[Paper Review] F-VIPGI: a new adapted version of VIPGI for FORS2 spectroscopy. Application to a sample of 16 X-ray selected galaxy clusters at 0.6 < z < 1.2

A. Nastasi, M. Scodeggio+6 more|arXiv (Cornell University)|Feb 1, 2013

Galaxies: Formation, Evolution, Phenomena39 references3 citations

TL;DR

This paper introduces F-VIPGI, a new pipeline adapted for FORS2 spectroscopy that accelerates data reduction by a factor of ~10 compared to IRAF, enabling efficient analysis of 16 high-redshift X-ray-selected galaxy clusters (0.6 ≤ z ≤ 1.2). The study reveals that passive cluster galaxies at z ~ 0.8 are more evolved than field galaxies at similar redshift, suggesting accelerated evolution in dense environments, though mass may also play a key role.

ABSTRACT

Author: Nastasi, A. et al.; Genre: Journal Article; Issued: 2013-02; Title: F-VIPGI: a new adapted version of VIPGI for FORS2 spectroscopy - application to a sample of 16 X-ray selected galaxy clusters at 0.6 ≤ z ≤ 1.2

Motivation & Objective

• To develop F-VIPGI, a new pipeline tailored for FORS2 spectroscopic data to improve reduction efficiency.
• To analyze the spectro-photometric properties of galaxies in 16 distant X-ray-selected galaxy clusters at 0.6 ≤ z ≤ 1.2.
• To compare the composite spectra of passive galaxies in high-redshift clusters with those in the field and in local clusters like Coma.
• To assess whether environmental density or galaxy mass is the dominant driver of accelerated galaxy evolution.

Proposed method

• Adapted the VIPGI pipeline for FORS2 data using standard instrument configurations.
• Applied F-VIPGI to reduce optical spectra of member galaxies in 16 X-ray-selected clusters from the XMM-Newton Distant Cluster Project.
• Performed spectral index analysis on extracted spectra to create high signal-to-noise composite templates for passive and star-forming galaxies.
• Stacked individual spectra to generate high-quality spectral templates representative of galaxy populations in distant clusters.
• Compared the photometric properties (e.g., (U−B) colors, H-band luminosities) of the composite templates with those of local Coma Cluster galaxies.
• Used the library of composite spectra to investigate evolutionary trends across cosmic time and environments.

Experimental results

Research questions

• RQ1 How does the F-VIPGI pipeline improve the efficiency and accuracy of FORS2 spectroscopic data reduction compared to standard IRAF methods?
• RQ2 Are passive galaxies in high-redshift clusters (z ~ 0.8) more evolved than their field counterparts at similar redshift?
• RQ3 How do the spectro-photometric properties of passive galaxies in distant clusters compare to those of local cluster galaxies, such as in the Coma Cluster?
• RQ4 To what extent is the observed evolution in cluster galaxies driven by environmental density versus intrinsic galaxy mass?
• RQ5 Do the (U−B) colors and H-band luminosities of star-forming galaxies in high-redshift clusters match those of local cluster galaxies?

Key findings

• F-VIPGI reduces FORS2 spectroscopic data reduction time by a factor of approximately 10 compared to standard IRAF procedures.
• The stacked optical spectra of passive galaxies in distant clusters (z ~ 0.8) show signs of advanced evolutionary status, indicating they are more evolved than field galaxies at similar redshift.
• The (U−B) colors of passive galaxies in high-redshift clusters are consistent with those of local Coma Cluster galaxies, suggesting that stellar mass assembly was largely complete by z ~ 0.8.
• Star-forming galaxies at z ≥ 0.65 are significantly more luminous in the H band than their local counterparts, possibly due to downsizing or selection bias.
• The similarity between the composite passive spectrum of distant clusters and luminous red galaxy templates at intermediate redshift supports the role of mass in galaxy evolution.
• Despite environmental effects, the study cannot exclude mass as a primary driver of galaxy evolution, as the composite spectra resemble those of massive, evolved systems.