THREE-DIMENSIONAL INTEGRAL FIELD OBSERVATIONS OF 10 GALACTIC WINDS. I. EXTENDED PHASE (≳10 Myr) OF MASS/ENERGY INJECTION BEFORE THE WIND BLOWS

By R. Sharp, Joss Bland-Hawthorn. 2010

170 citations recorded by the source corpus.

In recent years, we have come to recognize the widespread importance of large-scale winds in the life cycle of galaxies. The onset and evolution of a galactic wind is a highly complex process which must be understood if we are to understand how energy and metals are recycled throughout the galaxy and beyond. Here we present three-dimensional spectroscopic observations of a sample of 10 nearby galaxies with the AAOmega-SPIRAL integral-field spectrograph on the 3.9 m Anglo-Australian Telescope, the largest survey of its kind to date. The double-beam spectrograph provides spatial maps in a range of spectral diagnostics: [O iii]5007, Hβ, Mg b, Na d, [O i]6300, Hα, [N ii]6583, [S ii]6717, 6731. We demonstrate that these flows can often separate into highly ordered structures through the use of ionization diagnostics and kinematics. All of the objects in our survey show extensive wind-driven filamentation along the minor axis, in addition to large-scale disk rotation. Our sample can be divided into either starburst galaxies or active galactic nuclei (AGNs), although some objects appear to be a combination of these. The total ionizing photon budget available to both classes of galaxies is sufficient to ionize all of the wind-blown filamentation out to large radius. We find, however, that while AGN photoionization always dominates in the wind filaments, this is not the case in starburst galaxies where shock ionization dominates. This clearly indicates that after the onset of star formation, there is a substantial delay (≳10 Myr) before a starburst wind develops. We show why this behavior is expected by deriving “ionization” and dynamical timescales for both AGNs and starbursts. We establish a sequence of events that lead to the onset of a galactic wind. The clear signature provided by the ionization timescale is arguably the strongest evidence yet that the starburst phenomenon is an impulsive event. A well-defined ionization timescale is not expected in galaxies with a protracted history of circumnuclear star formation. Our three-dimensional data provide important templates for comparisons with high-redshift galaxies.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/a618d07cad1fc57361adace76b688cb3abdc5308

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Citations in the corpus

• The Sydney-AAO Multi-object Integral field spectrograph (2011, background): “Indeed, IFS observations of local galaxies with observed outflows demonstrates that the AGN timescale is significantly longer than the starburst timescale (Sharp & Bland-Hawthorn 2010).”
• OVERVIEW OF THE SDSS-IV MaNGA SURVEY: MAPPING NEARBY GALAXIES AT APACHE POINT OBSERVATORY (2014, background): “Resolved maps of the classical Baldwin-PhillipsTerlevich (BPT; Baldwin et al. 1981; Veilleux & Osterbrock 1987) diagram composed of the line ratio [O III]/Hβ versus [N II]/Hα and [S II]/Hα, are a valuable way of distinguishing ionization sources (e.g., Sharp & Bland-Hawthorn 2010).”
• The SAMI Galaxy Survey: shocks and outflows in a normal star-forming galaxy (2014, background): “Sharp & Bland-Hawthorn (2010) use the ionization properties of the wind material to identify the likely source of the ionization.”
• THEORETICAL EVOLUTION OF OPTICAL STRONG LINES ACROSS COSMIC TIME (2013, background): “Extended LINER emission (> 1 kpc) may be produced by shock excitation (Heckman 1980; Ĺıpari et al. 2004; Monreal-Ibero et al. 2006; Sharp & Bland-Hawthorn 2010; Rich et al. 2010, 2011).”
• Galaxy And Mass Assembly (GAMA): Spectroscopic analysis (2013, background): “This ionisation signature may also be more characteristic of shock-excitation than the more prevalent active nucleus driven ionisation in massivegalaxies (Sharp & Bland-Hawthorn 2010; Farage et al. 2010; Rich etal.”
• Galactic winds driven by cosmic ray streaming (2012, background): “…of classic ionization diagnostic diagrams allows us to cleanly separate winds that are driven by either starbursts or active galactic nuclei (AGN; Sharp & Bland-Hawthorn 2010): while AGN photoionization always dominates in the wind filaments, this is not the case in starburst galaxies where…”
• EVIDENCE FOR WIDE-SPREAD ACTIVE GALACTIC NUCLEUS-DRIVEN OUTFLOWS IN THE MOST MASSIVE z ∼ 1–2 STAR-FORMING GALAXIES (2014, background): “…but its broad emission almost certainly is due to a BLR. Combining the constraints, the alternative of pure shock excitation (Dopita & Sutherland 1995; Allen et al. 2008; Rich et al. 2010, 2011; Sharp & Bland-Hawthorn 2010) also seems unlikely in these cases, with the exception of D3a6004.”
• GIANT GAMMA-RAY BUBBLES FROM FERMI-LAT: ACTIVE GALACTIC NUCLEUS ACTIVITY OR BIPOLAR GALACTIC WIND? (2010, background): “AGN or starburst galaxies show bipolar outflows (Gallimore et al. 2006; Sharp & Bland-Hawthorn 2010).”
• THE MULTIPHASE STRUCTURE AND POWER SOURCES OF GALACTIC WINDS IN MAJOR MERGERS (2013, background): “Outflowing warm ionized gas is typically shock-excited in cases where the wind is driven by a starburst alone (Veilleux & Rupke 2002; Sharp & Bland-Hawthorn 2010; Rich et al. 2010), and photoionized by the AGN radiation field in cases where an AGN is also present (Veilleux et al. 2003; Sharp &…”
• GALAXY-WIDE SHOCKS IN LATE-MERGER STAGE LUMINOUS INFRARED GALAXIES (2011, background): “…applied to Integral field spectra (as well as narrow-band and tunable filter data) to investigate emission line gas over entire galaxies or regions of a galaxy to probe the distribution of ionizing sources (e.g. Shopbell & Bland-Hawthorn 1998; Sharp & Bland-Hawthorn 2010; Rich et al. 2010).”
• SDSS IV MaNGA – spatially resolved diagnostic diagrams: a proof that many galaxies are LIERs (2016, background): “However, a large amount of previous investigations using IFS (see for example Rich et al. 2010; Sharp & Bland-Hawthorn 2010; Singh et al. 2013; Davies et al. 2014; Belfiore et al. 2015; Gomes et al. 2015a) have MNRAS 000, 1–22 (2016) paved the way to the realisation that emission line…”