Characterisation of the stellar content of SDSS EELGs through self-consistent spectral modelling

Breda, Iris; Vı́lchez, J. M.; Papaderos, P.; Cardoso, Leandro S. M.; Amorín, R.; Arroyo-Polonio, A.; Iglésias-Páramo, J.; Kehrig, C.; Pérez-Montero, E.

doi:10.1051/0004-6361/202142805

Cited by 7 publications

(15 citation statements)

References 67 publications

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“…In this way, the apparent disagreement of the results from Breda et al (2022) with the results reported here and in Cardoso et al (2022) is probably related to the level of the nebular continuum contribution of the galaxies that is included in the sample used in each of these works. In our sample, the median value of the Hα EW is 34 Å and only 6% of the galaxies in the sample have an EW(Hα)>100 Å (in Figure 3 is presented the EW(Hα) distribution).…”

Section: Discussionmentioning

confidence: 50%

“…The estimate of comparable stellar masses by FADO relative to a purely stellar approach to SED fitting was also observed in Cardoso et al (2022). However, Breda et al (2022) observed that not considering the nebular contribution leads to an overestimation of the stellar mass.…”

Section: Discussionmentioning

confidence: 53%

“…Of the different results presented in Cardoso et al (2022), the most relevant result for this work is that the estimated stellar mass is minimally affected by taking into consideration the nebular con-tinuum because FADO obtains stellar masses just slightly higher than STARLIGHT (see Table 1 of Cardoso et al 2022). Breda et al (2022) studied a sample of 414 extreme emission line galaxies (EELGs) and 697 normal SF galaxies from the SDSS, providing insight into how stellar properties, such as stellar mass and mean stellar age, are affected by the additional modelling of the nebular continuum. The specific SFR (sSFR) and the sum of the flux of the most prominent emission lines were used as indicators of the degree of star formation activity, thus enabling the interpretation of the results considering the level of the nebular contribution.…”

Section: Discussionmentioning

confidence: 98%

“…Thus, an agreement between the physical properties retrieved by FADO and by a pure stellar code is observed, as is the case in what regards the MPA-JHU catalogue. On the other hand, in Breda et al (2022) the sample of EELGs has an average Hα EW of ≈400 Å (see Fig. 1 of Breda et al 2022, for the EW(Hα) distribution).…”

Section: Discussionmentioning

confidence: 99%

“…The impact of considering the nebular contribution in the fitting process of the SED was recently studied in Cardoso et al (2022) and Breda et al (2022). In both these works, FADO, with its self-consistent treatment of the stellar and nebular continuum, was compared to the purely stellar synthesis code STARLIGHT.…”

Section: Discussionmentioning

confidence: 99%

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An investigation of the star-forming main sequence considering the nebular continuum emission at low-z

Miranda

Pappalardo

Papaderos

et al. 2022

A&A

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Context. Galaxy evolution has been studied by interpreting the spectral energy distribution of galaxies using spectral synthesis codes. This method has been crucial in discovering different pillars of modern galaxy evolution theories. However, this analysis was mostly carried out using spectral synthesis codes that are purely stellar, that is, they assume that the nebular contribution to the total continuum is negligible. The code FADO is the first publicly available population spectral synthesis tool that treats the contribution from ionised gas to the observed emission self-consistently. This is expected to have a particularly strong effect in star-forming (SF) galaxies. Aims. We study the impact of the nebular contribution on the determination of the star formation rate (SFR), stellar mass, and consequent effect on the star-forming main sequence (SFMS) at low redshift. Methods. We applied FADO to the spectral database of the SDSS to derive the physical properties of galaxies. As a comparison, we used the data in the MPA-JHU catalogue, which contains the properties of SDSS galaxies derived without the nebular contribution. We selected a sample of SF galaxies with Hα and Hβ flux measurements, and we corrected the fluxes for the nebular extinction through the Balmer decrement. We then calculated the Hα luminosity to estimate the SFR. Then, by combining the stellar mass and SFR estimates from FADO and MPA-JHU, the SFMS was obtained. Results. The Hα flux estimates are similar between FADO and MPA-JHU. Because the Hα flux was used as tracer of the SFR, FADO and MPA-JHU agree in their SFR. The stellar mass estimates are slightly higher for FADO than for MPA-JHU on average. However, considering the uncertainties, the differences are negligible. With similar SFR and stellar mass estimates, the derived SFMS is also similar between FADO and MPA-JHU. Conclusions. Our results show that for SDSS normal SF galaxies, the additional modelling of the nebular contribution does not affect the retrieved fluxes and consequentially also does not influence SFR estimators based on the extinction-corrected Hα luminosity. For the stellar masses, the results point to the same conclusion. These results are a consequence of the fact that the vast majority of normal SF galaxies in the SDSS have a low nebular contribution. However, the obtained agreement might only hold for local SF galaxies, but higher-redshift galaxies might show different physical properties when FADO is used. This would then be an effect of the expected increased nebular contribution.

