The OTELO survey as a morphological probe. Last ten Gyr of galaxy evolution

Abstract

Context. The morphology of galaxies provide us with a unique tool for relating and understanding other physical properties and their changes over the course of cosmic time. It is only recently that we have been afforded access to a wealth of data for an unprecedented number galaxies thanks to large and deep surveys. Aims. We present the morphological catalogue of the OTELO survey galaxies detected with the Hubble Space Telescope (HST)-ACS F814W images. We explore various methods applied in previous works to separate early-type (ET) and late-type (LT) galaxies classified via spectral energy distribution (SED) fittings using galaxy templates. Together with this article, we are releasing a catalogue containing the main morphological parameters in the F606W and F814W bands derived for more than 8000 sources. Methods. The morphological analysis is based on the single-Sérsic profile fit. We used the GALAPAGOS2 software to provide multi-wavelength morphological parameters fitted simultaneously in two HST-ACS bands. The GALAPAGOS2 software detects, prepares guess values for GALFIT-M, and provides the best-fitting single-Sérsic model in both bands for each source. Stellar masses were estimated using synthetic rest-frame magnitudes recovered from SED fittings of galaxy templates. The morphological catalogue is complemented with concentration indexes from a separate SExtractor dual, high dynamical range mode. Results. A total of 8812 sources were successfully fitted with single-Sérsic profiles. The analysis of a carefully selected sample of ∼3000 sources up to zphot = 2 is presented in this work, of which 873 sources were not detected in previous studies. We found no statistical evidence for the evolution of the low-mass end of mass–size relation for ET and LT since z = 2. Furthermore, we found a good agreement for the median size evolution for ET and LT galaxies, for a given stellar mass, with the data from the literature. Compared to previous works on faint field galaxies, we found similarities regarding their rest-frame colours as well as the Sérsic and concentration indices.

Implications of a spatially resolved main sequence for the size evolution of star forming galaxies

“…Extending the pioneering work of Lilly et al (1998) and including a treatment to convert surface brightness into mass surface density, Barden et al (2005) found evidence for a non-evolving mass-size relation (𝛽 𝑧 = 0) since 𝑧 = 1 (though note that van der Wel et al 2014 associates a small but non-vanishing 𝛽 𝑧 = 0.2 to the same work). A similarly small value 𝛽 𝑧 = 0.17 can be derived from the more recent results of Barone et al (2021) in the redshift range 0.014 < 𝑧 < 0.76, while Nadolny et al (2021) found statistically insignificant evolution since 𝑧 ∼ 1.5 (see also Nagy et al 2011, who found 𝛽 𝑧 = 1.42 for 𝑧 > 1.5 and predicted convergence to the local relation by 𝑧 ∼ 1). Perhaps unsurprisingly, studies involving intermediate baselines 0.2 𝑧 2.5 find intermediate values 𝛽 𝑧 ∼ 0.75 (van der Wel et al 2014;Paulino-Afonso et al 2017).…”

“…Mowla et al 2019Nedkova et al 2021) and some others finding little or no evolution out to 𝑧 1.5 (e.g. Nadolny et al 2021). In addition to the considerations above, uncertainties in the recent evolution may also be related to the fact that, when directly comparing observed sizes at different redshifts, a small redshift leverage also implies that variations may become subtle to discern (e.g.…”

Nonsequential neural network for simultaneous, consistent classification, and photometric redshifts of OTELO galaxies

“…The OTELO catalog includes OTELO detections and reprocessed ancillary data from Chandra, GALEX, CFHT, WIRDS, and IRAC covering from ultraviolet to the mid-infrared. Our sample consists of 370 OTELO galaxies included in the Nadolny et al (2021) morphological analysis, of which 31 are early-type and 339 latetype. All these galaxies have spectral redshift z < 1.41 obtained from the DEEP2 Galaxy Redshift Survey (Newman et al 2013;Bongiovanni et al 2019).…”

The OTELO survey

“…Stellar masses (M * ) for the overall OTELO sample were computed from the mass-to-light ratio prescription of López-Sanjuan et al ( 2019) for star-forming galaxies (more details about obtaining stellar masses in the OTELO survey can be found in Nadolny et al (2021). The stellar mass for the Hβ sample is in the range of 10 7.6 < M * < 10 10.7 M .…”

“…To determine the morphological features of our galaxy sample, we made use of the available 2 HST high-resolution (F606W and F814W) images for a visual morphological classification. The detailed morphological analysis of all OTELO sources up to z = 2 is in the scope of a forthcoming paper (Nadolny et al 2021).…”