Exploring the Dust Content of Galactic Winds with Herschel:

Nearby Dwarf Galaxies Galactic-scale winds manifest as the "smoking gun" of negative feedback, an essential

mechanism for understanding galaxy

evolution. Negative feedback has been

invoked to resolve a number of issues: the

mass-metalicity relation of star-forming galaxies, the tight bulge - black hole mass

relation, and the presence of metals in galaxy

halos and the intergalactic and intracluster

media. Although negative feedback may assert

even greater influence at high redshift, where strong starbursts and active galactic nuclei are

more commonplace, nearby sources provide

the best opportunities for detailed observations

of the resultant winds. In recent years, observations have begun to illuminate the less

obvious components of galactic-scale winds,

including dust and molecular gas. Investigating the spatial distribution and properties of the

dust in concert with host galaxy characteristics

gives insight into the physics of dust

entrainment, outflow energetics, and why the

dust survives far outside the host galaxy. We present results from new, deep Herschel

observations of several nearby dwarf galaxies

with known galactic-scale winds. We are

comparing flux measurements and the spatial

distribution of cold dust in the outflows with star formation properties of the host galaxies.

We a re a l so compar ing these new

observations with archival Spitzer and previous

H-alpha observations.

McCormick, Alexander (UMD); Veilleux, Sylvain (UMD); Melendez, Marcio (UMD);

Bland-Hawthorn, Joss (Univ. of Sydney); Cecil, Gerald (UNC); Engelbracht, Chad

(U of A); Heitsch, Fabian (UNC); Martin, Crystal L. (UCSB); Müller, Thomas (MPE);

Rupke, David (Rhodes College); Sturm, Eckhard (MPE); Trippe, Margaret (JHU

Applied Physics Laboratory); Zastrow, Jordan (UMich)

REFERENCES: Bendo et al. 2012, MNRAS, 423, 197; 4Dalcanton et al. 2009, ApJS, 183, 67; Draine 2003, ARA&A, 41, 241; 2Grocholski et al. 2008, ApJ,

686, L79; Martin 1998, ApJ, 506, 222; McCormick et al. 2013, ApJ, 774, 126; Roussel 2013, PASP, 125, 1126; 5Sakai et al. 2004, ApJ, 608, 42; 3Tosi et al.

2001, AJ, 122, 1271; 1Tully 1988, Nearby Galaxies Catalogue

H! IRAC 4.5 µm IRAC 8.0 µm

MIPS 24 µm PACS 70 µm PACS 160 µm

SPIRE 250 µm SPIRE 350 µm SPIRE 500 µm

Comparing NGC 1569 H! (Martin 1998), Spitzer IRAC 4.5 and

8.0 µm (McCormick et al. 2013), Spitzer MIPS 24 µm (Bendo et al. 2012), Herschel

PACS 70 and 160 µm, and SPIRE 250,

350, and 500 µm (this work). The Herschel

maps were made with the Scanamorphos

software (Roussel 2013). All images are displayed with a logarithmic scale. North is

up and East is to the left in all images,

each of which covers ~ 5’ x 7’.

Alex McCormick is a graduate student in the

Department of Astronomy at the University of Maryland,

College Park (UMD).

Contact him here:

alexm@astro.umd.edu

Artist concept of the

Herschel Space Observatory

ESA / AOES Medialab

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NGC 1569: PACS 70 µm / 160 µm This ratio map of the 70 µm and 160 µm Herschel

PACS bands provides a rough picture of the dust temperature distribution. The ratio map was limited

to pixels where the 160 µm band had values > 1e-3

Jy/pixel. North is up and East is left.

Global SED Fit ! Dust Mass & Temperature We determined the global galaxy dust mass and temperature by fitting

a single modified black body to the PACS and SPIRE flux measurements. We used the modified black body shown above,

where Md is the global dust mass, "# is the dust emissivity:

"# = "0 (# / #0 )$ where "0 is the dust opacity at 350 µm, 0.192 m2 kg-1

(Draine 2003). Md, Td, and $ are the free parameters in the fit.

Nearby Dwarf Galaxy Sample & Observations We obtained 70 and 160 µm PACS image data as well as 250, 350,

and 500 µm SPIRE image data from the Herschel Space Observatory:

Galaxy Distance (Mpc) PACS (hrs) SPIRE (s) He 2-10 10.51 6.56 *

NGC 1569 3.42 6.56 *

NGC 1705 5.13 6.56 *

NGC 1800 7.41 6.56 583

NGC 3077 3.84 8.74 * NGC 5253 3.85 8.74 *

1,2,3,4,5 please see References below.

* used publicly available SPIRE data.

ACKNOWLEDGEMENTS Support for this work was provided by

NASA through Herschel contracts

1427277 and 1454738 (S.V. and M.M.)

Herschel is an ESA space observatory with science instruments provided by

European-led Principle Investigator

consortia and with important

participation from NASA.!

In Progress •! Pixel-by-pixel

SED fits!•! Galactic wind

dust mass and

temperature

versus Global

dust mass and temperature

•! Comparison with

galaxy properties

1’

(µm)