63 research outputs found
Spatially resolved analysis of neutralwWinds, stars, and ionized gas kinematics with MEGARA/GTC: new insights on the nearby galaxy UGC 10205
We present a comprehensive analysis of the multiphase structure of the interstellar medium (ISM) and the stellar kinematics in the edge-on nearby galaxy UGC 10205 using integral field spectroscopy (IFS) data taken with MultiEspectrógrafo en GTC de Alta Resolución para Astronomía (MEGARA) at the GTC. We explore both the neutral and the ionized gas phases using the interstellar Na I D doublet absorption (LR−V setup, R ∼ 6000) and the Hα emission line (HR−R setup, R ∼ 18000), respectively. The high-resolution data show the complexity of the Hα emission-line profile revealing the detection of up to three kinematically distinct gaseous components. Despite of this fact, a thin-disk model is able to reproduce the bulk of the ionized gas motions in the central regions of UGC 10205. The use of asymmetric drift corrections is needed to reconciliate the ionized and the stellar velocity rotation curves. We also report the detection of outflowing neutral gas material blueshifted by ∼ 87 km s^(−1) . The main physical properties that describe the observed outflow are a total mass M_(out) = (4.55 ± 0.06) × 10^(7) Mʘ and a coldgas mass outflow rate M_(out) = 0.78 0.03 Mʘ yr^(−1) . This work points out the necessity of exploiting highresolution IFS data to understand the multiphase components of the ISM and the multiple kinematical components in the central regions of nearby galaxies
Fossil Groups Origins III. Characterization of the sample and observational properties of fossil systems
(Abridged) Fossil systems are group- or cluster-sized objects whose
luminosity is dominated by a very massive central galaxy. In the current cold
dark matter scenario, these objects formed hierarchically at an early epoch of
the Universe and then slowly evolved until present day. That is the reason why
they are called {\it fossils}. We started an extensive observational program to
characterize a sample of 34 fossil group candidates spanning a broad range of
physical properties. Deep band images were taken for each candidate and
optical spectroscopic observations were obtained for 1200 galaxies. This
new dataset was completed with SDSS DR7 archival data to obtain robust cluster
membership and global properties of each fossil group candidate. For each
system, we recomputed the magnitude gaps between the two brightest galaxies
() and the first and fourth ranked galaxies ()
within 0.5 . We consider fossil systems those with mag or mag within the errors. We find
that 15 candidates turned out to be fossil systems. Their observational
properties agree with those of non-fossil systems. Both follow the same
correlations, but fossils are always extreme cases. In particular, they host
the brightest central galaxies and the fraction of total galaxy light enclosed
in the central galaxy is larger in fossil than in non-fossil systems. Finally,
we confirm the existence of genuine fossil clusters. Combining our results with
others in the literature, we favor the merging scenario in which fossil systems
formed due to mergers of galaxies. The large magnitude gap is a
consequence of the extreme merger ratio within fossil systems and therefore it
is an evolutionary effect. Moreover, we suggest that at least one candidate in
our sample could represent a transitional fossil stage.Comment: 14 pages, 11 figures, accepted for publication in A&
The space density distribution of galaxies in the absolute magnitude - rotation velocity plane: a volume-complete Tully-Fisher relation from CALIFA stellar kinematics
The space density distribution of galaxies in the absolute magnitude -
rotation velocity plane: a volume-complete Tully-Fisher relation from CALIFA
stellar kinematicsComment: Accepted to A&
Physics of ULIRGs with MUSE and ALMA: The PUMA project: I. Properties of the survey and first MUSE data results
Ultraluminous infrared galaxies (ULIRGs) are characterised by extreme
starburst (SB) and AGN activity, and are therefore ideal laboratories for
studying the outflow phenomena. We have recently started a project called
Physics of ULIRGs with MUSE and ALMA (PUMA), which is a survey of 25 nearby (z
< 0.165) ULIRGs observed with the integral field spectrograph MUSE and the
interferometer ALMA. This sample includes systems with both AGN and SB nuclear
activity in the pre- and post-coalescence phases of major mergers. The main
goals of the project are to study the prevalence of multi-phase outflows as a
