Galaxies with Wolf-Rayet signatures in the low-redshift Universe. A survey using the Sloan Digital Sky Survey
By J. Brinchmann, D. Kunth, F. L. Observatory, Caup, Iap. 2008
176 citations recorded by the source corpus.
Context. The availability of large spectroscopic datasets has opened up the possibility of constructing large samples of rare objects in a systematic manner. Aims. The goal of this study is to analyse the properties of galaxies showing Wolf-Rayet features in their optical spectrum using spectra from the Sloan Digital Sky Survey Release 6. With this unprecedentedly large sample we aim to constrain the properties of the Wolf-Rayet phase and its impact on the surrounding interstellar medium. Methods. We carried out very careful continuum subtraction on all galaxies with equivalent widths of H$\beta>2$ A in emission and identify Wolf-Rayet features using a mixture of automatic and visual classification. We combined this with spectroscopic and photometric information from the SDSS and derive metal abundances using a number of methods. Results. We find a total of 570 galaxies with significant Wolf-Rayet (WR) features and a further 1115 potential candidates, several times more than even the largest heterogeneously assembled catalogues. We discuss in detail the properties of galaxies showing Wolf-Rayet features with a focus on their empirical properties. We are able to accurately quantify the incidence of Wolf-Rayet galaxies with metal abundance and show that the likelihood of otherwise similar galaxies showing Wolf-Rayet features increases with increasing metallicity, but that WR features are found in galaxies of a wide range in morphology. The large sample allows us to show explicitly that there are systematic differences in the metal abundances of WR and non-WR galaxies. The most striking result is that, below EW (${\rm H}\beta$) = 100 A, Wolf-Rayet galaxies show an elevated N/O relative to non-WR galaxies. We interpret this as a rapid enrichment of the ISM from WR winds. We also show that the model predictions for WR features strongly disagree with the observations at low metallicity; while they do agree quite well with the data at solar abundances. We discuss possible reasons for this and show that models incorporating binary evolution reproduce the low-metallicity results reasonably well. Finally we combine the WR sample with a sample of galaxies with nebular He ii $\lambda 4686$ to show that, at $12 + \log {\rm O/H}< 8$, the main sources of He ii ionising photons appears to be O stars, arguing for a less dense stellar wind at these metallicities, while at higher abundances WN stars might increasingly dominate the ionisation budget.
Subfields: Astronomy and Astrophysics, Instrumentation
View Paper: https://www.semanticscholar.org/paper/ca7ab2f35436da754e6edb4446238fb8748b87f8
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Citations in the corpus
- PHYSICAL CONDITIONS IN A YOUNG, UNREDDENED, LOW-METALLICITY GALAXY AT HIGH REDSHIFT (2010, methodology): “…weak emission in the composite shown in Figure 9 has equivalent width W0 ∼ 0.6 Å, and He II emission is clearly seen in the composite spectrum of z ∼ 3 Lyman break galaxies analyzed by Shapley et al. (2003), with W0 = 1.3 ± 0.3 Å (as measured by Brinchmann et al. 2008b) and FWHM ∼ 1500 km s−1 .”
- THEORETICAL EVOLUTION OF OPTICAL STRONG LINES ACROSS COSMIC TIME (2013, background): “The broad He II feature has been attributed to a significant contribution from O and Wolf-Rayet stars to the ionizing EUV radiation field at low metallicity (Brinchmann et al. 2008a).”
- EVIDENCE FOR PopIII-LIKE STELLAR POPULATIONS IN THE MOST LUMINOUS Lyα EMITTERS AT THE EPOCH OF REIONIZATION: SPECTROSCOPIC CONFIRMATION (2015, background): “Thus, so far, not a single source has been found with high EW Lyα, HeII detection with high EW, no AGN signatures, no WR star signatures (e.g. P-Cygni profiles, broad lines, and many other metal lines e.g. Brinchmann et al. 2008) and with no other metal lines.”
- DWARF GALAXIES WITH OPTICAL SIGNATURES OF ACTIVE MASSIVE BLACK HOLES (2013, methodology): “WR stars are identified in the integrated spectra of galaxies by the blended emission from helium, carbon and nitrogen at λ4650 − 4690 known as the “WR bump” and this feature is only detected in four of our broad-line AGN candidates by Brinchmann et al. (2008)7.”
- PHYSICAL PROPERTIES OF EMISSION-LINE GALAXIES AT z ∼ 2 FROM NEAR-INFRARED SPECTROSCOPY WITH MAGELLAN FIRE (2014, background): “…on average, in galaxies at high redshift, possibly as a result of higher nebular electron densities, harder ionizing radiation fields, different gas volume filling factors, or some combination of these (Shapley et al. 2005; Brinchmann et al. 2008b; Shirazi et al. 2013; Kewley et al. 2013a,b).”
- Quasar feedback and the origin of radio emission in radio-quiet quasars (2014, background): “This feature is somewhat reminiscent of the broad emission signatures of Wolf-Rayet stars (Brinchmann et al. 2008; Liu et al. 2009) – massive young stars which can radiatively drive outflows from their photospheres with velocities reaching 2000 km/sec.”
- Kiloparsec-scale outflows are prevalent among luminous AGN: outflows and feedback in the context of the overall AGN population (2014, background): “J1216+1417 Spectroscopy of J1216+1417 has previously identified Wolf-Rayet stars are located in this source and consequently shows thata recent star formation episode has occurred (i.e.,≈ 2–5 Myrs; Brinchmann et al. 2008).”