J/A+A/701/A29 Photoionization models (Peluso+, 2025)
The interplay between active galactic nuclei and ram-pressure stripping:
spatially-resolved gas-phase abundances of stripped and undisturbed galaxies.
Peluso G., Vulcani B., Radovich M., Moretti A., Poggianti B.M., Watson P.,
Acharyya A., Lassen A.E., Gullieuszik M., Fritz J., Ignesti A., Tomicic N.,
Delvecchio I., Khoram A.H.
<Astron. Astrophys. 701, A29 (2025)>
=2025A&A...701A..29P 2025A&A...701A..29P (SIMBAD/NED BibCode)
ADC_Keywords: Models ; Active gal. nuclei ; Abundances
Keywords: galaxies: abundances : galaxies: active : galaxies: evolution
Abstract:
It has been reported that the gas-phase oxygen abundance of the
circumnuclear regions around supermassive black holes (SMBHs) could be
affected by the presence of an active galactic nucleus (AGN). However,
there is currently no agreement on the processes behind this effect.
Some studies have measured higher metallicities in the nuclear regions
of AGN hosts compared to those of star-forming (SF) galaxies, while
others have observed the opposite result.
In this work, we explore whether the interplay between AGN activity
and the Ram-Pressure Stripping (RPS) acting in the cluster environment
can alter the metallicity distributions of nearby (z<0.07) galaxies.
We measure the spatially resolved gas-phase oxygen abundances of 10
AGN hosts experiencing RPS from the GASP survey and 52 AGN hosts
located in the field and hence undisturbed by the RP drawn from the
MaNGA DR15. To measure the oxygen abundances in SF and AGN-ionized
regions, we present a set of strong emission line (SEL) calibrators
obtained through an indirect method in which the [OIII]/[SII] and
[NII]/[SII] line ratios, observed and predicted from Cloudy
photoionization models, were matched through the code NebulaBayes.
We find that the metallicity gradients of RPS and field AGN do not
present significant differences within the errors, but that 2 out of
the 10 RP-stripped AGNs show lower oxygen abundances at any given
radius than the rest of the AGN sample. Overall, this result
highlights that the interplay between AGN and RPS seems not to play a
major role in shaping the metallicity distributions of stripped
galaxies within 1.5 times the galaxy's effective radius (r<1.5Re),
but larger samples are needed to draw more robust conclusions. By
adding a control sample of SF galaxies, both experiencing RPS and in
the field, we find that the AGN hosts are more metal-enriched than SF
galaxies at any given radius, but that the steepness of the gradients
in the nuclear regions (r<0.5Re) is higher in AGN hosts than in SF
galaxies. Particularly, AGN hosts show a metal enrichment in the
nuclear regions ~=1.8-2.3 times higher than the enhancement in the
disk at r∼1.25Re, regardless of the host galaxy's stellar mass.
These results favor the hypothesis that the AGN activity is causing
metal pollution in the galaxy's nuclear regions.
Description:
These datasets contain photoionization models generated using the
CLOUDY v17.02 code (Ferland et al., 2017RMxAA..53..385F 2017RMxAA..53..385F).
Two primary types of ionizing sources are considered:
sfgrids.dat = the ionization comes from stellar radiation
agngrids.dat = the ionization comes from the radiation of an active
galactic nucleus (AGN)
A combination of these two is used to produce composite models
(AGN + SF) = compgrid.dat, mixing the AGN and SF models with the parameter
fAGN. The parameter "AGN fraction" (fAGN) is defined as the fraction
of Hβ flux arising from the AGN with respect to the total
(SF+AGN) Hβ flux.
Our main assumptions regarding these models include a gas density of
nH=100cm-3, a stellar age of t*=4Myr, and a simple power law to
model the AGN continuum with a slope α=-2.0 from infrared to
X-ray wavelengths. To calculate the metallicity in the Composite (AGN
+ SF) models, we combined the HII models, which have a fixed
ionization parameter log UHII=-3, with AGN models (for which
-4<logUNLR←1). This was achieved using the expression (1) of the
paper. Also, to generate the Composite models, we assume that HII
regions and NLR clouds within the same aperture have the same
metallicity (ZHII=ZAGN).