function of the galaxy properties, to constrain the driving mechanisms of the
outflows (e.g. distinguish between SB and AGN winds), and to identify feedback
effects on the host galaxy. In this first paper, we present details on the
sample selection, MUSE observations, and derive first data products. MUSE data
were analysed to study the dynamical status of each of the 21 ULIRGs observed
so far, taking the stellar kinematics and the morphological properties inferred
from MUSE narrow-band images into account. We also located the ULIRG nuclei,
using near-IR (HST) and mm (ALMA) data, and studied their optical spectra to
infer the ionisation state through BPT diagnostics, and outflows in both
ionised and neutral gas. We show that the morphological and stellar kinematic
classifications are consistent: post-coalescence systems are more likely
associated with ordered motions, while interacting (binary) systems are
dominated by non-ordered and streaming motions. We also find broad and
asymmetric [OIII] and NaID profiles in almost all nuclear spectra, with line
widths in the range 300-2000 km/s, possibly associated with AGN- and SB-driven
winds. This result reinforces previous findings that indicated that outflows
are ubiquitous during the pre- and post-coalescence phases of major mergers.ERC
STF
MUSE view of Arp220: Kpc-scale multi-phase outflow and evidence for positive feedback
Arp220 is the nearest and prototypical ULIRG, and shows evidence of pc-scale
molecular outflows in its nuclear regions and strongly perturbed ionised gas
kinematics on kpc scales. It is therefore the ideal system for investigating
outflows and feedback phenomena in details. We investigate the feedback effects
on the Arp220 ISM, deriving a detailed picture of the atomic gas in terms of
physical and kinematic properties, with a spatial resolution never obtained
before (0.56", i.e. ~ 210 pc). We use optical IFS observations from VLT/MUSE-AO
to obtain spatially resolved stellar and gas kinematics, for both ionised ([N
II]6583) and neutral (Na ID5891,96) components; we also derive dust
attenuation, electron density, ionisation conditions and hydrogen column
density maps to characterise the ISM properties. Arp220 kinematics reveal the
presence of a disturbed, kpc-scale disk in the innermost nuclear regions, and
highly perturbed, multi-phase (neutral and ionised) gas along the minor-axis of
the disk, which we interpret as a galactic-scale outflow emerging from the
Arp220 eastern nucleus. This outflow involves velocities up to ~ 1000 km/s at
galactocentric distances of ~ 5 kpc, and has a mass rate of ~ 50 Msun/yr, and
kinetic and momentum power of ~ 1e43 erg/s and ~ 1e35 dyne, respectively. The
inferred energetics do not allow us to distinguish the origin of the outflows,
i.e. whether they are AGN-driven or starburst-driven. We also present evidence
for enhanced star formation at the edges of - and within - the outflow, with a
star formation rate SFR ~ 5 Msun/yr (i.e. ~ 2% of the total SFR). Our findings
suggest the presence of powerful winds in Arp220: they might be capable of
removing or heating large amounts of gas from the host ("negative feedback"),
but could be also responsible for triggering star formation ("positive
feedback").STFC
ER
Observational hints of radial migration in disc galaxies from CALIFA
Context. According to numerical simulations, stars are not always kept at their birth galactocentric distances but they have a tendency to migrate. The importance of this radial migration in shaping galactic light distributions is still unclear. However, if radial migration is indeed important, galaxies with different surface brightness (SB) profiles must display differences in their stellar population properties.
Aims: We investigate the role of radial migration in the light distribution and radial stellar content by comparing the inner colour, age, and metallicity gradients for galaxies with different SB profiles. We define these inner parts, avoiding the bulge and bar regions and up to around three disc scale lengths (type I, pure exponential) or the break radius (type II, downbending; type III, upbending).
Methods: We analysed 214 spiral galaxies from the CALIFA survey covering different SB profiles. We made use of GASP2D and SDSS data to characterise the light distribution and obtain colour profiles of these spiral galaxies. The stellar age and metallicity profiles were computed using a methodology based on full-spectrum fitting techniques (pPXF, GANDALF, and STECKMAP) to the Integral Field Spectroscopic CALIFA data.