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Section: Discussionmentioning

confidence: 50%

Section: Discussionmentioning

confidence: 53%

Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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An investigation of the star-forming main sequence considering the nebular continuum emission at low-z

Miranda

Pappalardo

Papaderos

et al. 2022

A&A

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Exploring the genesis of spiral galaxies

Breda

Papaderos

2023

A&A

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Context. A tantalizing enigma in extragalactic astronomy concerns the chronology and driving mechanisms of the build-up of latetype galaxies (LTGs). The standard scenario envisages two formation routes, with classical bulges (CBs) assembling first in a quick and violent quasi-monolithic episode followed by gradual disk assembly, and pseudo-bulge (PB) formation occurring gradually over the gigayear-long secular evolution of LTGs through gentle gas inflow from the disk and in situ star formation at its centre. An expectation from this antagonistic rationale is the segregation of present-day LTG bulges into two evolutionary distinct groups, which is in sharp contrast with recent observations. Aims. The present study aims for a thorough investigation of the star formation history (SFH) of LTGs with its ultimate goal being to outline a coherent framework for the formation and evolution of spiral galaxies and their main stellar components. Methods. Using population spectral synthesis models, we analyse the spatially resolved SFH of the bulge and the disk for 135 LTGs from the CALIFA survey that adequately cover the relevant range in LTG mass. Complementarily, characteristic physical properties of bulges and disks, such as mean colours, mass-and light-weighted stellar age and metallicity, and EW(Hα), were contrasted with predictions from evolutionary synthesis models. The latter adopted exponentially declining SFHs, with an e-folding time τ between 0.1 and 20 Gyr. Results. Analysis of the SFH of approximately half a million spaxels consistently reveals that the main physical and evolutionary properties of both bulges and disks show a continuous distribution across present-day total stellar mass M ,T . The e-folding time τ in spiral galaxies with log(M ,T ) > 10 increases from the centre to the periphery, suggesting that these systems grow in an inside-out fashion. Quite importantly, the radial gradient of τ in gigayear over kiloparsec in an individual galaxy increases with increasing M ,T , which is consistent with a high bulge-to-disk age contrast in high-mass spirals, while lower-mass LTGs display roughly the same τ throughout their entire radial extent, with intermediate mass galaxies in between. Predictions obtained through evolutionary synthesis are overall consistent with observed properties, such as mean colours, stellar ages, and Hα equivalent widths. Finally, bulges and disks of higher mass galaxies exhibit shorter formation timescales as compared to their lower mass counterparts. Conclusions. Collectively, the obtained results evince a coherent and unified picture for the formation and evolution of LTGs, in which PBs and CBs denote extremities of a continuous mass sequence. This analysis is consistent with the framework where bulges are assembled jointly with their parent disks by gradual inside-out growth, at a pace that is regulated by the depth of the galactic potential. In accordance with this is the fact that the revealed correlations are entirely devoid of a bimodality, which would be expected if CBs and...

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Bulgeless disks, dark galaxies, inverted color gradients, and other expected phenomena at higher z

Papaderos¹,

Östlin²,

Breda³

2023

A&A

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The spectral energy distribution (SED) of galaxies varies both between galaxies and within them. For instance, early-type spiral galaxies have a red bulge surrounded by a bluer star-forming disk with H II regions within. When observing redshifted galaxies, a given photometric filter probes light at a bluer rest frame, and in relating the observed magnitudes to the rest frame of the filter, so-called k corrections are commonly applied to account for the relative dimming or brightening in addition to the pure distance effect. The amount of correction depends on the shape of the spectrum (SED), so different k corrections apply to galaxies of different spectral types. This is, however, only part of the story, since any galaxy with a spatially non-homogeneous SED will experience a spatially varying relative dimming or brightening as a function of observed wavelength. Also, the morphological appearance of galaxies will therefore change with redshift. For instance, an early spiral galaxy observed in the V band would show a prominent bulge at z = 0, whereas, if at redshift z ∼ 1, the V filter probes emission in the rest-frame near-ultraviolet where the bulge is faint and the disk relatively brighter, thus the galaxy may appear as bulgeless. One popular way of studying spatial variations in the stellar population and dust content of galaxies is the use of color maps. For star-forming galaxies that have an appreciable contribution from nebular emission (lines and continuum), an additional effect is that the shifting of strong features in or out of filters will result in a non-monotonous color evolution with redshift. Hence, unlike the effects of distance, cosmological surface brightness dimming, and gravitational lensing, which are all achromatic, the fact that most galaxies have a spatially varying SED leads to a chromatic surface brightness modulation (CMOD) with redshift. While the CMOD effects are in principle easy to grasp, they affect multicolor imaging surveys and photometric properties derived from such surveys in a complex fashion. Properties such as the bulge-to-disk ratio, Sérsic exponent, light concentration, asymmetry index and effective radius, radial color gradients, and stellar mass determinations from SED fitting will depend on the redshift, the filters employed, and the rest-frame 2D SED patterns in a galaxy and will bias results inferred on galaxy evolution across cosmic time (e.g., the evolution of the mass-size, bulge-supermassive black hole, and Tully-Fisher relation), and potentially also weak lensing, if these effects are not properly taken into account. In this article we quantify the CMOD effects for idealized galaxies built from spectral synthesis models and from galaxies with observed integral field spectroscopy, and we show that they are significant and should be taken into account in studies of resolved galaxy properties and their evolution with redshift.

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Characterisation of the stellar content of SDSS EELGs through self-consistent spectral modelling

Cited by 7 publications

References 67 publications

An investigation of the star-forming main sequence considering the nebular continuum emission at low-z

An investigation of the star-forming main sequence considering the nebular continuum emission at low-z

Exploring the genesis of spiral galaxies

Bulgeless disks, dark galaxies, inverted color gradients, and other expected phenomena at higher z

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