Active galactic nucleus (AGN) driven outflows are believed to play an important role in regulating the growth of galaxies, mostly via negative feedback. However, their effects on their hosts are far ...from clear, especially for low- and moderate-luminosity Seyferts. To investigate this issue, we obtained cold molecular gas observations, traced by the CO(2-1) transition, using the NOEMA interferometer of five nearby (distances between 19 and 58 Mpc) Seyfert galaxies. The resolution of ∼0.3–0.8 (∼30–100 pc) and field of view of NOEMA allowed us to study the CO(2-1) morphology and kinematics in the nuclear regions (∼100 pc) and up to radial distances of ∼900 pc. We detected CO(2-1) emission in all five galaxies with disky or circumnuclear ring-like morphologies. We derived cold molecular gas masses on nuclear (∼100 pc) and circumnuclear (∼650 pc) scales in the range from 10
6
to 10
7
M
⊙
and from 10
7
to 10
8
M
⊙
, respectively. In all of our galaxies, the bulk of this gas is rotating in the plane of the galaxy. However, noncircular motions are also present. In NGC 4253, NGC 4388, and NGC 7465, we can ascribe the streaming motions to the presence of a large-scale bar. In Mrk 1066 and NGC 4388, the noncircular motions in the nuclear regions are explained as outflowing material due to the interaction of the AGN wind with molecular gas in the galaxy disk. We conclude that for an unambiguous and precise interpretation of the kinematics of the cold molecular gas, we need detailed knowledge of the host galaxy (i.e., presence of bars, interactions, etc.), and also of the ionized gas kinematics and ionization cone geometry.
ABSTRACT
We simulate the flux emitted from galaxy haloes in order to quantify the brightness of the circumgalactic medium (CGM). We use dedicated zoom-in cosmological simulations with the ...hydrodynamical adaptive mesh refinement code ramses, which are evolved down to z = 0 and reach a maximum spatial resolution of 380 h−1 pc and a gas mass resolution up to $1.8\times 10^{5} \, h^{-1}\, \rm {M}_{\odot }$ in the densest regions. We compute the expected emission from the gas in the CGM using cloudy emissivity models for different lines (e.g. Lyα, C iv, O vi, C vi, O viii) considering UV background fluorescence, gravitational cooling and continuum emission. In the case of Lyα, we additionally consider the scattering of continuum photons. We compare our predictions to current observations and find them to be in good agreement at any redshift after adjusting the Lyα escape fraction. We combine our mock observations with instrument models for Faint Intergalactic Redshifted Emission Balloon-2 (FIREBall-2; UV balloon spectrograph) and HARMONI (visible and NIR IFU on the ELT) to predict CGM observations with either instrument and optimize target selections and observing strategies. Our results show that Lyα emission from the CGM at a redshift of 0.7 will be observable with FIREBall-2 for bright galaxies (NUV∼18 mag), while metal lines like O vi and C iv will remain challenging to detect. HARMONI is found to be well suited to study the CGM at different redshifts with various tracers.
We analyse the star formation (SF) relations in a sample of 16 nearby luminous infrared galaxies (LIRGs) with more than 2800 regions defined on scales of 90 to 500 pc. We used ALMA to map the ...distribution of the cold molecular gas traced by the
J
= 2–1 line of CO and archival Pa
α
HST/NICMOS imaging to trace the recent SF. In four objects we find two different branches in the Kennicutt-Schmidt relation at 90 pc scales, suggesting the existence of a duality in this relation. The two branches correspond to two different dynamical environments within each galaxy. One branch, which corresponds to the central region of these galaxies (90% of the regions are located at radii < 0.85 kpc), shows higher gas and SF rate surface densities with higher velocity dispersion. The other branch, which shows lower molecular gas and SF rate surface densities, corresponds to the more external disk regions (
r
∼ 1 kpc). Despite the scatter, the SF efficiency of the galaxies with dual behaviour increases with increasing boundedness as measured by the
b
parameter (
b
≡ Σ
H2
/
σ
2
∝
α
vir
−1
). At larger spatial scales (250 and 500 pc), the duality disappears. The rest of the sample does not show evidence of this dual behaviour at any scale.