Results: The distributions of the colour, stellar age, and stellar metallicity gradients in the inner parts for galaxies displaying different SB profiles are unalike as suggested by Kolmogorov-Smirnov and Anderson-Darling tests. We find a trend in which type II galaxies show the steepest profiles of all, type III show the shallowest, and type I display an intermediate behaviour.
Conclusions: These results are consistent with a scenario in which radial migration is more efficient for type III galaxies than for type I systems, where type II galaxies present the lowest radial migration efficiency. In such a scenario, radial migration mixes the stellar content, thereby flattening the radial stellar properties and shaping different SB profiles. However, in light of these results we cannot further quantify the importance of radial migration in shaping spiral galaxies, and other processes, such as recent star formation or satellite accretion, might play a role
Physics of ULIRGs with MUSE and ALMA: The PUMA project: III. Incidence and properties of ionised gas disks in ULIRGs, associated velocity dispersion, and its dependence on starburstiness
CONTEXT:
A classical scenario suggests that ultra-luminous infrared galaxies (ULIRGs) transform colliding spiral galaxies into a spheroid-dominated early-type galaxy. Recent high-resolution simulations have instead shown that, under some circumstances, rotation disks can be preserved during the merging process or rapidly regrown after coalescence. Our goal is to analyse in detail the ionised gas kinematics in a sample of ULIRGs to infer the incidence of gas rotational dynamics in late-stage interacting galaxies and merger remnants.
AIMS:
We analysed integral field spectrograph MUSE data of a sample of 20 nearby (z < 0.165) ULIRGs (with 29 individual nuclei) as part of the Physics of ULIRGs with MUSE and ALMA (PUMA) project. We used multi-Gaussian fitting techniques to identify gaseous disk motions and the 3D-Barolo tool to model them.
METHODS:
We found that 27% (8 out of 29) individual nuclei are associated with kiloparsec-scale disk-like gas motions. The rest of the sample displays a plethora of gas kinematics, dominated by winds and merger-induced flows, which makes the detection of rotation signatures difficult. On the other hand, the incidence of stellar disk-like motions is ∼2 times larger than gaseous disks, as the former are probably less affected by winds and streams. The eight galaxies with a gaseous disk present relatively high intrinsic gas velocity dispersion (σ0 ∈ [30 − 85] km s−1), rotationally supported motions (with gas rotation velocity over velocity dispersion vrot/σ0 ∼ 1 − 8), and dynamical masses in the range (2 − 7)×1010 M⊙. By combining our results with those of local and high-z disk galaxies (up to z ∼ 2) from the literature, we found a significant correlation between σ0 and the offset from the main sequence (δMS), after correcting for their evolutionary trends.
RESULTS:
Our results confirm the presence of kiloparsec-scale rotating disks in interacting galaxies and merger remnants in the PUMA sample, with an incidence going from 27% (gas) to ≲50% (stars). Their gas σ0 is up to a factor of ∼4 higher than in local normal main sequence galaxies, similar to high-z starbursts as presented in the literature; this suggests that interactions and mergers enhance the star formation rate while simultaneously increasing the velocity dispersion in the interstellar medium
The PUMA project. III. Incidence and properties of ionised gas disks in ULIRGs, associated velocity dispersion and its dependence on starburstiness
A classical scenario suggests that ULIRGs transform colliding spiral galaxies
into a spheroid dominated early-type galaxy. Recent high-resolution simulations
have instead shown that, under some circumstances, rotation disks can be
preserved during the merging process or rapidly regrown after coalescence. Our
goal is to analyze in detail the ionised gas kinematics in a sample of ULIRGs
to infer the incidence of gas rotational dynamics in late-stage interacting
galaxies and merger remnants. We analysed MUSE data of a sample of 20 nearby
(z<0.165) ULIRGs, as part of the "Physics of ULIRGs with MUSE and ALMA" (PUMA)
project. We found that 27% individual nuclei are associated with kpc-scale
disk-like gas motions. The rest of the sample displays a plethora of gas
