S7

The Siding Spring Southern Seyfert Spectroscopic Snapshot Survey

Data Release 2 (Aug 2017)

The full and final S7 data release, DR2, is now available. This data release includes all data cubes, nuclear spectra, and line fitting products. The data may be obtained from https://miocene.anu.edu.au/S7/Data_release_2

Data Release 1a (Mar 2016)

The LZIFU reduction of the cubes in to emission line flux components ( as fits files with extensions) are now available. These are based on the Data Release 1 data. The files are at: https://miocene.anu.edu.au/S7/Data_release_1

This data release provides the multi-component emission line fits associated with the datacubes from Data Release 1a (galaxies observed prior to 2016).

The emission line information is stored in multiple-extension fits files. These fits files were produced using the line-fitting code LZIFU (see Ho et al. 2014) and an artificial neural network called The Machine (Hampton et al., in prep). LZIFU uses pPXF (Cappellari & Emsellem 2004) to subtract the stellar continuum and then uses MPFIT (Markwardt 2009) to fit each emission line spectrum with 1, 2 and 3 Gaussian emission line components. The Machine then takes the 1, 2 and 3 component fits and determines how many components are required for each spectrum. During the emission line fitting process the fluxes for [NII]6548 are constrained to be one third of the fluxes for [NII]6583, and the fluxes for [OIII]4959 are constrained to be one third of the fluxes for [OIII]5007 (based on expectations from quantum mechanics).

Each LZIFU fits file contains 45 extensions. These extensions contain information about the emission-line fluxes and errors, the stellar and gas kinematics and the shape of the stellar continuum. The most relevant extensions are those named for an emission line, e.g. "HALPHA" and "HALPHA_ERR". The data for MOST of the emission line extensions are arranged in 25×38×4 cubes. The 0th 25×38 slice contains the total flux for the emission line in each of the 25×38 WiFeS spaxels. The 1st(2nd(3rd)) 25×38 slice contains the emission line fluxes for the 1st(2nd(3rd)) kinematic component.

In general, we do not have sufficient S/N to constrain the relative intensities of the individual kinematic components in [OII]3726,3729 or [OIII]4363. The flux and err data for these emission lines are each arranged in a single 25×38 image (instead of a 25×38×4 cube), and this image contains the total flux or error of the relevant line in each spaxel. Hbeta is also generally too weak to allow us to constrain the relative intensities of the individual kinematic components, but instead of providing only the total Hbeta flux in each spaxel, we re-distribute the total Hbeta flux into components in the same ratio as the Halpha flux components. This ensures that the Balmer decrement is consistent across all kinematic components within each spaxel.

We are unable to model the true shapes of the Balmer line profiles when a significant fraction of the emission line flux is contained within a Seyfert 1 broad component. In these spaxels, only the total flux is reported for Halpha and Hbeta.

Data Release 1 (Jan 2015)

Public Data Release 1 is available at https://miocene.anu.edu.au/S7/Data_release_1

About the Survey

The Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7) present results on 64 galaxies drawn from the first data release. The S7 uses the Wide Field Spectrograph (WiFeS) mounted on the ANU 2.3m telescope located at the Siding Spring Observatory to deliver an integral field of 38×25 arcsec at a spectral resolution of R = 7000 in the red (530−710nm), and R = 3000 in the blue (340 − 560nm). From these data cubes we have extracted the Narrow Line Region (NLR) spectra from a 4 arc sec aperture centred on the nucleus. We also determine the Hβ and [O III] λ5007 fluxes in the narrow lines, the nuclear reddening, the reddening-corrected relative intensities of the observed emission lines, and the Hβ and [O III] λ5007 luminosities determined from spectra for which the stellar continuum has been removed.

The S7 survey is by no means a complete survey of southern Seyfert, LINERs and other active galaxies but rather, offers a reasonably representative sample of radio-detected AGN in the nearby universe. The objects for the S7 were selected from the Véron-Cetty & Véron (2006) catalogue of active galaxies, which remains the most comprehensive compilation of active galaxies in the literature. Since, in the future, we wish to investigate the interaction of the bipolar plasma jets with the Narrow Line Region and the ISM of the host galaxy, we limited the sample to galaxies with radio flux densities high enough to permit radio aperture synthesis observations.

We adopted the following selection criteria:

Declination < 10° to avoid observations being made at too great a zenith distance. At a zenith distance of 60 degrees, the atmospheric dispersion between 3500 and 7000 Å is nearly 6 arcsec,which would seriously compromise the effective field coverage.
Galactic latitude > |20| degrees (with a few exceptions in the case of objects known to have an associated ENLR ). This galactic latitude requirement is set to avoid excessive galactic extinction.
Radio flux density at 20cm > 20mJy for those targets with declination N of -40°, which have NVSS measurements, and
Redshift < 0.02. This criterion (D < 80 Mpc) ensures that the spatial resolution of the data is better than 400 pc per arcsec, sufficient to resolve the ENLR, and to ensure that the important diagnostic [S II] lines are still within the spectral range of the WiFeS high-resolution red grating.

Publications

The survey has generated these recent publications:

Paper to appear in the proceedings of IAU Symposium 309 : "S7 : Probing the physics of Seyfert Galaxies through their ENLR & HII Regions", Proceedings IAU Symposium No. 309, 2014 :
S7_iau309.pdf
Paper accepted for publication ApJS : "Probing the Physics of Narrow Line Regions in Active Galaxies II: The Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7)" :
S7_survey.pdf
Paper III accepted for publication ApJ : "Probing the Physics of Narrow Line Regions in Active Galaxies III: Accretion and Cocoon Shocks in the LINER NGC 1052" :
S7_ApJ97168_v2.pdf

All S7 publications can be found in the Publications area.

Sample Images from the Survey

These images of Seyfert Galaxies courtesy of the Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7) They are all obtained with the Wide Field Spectrograph (WiFeS) an integral field unit mounted on the ANU 2.3m telescope. The field is 25x38 arcsec.

Blue represents emission in [O III], green [N II] and red, H-alpha emission. These distinguish the mode of excitation of the gas. Star forming regions appear red, orange or yellow. Regions ionised by the central Active Galactic Nucleus appear purple, blue or even green.

The S7 aims to map these Extended Narrow Line Regions (ENLR). (Also available as a PDF download)