ABSTRACT
Compact Obscured Nuclei (CONs) potentially hide extreme supermassive black hole (SMBH) growth behind large column densities of gas/dust. We present a spectroscopic analysis of the heavily ...obscured nucleus and the surrounding environment of the eastern region of the nearby (z = 0.02007) interacting galaxy VV 114 with the JWST Mid-InfraRed Instrument (MIRI). We model the spectrum from 4.9 to 28 μm to extract polycyclic aromatic hydrocarbon (PAH) emission and the underlying obscured continuum. We find that the NE nucleus (A) is highly obscured where the low PAH equivalent width (EW) ratio, EW(12.7)/EW(11.3), reveals a dust enshrouded continuum source. This is confirmed by decomposing the continuum into nuclear and star-forming where the nuclear component is found to be typical of CONs. The 11.3/6.2 PAH flux ratio is consistent with originating in star-forming regions rather than typical AGN. The second nucleus (B) is much less obscured, with PAH flux ratios also typical of star-forming regions. We do not detect any high ionization lines such as Ne v or Ne vi which suggests that if an AGN is present it must be highly obscured. Additionally, we detect a shock front south of the secondary nucleus (B) in the Fe ii (5.34 μm) line and in warm molecular hydrogen. The 6.2 PAH emission does not spatially coincide with the low-J transitions of H2 but rather appears strong at the shock front which may suggest destruction of the ionized PAHs in the post-shock gas behind the shock front.
Context.
4C12.50 (IRAS 13451+1232) at
z
= 0.122 is an ultraluminous infared radio galaxy that has often been proposed as a prime candidate for the link between ultraluminous infared galaxies and ...young radio galaxies. It is also an interesting target to investigate whether and how radio-induced feedback affects the evolution of galaxies in the early phases of radio activity.
Aims.
We study, in detail for the first time, the hot (≥1500 K) molecular gas in 4C12.50. The potential impact of the radio jet on this gas phase, as well as on the star formation activity, are investigated. We also study the ionised (including coronal) gas as traced by the near-infrared lines.
Methods.
Using near-infrared long slit spectroscopy obtained with EMIR on GTC and X-shooter on VLT, we analyse the emission line spectrum of the ionised, coronal, and, specially, the hot molecular gas in the western nucleus hosting the compact radio jet. Based on high spatial resolution ALMA CO(2–1) data, we also revise the location of 4C12.50 in the Kennicutt-Schmidt diagram in order to investigate whether star formation is suppressed.
Results.
4C12.50 hosts (2.1 ± 0.4) × 10
4
M
⊙
of hot molecular gas. An unusually high rotational temperature
T
rot
= 3020 ± 160 K is inferred. The molecular gas mass obeys a power-law temperature distribution, d
M
H2
/d
T
∝
T
−5
, from
T
∼ 300 K and up to ∼3000 K. Both results support the idea that shocks (probably induced by the radio jet) contribute to the heating and excitation of the hot molecular gas. A molecular outflow is not detected. The coupling of the outflowing ionised and neutral outflows with the hot molecular gas is poor. Contrary to other studies, we claim that there is no evidence for star formation suppression in this object.
Conclusions.
If radio-induced feedback can regulate the star formation activity in galaxies, 4C12.50 is a promising candidate to reveal this phenomenon in action. However, we find no solid evidence for a current or past impact of this mechanism on the evolution of this system, neither by clearing out the dusty central cocoon efficiently, nor by suppressing the star formation activity.
Context. Galaxy evolution scenarios predict that the feedback of star formation and nuclear activity (AGN) can drive the transformation of gas-rich spiral mergers into (ultra) luminous infrared ...galaxies and, eventually, lead to the build-up of QSO/elliptical hosts. Aims. We study the role that star formation and AGN feedback have in launching and maintaining the molecular outflows in two starburst-dominated advanced mergers, NGC 1614 (DL = 66 Mpc) and IRAS 17208-0014 (DL = 181 Mpc), by analyzing the distribution and kinematics of their molecular gas reservoirs. Both galaxies present evidence of outflows in other phases of their ISM. Methods. We used the Plateau de Bure interferometer (PdBI) to image the CO(1–0) and CO(2–1) line emissions in NGC 1614 and IRAS 17208-0014, respectively, with high spatial resolution (0''̣5–1''̣2). The velocity fields of the gas were analyzed and modeled to find the evidence of molecular outflows in these sources and characterize the mass, momentum, and energy of these components. Results. While most (≥95%) of the CO emission stems from spatially resolved (~2−3 kpc-diameter) rotating disks, we also detect in both mergers the emission from high-velocity line wings that extend up to ±500–700 km s-1, well beyond the estimated virial range associated with rotation and turbulence. The kinematic major axis of the line-wing emission is tilted by ~90° in NGC 1614 and by ~180° in IRAS 17208-0014 relative to the major axes of their respective rotating disks. These results can be explained by the existence of non-coplanar molecular outflows in both systems: the outflow axis is nearly perpendicular to the rotating disk in NGC 1614, but it is tilted relative to the angular momentum axis of the rotating disk in IRAS 17208-0014. Conclusions. In stark contrast to NGC 1614, where star formation alone can drive its molecular outflow, the mass, energy, and momentum budget requirements of the molecular outflow in IRAS 17208-0014 can be best accounted for by the existence of a so far undetected (hidden) AGN of LAGN ~ 7 × 1011 L⊙. The geometry of the molecular outflow in IRAS 17208-0014 suggests that the outflow is launched by a non-coplanar disk that may be associated with a buried AGN in the western nucleus.