kinematics, dominated by winds and merger-induced flows, which make the
detection of rotation signatures difficult. On the other hand, the incidence of
stellar disk-like motions is ~2 times larger than gaseous disks, as the former
are probably less affected by winds and streams. The eight galaxies with a
gaseous disk present relatively high intrinsic gas velocity dispersion (sigma =
30-85 km/s), rotationally-supported motions (with gas rotation velocity over
velocity dispersion vrot/sigma > 1-8), and dynamical masses in the range
(2-7)x1e10 Msun. By combining our results with those of local and high-z disk
galaxies from the literature, we found a significant correlation between sigma
and the offset from the main sequence (MS), after correcting for their
evolutionary trends. Our results confirm the presence of kpc-scale rotating
disks in interacting galaxies and merger remnants, with an incidence going from
27% (gas) to ~50% (stars). The ULIRGs gas velocity dispersion is up to a factor
of ~4 higher than in local normal MS galaxies, similar to high-z starbursts as
presented in the literature
Spiral-like star-forming patterns in CALIFA early-type galaxies
Based on a combined analysis of SDSS imaging and CALIFA integral field
spectroscopy data, we report on the detection of faint (24 < {\mu}
mag/arcsec < 26) star-forming spiral-arm-like features in the periphery of
three nearby early-type galaxies (ETGs). These features are of considerable
interest because they document the still ongoing inside-out growth of some
local ETGs and may add valuable observational insight into the origin and
evolution of spiral structure in triaxial stellar systems. A characteristic
property of the nebular component in the studied ETGs, classified i+, is a
two-radial-zone structure, with the inner zone that displays faint
(EW(H\alpha)1{\AA}) low-ionization nuclear emission-line region (LINER)
properties, and the outer one (3{\AA}<EW(H\alpha)<~20{\AA}) HII-region
characteristics. This spatial segregation of nebular emission in two physically
distinct concentric zones calls for an examination of aperture effects in
studies of type i+ ETGs with single-fiber spectroscopic data.Comment: Accepted to A&A, 5 pages, 1 figur
Spectroscopic aperture biases in inside-out evolving early-type galaxies from CALIFA
Integral field spectroscopy studies based on CALIFA data have recently
revealed the presence of ongoing low-level star formation (SF) in the periphery
of ~10% of local early-type galaxies (ETGs), witnessing a still ongoing
inside-out galaxy growth process. A distinctive property of the nebular
component in these ETGs, classified i+, is a two-radial-zone structure, with
the inner zone displaying LINER emission with a H\alpha equivalent width
EW~1{\AA}, and the outer one (3{\AA}<EW<~20{\AA}) showing HII-region
characteristics. Using CALIFA IFS data, we empirically demonstrate that the
confinement of nebular emission to the galaxy periphery leads to a strong
aperture (or, redshift) bias in spectroscopic single-fiber studies of type i+
ETGs: At low redshift (<~0.45), SDSS spectroscopy is restricted to the inner
(SF-devoid LINER) zone, thereby leading to their erroneous classification as
"retired" galaxies (systems lacking SF and whose faint emission is powered by
pAGB stars). Only at higher z's the SDSS aperture can encompass the outer SF
zone, permitting their unbiased classification as "composite SF/LINER". We also
demonstrate that the principal effect of a decreasing aperture on the
classification of i+ ETGs via standard BPT emission-line ratios consists in a
monotonic up-right shift precisely along the upper-right wing of the "seagull"
distribution. Motivated by these insights, we also investigate theoretically
these biases in aperture-limited studies of inside-out growing galaxies as a
function of z. To this end, we devise a simple model, which involves an
outwardly propagating SF process, that reproduces the radial extent and
two-zone EW distribution of i+ ETGs. By simulating on this model the
spectroscopic SDSS aperture, we find that SDSS studies at z<~1 are
progressively restricted to the inner LINER-zone, and miss an increasingly
large portion of the H\alpha-emitting periphery.Comment: Accepted to A&A, 6 pages, 4 figure
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