The Centro de Estudios de Física del Cosmos de Aragón (CEFCA) invites applications for one postdoctoral position within the projects FEEDBACK BARIÓNICO EN GALAXIAS MASIVAS Y ENANAS "BARMASS" (CNS2023-145339) - funded by the Spanish Ministry of Science, Innovation and Universities (MCIU/AEI/10.13039/501100011033) and the European Union NextGenerationEU/PRTR - and LA NATURALEZA Y EVOLUCION COSMICA DE LAS GALAXIAS CON LINEA DE EMISION EXTREMA "XTREM" (PID2023-147386NB-I00) - funded by MCIU /AEI /10.13039/501100011033 / FEDER, UE. The position is available immediately, with a contract of up to two years, ending no later than December 31, 2027.

The successful candidate will pursue research aligned with the main objectives of BARMASS and XTREM, focusing on the study of extreme emission-line galaxies (EELGs) across cosmic time through multi-wavelength spectrophotometric datasets.

EELGs are selected by their compact morphology and strong nebular emission, which make them readily identifiable in spectrophotometric surveys, such as J-PLUS, J-PAS and DESI. From HST and JWST observations, they have recently emerged as key contributors to cosmic reionization and as prime laboratories for investigating starburst-driven galaxy evolution in quasi-pristine environments akin to those of the early universe. At lower redshifts, EELGs become increasingly rare and are often regarded as local analogs of their high-redshift counterparts, enabling spatially resolved studies not possible at earlier epochs.

The goals of BARMASS and XTREM include assembling an unprecedented, statistically complete census of EELGs and characterizing their physical properties across cosmic history. This effort is crucial for assessing their contribution to the cosmic star formation history and for building representative samples to investigate the physics of star formation and feedback, nebular ionization conditions, chemical enrichment, and the early development of black hole activity in low-mass galaxies.

In this context, CEFCA seeks a postdoctoral researcher to carry out ambitious research on one or more of the following topics:
- Star formation histories of EELGs and physical processes fueling and regulating star formation in low-mass systems.
- Emission-line diagnostics relevant to ionizing-photon production and escape and their implications for reionization-era galaxies.
- Chemical abundances and fundamental relations (e.g. mass–metallicity–SFR) and their interpretation with chemical evolution models.
- Gas kinematics, turbulence, outflows, and their relation with feedback processes.
- Dust formation and composition in low-metallicity environments.

The researcher will have access to XTREM datasets, including multiwavelength imaging and spectroscopy from JWST, HST, VLT/MUSE, among others. They will also have opportunities to contribute to the J-PAS survey and to participate in major international collaborations such as JWST/VENUS and CAPERS, as well as future observing programs with large telescopes led by the team.

The appointee will work within the group of Dr. Ricardo Amorín (PI of XTREM), in close collaboration with Dr. Juan A. Fernández Ontiveros (PI of BARMASS), and will take part in all BARMASS and XTREM activities, including regular working visits to collaborators at IAA-CSIC and to international partner institutions. The position is based at CEFCA’s headquarters in Teruel, Spain. In addition to salary and equipment, funding will be provided for participation in national and international conferences and workshops.

CEFCA in a nutshell
CEFCA is a research institution located in Teruel, Spain, in charge of the operation, data management and scientific exploitation of the Observatorio Astrofísico de Javalambre (OAJ), an astronomical facility specifically suited for carrying out large astronomical surveys with very large field-of-view (FoV) telescopes: the 2.5m Javalambre Survey Telescope (JST250; 3deg diameter FoV) and the 83cm Javalambre Auxiliary Survey Telescope (JAST80; 2deg diameter FoV).

JST250 is equipped with JPCam, a ~1.2Mpix panoramic camera consisting of a mosaic of 14 CCDs of ~9.2k x 9.2kpix. The JPCam/JST250 system provides a 4.1 deg2 FoV and hosts a complete new set of 54 filters of ~140A width, covering the whole optical spectral range plus two broader filters at the blue and red ends. In the coming years, JPCam/JST250 will be primarily devoted to carry out the Javalambre Physics of the accelerating Universe Astrophysical Survey (J-PAS), which will produce photo-spectra of hundreds of millions of astronomical objects with wide-ranging applications in astrophysics and cosmology.

JAST80 is equipped with the panoramic camera T80Cam, hosting one CCD identical to those in JPCam. The T80Cam/JAST80 system provides an effective FoV of 2 deg2. Since 2016, it is primarily dedicated to conducting the Javalambre Photometric Local Universe Survey (J-PLUS), whose third data release (~ 3200deg2) was made public in December 2022.

The OAJ is a Spanish ICTS (Unique Scientific and Technical Infrastructure). As such, CEFCA offers 20% of OAJ Open Time to competitive PI-led projects, including Legacy Surveys with JAST80. In addition, CEFCA is a leading node of the Ground Segment OU-EXT of the ESA Euclid mission. JPCam@JST250 will conduct the Javalambre–Euclid Deep Imaging Survey in the g-band (JEDIS-g) in the coming years.

CEFCA is also a core institution of the ARRAKIHS consortium, the first F-class ESA space mission led by a Spanish institution. The mission ARRAKIHS (Analysis of Resolved Remnants of Accreted galaxies as a Key Instrument for Halo Surveys) aims to test our current understanding about dark matter by observing a hundred Milky Way-like galaxies reaching unprecedented low-surface brightness limit, sufficient to detect the faint tidal tails predicted by current galaxy formation theories.

The OAJ data are reduced, calibrated, and released by the Data Processing and Archiving Department (DPAD) at CEFCA. In addition, the data from the main CEFCA surveys, such as J-PAS and J-PLUS, are validated and scientifically exploited by members of the Research Area at CEFCA.

Valuable Skills and Experience
- Experience in the analysis of spectroscopic datasets; prior experience with JWST and/or HST data will be considered an asset.
- Background in chemical abundances, the physics of dust and gas, and the star formation history of galaxies will be highly valuable.
- Previous work on extreme emission-line galaxies (EELGs) is not mandatory, but will be regarded as a plus.

Evaluation process
Applications will be evaluated by a committee composed of several CEFCA members and the PIs of BARMASS and XTREM. Candidates will first be assessed based on their CVs, research statements, and reference letters. Shortlisted candidates will then be invited for a final interview. Recognizing the impact of family leaves on scientific careers—including maternity, paternity, adoption, or caregiving for family members with serious health conditions—properly documented family leaves will be duly taken into account during the evaluation process.

CEFCA strongly encourages applications from women and underrepresented minorities.

Terms and conditions
Education: Applicants should hold a PhD in Physics/Astronomy or equivalent.
Languages: Fluent in English.
Work Place: CEFCA Headquarters, Teruel, Spain.
Contract Duration: The appointment is for up to 2 years, concluding no later than December 31, 2027.
Salary: Depending on the level of experience of the candidate.
Deadline: November 9th, 2025 (14:00 CET).
Applications: In order to be considered, the applications should include:: 1) a CV; 2) a brief research statement related to the topic of this project (4 pages maximum); and 3) two reference letters, to be submitted via email (Subject: "Ref.0138.Postdoc BARMASS/XTREM”) to jobs@cefca.es by the aforementioned deadline. The letters should be directly submitted to the email address by the referees.

For additional information, please contact Dr. Ricardo Amorín (ramorin [at] cefca.es), or Dr. Juan A. Fernández Ontiveros (jafernandez [at] cefca.es).