Origin of Disk Lopsidedness in Spiral Galaxies

R. A. Angiras; C. J. Jog; K. S. Dwarakanath; A. Omar; M. A. W. Verheijen

Origin of Disk Lopsidedness in Spiral Galaxies

R. A. Angiras, C. J. Jog, K. S. Dwarakanath, A. Omar, M. A. W. Verheijen

Astronomy

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Academic › peer-review

Abstract

In our work we have used the atomic hydrogen [H I] gas distribution in the H I 21-cm line emission to study the dark matter halo perturbations. For this analysis, the 2-D H I surface density and velocity maps (archival) of the galaxies in the Eridanus group (obtained using the GMRT) and in the Ursa Major group (obtained from WSRT) were used. In addition a few Hickson Compact Groups of galaxies were also studied using the GMRT. The H I maps of these galaxies were Fourier analysed to estimate the asymmetry in the distribution and motion of gas. The average asymmetry parameter in the 1.5 to 2.5 K'-band scale lengths was found to be ˜ 0.27 for the Eridanus group of galaxies while it was ˜ 0.14 for the Ursa Major group of galaxies. The asymmetries in the distribution of H I as a function of Hubble type of galaxies were also studied and was found to be directly correlated with the compactness of the groups. In addition, the trend in the asymmetry as a function of the Hubble type of galaxies was opposite to that seen in the field galaxies, i.e., in the group galaxies, the early type galaxies showed more asymmetry than late type. These two aspects indicated that tidal interactions between the galaxies in a group environment to be the major cause of asymmetries. The observed asymmetry parameters were consistent with recent numerical simulations of asymmetries of gas disk caused by fly-by interactions. We have also estimated the perturbation of dark matter halo using the asymmetry parameter obtained from the Fourier series analysis of the surface density maps.

Original language	English
Title of host publication	The Low-Frequency Radio Universe
Subtitle of host publication	proceedings of the conference held 8-12 December 2008, at National Centre for Radio Astrophysics (NCRA), TIFR, Pune, India
Editors	D.J. Saikia, D.A. Green, Y. Gupta, T. Venturi
Place of Publication	San Francisco
Publisher	Astronomical Society of the Pacific
Pages	79
Volume	407
Publication status	Published - 1-Sept-2009
Event	Conference and Workshop on the Low-Frequency Radio Universe - , India Duration: 8-Dec-2008 → 12-Dec-2008

Publication series

Name	ASP Conference Series

Other

Other	Conference and Workshop on the Low-Frequency Radio Universe
Country/Territory	India
Period	08/12/2008 → 12/12/2008

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Angiras, R. A., Jog, C. J., Dwarakanath, K. S., Omar, A., & Verheijen, M. A. W. (2009). Origin of Disk Lopsidedness in Spiral Galaxies. In D. J. Saikia, D. A. Green, Y. Gupta, & T. Venturi (Eds.), The Low-Frequency Radio Universe : proceedings of the conference held 8-12 December 2008, at National Centre for Radio Astrophysics (NCRA), TIFR, Pune, India (Vol. 407, pp. 79). (ASP Conference Series). Astronomical Society of the Pacific. http://adsabs.harvard.edu/abs/2009ASPC..407...79A

Angiras, R. A. ; Jog, C. J. ; Dwarakanath, K. S. et al. / Origin of Disk Lopsidedness in Spiral Galaxies. The Low-Frequency Radio Universe : proceedings of the conference held 8-12 December 2008, at National Centre for Radio Astrophysics (NCRA), TIFR, Pune, India. editor / D.J. Saikia ; D.A. Green ; Y. Gupta ; T. Venturi. Vol. 407 San Francisco : Astronomical Society of the Pacific, 2009. pp. 79 (ASP Conference Series).

@inproceedings{43039c655d0e472ea0c22bdda6f84eff,

title = "Origin of Disk Lopsidedness in Spiral Galaxies",

abstract = "In our work we have used the atomic hydrogen [H I] gas distribution in the H I 21-cm line emission to study the dark matter halo perturbations. For this analysis, the 2-D H I surface density and velocity maps (archival) of the galaxies in the Eridanus group (obtained using the GMRT) and in the Ursa Major group (obtained from WSRT) were used. In addition a few Hickson Compact Groups of galaxies were also studied using the GMRT. The H I maps of these galaxies were Fourier analysed to estimate the asymmetry in the distribution and motion of gas. The average asymmetry parameter in the 1.5 to 2.5 K'-band scale lengths was found to be ˜ 0.27 for the Eridanus group of galaxies while it was ˜ 0.14 for the Ursa Major group of galaxies. The asymmetries in the distribution of H I as a function of Hubble type of galaxies were also studied and was found to be directly correlated with the compactness of the groups. In addition, the trend in the asymmetry as a function of the Hubble type of galaxies was opposite to that seen in the field galaxies, i.e., in the group galaxies, the early type galaxies showed more asymmetry than late type. These two aspects indicated that tidal interactions between the galaxies in a group environment to be the major cause of asymmetries. The observed asymmetry parameters were consistent with recent numerical simulations of asymmetries of gas disk caused by fly-by interactions. We have also estimated the perturbation of dark matter halo using the asymmetry parameter obtained from the Fourier series analysis of the surface density maps.",

author = "Angiras, {R. A.} and Jog, {C. J.} and Dwarakanath, {K. S.} and A. Omar and Verheijen, {M. A. W.}",

year = "2009",

month = sep,

day = "1",

language = "English",

volume = "407",

series = "ASP Conference Series",

publisher = "Astronomical Society of the Pacific",

pages = "79",

editor = "D.J. Saikia and D.A. Green and Y. Gupta and { Venturi}, T.",

booktitle = "The Low-Frequency Radio Universe",

note = "Conference and Workshop on the Low-Frequency Radio Universe ; Conference date: 08-12-2008 Through 12-12-2008",

