54 research outputs found
Serendipitous discovery of a strong-lensed galaxy in integral field spectroscopy from MUSE
2MASX J04035024-0239275 is a bright red elliptical galaxy at redshift 0.0661
that presents two extended sources at 2\arcsec~to the north-east and
1\arcsec~to the south-west. The sizes and surface brightnesses of the two blue
sources are consistent with a gravitationally-lensed background galaxy. In this
paper we present MUSE observations of this galaxy from the All-weather MUse
Supernova Integral-field Nearby Galaxies (AMUSING) survey, and report the
discovery of a background lensed galaxy at redshift 0.1915, together with other
15 background galaxies at redshifts ranging from 0.09 to 0.9, that are not
multiply imaged. We have extracted aperture spectra of the lens and all the
sources and fit the stellar continuum with STARLIGHT to estimate their stellar
and emission line properties. A trace of past merger and active nucleus
activity is found in the lensing galaxy, while the background lensed galaxy is
found to be star-forming. Modeling the lensing potential with a singular
isothermal ellipsoid, we find an Einstein radius of 1\farcs450\farcs04,
which corresponds to 1.9 kpc at the redshift of the lens and it is much smaller
than its effective radius ( 9\arcsec). Comparing the Einstein
mass and the STARLIGHT stellar mass within the same aperture yields a dark
matter fraction of \% within the Einstein radius. The advent of
large surveys such as the Large Synoptic Survey Telescope (LSST) will discover
a number of strong-lensed systems, and here we demonstrate how wide-field
integral field spectroscopy offers an excellent approach to study them and to
precisely model lensing effects.Comment: 12 pages, 12 Figures, 4 Tables. Accepted in MNRA
Morphology and kinematics of orbital components in CALIFA galaxies across the Hubble sequence
Based on the stellar orbit distribution derived from orbit-superposition
Schwarzschild models, we decompose each of 250 representative present-day
galaxies into four orbital components: cold with strong rotation, warm with
weak rotation, hot with dominant random motion and counter-rotating (CR). We
rebuild the surface brightness () of each orbital component and we
present in figures and tables a quantification of their morphologies using the
Sersic index \textit{n}, concentration and intrinsic flattening
and , with the half-light-radius and
the CALIFA data coverage. We find that: (1) kinematic hotter
components are generally more concentrated and rounder than colder components,
and (2) all components become more concentrated and thicker/rounder in more
massive galaxies; they change from disk-like in low mass late-type galaxies to
bulge-like in high-mass early type galaxies. Our findings suggest that Sersic
\textit{n} is not a good discriminator between rotating bulges and non-rotating
bulges. The luminosity fraction of cold orbits is well
correlated with the photometrically-decomposed disk fraction as
. Similarly, the hot
orbit fraction is correlated with the bulge fraction as . The
warm orbits mainly contribute to disks in low-mass late-type galaxies, and to
bulges in high-mass early-type galaxies. The cold, warm, and hot components
generally follow the same morphology () versus
kinematics () relation as the thin
disk, thick disk/pseudo bulge, and classical bulge identified from cosmological
simulations.Comment: accepted by MNRA
Kinematical Signatures of Disc Instabilities and Secular Evolution in the MUSE TIMER Survey
The MUSE TIMER Survey has obtained high signal and high spatial resolution
integral-field spectroscopy data of the inner kpc of 21 nearby
massive disc galaxies. This allows studies of the stellar kinematics of the
central regions of massive disc galaxies that are unprecedented in spatial
resolution. We confirm previous predictions from numerical and hydrodynamical
simulations of the effects of bars and inner bars on stellar and gaseous
kinematics, and also identify box/peanuts via kinematical signatures in mildly
and moderately inclined galaxies, including a box/peanut in a face-on inner
bar. In 20/21 galaxies we find inner discs and show that their properties are
fully consistent with the bar-driven secular evolution picture for their
formation. In addition, we show that these inner discs have, in the region
where they dominate, larger rotational support than the main galaxy disc, and
discuss how their stellar population properties can be used to estimate when in
cosmic history the main bar formed. Our results are compared with photometric
studies in the context of the nature of galaxy bulges and we show that inner
discs are identified in image decompositions as photometric bulges with
exponential profiles (i.e., S\'ersic indices near unity).Comment: 4 pages, 5 figures, to appear in Galactic Dynamics in the Era of
Large Surveys, M. Valluri & J. A. Sellwood (eds.
