TY - JOUR
T1 - The less significant role of large-scale environment than optical AGN in nearby, isolated elliptical galaxies
AU - Lacerna, I.
AU - Argudo-Fernández, M.
AU - Duarte Puertas, S.
N1 - Funding Information:
Acknowledgements. We thank the anonymous referee for the constructive revision of our paper. IL acknowledges partial financial support from PROYECTO FONDECYT REGULAR 1150345. MAF is grateful for financial support from the CONICYT Astronomy Program CAS-CONICYT project No. CAS17002 and from CONICYT FONDECYT project No. 3160304. SDP acknowledges financial support from the Spanish Ministerio de Economía y Competitividad under grant AYA2013-47742-C4-1-P, AYA2017-79724-C4-4-P from the Spanish PNAYA, and from Junta de Andalucía Excellence Project PEX2011-FQM-7058. This research made use of astropy, a community-developed core python (http://www.python.org) package for Astronomy (Astropy Collaboration 2013); ipython (Pérez & Granger 2007); matplotlib (Hunter 2007); numpy (Walt et al. 2011); pandas (McKinney 2010); and scipy (Jones et al. 2001). Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. Department of Energy Office of Science. The SDSS-III website is http://www.sdss3.org/. SDSS-III is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS-III Collaboration including the University of Arizona, the Brazilian Participation Group, Brookhaven National Laboratory, University of Cambridge, University of Florida, the French Participation Group, the German Participation Group, the Instituto de Astrofisica de Canarias, the Michigan State/Notre Dame/JINA Participation Group, Johns Hopkins University, Lawrence Berkeley National Laboratory, Max Planck Institute for Astrophysics, New Mexico State University, New York University, Ohio State University, Pennsylvania State University, University of Portsmouth, Princeton University, the Spanish Participation Group, University of Tokyo, University of Utah, Vanderbilt University, University of Virginia, University of Washington, and Yale University.
Publisher Copyright:
© ESO 2018.
PY - 2018/12/1
Y1 - 2018/12/1
N2 - Context. The formation and evolution of elliptical galaxies in low-density environments are less understood than classical elliptical galaxies in high-density environments. Isolated galaxies are defined as galaxies without massive neighbors within scales of galaxy groups. The effect of the environment at several Mpc scales on their properties has been barely explored. We study the role of the large-scale environment in 573 isolated elliptical galaxies out to z = 0.08. Aims. We aim to explore whether the large-scale environment affects some of the physical properties of the isolated galaxies studied in this work. Methods. We used three environmental estimators of the large-scale structure within a projected radius of 5 Mpc around isolated galaxies: the tidal strength parameter, projected density η k,LSS , and distance to the fifth nearest neighbor galaxy. We studied isolated galaxies regarding stellar mass, integrated optical g - i color, specific star formation rate (sSFR), and emission lines. Results. We find 80% of galaxies at lower densities correspond to "red and dead" elliptical galaxies. Blue and red galaxies do not tend to be located in different environments according to η k,LSS . Almost all the isolated ellipticals in the densest large-scale environments are red or quenched, of which a third are low-mass galaxies. The percentage of isolated elliptical galaxies located in the active galactic nucleus (AGN) region of the BPT diagram is 64%. We identified 33 blue, star-forming (SF) isolated ellipticals using both color and sSFR. Half of these are SF nuclei in the BPT diagram, which amounts to 5% of the galaxies in this diagram. Conclusions. The large-scale environment does not play the primary role in determining the color or sSFR of isolated elliptical galaxies. The large-scale environment seems to be negligible from a stellar mass scale around 10 10.6 M ⊙ , probably because of the dominant presence of AGN at higher masses. For lower masses, the processes of cooling and infall of gas from large scales are very inefficient in ellipticals. Active galactic nuclei might also be an essential ingredient to keep most of the low-mass isolated elliptical galaxies quenched.
AB - Context. The formation and evolution of elliptical galaxies in low-density environments are less understood than classical elliptical galaxies in high-density environments. Isolated galaxies are defined as galaxies without massive neighbors within scales of galaxy groups. The effect of the environment at several Mpc scales on their properties has been barely explored. We study the role of the large-scale environment in 573 isolated elliptical galaxies out to z = 0.08. Aims. We aim to explore whether the large-scale environment affects some of the physical properties of the isolated galaxies studied in this work. Methods. We used three environmental estimators of the large-scale structure within a projected radius of 5 Mpc around isolated galaxies: the tidal strength parameter, projected density η k,LSS , and distance to the fifth nearest neighbor galaxy. We studied isolated galaxies regarding stellar mass, integrated optical g - i color, specific star formation rate (sSFR), and emission lines. Results. We find 80% of galaxies at lower densities correspond to "red and dead" elliptical galaxies. Blue and red galaxies do not tend to be located in different environments according to η k,LSS . Almost all the isolated ellipticals in the densest large-scale environments are red or quenched, of which a third are low-mass galaxies. The percentage of isolated elliptical galaxies located in the active galactic nucleus (AGN) region of the BPT diagram is 64%. We identified 33 blue, star-forming (SF) isolated ellipticals using both color and sSFR. Half of these are SF nuclei in the BPT diagram, which amounts to 5% of the galaxies in this diagram. Conclusions. The large-scale environment does not play the primary role in determining the color or sSFR of isolated elliptical galaxies. The large-scale environment seems to be negligible from a stellar mass scale around 10 10.6 M ⊙ , probably because of the dominant presence of AGN at higher masses. For lower masses, the processes of cooling and infall of gas from large scales are very inefficient in ellipticals. Active galactic nuclei might also be an essential ingredient to keep most of the low-mass isolated elliptical galaxies quenched.
KW - Galaxies: active
KW - Galaxies: elliptical and lenticular, cD
KW - Galaxies: fundamental parameters
KW - Galaxies: photometry
KW - Galaxies: star formation
UR - http://www.scopus.com/inward/record.url?scp=85058509557&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/201833579
DO - 10.1051/0004-6361/201833579
M3 - Article
AN - SCOPUS:85058509557
VL - 620
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
SN - 0004-6361
M1 - A117
ER -