63 research outputs found
Feeding and Feedback in the Inner Kiloparsec of the Active Galaxy NGC2110
We present two-dimensional gaseous kinematics of the inner 1.1 x 1.6kpc^2 of
the Seyfert 2 galaxy NGC2110, from optical spectra obtained with the GMOS
integral field spectrograph on the Gemini South telescope at a spatial
resolution of 100pc. Gas emission is observed over the whole field-of-view,
with complex - and frequently double - emission-line profiles. We have
identified four components in the emitting gas, according to their velocity
dispersion (sigma), which we refer to as: (1) warm gas disk (sigma =
100-220km/s); (2) cold gas disk (sigma = 60-90km/s); (3) nuclear component
(sigma = 220-600km/s); and (4) northern cloud (sigma = 60-80km/s). Both the
cold and warm disk components are dominated by rotation and have similar gas
densities, but the cold gas disk has lower velocity dispersions and reaches
higher rotation velocities. We attribute the warm gas disk to a thick gas layer
which encompasses the cold disk as observed in some edge-on spiral galaxies.
After subtraction of a rotation model from the cold disk velocity field, we
observe excess blueshifts of 50km/s in the far side of the galaxy as well as
similar excess redshifts in the near side. These residuals can be interpreted
as due to nuclear inflow in the cold gas, with an estimated ionized gas mass
inflow rate of 2.2 x 10^(-2)Msun/yr. We have also subtracted a rotating model
from the warm disk velocity field and found excess blueshifts of 100km/s to the
SW of the nucleus and excess redshifts of 40km/s to the NE, which we attribute
to gas disturbed by an interaction with a nuclear spherical outflow. This
nuclear outflow is the origin of the nuclear component observed within the
inner 300pc and it has a mass outflow rate of 0.9Msun/yr. In a region between
1" and 4" north of the nucleus we find a new low sigma component of ionized gas
which we attribute to a high latitude cloud photoionized by the nuclear source.Comment: 17 pages, 13 figures, 1 table; accepted for publication in MNRA
The Origin of Massive Compact Galaxies: Lessons from IllustrisTNG
We investigate the formation and evolution of z=0 massive compact galaxies
(MCGs) in the IllustrisTNG cosmological simulation. We found that, as in
observations, MCGs are mainly old (median age Gyr), have
super-solar metallicities (median ) and are
-enhanced (median ). The age distribution extends
to younger ages, however, and a few MCGs are as young as Gyr. In
general, MCGs assemble their mass early and accrete low angular momentum gas,
significantly increasing their mass while growing their size much slower. A
small fraction of MCGs follow another evolutionary path, going through a
compaction event, with their sizes shrinking by 40% or more. The accretion of
low angular momentum gas leads to enhanced SMBH growth, and MCGs reach the
threshold SMBH mass of - when kinetic
AGN feedback kicks in and quenches the galaxy - earlier than non-compact
galaxies. Comparing MCGs to a sample of median-sized quiescent galaxies matched
in effective velocity dispersion, we find that their accretion histories are
very different. 71% of MCGs do not merge after quenching compared to 37% of
median-sized quiescent galaxies. Moreover, tracing these populations back in
time, we find that at least a third of median-sized quiescent galaxies do not
have a compact progenitor, underscoring that both dry mergers and progenitor
bias effects are responsible for the differences in the kinematics and stellar
population properties of MCGs and median-sized quiescent galaxies.Comment: 15 pages, 15 figures (not including appendices). Accepted for
publication in the Monthly Notices of the Royal Astronomical Societ
Zooming into local active galactic nuclei: The power of combining SDSS-IV MaNGA with higher resolution integral field unit observations
Ionised gas outflows driven by active galactic nuclei (AGN) are ubiquitous in
high luminosity AGN with outflow speeds apparently correlated with the total
bolometric luminosity of the AGN. This empirical relation and theoretical work
suggest that in the range L_bol ~ 10^43-45 erg/s there must exist a threshold
luminosity above which the AGN becomes powerful enough to launch winds that
will be able to escape the galaxy potential. In this paper, we present pilot
observations of two AGN in this transitional range that were taken with the
Gemini North Multi-Object Spectrograph Integral Field Unit (IFU). Both sources
have also previously been observed within the Sloan Digital Sky Survey-IV
(SDSS) Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey.
