values, implying steeper extinction curves and the predominance of smaller or less evolved dust grains within these mixed-phase environments. This contrasts with larger Rv values found elsewhere in the dust clouds, suggesting grain growth or survival mechanisms within shielded cold gas.
Paper Structure (14 sections, 4 figures, 2 tables)

This paper contains 14 sections, 4 figures, 2 tables.

Table of Contents

  1. Introduction
  2. The galaxy sample
  3. Observations
  4. HST Data
  5. MUSE Data
  6. ALMA Data
  7. Chandra Data
  8. Results
  9. Dust Absorption Maps
  10. H$\alpha$ maps
  11. X-Ray maps
  12. ALMA maps
  13. Analysis
  14. Dust Extinction Properties

Figures (4)

  • Figure 1: HST images of the central few kpc of our sample galaxies. The optical dust maps were generated from archival HST data recorded with the Wide Field Planetary Camera 2 (WFPC2) using the broadband filters. Dust absorption features are evident as bright filamentary structures in the maps with increasing dust following the blue $\rightarrow$ green $\rightarrow$ yellow $\rightarrow$ red color scheme. ALMA detection of CO clouds are indicated with white contours (black contours in the inset of NGC 4636 and NGC 5846) defined as the area where the emission line signal-to-noise is greater than 4.
  • Figure 2: MUSE H$\alpha$ maps of NGC 4636, NGC 5044, NGC 5813, and NGC 5846.
  • Figure 3: Chandra X-ray maps in the 0.5 - 7 keV band of NGC 4636, NGC 5044, NGC 5813, and NGC 5846.
  • Figure 4: Left panels show the regions of strongest dust absorption where we measure the extinction; colors and numerical labels mark individual regions in each galaxy. The right panels display the corresponding A$_V$ and A$_I$ values, using the same colors for each region, together with their total uncertainties.