667 research outputs found
The Calar Alto Legacy Integral Field Area Survey: extended and remastered data release
This paper describes the extended data release of the Calar Alto Legacy
Integral Field Area (CALIFA) survey (eDR). It comprises science-grade quality
data for 895 galaxies obtained with the PMAS/PPak instrument at the 3.5 m
telescope at the Calar Alto Observatory along the last 12 years, using the V500
setup (3700-7500{\AA}, 6{\AA}/FWHM) and the CALIFA observing strategy. It
includes galaxies of any morphological type, star-formation stage, a wide range
of stellar masses (10 10 Msun ), at an average redshift of
0.015 (90\% within 0.005z0.05). Primarily selected based on the
projected size and apparent magnitude, we demonstrate that it can be volume
corrected resulting in a statistically limited but representative sample of the
population of galaxies in the nearby Universe. All the data were homogeneous
re-reduced, introducing a set of modifications to the previous reduction. The
most relevant is the development and implementation of a new
cube-reconstruction algorithm that provides with an (almost) seeing-limited
spatial resolution (FWHM PSF 1.0").To illustrate the usability and
quality of the data, we extracted two aperture spectra for each galaxy (central
1.5" and fully integrated), and analyze them using pyFIT3D. We obtain a set of
observational and physical properties of both the stellar populations and the
ionized gas, that have been compared for the two apertures, exploring their
distributions as a function of the stellar masses and morphologies of the
galaxies, comparing with recent results in the literature. DATA RELEASE:
http://ifs.astroscu. unam.mx/CALIFA_WEB/public_html/Comment: 30 pages, 26 figures, accepted for publishing in the MNRA
Using late-time optical and near-infrared spectra to constrain Type Ia supernova explosion properties
The late-time spectra of Type Ia supernovae (SNe Ia) are powerful probes of
the underlying physics of their explosions. We investigate the late-time
optical and near-infrared spectra of seven SNe Ia obtained at the VLT with
XShooter at 200 d after explosion. At these epochs, the inner Fe-rich ejecta
can be studied. We use a line-fitting analysis to determine the relative line
fluxes, velocity shifts, and line widths of prominent features contributing to
the spectra ([Fe II], [Ni II], and [Co III]). By focussing on [Fe II] and [Ni
II] emission lines in the ~7000-7500 \AA\ region of the spectrum, we find that
the ratio of stable [Ni II] to mainly radioactively-produced [Fe II] for most
SNe Ia in the sample is consistent with Chandrasekhar-mass delayed-detonation
explosion models, as well as sub-Chandrasekhar mass explosions that have
metallicity values above solar. The mean measured Ni/Fe abundance of our sample
is consistent with the solar value. The more highly ionised [Co III] emission
lines are found to be more centrally located in the ejecta and have broader
lines than the [Fe II] and [Ni II] features. Our analysis also strengthens
previous results that SNe Ia with higher Si II velocities at maximum light
preferentially display blueshifted [Fe II] 7155 \AA\ lines at late times. Our
combined results lead us to speculate that the majority of normal SN Ia
explosions produce ejecta distributions that deviate significantly from
spherical symmetry.Comment: 17 pages, 12 figure, accepted for publication in MNRA
MUSE Reveals a Recent Merger in the Post-starburst Host Galaxy of the TDE ASASSN-14li
We present MUSE integral field spectroscopic observations of the host galaxy
(PGC 043234) of one of the closest (, Mpc) and
best-studied tidal disruption events (TDE), ASASSN-14li. The MUSE integral
field data reveal asymmetric and filamentary structures that extend up to
kpc from the post-starburst host galaxy of ASASSN-14li. The
structures are traced only through the strong nebular [O III] 5007, [N
II] 6584, and H emission lines. The total off nuclear [O III]
5007 luminosity is luminosity is erg s and
the ionized H mass is . Based on the BPT
diagram, the nebular emission can be driven by either AGN photoionization or
shock excitation, with AGN photoionization favored given the narrow intrinsic
line widths. The emission line ratios and spatial distribution strongly
resemble ionization nebulae around fading AGNs such as IC 2497 (Hanny's
Voorwerp) and ionization "cones" around Seyfert 2 nuclei. The morphology of the
emission line filaments strongly suggest that PGC 043234 is a recent merger,
which likely triggered a strong starburst and AGN activity leading to the
post-starburst spectral signatures and the extended nebular emission line
features we see today. We briefly discuss the implications of these
observations in the context of the strongly enhanced TDE rates observed in
post-starburst galaxies and their connection to enhanced theoretical TDE rates
produced by supermassive black-hole binaries.Comment: Accepted for publication in ApJ
Type II supernovae as probes of environment metallicity: observations of host HII regions
Spectral modelling of SNII atmospheres indicates a clear dependence of metal
line strengths on progenitor metallicity. This motivates further work to
evaluate the accuracy with which these SNe can be used as metallicity
indicators. To assess this accuracy we present a sample of SNII HII-region
spectroscopy, from which environment abundances are derived. These environment
abundances are compared to the observed strength of metal lines in SN spectra.