An Integral View of Balmer-dominated Shocks in Supernova Remnants
We present integral-field spectroscopic observations with the VIMOS-IFU at the VLT of fast (2000-3000 kms−1) Balmer-dominated shocks surrounding the northwestern rim of the remnant of supernova 1006. The high spatial and spectral resolution of the instrument enable us to show that the physical characteristics of the shocks exhibit a strong spatial variation over few atomic scale lengths across 133 sky locations. Our results point to the presence of a population of non-thermal protons (10-100 keV) which might well be the seed particles for generating high-energy cosmic rays. We also present observations of Tycho's supernova remnant taken with the narrow-band tunable filter imager OSIRIS at the GTC and the Fabry-Perot interferometer GHaFaS at the WHT to resolve respectively the broad and narrow Hα lines across a large part of the remnan
The universal variability of the stellar initial mass function probed by the TIMER survey
The debate about the universality of the stellar initial mass function (IMF) revolves around two competing lines of evidence. While measurements in the Milky Way, an archetypal spiral galaxy, seem to support an invariant IMF, the observed properties of massive early-type galaxies (ETGs) favor an IMF somehow sensitive to the local star-formation conditions. However, the fundamental methodological and physical differences between the two approaches have hampered a comprehensive understanding of IMF variations. Here, we describe an improved modeling scheme that, for the first time, allows consistent IMF measurements across stellar populations with different ages and complex star-formation histories (SFHs). Making use of the exquisite MUSE optical data from the TIMER survey and powered by the MILES stellar population models, we show the age, metallicity, [Mg/Fe], and IMF slope maps of the inner regions of NGC 3351, a spiral galaxy with a mass similar to that of the Milky Way. The measured IMF values in NGC 3351 follow the expectations from a Milky Way-like IMF, although they simultaneously show systematic and spatially coherent variations, particularly for low-mass stars. In addition, our stellar population analysis reveals the presence of metal-poor and Mg-enhanced star-forming regions that appear to be predominantly enriched by the stellar ejecta of core-collapse supernovae. Our findings therefore showcase the potential of detailed studies of young stellar populations to provide the means to better understand the early stages of galaxy evolution and, in particular, the origin of the observed IMF variations beyond and within the Milky Way
Creating lenticular galaxies with major mergers
Lenticular galaxies (S0s) represent the majority of early-type galaxies in the local Universe, but their formation channels are still poorly understood. While galaxy mergers are obvious pathways to suppress star formation and increase bulge sizes, the marked parallelism between spiral and lenticular galaxies (e.g. photometric bulge-disc coupling) seemed to rule out a potential merger origin. Here, we summarise our recent work in which we have shown, through N-body numerical simulations, that disc-dominated lenticulars can emerge from major mergers of spiral galaxies, in good agreement with observational photometric scaling relations. Moreover, we show that mergers simultaneously increase the light concentration and reduce the angular momentum relative to their spiral progenitors. This explains the mismatch in angular momentum and concentration between spirals and lenticulars recently revealed by CALIFA observations, which is hard to reconcile with simple fading mechanisms (e.g. ram-pressure stripping)
An Integral View of Balmer-dominated Shocks in Supernova Remnants
We present integral-field spectroscopic observations with the VIMOS-IFU at the VLT of fast (2000-3000 kms−1) Balmer-dominated shocks surrounding the northwestern rim of the remnant of supernova 1006. The high spatial and spectral resolution of the instrument enable us to show that the physical characteristics of the shocks exhibit a strong spatial variation over few atomic scale lengths across 133 sky locations. Our results point to the presence of a population of non-thermal protons (10-100 keV) which might well be the seed particles for generating high-energy cosmic rays. We also present observations of Tycho's supernova remnant taken with the narrow-band tunable filter imager OSIRIS at the GTC and the Fabry-Perot interferometer GHaFaS at the WHT to resolve respectively the broad and narrow Hα lines across a large part of the remnant
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