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
agngrids.dat 235 112 Photoionization models generated using the
CLOUDY v17.02 code, ionization comes from the
radiation of an active galactic nucleus (AGN)
sfgrids.dat 243 98 Photoionization models generated using the
CLOUDY v17.02 code, ionization comes from the
star forming galaxies (SF)
compgrid.dat 221 420 Photoionization models generated using the
CLOUDY v17.02 code, composite models (AGN + SF)
maps/* . 2 63 AGN and 412 SF maps
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Byte-by-byte Description of file: agngrids.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 F5.1 cm-3 nH [100] Gas density
7- 10 F4.1 --- alpha [-2.0] AGN continuum slope (1)
12- 16 F5.2 --- dg [-0.52] Dust-to-gas ratio (G2)
18- 21 F4.1 --- logU [-4.0/-0.5] Ionization parameter (G3)
23- 26 F4.1 --- logZ [-1.0/0.7] Gas-phase metallicity (G4)
28- 47 F20.18 --- OIIa Predicted emission line flux relative
to Hβ for [OII]λ3726
49- 68 F20.18 --- OIIb Predicted emission line flux relative
to Hβ for [OII]λ3729
70- 89 F20.18 --- OII Predicted emission line flux relative
to Hβ for [OII]λλ3726,29
91-108 F18.16 --- Ha Predicted emission line flux relative
to Hβ for Hαλ6563
110-130 F21.18 --- OIIIb Predicted emission line flux relative
to Hβ for [OIII]λ5007
132-152 F21.19 --- OI Predicted emission line flux relative
to Hβ for [OI] λ6300
154-173 F20.18 --- NIIb Predicted emission line flux relative
to Hβ for [NII] λ6584
175-194 F20.18 --- SIIa Predicted emission line flux relative
to Hβ for [SII] λ6716
196-215 F20.18 --- SIIb Predicted emission line flux relative
to Hβ for [SII] λ6731
217-235 F19.17 --- SII Predicted emission line flux relative
to Hβ for [SII] λλ6716,31
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Note (1): slope of the power law AGN continuum (command 'table power law'
in Cloudy) between 10um and 50keV.
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Byte-by-byte Description of file: sfgrids.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.1 yr Age [4000000] Stellar age
11- 15 F5.1 cm-3 nH [100] Gas density
17- 21 F5.2 --- dg [-0.52] Dust-to-gas ratio (G2)
23- 26 F4.1 --- logU [-4.0/-1.0] Ionization parameter (G3)
28- 31 F4.1 --- logZ [-2.0/0.5] Gas-phase metallicity (G4)
33- 52 F20.18 --- OIIa Predicted emission line flux relative
to Hβ for [OII]λ3726
54- 73 F20.18 --- OIIb Predicted emission line flux relative
to Hβ for [OII]λ3729
75- 94 F20.18 --- OII Predicted emission line flux relative
to Hβ for [OII]λλ3726,29
96-113 F18.16 --- Ha Predicted emission line flux relative
to Hβ for Hαλ6563
115-134 F20.18 --- OIIIb Predicted emission line flux relative
to Hβ for [OIII]λ5007
136-156 F21.19 --- OI Predicted emission line flux relative
to Hβ for [OI] λ6300
158-178 F21.19 --- NIIb Predicted emission line flux relative
to Hβ for [NII] λ6584
180-200 F21.19 --- SIIa Predicted emission line flux relative
to Hβ for [SII] λ6716
202-222 F21.19 --- SIIb Predicted emission line flux relative
to Hβ for [SII] λ6731
224-243 F20.18 --- SII Predicted emission line flux relative
to Hβ for [SII] λλ6716,31
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Byte-by-byte Description of file: compgrid.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 F3.1 --- fNLR [0.2/1.0] Fraction of Narrow Line Region (NLR)
5- 9 F5.1 cm-3 nH [100] Gas density
11- 15 F5.2 --- dg [-0.52] Dust-to-gas ratio (G2)
17- 20 F4.1 --- logU-HII [-3] HII Ionization parameter (G3)
22- 25 F4.1 --- logU-NLR [-4/-1] NLR Ionization parameter (G3)
27- 30 F4.1 --- logZ [-1.0/0.5] Gas-phase metallicity (G4)
32- 49 F18.16 --- OIIa Predicted emission line flux relative
to Hβ for [OII]λ3726
51- 68 F18.16 --- OIIb Predicted emission line flux relative
to Hβ for [OII]λ3729
70- 87 F18.16 --- OII Predicted emission line flux relative
to Hβ for [OII]λλ3726,29
89-106 F18.16 --- Ha Predicted emission line flux relative
to Hβ for Hαλ6563
108-126 F19.16 --- OIIIb Predicted emission line flux relative
to Hβ for [OIII]λ5007
128-145 F18.16 --- OI Predicted emission line flux relative
to Hβ for [OI] λ6300
147-164 F18.16 --- NIIb Predicted emission line flux relative
to Hβ for [NII] λ6584
166-183 F18.16 --- SIIa Predicted emission line flux relative
to Hβ for [SII] λ6716
185-202 F18.16 --- SIIb Predicted emission line flux relative
to Hβ for [SII] λ6731
204-221 F18.16 --- SII Predicted emission line flux relative
to Hβ for [SII] λλ6716,31
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Global notes:
Note (G2): fraction of gas-phase elements trapped in the dust grains
(see Dopita et al., 2000ApJ...542..224D 2000ApJ...542..224D).
Note (G3): In the Composite models, log U_NLR represents the ionization
parameter from the AGN model, while log U_HII is derived from the HII model
and is fixed at -3.
Note (G4): to convert logZ to log O/H, we assume a solar oxygen abundance
12 + log (O/H)☉ = 8.69.
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Acknowledgements:
Giorgia Peluso, giorgia.peluso(at)inaf.it
(End) Patricia Vannier [CDS] 02-Jul-2025