Issue |
A&A
Volume 613, May 2018
|
|
---|---|---|
Article Number | A1 | |
Number of page(s) | 19 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361/201732185 | |
Published online | 15 May 2018 |
Validity of abundances derived from spaxel spectra of the MaNGA survey
1
The International Center of Future Science of the Jilin University,
2699 Qianjin St.,
130012
Changchun,
PR China
2
Main Astronomical Observatory,
National Academy of Sciences of Ukraine,
27 Akademika Zabolotnoho St,
03680
Kiev,
Ukraine
e-mail: pilyugin@MAO.Kiev.UA
3
Astronomisches Rechen-Institut,
Zentrum für Astronomie der Universität Heidelberg,
Mönchhofstr. 12–14,
69120
Heidelberg,
Germany
4
Kazan Federal University,
18 Kremlyovskaya St.,
420008
Kazan,
Russian Federation
5
Institut of Radio Astronomy of National Academy of Sciences of Ukraine,
4 Mystetstv str.,
61002
Kharkov,
Ukraine
6
College of Physics,
The Jilin University,
2699 Qianjin St.,
130012
Changchun,
PR China
Received:
27
October
2017
Accepted:
27
November
2017
We measured the emission lines in the spaxel spectra of Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) galaxies in order to determine the abundance distributions therein. It has been suggested that the strength of the low-ionization lines, R2, N2, and S2, may be increased (relative to Balmer lines) in (some) spaxel spectra of the MaNGA survey due to a contribution of the radiation of the diffuse ionized gas. Consequently, the abundances derived from the spaxel spectra through strong-line methods may suffer from large errors. We examined this expectation by comparing the behaviour of the line intensities and the abundances estimated through different calibrations for slit spectra of H II regions in nearby galaxies, for fibre spectra from the Sloan Digital Sky Survey, and for spaxel spectra of the MaNGA survey. We found that the S2 strength is increased significantly in the fibre and spaxel spectra. The mean enhancement changes with metallicity and can be as large as a factor of ~2. The mean distortion of R2 and N2 is less than a factor of ~1.3. This suggests that Kaufmann et al.’s (2003, MNRAS, 346, 1055) demarcation line between active galactic nuclei and H II regions in the Baldwin, Phillips, & Terlevich (BPT, 1981, PASP, 93, 5) diagram is a useful criterion to reject spectra with significantly distorted strengths of the N2 and R2 lines. We find that the three-dimensional R calibration, which uses the N2 and R2 lines, produces reliable abundances in the MaNGA galaxies. The one-dimensional N2 calibration produces either reliable or wrong abundances depending on whether excitation and N/O abundance ratio in the target region (spaxel) are close to or differ from those parameters in the calibrating points located close to the calibration relation. We then determined abundance distributions within the optical radii in the discs of 47 MaNGA galaxies. The optical radii of the galaxies were estimated from the surface brightness profiles constructed based on the MaNGA observations.
Key words: galaxies: abundances / galaxies: ISM / galaxies: spiral
© ESO 2018
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.