A search for double-peaked narrow emission line galaxies and AGNs in the LAMOST DR1

Abstract

LAMOST has released more than two million spectra, which provide the opportunity to search for double-peaked narrow emission line (NEL) galaxies and AGNs. The double-peaked narrow-line profiles can be well modeled by two velocity components, respectively blueshifted and redshifted with respect to the systemic recession velocity. This paper presents 20 double-peaked NEL galaxies and AGNs found from LAMOST DR1 using a search method based on multi-gaussian fit of the narrow emission lines. Among them, 10 have already been published by other authors, either listed as genuine double-peaked NEL objects or as asymmetric NEL objects, the remaining 10 being first discoveries. We discuss some possible origins for double-peaked narrow-line features, as interaction between jet and narrow line regions, interaction with companion galaxies and black hole binaries. Spatially resolved optical imaging and/or follow-up observations in other spectral bands are needed to further discuss the physical mechanisms at work.

The quest for dual and binary supermassive black holes: A multi-messenger view

“…Other high-ionization lines, such as [NeV] λ3426 or [NeIII] λ3869, can be be used in a similar way in the higherredshift sources. High-ionization double-peaked emission lines have been identified serendipitously in individual sources (Gerke et al, 2007;Xu and Komossa, 2009;Barrows et al, 2012;Benítez et al, 2013) or through systematic studies of large spectroscopic databases such as SDSS (Wang et al, 2009;Smith et al, 2010;Liu et al, 2010b;Pilyugin et al, 2012;Ge et al, 2012;Barrows et al, 2013;Lyu and Liu, 2016), LAMOST (Shi et al, 2014) or DEEP2 and AGES (Comerford et al, 2013). Those systematic studies revealed that roughly one per cent of the AGN population exhibit double peaks in the forbidden highionization lines.…”

The Nature of Active Galactic Nuclei With Velocity Offset Emission Lines*

“…When one or both SMBHs power AGNs, the systems are known as offset AGNs and dual AGNs,respectively. 4 During the past few years, dual AGN candidates have been identified spectroscopically as galaxies with double-peaked narrow AGN emission lines (Comerford et al 2009;Wang et al 2009;Liu et al 2010;Smith et al 2010;Ge et al 2012;Barrows et al 2013;Comerford et al 2013;Shi et al 2014), and confirmations have been produced through follow-up observations at either radio or X-ray wavelengths (Komossa et al 2003;Fu et al 2011b;Koss et al 2011Koss et al , 2012Mazzarella et al 2012;Liu et al 2013;Comerford et al 2015;Müller-Sánchez et al 2015). However, these double peaks can also be produced by AGN-driven outflows and/or a rotating narrow line region (NLR; e.g., Heckman et al 1981;Crenshaw et al 2010).…”

Double-peaked narrow emission-line galaxies in LAMOST survey

“…Among these, 188 objects exhibit a clear "trough" in their profiles, while the other 137 ones show obvious asymmetric features. Figure 1 displays Wang et al 2009;Liu et al 2010;Smith et al 2010;Ge et al 2012) and one relevant searching work based on LAMOST DR1 dataset (see Shi et al 2014). Samples in this paper has already excluded the overlapping 20 objects presented by Shi.…”