We use spatially and temporally resolved maps of stellar population properties of 300 galaxies from the CALIFA integral field survey to investigate how the stellar metallicity (Z sub(*)) relates to ...the total stellar mass (M sub(*)) and the local mass surface density ( mu sub(*)) in both spheroidal- and disk-dominated galaxies. The galaxies are shown to follow a clear stellar mass-metallicity relation (MZR) over the whole 10 super(9)-10 super(12) M sub(middot in circle) range. This relation is steeper than the one derived from nebular abundances, which is similar to the flatter stellar MZR derived when we consider only young stars. We also find a strong relation between the local values of mu sub(*) and Z sub(*) (the mu ZR), betraying the influence of local factors in determining Z sub(*). This shows that both local ( mu sub(*)-driven) and global (M sub(*)-driven) processes are important in determining metallicity in galaxies. We find that the overall balance between local and global effects varies with the location within a galaxy. In disks, mu sub(*) regulates Z sub(*), producing a strong mu ZR whose amplitude is modulated by M sub(*). In spheroids it is M sub(*) that dominates the physics of star formation and chemical enrichment, with mu sub(*) playing a minor, secondary role. These findings agree with our previous analysis of the star formation histories of CALIFA galaxies, which showed that mean stellar ages are mainly governed by surface density in galaxy disks and by total mass in spheroids.
MiniJPAS is a ∼1 deg
2
imaging survey of the AEGIS field in 60 bands, performed to demonstrate the scientific potential of the upcoming Javalambre-Physics of the Accelerating Universe Astrophysical ...Survey (J-PAS). Full coverage of the 3800–9100 Å range with 54 narrow-band filters, in combination with 6 optical broad-band filters, allows for extremely accurate photometric redshifts (photo-
z
), which, applied over areas of thousands of square degrees, will enable new applications of the photo-
z
technique, such as measurement of baryonic acoustic oscillations. In this paper we describe the method we used to obtain the photo-
z
that is included in the publicly available miniJPAS catalogue, and characterise the photo-
z
performance. We built photo-spectra with 100 Å resolution based on forced-aperture photometry corrected for point spread function. Systematic offsets in the photometry were corrected by applying magnitude shifts obtained through iterative fitting with stellar population synthesis models. We computed photo-
z
with a customised version of L
E
P
HARE
, using a set of templates that is optimised for the J-PAS filter-set. We analysed the accuracy of miniJPAS photo-
z
and their dependence on multiple quantities using a subsample of 5266 galaxies with spectroscopic redshifts from SDSS and DEEP, which we find to be representative of the whole
r
< 23 miniJPAS sample. Formal 1
σ
uncertainties for the photo-
z
that are calculated with the Δ
χ
2
method underestimate the actual redshift errors. The
o
d
d
s
parameter has a stronger correlation with |Δ
z
| and accurately reproduces the probability of a redshift outlier (|Δ
z
| > 0.03), regardless of the magnitude, redshift, or spectral type of the sources. We show that the two main summary statistics characterising the photo-
z
accuracy for a population of galaxies (
σ
NMAD
and
η
) can be predicted by the distribution of
o
d
d
s
in this population, and we use this to estimate the statistics for the whole miniJPAS sample. At
r
< 23, there are ∼17 500 galaxies per deg
2
with valid photo-
z
estimates, ∼4200 of which are expected to have |Δ
z
| < 0.003. The typical error is
σ
NMAD
= 0.013 with an outlier rate
η
= 0.39. The target photo-
z
accuracy
σ
NMAD
= 0.003 is achieved for
o
d
d
s
> 0.82 with
η
= 0.05, at the cost of decreasing the density of selected galaxies to
n
∼ 5200 deg
−2
(∼2600 of which have |Δ
z
| < 0.003).