While the MaNGA IFU maps probe the gas fields on galaxy-wide scales and show
that some regions are dominated by AGN ionization, the new Gemini IFU data zoom
into the centre with four times better spatial resolution. In the object with
the lower L_bol we find evidence of a young or stalled biconical AGN-driven
outflow where none was obvious at the MaNGA resolution. In the object with the
higher L_bol we trace the large-scale biconical outflow into the nuclear region
and connect the outflow from small to large scales. These observations suggest
that AGN luminosity and galaxy potential are crucial in shaping wind launching
and propagation in low-luminosity AGN. The transition from small and young
outflows to galaxy-wide feedback can only be understood by combining
large-scale IFU data that trace the galaxy velocity field with higher
resolution, small scale IFU maps.Comment: 14 pages, accepted for publication in MNRA
An outflow in the Seyfert ESO 362-G18 revealed by Gemini-GMOS/IFU observations
Indexación: Scopus.We present two-dimensional stellar and gaseous kinematics of the inner 0.7 × 1.2 kpc2 of the Seyfert 1.5 galaxy ESO 362-G18, derived from optical (4092-7338 Å) spectra obtained with the GMOS integral field spectrograph on the Gemini South telescope at a spatial resolution of ≈ 170 pc and spectral resolution of 36 km s-1. ESO 362-G18 is a strongly perturbed galaxy of morphological type Sa or S0/a, with a minor merger approaching along the NE direction. Previous studies have shown that the [O III] emission shows a fan-shaped extension of ≈ 10′′ to the SE. We detect the [O III] doublet, [N II] and Hα emission lines throughout our field of view. The stellar kinematics is dominated by circular motions in the galaxy plane, with a kinematic position angle of ≈ 137° and is centred approximately on the continuum peak. The gas kinematics is also dominated by rotation, with kinematic position angles ranging from 122° to 139°, projected velocity amplitudes of the order of 100 km s-1, and a mean velocity dispersion of 100 km s-1. A double-Gaussian fit to the [O III]λ5007 and Hα lines, which have the highest signal to noise ratios of the emission lines, reveal two kinematic components: (1) a component at lower radial velocities which we interpret as gas rotating in the galactic disk; and (2) a component with line of sight velocities 100-250 km s-1 higher than the systemic velocity, interpreted as originating in the outflowing gas within the AGN ionization cone. We estimate a mass outflow rate of 7.4 × 10-2 M⊙ yr-1 in the SE ionization cone (this rate doubles if we assume a biconical configuration), and a mass accretion rate on the supermassive black hole (SMBH) of 2.2 × 10-2 M⊙ yr-1. The total ionized gas mass within ∼84 pc of the nucleus is 3.3 × 105 M⊙; infall velocities of ∼34 km s-1 in this gas would be required to feed both the outflow and SMBH accretion. © ESO 2018.https://www.aanda.org/articles/aa/abs/2018/06/aa31671-17/aa31671-17.htm
Globular Cluster Systems of Relic Galaxies
We analyse the globular cluster (GC) systems of a sample of 15 massive,
compact early-type galaxies (ETGs), 13 of which have already been identified as
good relic galaxy candidates on the basis of their compact morphologies, old
stellar populations and stellar kinematics. These relic galaxy candidates are
likely the nearby counterparts of high redshift red nugget galaxies. Using
F814W (~I) and F160W (~H) data from the WFC3 camara onboard the Hubble Space
Telescope we determine the total number, luminosity function, specific
frequency, colour and spatial distribution of the GC systems. We find lower
specific frequencies (SN<2.5 with a median of SN=1) than ETGs of comparable
mass. This is consistent with a scenario of rapid, early dissipative formation,
with relatively low levels of accretion of low-mass, high-SN satellites. The GC
half-number radii are compact, but follow the relations found in normal ETGs.