}

Angiras, RA, Jog, CJ, Dwarakanath, KS, Omar, A & Verheijen, MAW 2009, Origin of Disk Lopsidedness in Spiral Galaxies. in DJ Saikia, DA Green, Y Gupta & T Venturi (eds), The Low-Frequency Radio Universe : proceedings of the conference held 8-12 December 2008, at National Centre for Radio Astrophysics (NCRA), TIFR, Pune, India. vol. 407, ASP Conference Series, Astronomical Society of the Pacific, San Francisco, pp. 79, Conference and Workshop on the Low-Frequency Radio Universe, India, 08/12/2008. <http://adsabs.harvard.edu/abs/2009ASPC..407...79A>

Origin of Disk Lopsidedness in Spiral Galaxies. / Angiras, R. A.; Jog, C. J.; Dwarakanath, K. S. et al.
The Low-Frequency Radio Universe : proceedings of the conference held 8-12 December 2008, at National Centre for Radio Astrophysics (NCRA), TIFR, Pune, India. ed. / D.J. Saikia; D.A. Green; Y. Gupta; T. Venturi. Vol. 407 San Francisco: Astronomical Society of the Pacific, 2009. p. 79 (ASP Conference Series).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Academic › peer-review

TY - GEN

T1 - Origin of Disk Lopsidedness in Spiral Galaxies

AU - Angiras, R. A.

AU - Jog, C. J.

AU - Dwarakanath, K. S.

AU - Omar, A.

AU - Verheijen, M. A. W.

PY - 2009/9/1

Y1 - 2009/9/1

N2 - In our work we have used the atomic hydrogen [H I] gas distribution in the H I 21-cm line emission to study the dark matter halo perturbations. For this analysis, the 2-D H I surface density and velocity maps (archival) of the galaxies in the Eridanus group (obtained using the GMRT) and in the Ursa Major group (obtained from WSRT) were used. In addition a few Hickson Compact Groups of galaxies were also studied using the GMRT. The H I maps of these galaxies were Fourier analysed to estimate the asymmetry in the distribution and motion of gas. The average asymmetry parameter in the 1.5 to 2.5 K'-band scale lengths was found to be ˜ 0.27 for the Eridanus group of galaxies while it was ˜ 0.14 for the Ursa Major group of galaxies. The asymmetries in the distribution of H I as a function of Hubble type of galaxies were also studied and was found to be directly correlated with the compactness of the groups. In addition, the trend in the asymmetry as a function of the Hubble type of galaxies was opposite to that seen in the field galaxies, i.e., in the group galaxies, the early type galaxies showed more asymmetry than late type. These two aspects indicated that tidal interactions between the galaxies in a group environment to be the major cause of asymmetries. The observed asymmetry parameters were consistent with recent numerical simulations of asymmetries of gas disk caused by fly-by interactions. We have also estimated the perturbation of dark matter halo using the asymmetry parameter obtained from the Fourier series analysis of the surface density maps.

AB - In our work we have used the atomic hydrogen [H I] gas distribution in the H I 21-cm line emission to study the dark matter halo perturbations. For this analysis, the 2-D H I surface density and velocity maps (archival) of the galaxies in the Eridanus group (obtained using the GMRT) and in the Ursa Major group (obtained from WSRT) were used. In addition a few Hickson Compact Groups of galaxies were also studied using the GMRT. The H I maps of these galaxies were Fourier analysed to estimate the asymmetry in the distribution and motion of gas. The average asymmetry parameter in the 1.5 to 2.5 K'-band scale lengths was found to be ˜ 0.27 for the Eridanus group of galaxies while it was ˜ 0.14 for the Ursa Major group of galaxies. The asymmetries in the distribution of H I as a function of Hubble type of galaxies were also studied and was found to be directly correlated with the compactness of the groups. In addition, the trend in the asymmetry as a function of the Hubble type of galaxies was opposite to that seen in the field galaxies, i.e., in the group galaxies, the early type galaxies showed more asymmetry than late type. These two aspects indicated that tidal interactions between the galaxies in a group environment to be the major cause of asymmetries. The observed asymmetry parameters were consistent with recent numerical simulations of asymmetries of gas disk caused by fly-by interactions. We have also estimated the perturbation of dark matter halo using the asymmetry parameter obtained from the Fourier series analysis of the surface density maps.

M3 - Conference contribution

VL - 407

T3 - ASP Conference Series

SP - 79

BT - The Low-Frequency Radio Universe

A2 - Saikia, D.J.

A2 - Green, D.A.

A2 - Gupta, Y.

A2 - Venturi, T.

PB - Astronomical Society of the Pacific

CY - San Francisco

T2 - Conference and Workshop on the Low-Frequency Radio Universe

Y2 - 8 December 2008 through 12 December 2008

ER -

Angiras RA, Jog CJ, Dwarakanath KS, Omar A, Verheijen MAW. Origin of Disk Lopsidedness in Spiral Galaxies. In Saikia DJ, Green DA, Gupta Y, Venturi T, editors, The Low-Frequency Radio Universe : proceedings of the conference held 8-12 December 2008, at National Centre for Radio Astrophysics (NCRA), TIFR, Pune, India. Vol. 407. San Francisco: Astronomical Society of the Pacific. 2009. p. 79. (ASP Conference Series).

Origin of Disk Lopsidedness in Spiral Galaxies

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