In the years to come, the Javalambre-Physics of the Accelerated Universe Astrophysical Survey (J-PAS) will observe 8000 deg
2
of the northern sky with 56 photometric bands. J-PAS is ideal for the ...detection of nebular emission objects. This paper presents a new method based on artificial neural networks (ANNs) that is aimed at measuring and detecting emission lines in galaxies up to
z
= 0.35. These lines are essential diagnostics for understanding the evolution of galaxies through cosmic time. We trained and tested ANNs with synthetic J-PAS photometry from CALIFA, MaNGA, and SDSS spectra. To this aim, we carried out two tasks. First, we clustered galaxies in two groups according to the values of the equivalent width (EW) of H
α
, H
β
, N
II
, and O
III
lines measured in the spectra. Then we trained an ANN to assign a group to each galaxy. We were able to classify them with the uncertainties typical of the photometric redshift measurable in J-PAS. Second, we utilized another ANN to determine the values of those EWs. Subsequently, we obtained the N
II
/H
α
, O
III
/H
β
, and O 3N 2 ratios, recovering the BPT diagram (O
III
/H
β
versus N
II
/H
α
). We studied the performance of the ANN in two training samples: one is only composed of synthetic J-PAS photo-spectra (J-spectra) from MaNGA and CALIFA (CALMa set) and the other one is composed of SDSS galaxies. We were able to fully reproduce the main sequence of star-forming galaxies from the determination of the EWs. With the CALMa training set, we reached a precision of 0.092 and 0.078 dex for the N
II
/H
α
and O
III
/H
β
ratios in the SDSS testing sample. Nevertheless, we find an underestimation of those ratios at high values in galaxies hosting an active galactic nuclei. We also show the importance of the dataset used for both training and testing the model. Such ANNs are extremely useful for overcoming the limitations previously expected concerning the detection and measurements of the emission lines in such surveys as J-PAS. Furthermore, we show the capability of the method to measure a EW of 10 Å in H
α
, H
β
, N
II
and O
III
lines with a signal-to-noise ratio (S/N) of 5, 1.5, 3.5, and 10, respectively, in the photometry. Finally, we compare the properties of emission lines in galaxies observed with miniJPAS and SDSS. Despite the limitation of such a comparison, we find a remarkable correlation in their EWs.
Bar pattern speeds in CALIFA galaxies Aguerri, J A L; Mendez-Abreu, J; Falcon-Barroso, J ...
Astronomy and astrophysics (Berlin),
4/2015, Letnik:
576
Journal Article
Recenzirano
Odprti dostop
The bar pattern speed (Omegab) is defined as the rotational frequency of the bar, and it determines the bar dynamics. Several methods have been proposed for measuring Omegab. This method has been ...applied so far to 17 galaxies, most of them SB0 and SBa types. We have applied the TW method to a new sample of 15 strong and bright barred galaxies, spanning a wide range of morphological types from SB0 to SBbc. Combining our analysis with previous studies, we investigate 32 barred galaxies with their pattern speed measured by the TW method. We measured Omegab using the TW method on the stellar velocity maps provided by the integral-field spectroscopy data from the CALIFA survey. Our results indicate that independent of the Hubble type, bars have been formed and then evolve as fast rotators. This observational result will constrain the scenarios of formation and evolution of bars proposed by numerical simulations.
Aims. Our goal is to develop and test a novel methodology to compute accurate close-pair fractions with photometric redshifts. Methods. We improved the currently used methodologies to estimate the ...merger fraction fm from photometric redshifts by (i) using the full probability distribution functions (PDFs) of the sources in redshift space; (ii) including the variation in the luminosity of the sources with z in both the sample selection and the luminosity ratio constrain; and (iii) splitting individual PDFs into red and blue spectral templates to reliably work with colour selections. We tested the performance of our new methodology with the PDFs provided by the ALHAMBRA photometric survey. Results. The merger fractions and rates from the ALHAMBRA survey agree excellently well with those from spectroscopic work for both the general population and red and blue galaxies. With the merger rate of bright (MB ≤ −20−1.1z) galaxies evolving as (1 + z)n, the power-law index n is higher for blue galaxies (n = 2.7 ± 0.5) than for red galaxies (n = 1.3 ± 0.4), confirming previous results. Integrating the merger rate over cosmic time, we find that the average number of mergers per galaxy since z = 1 is Nmred = 0.57 ± 0.05 for red galaxies and Nmblue = 0.26 ± 0.02 for blue galaxies. Conclusions. Our new methodology statistically exploits all the available information provided by photometric redshift codes and yields accurate measurements of the merger fraction by close pairs from using photometric redshifts alone. Current and future photometric surveys will benefit from this new methodology.