We identify an anticorrelation between the specific angular momentum (lambda_R)
of the host galaxy and the (I-H) colour distribution width of their GC systems.
Assuming that lambda_R provides a measure of the degree of dissipation in
massive ETGs, we suggest that the (I-H) colour distribution width can be used
as a proxy for the degree of complexity of the accretion histories in these
systems.Comment: MNRAS accepte
Exploring the AGN-Merger Connection in Arp 245 I: Nuclear Star Formation and Gas Outflow in NGC 2992
Galaxy mergers are central to our understanding of galaxy formation,
especially within the context of hierarchical models. Besides having a large
impact on the star formation history, mergers are also able to influence gas
motions at the centre of galaxies and trigger an Active Galactic Nucleus (AGN).
In this paper, we present a case study of the Seyfert galaxy NGC 2992, which
together with NGC 2993 forms the early-stage merger system Arp 245. Using
Gemini Multi-Object Spectrograph (GMOS) integral field unit (IFU) data from the
inner 1.1 kpc of the galaxy we were able to spatially resolve the stellar
populations, the ionisation mechanism and kinematics of ionised gas. From full
spectral synthesis, we found that the stellar population is primarily composed
by old metal-rich stars (t 1.4 Gyr, \zsun), with a
contribution of at most 30 per cent of the light from a young and metal-poor
population (t 100 Myr, \zsun). We detect \halpha and \hbeta
emission from the Broad Line Region (BLR) with a Full Width at Half Maximum
(FWHM) of 2000\kms. The Narrow Line Region (NLR) kinematics presents two
main components: one from gas orbiting the galaxy disk and a blueshifted
(velocity -200\kms) outflow, possibly correlated with the radio
emission, with mass outflow rate of 2 M yr and a
kinematic power of 2 erg s (\Eout/\Lbol
0.2 per cent). We also show even though the main ionisation mechanism
is the AGN radiation, ionisation by young stars and shocks may also contribute
to the emission line ratios presented in the innermost region of the galaxy.Comment: 20 pages, 13 Figs, Accepted for publication to the MNRA
An outflow in the Seyfert ESO 362-G18 revealed by Gemini-GMOS/IFU Observations
We present two-dimensional stellar and gaseous kinematics of the inner 0.7
1.2 kpc of the Seyfert galaxy ESO 362-G18, derived from optical
spectra obtained with the GMOS/IFU on the Gemini South telescope at a spatial
resolution of 170 pc and spectral resolution of 36 km s. ESO
362-G18 is a strongly perturbed galaxy of morphological type Sa or S0/a, with a
minor merger approaching along the NE direction. Previous studies have shown
that the [OIII] emission shows a fan-shaped extension of 10\arcsec\
to the SE. We detect the [OIII] doublet, [NII] and H emission lines
throughout our field of view. The stellar kinematics is dominated by circular
motions in the galaxy plane, with a kinematic position angle of
137. The gas kinematics is also dominated by rotation, with
kinematic position angles ranging from 122 to 139. A
double-Gaussian fit to the [OIII]5007 and H lines, which
have the highest signal to noise ratios of the emission lines, reveal two
kinematic components: (1) a component at lower radial velocities which we
interpret as gas rotating in the galactic disk; and (2) a component with line
of sight velocities 100-250 km s higher than the systemic velocity,
interpreted as originating in the outflowing gas within the AGN ionization
cone. We estimate a mass outflow rate of 7.4 10 M
yr in the SE ionization cone (this rate doubles if we assume a biconical
configuration), and a mass accretion rate on the supermassive black hole (SMBH)
of 2.2 10 M yr. The total ionized gas mass
within 84 pc of the nucleus is 3.3 10 M; infall
velocities of 34 km s in this gas would be required to feed both
the outflow and SMBH accretion.Comment: 18 pages, 14 figure
Globular cluster systems of relic galaxies