A prominent jet-driven outflow of CO(2–1) molecular gas is found along the kinematic minor axis of the Seyfert 2 galaxy ESO 420-G13, at a distance of 340–600 pc from the nucleus. The wind morphology ...resembles the characteristic funnel shape, formed by a highly collimated filamentary emission at the base, and likely traces the jet propagation through a tenuous medium, until a bifurcation point at 440 pc. Here the jet hits a dense molecular core and shatters, dispersing the molecular gas into several clumps and filaments within the expansion cone. We also trace the jet in ionised gas within the inner ≲340 pc using the Ne
II
12.8
μ
m
line emission, where the molecular gas follows a circular rotation pattern. The wind outflow carries a mass of ∼8 × 10
6
M
⊙
at an average wind projected speed of ∼160 km s
−1
, which implies a mass outflow rate of ∼14
M
⊙
yr
−1
. Based on the structure of the outflow and the budget of energy and momentum, we discard radiation pressure from the active nucleus, star formation, and supernovae as possible launching mechanisms. ESO 420-G13 is the second case after NGC 1377 where a previously unknown jet is revealed through its interaction with the interstellar medium, suggesting that unknown jets in feeble radio nuclei might be more common than expected. Two possible jet-cloud configurations are discussed to explain an outflow at this distance from the AGN. The outflowing gas will likely not escape, thus a delay in the star formation rather than quenching is expected from this interaction, while the feedback effect would be confined within the central few hundred parsecs of the galaxy.
Abstract
The abundance of metals in galaxies is a key parameter that permits to distinguish between different galaxy formation and evolution models. Most of the metallicity determinations are based ...on optical line ratios. However, the optical spectral range is subject to dust extinction and, for high-z objects (z > 3), some of the lines used in optical metallicity diagnostics are shifted to wavelengths not accessible to ground-based observatories. For this reason, we explore metallicity diagnostics using far-infrared (far-IR) line ratios which can provide a suitable alternative in such situations. To investigate these far-IR line ratios, we modelled the emission of a starburst with the photoionization code cloudy. The most sensitive far-IR ratios to measure metallicities are the O iii52 μm and 88 μm to N iii57 μm ratios. We show that this ratio produces robust metallicities in the presence of an active galactic nucleus and is insensitive to changes in the age of the ionizing stellar. Another metallicity-sensitive ratio is the O iii88 μm/N ii122 μm ratio, although it depends on the ionization parameter. We propose various mid- and far-IR line ratios to break this dependence. Finally, we apply these far-IR diagnostics to a sample of 19 local ultraluminous IR galaxies (ULIRGs) observed with Herschel and Spitzer. We find that the gas-phase metallicity in these local ULIRGs is in the range
$0.7<Z_{\rm gas}/$
Z⊙ < 1.5, which corresponds to
$8.5 <12 + \log ({\rm O / H}) < 8.9$
. The inferred metallicities agree well with previous estimates for local ULIRGs and this confirms that they lie below the local mass–metallicity relation.
We present new estimates of AGN accretion and star formation (SF) luminosity in galaxies obtained for the local 12 μm sample of Seyfert galaxies (12MGS), by performing a detailed broad-band spectral ...energy distribution (SED) decomposition including the emission of stars, dust heated by SF and a possible AGN dusty torus. Thanks to the availability of data from the X-rays to the sub-millimetre, we constrain and test the contribution of the stellar, AGN and SF components to the SEDs. The availability of Spitzer-InfraRed Spectrograph (IRS) low-resolution mid-infrared (mid-IR) spectra is crucial to constrain the dusty torus component at its peak wavelengths. The results of SED fitting are also tested against the available information in other bands: the reconstructed AGN bolometric luminosity is compared to those derived from X-rays and from the high excitation IR lines tracing AGN activity like Ne v and O iv. The IR luminosity due to SF and the intrinsic AGN bolometric luminosity are shown to be strongly related to the IR line luminosity. Variations of these relations with different AGN fractions are investigated, showing that the relation dispersions are mainly due to different AGN relative contribution within the galaxy. Extrapolating these local relations between line and SF or AGN luminosities to higher redshifts, by means of recent Herschel galaxy evolution results, we then obtain mid- and far-IR line luminosity functions useful to estimate how many star-forming galaxies and AGN we expect to detect in the different lines at different redshifts and luminosities with future IR facilities (e.g. JWST, SPICA).
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