Dust in edge-on spiral galaxies from the J-band of the 2MASS Large Galaxy AtlasDust in edge-on spiral galaxies from the

J-band of the 2MASS Large Galaxy Atlas

Angelos Misiriotis (1) and Manolis Xilouris (2)

(1) University of Crete, Department of physics(2) National observatory of Athens

Motivation(a case for “optical” detection of dust)

Motivation(a case for “optical” detection of dust)

Optical studies are coplementary to FIR observations

Require less exotic equipment Take advantage of huge archaives Constrain the emissivity

Why edge-on ?Why edge-on ?

Image from the 2MASS L.G.A. Jarrett T. H., Chester T., Cutri, R. Schneider, S. E. Huchra, J. P., 2003, AJ, 125, 525

Figure from:Bosma A., Byun Y., Freeman K. C. Athanassoula E., 1992, ApJ, 400, 21

In the J Band (τ ~ 0.1) The edge-on line of sight reaches the center The dust lane is still visible

Why J-band ?Why J-band ?

Why the 2MASS, Large Galaxy Atlas(*)?Why the 2MASS, Large Galaxy Atlas(*)?

(*)Jarrett, T. H.; Chester, T.; Cutri, R.; Schneider, S. E.; Huchra, J. P., 2003AJ....125..525J

Large homogenious sample Easily available Good pilot before spending months for deeper observations

Out of the LGA 28 edge-on galaxies wereselected for this study.

The ModelThe Model

A stellar bulge (de Vaucoulers)

Xilouris E. M., Byun Y. I., Kylafis N. D., Paleologou E. V., Papamastorakis, J., 1999, A&A, 344, 868

The ModelThe Model

A stellar bulge (de Vaucoulers)A stellar exponential disk

Xilouris E. M., Byun Y. I., Kylafis N. D., Paleologou E. V., Papamastorakis, J., 1999, A&A, 344, 868

The ModelThe Model

A stellar bulge (de Vaucoulers)A stellar exponential diskAn exponential dust disk

Xilouris E. M., Byun Y. I., Kylafis N. D., Paleologou E. V., Papamastorakis, J., 1999, A&A, 344, 868

Textbook Cases(7/28 galaxies )

Textbook Cases(7/28 galaxies )

Observation

Model

Passable Cases(8/28 galaxies )

Passable Cases(8/28 galaxies )

Impossible Cases(5+8/28)

Impossible Cases(5+8/28)

Which leaves us with 15/28 galaxies to draw some results on the dust properties.

ResultsOptical depth as a function of MK

ResultsOptical depth as a function of MK

ResultsOptical depth as a function of dust mass

ResultsOptical depth as a function of dust mass

ConclusionsConclusions

J-Band is ideal for optical studies of dust in edge-on galaxies provided a high resolution.

Larger spirals exhibit higher face-on optical depth.

There might be a threshold of the optical depth in normal spiral galaxies.