We analyse the globular cluster (GC) systems of a sample of 15 massive, compact early-type galaxies (ETGs), 13 of which have already been identified as good relic galaxy candidates on the basis of their compact morphologies, old stellar populations and stellar kinematics. These relic galaxy candidates are likely the nearby counterparts of high-redshift red nugget galaxies. Using F814W (≈I) and F160W (≈H) data from the WFC3 camara onboard the Hubble Space Telescope, we determine the total number, luminosity function, specific frequency, colour, and spatial distribution of the GC systems (GCSs). We find lower specific frequencies (SN < 2.5 with a median of SN = 1) than ETGs of comparable mass. This is consistent with a scenario of rapid, early dissipative formation, with relatively low levels of accretion of low-mass, high-SN satellites. The GC half-number radii are compact, but follow the relations found in normal ETGs. We identify an anticorrelation between the specific angular momentum (λR) of the host galaxy and the (I − H) colour distribution width of their GCSs. Assuming that λR provides a measure of the degree of dissipation in massive ETGs, we suggest that the (I − H) colour distribution width can be used as a proxy for the degree of complexity of the accretion histories in these systems
The puzzling origin of massive compact galaxies in MaNGA
We characterized the kinematics, morphology, and stellar population (SP) properties of a sample of massive compact quiescent galaxies (MCGs, 10 log M /M 11 and re ∼ 1–3 kpc) in the MaNGA Survey, with the goal of constraining their formation, assembly history, and assessing their relation with non-compact quiescent galaxies. We compared their properties with those of a control sample of median-sized quiescent galaxies (re ∼ 4–8 kpc) with similar effective velocity dispersions. MCGs have elevated rotational support, as evidenced by a strong anticorrelation between the Gauss–Hermite moment h3 and V/σ. In contrast, 30 per cent of control sample galaxies (CSGs) are slow rotators, and fast-rotating CSGs generally show a weak h3–V/σ anticorrelation. MCGs and CSGs have similar ages, but MCGs are more metal-rich and α-enhanced. Both MCGs and CSGs have shallow negative metallicity gradients and flat [α/Fe] gradients. On average, MCGs and CSGs have flat age gradients, but CSGs have a significantly larger dispersion of gradient values. The kinematics and SP properties of MCGs suggest that they experienced highly dissipative gas-rich events, such as mergers, followed by an intense, short, and centrally concentrated burst of star formation, between 4 and 10 Gyr ago (z ∼ 0.4–2), and had a quiet accretion history since then. This sequence of events might be analogous to, although less extreme than, the compaction events that formed compact quiescent galaxies at z ∼ 2. The small sizes of MCGs, and the high efficiency and short duration of their last star formation episode suggest that they are descendants of compact post-starburst galaxies
Nuclear kinematics in nearby AGN. I. An ALMA perspective on the Morphology and Kinematics of the molecular CO(2-1) emission
We present the molecular gas morphology and kinematics of seven nearby
Seyfert galaxies obtained from our 230~GHz ALMA observations. The CO J=2-1
kinematics within the inner " (~kpc) reveals rotation
patterns that have been explored using the Bertola rotation model and a
modified version of the Kinemetry package. The latter algorithm reveals various
deviations from pure circular rotation in the inner kiloparsec of all seven
galaxies, including kinematic twists, decoupled and counter-rotating cores. A
comparison of the global molecular gas and stellar kinematics show overall
agreement in the position angle of the major axis and the systemic velocity,
but larger discrepancies in the disc inclination. The residual maps obtained
with both the methods shows the presence of non-circular motions in most of the
galaxies. Despite its importance, a detailed interpretation of the physics
responsible for non-circular motions will be discussed in a forthcoming work.Comment: 28 pages in total, 20 figures, 4 tables. Accepted for publication in
MNRA
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