Towards DIB mapping in galaxies beyond 100 Mpc

Abstract

Context. Diffuse interstellar bands (DIBs) are non-stellar weak absorption features of unknown origin found in the spectra of stars viewed through one or several clouds of the interstellar medium (ISM). Research of DIBs outside the Milky Way is currently very limited. In particular, spatially resolved investigations of DIBs outside of the Local Group are, to our knowledge, inexistent. Aims. In this contribution, we explore the capability of the high-sensitivity integral field spectrograph, MUSE, as a tool for mapping diffuse interstellar bands at distances larger than 100 Mpc. Methods. We used MUSE commissioning data for AM 1353-272 B, the member with the highest extinction of the Dentist's Chair, an interacting system of two spiral galaxies. High signal-to-noise spectra were created by co-adding the signal of many spatial elements distributed in a geometry of concentric elliptical half-rings. Results. We derived decreasing radial profiles for the equivalent width of the λ5780.5 DIB both in the receding and approaching side of the companion galaxy up to distances of ∼4.6 kpc from the centre of the galaxy. The interstellar extinction as derived from the Hα/Hβ line ratio displays a similar trend, with decreasing values towards the external parts. This translates into an intrinsic correlation between the strength of the DIB and the extinction within AM 1353-272 B, consistent with the currently existing global trend between these quantities when using measurements for Galactic and extragalactic sightlines. Conclusions. It seems feasible to map the DIB strength in the Local Universe, which has up to now only been performed for the Milky Way. This offers a new approach to studying the relationship between DIBs and other characteristics and species of the ISM in addition to using galaxies in the Local Group or sightlines towards very bright targets outside the Local Group.

Diffuse interstellar bands λ5780 and λ5797 in the Antennae Galaxy as seen by MUSE

“…The figure is similar to Fig. 4 by Monreal-Ibero et al (2015b), but with the new data for the Antennae Galaxy overplotted. It illustrates beautifully the enormous potential of IFSs for extragalactic DIB research: passing from a few tens to a few hundreds of extragalactic measurements of the λ5780 DIB was possible by adding only one set of observations.…”

“…For the Antennae Galaxy data, a Galactic reddening E(B − V) gal = 0.041 has been subtracted. Regarding the data for other galaxies, we included two sets of observations for Galactic targets (blue triangles; filled: Puspitarini et al (2013), open: Friedman et al (2011), several sets of data for galaxies in the Local Group (inverted salmon triangles: Magellanic Clouds (Welty et al 2006); filled burgundy "x": M 31 (Cordiner et al 2011), open burgundy "x": M 33 (Cordiner et al 2008)), a set of measurements through dusty starbursts (black diamonds, Heckman & Lehnert (2000)), some measurements in the lines of sight of supernovae (filled blue crosses, Phillips et al 2013), including one in M 82 (coral pink pentagon, Welty et al 2014) and our previous results for AM 1353-272 B (red circles and blue stars, Monreal-Ibero et al 2015b). This is summarised in Fig.…”

“…Integral field spectrographs (IFSs) constitute a special case of this kind of instrumentation where this information is recorded in an extended continuous field. In Monreal-Ibero et al (2015b), we proposed the use of high-sensitivity IFSs as a tool to detect and map DIBs outside the Local Group. The experiment, conducted using the Multi Unit Spectroscopic Explorer (MUSE) commissioning data, led to the first determination of a DIB radial profile in a galaxy outside the Local Group.…”

Near-infrared diffuse interstellar bands in APOGEE telluric standard star spectra

“…A DIB radial gradient was established for the first time in a 160 Mpc distant galaxy (Monreal-Ibero et al 2015). Carbon is involved in most of the proposed candidates for DIB carriers in the form of hydrocarbon chains (e.g., Maier et al 2004), polycyclic aromatic hydrocarbons (PAHs, e.g., van der Zwet & Allamandola 1985; Leger & D'Hendecourt 1985;Crawford et al 1985;Salama et al 1996;Kokkin et al 2008), and/or fullerenes (Iglesias-Groth 2007; Sassara et al 2001).…”

A CATALOG OF 1.5273 μm DIFFUSE INTERSTELLAR BANDS BASED ON APOGEE HOT TELLURIC CALIBRATORS

“…Still, they have also been detected in the Magellanic clouds, M31 and M33 (Ehrenfreund et al 2002;Welty et al 2006;Cordiner et al 2008aCordiner et al , 2008bCordiner et al , 2011van Loon et al 2013) and in a few line of sights toward e.g., starburst galaxies or in SNe Ia spectra (Sollerman et al 2005;Cox & Patat 2008;Heckman & Lehnert 2000;Phillips et al 2013). Recently a DIB gradient was established for the first time in a 160 Mpc distant galaxy (Monreal-Ibero et al 2015).…”