ABSTRACT We present spatially resolved kinematic measurements of stellar and ionized gas components of dwarf galaxies in the stellar mass range $10^{8.5}\!-\!10^{10} \, \mathrm{M}_{\odot }$, selected from Sloan Digital Sky Survey DR7 and DR8 and followed up with Keck/Low-Resolution Imaging Spectrometer spectroscopy. We study the potential effects of active galactic nuclei (AGNs) on Galaxy-wide gas kinematics by comparing rotation curves of 26 Galaxies containing AGNs, and 19 control Galaxies with no optical or infrared signs of AGNs. We find a strong association between AGN activity and disturbed gas kinematics in the host Galaxies. While star-forming Galaxies in this sample tend to have orderly gas discs that co-rotate with the stars, 73 per cent of the AGNs have disturbed gas. We find that 5 out of 45 Galaxies have gaseous components in counter-rotation with their stars, and all Galaxies exhibiting counter-rotation contain AGNs. Six out of seven isolated Galaxies with disturbed ionized gas host AGNs. At least three AGNs fall clearly below the stellar–halo mass relation, which could be interpreted as evidence for ongoing star formation suppression. Taken together, these results provide new evidence supporting the ability of AGN to influence gas kinematics and suppress star formation in dwarf galaxies. This further demonstrates the importance of including AGN as a feedback mechanism in galaxy formation models in the low-mass regime.
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The AGN contribution to the UV–FIR luminosities of interacting galaxies and its role in identifying the main sequence
ABSTRACT Emission from active galactic nuclei (AGNs) is known to play an important role in the evolution of many galaxies including luminous and ultraluminous systems (U/LIRGs), as well as merging systems. However, the extent, duration, and exact effects of its influence are still imperfectly understood. To assess the impact of AGNs on interacting systems, we present a spectral energy distribution (SED) analysis of a sample of 189 nearby galaxies. We gather and systematically re-reduce archival broad-band imaging mosaics from the ultraviolet to the far-infrared using data from GALEX, SDSS, 2MASS, IRAS, WISE, Spitzer, and Herschel. We use spectroscopy from Spitzer/IRS to obtain fluxes from fine-structure lines that trace star formation and AGN activity. Utilizing the SED modelling and fitting tool cigale, we derive the physical conditions of the interstellar medium, both in star-forming regions and in nuclear regions dominated by the AGN in these galaxies. We investigate how the star formation rates (SFRs) and the fractional AGN contributions (fAGN) depend on stellar mass, galaxy type, and merger stage. We find that luminous galaxies more massive than about $10^{10} \,\rm {M}_{*}$ are likely to deviate significantly from the conventional galaxy main-sequence relation. Interestingly, infrared AGN luminosity and stellar mass in this set of objects are much tighter than SFR and stellar mass. We find that buried AGNs may occupy a locus between bright starbursts and pure AGNs in the fAGN–[Ne v]/[Ne ii] plane. We identify a modest correlation between fAGN and mergers in their later stages.
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- Award ID(s):
- 1659473
- NSF-PAR ID:
- 10250314
- Date Published:
- Journal Name:
- Monthly Notices of the Royal Astronomical Society
- Volume:
- 499
- Issue:
- 3
- ISSN:
- 0035-8711
- Page Range / eLocation ID:
- 4325 to 4369
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1093/mnras/staa2813