Combining our sample with measurements from the literature, we present oxygen
abundances of 119 host HII regions, by extracting emission line fluxes and
using abundance diagnostics. Then, following Dessart et al., these abundances
are compared to equivalent widths of Fe 5018 A at various time and colour
epochs. Our distribution of inferred SNII host HII-region abundances has a
range of ~0.6 dex. We confirm the dearth of SNeII exploding at metallicities
lower than those found (on average) in the Large Magellanic Cloud. The
equivalent width of Fe 5018 A at 50 days post explosion shows a statistically
significant correlation with host HII-region oxygen abundance. The strength of
this correlation increases if one excludes abundance measurements derived far
from SN explosion sites. The correlation significance also increases if we only
analyse a 'gold' IIP sample, and if a colour epoch is used in place of time. In
addition, no evidence is found of correlation between progenitor metallicity
and SN light-curve or spectral properties - except for that stated above with
respect to Fe 5018 A equivalent width - suggesting progenitor metallicity is
not a driving factor in producing the diversity observed in our sample. This
study provides observational evidence of the usefulness of SNII as metallicity
indicators. We finish with a discussion of the methodology needed to use SN
spectra as independent metallicity diagnostics throughout the Universe.Comment: Accepted for publication in Astronomy and Astrophyci
The local and global relations between , and that regulate star-formation
Star-formation is one of the main processes that shape galaxies, defining its
stellar population and metallicity production and enrichment. It is nowadays
known that this process is ruled by a set of relations that connect three
parameters: the molecular gas mass, the stellar mass and the star-formation
rate itself. These relations are fulfilled at a wide range of scales in
galaxies, from galaxy wide to kpc-scales. At which scales they are broken, and
how universal they are (i.e., if they change at different scales or for
different galaxy types) it is still an open question. We explore here how those
relations compare at different scales using as proxy the new analysis done
using Integral Field Spectroscopy data and CO observations data from the
EDGE-CALIFA survey and the AMUSSING++ compilation.Comment: 8 pages, 3 figures, 1 table, proceedings of the IAU Symposium 373:
Resolving the Rise and Fall of Star Formation in Galaxie
Nearby supernova host galaxies from the CALIFA Survey: II. SN environmental metallicity
The metallicity of a supernova (SN) progenitor, together with its mass, is
one of the main parameters that rules their outcome. We present a metallicity
study of 115 nearby SN host galaxies (0.005<z<0.03) which hosted 142 SNe using
Integral Field Spectroscopy (IFS) from the CALIFA survey. Using O3N2 we found
no statistically significant differences between the gas-phase metallicities at
the locations of the three main SN types (Ia, Ib/c and II) all having
~8.500.02 dex. The total galaxy metallicities are also very similar and we
argue that this is because our sample consists only of SNe discovered in
massive galaxies (log(M/Msun)>10 dex) by targeted searches. We also found no
evidence that the metallicity at the SN location differs from the average
metallicity at the GCD of the SNe. By extending our SN sample with published
metallicities at the SN location, we studied the metallicity distributions for
all SN subtypes split into SN discovered in targeted and untargeted searches.
We confirm a bias toward higher host masses and metallicities in the targeted
searches. Combining data from targeted and untargeted searches we found a
sequence from higher to lower local metallicity: SN Ia, Ic, and II show the
highest metallicity, which is significantly higher than SN Ib, IIb, and Ic-BL.
Our results support the picture of SN Ib resulting from binary progenitors and,
at least part of, SN Ic being the result of single massive stars stripped of
their outer layers by metallicity driven winds. We studied several proxies of
the local metallicity frequently used in the literature and found that the
total host metallicity allows for the estimation of the metallicity at the SN
location with an accuracy better than 0.08 dex and very small bias. In
addition, weak AGNs not seen in total spectra may only weakly bias (by 0.04
dex) the metallicity estimate from integrated spectra. (abridged)Comment: 24 pages, 16 Figures, 13 Tables, Accepted in A&
Resolving the age bimodality of galaxy stellar populations on kpc scales
Galaxies in the local Universe are known to follow bimodal distributions in
the global stellar populations properties. We analyze the distribution of the
local average stellar-population ages of 654,053 sub-galactic regions resolved
on ~1-kpc scales in a volume-corrected sample of 394 galaxies, drawn from the
CALIFA-DR3 integral-field-spectroscopy survey and complemented by SDSS imaging.
We find a bimodal local-age distribution, with an old and a young peak
primarily due to regions in early-type galaxies and star-forming regions of
spirals, respectively. Within spiral galaxies, the older ages of bulges and
inter-arm regions relative to spiral arms support an internal age bimodality.
Although regions of higher stellar-mass surface-density, mu*, are typically
older, mu* alone does not determine the stellar population age and a bimodal
distribution is found at any fixed mu*. We identify an "old ridge" of regions
of age ~9 Gyr, independent of mu*, and a "young sequence" of regions with age
increasing with mu* from 1-1.5 Gyr to 4-5 Gyr. We interpret the former as
regions containing only old stars, and the latter as regions where the relative
contamination of old stellar populations by young stars decreases as mu*
increases. The reason why this bimodal age distribution is not inconsistent
with the unimodal shape of the cosmic-averaged star-formation history is that
i) the dominating contribution by young stars biases the age low with respect
to the average epoch of star formation, and ii) the use of a single average age
per region is unable to represent the full time-extent of the star-formation
history of "young-sequence" regions.Comment: 17 pages, 11 figures, MNRAS accepte
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