We use optical integral field spectroscopy (IFS) of nearby supernova (SN) host galaxies (0.005 <z< 0.03) provided by the Calar Alto Legacy Integral Field Area (CALIFA) Survey with the goal of finding ...correlations in the environmental parameters at the location of different SN types. In this first study of a series we focus on the properties related with star formation (SF). We recover the sequence in association of different SN types to the star-forming regions by using several indicators of the ongoing and recent SF related to both the ionized gas and the stellar populations. While the total ongoing SF is on average the same for the three SN types, SNe Ibc/IIb tend to occur closer to star-forming regions and in higher SF density locations than SNe II and SNe Ia; the latter shows the weakest correlation. SNe Ia host galaxies have masses that are on average ~0.3−0.8 dex higher than those of the core collapse (CC) SNe hosts because the SNe Ia hosts contain alarger fraction of old stellar populations. Using the recent SN Ia delay-time distribution and the SFHs of the galaxies, we show that the SN Ia hosts in our sample are expected to produce twice as many SNe Ia as the CC SN hosts. Since both types occur in hosts with a similar SF rate and hence similar CC SN rate, this can explain the mass difference between the SN Ia and CC SN hosts, and reinforces the finding that at least part of the SNe Ia originate from very old progenitors. By comparing the mean SFH of the eight least massive galaxies with that of the massive SF SN Ia hosts, we find that the low-mass galaxies formed their stars during a longer time (0.65%, 24.46%, and 74.89% in the intervals 0–0.42 Gyr, 0.42–2.4 Gyr, and >2.4 Gyr, respectively) than the massive SN Ia hosts (0.04%, 2.01%, and 97.95% in these intervals). We estimate that the low-mass galaxies produce ten times fewer SNe Ia and three times fewer CC SNe than the high-mass group. Therefore the ratio between the number of CC SNe and SNe Ia is expected to increase with decreasing galaxy mass. CC SNe tend to explode at positions with younger stellar populations than the galaxy average, but the galaxy properties at SNe Ia locations are one average the same as the global galaxy properties.
Context. The morphological, spectroscopic, and kinematical properties of the warm interstellar medium (wim) in early-type galaxies (ETGs) hold key observational constraints to nuclear activity and ...the buildup history of these massive, quiescent systems. This article centers on a 2D investigation of the wim component in 32 nearby (?150 Mpc) ETGs from CALIFA, complementing a previous 1D analysis of the same sample. The analysis presented here includes Ha intensity and equivalent width (EW) maps and radial profiles, diagnostic emission-line ratios, and ionized-gas and stellar kinematics. It is supplemented by t-ratio maps, which are a more efficient means to quantify the role of photoionization by the post-AGB stellar component than alternative mechanisms (e.g., AGN, low-level star formation). This study adds further observational evidence for a considerable heterogeneity among ETGs with regard to the physical properties and 2D kinematics of their extended wim component, and it clearly shows that a comprehensive understanding of these systems requires IFS studies over their entire optical extent.
This paper presents the spatially resolved star formation history (SFH) of nearby galaxies with the aim of furthering our understanding of the different processes involved in the formation and ...evolution of galaxies. To this end, we apply the fossil record method of stellar population synthesis to a rich and diverse data set of 436 galaxies observed with integral field spectroscopy in the CALIFA survey. The sample covers a wide range of Hubble types, with stellar masses ranging from
M
⋆
~ 10
9
to 7 × 10
11
M
⊙
. Spectral synthesis techniques are applied to the datacubes to retrieve the spatially resolved time evolution of the star formation rate (SFR), its intensity (Σ
SFR
), and other descriptors of the 2D SFH in seven bins of galaxy morphology (E, S0, Sa, Sb, Sbc, Sc, and Sd) and five bins of stellar mass. Our main results are that (a) galaxies form very fast independently of their current stellar mass, with the peak of star formation at high redshift (
z
> 2). Subsequent star formation is driven by
M
⋆
and morphology, with less massive and later type spirals showing more prolonged periods of star formation. (b) At any epoch in the past, the SFR is proportional to
M
⋆
, with most massive galaxies having the highest absolute (but lowest specific) SFRs. (c) While today, the Σ
SFR
is similar for all spirals and significantly lower in early-type galaxies (ETG), in the past, the Σ
SFR
scales well with morphology. The central regions of today’s ETGs are where the Σ
SFR
reached the highest values (> 10
3
M
⊙
Gyr
-1
pc
-2
), similar to those measured in high-redshift star-forming galaxies. (d) The evolution of Σ
SFR
in Sbc systems matches that of models for Milky Way-like galaxies, suggesting that the formation of a thick disk may be a common phase in spirals at early epochs. (e) The SFR and Σ
SFR
in outer regions of E and S0 galaxies show that they have undergone an extended phase of growth in mass between
z
= 2 and 0.4. The mass assembled in this phase is in agreement with the two-phase scenario proposed for the formation of ETGs. (f) Evidence of an early and fast quenching is found only in the most massive (
M
⋆
> 2 × 10
11
M
⊙
) E galaxies of the sample, but not in spirals of similar mass, suggesting that halo quenching is not the main mechanism for the shut down of star formation in galaxies. Less massive E and disk galaxies show more extended SFHs and a slow quenching. (g) Evidence of fast quenching is also found in the nuclei of ETG and early spirals, with SFR and Σ
SFR
indicating that they can be the relic of the “red nuggets” detected at high redshift.
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