Bulletin of Taras Shevchenko National University of Kyiv. Astronomy, no. 57, p. 41-47 (2018)

Cоmpact star-forming galaxies: the fraction of thermal emission in the radio continuum at 1.4 GHz

S. Parnovsky, Dr. Sci., Prof.
I. Izotova, Ph. D.

Astronomical Observatory of Taras Shevchenko National University of Kyiv, Kyiv

Abstract

The fraction of thermal (free-free) emission in the radio continuum at the frequency of 1.4 GHz is derived in 193 compact star-forming galaxies(CSFG). These galaxies with detected radio emission represent the subsample of a larger CSFG sample of about 14 000 galaxies (Izotov, Y.I., Guseva, N.G., Fricke, K.J., Henkel, C.: Mon. Not. R. Astron. Soc. 2016, 462, 4427) selected from the Data Release 12 of the Sloan Digital Sky Survey(SDSS) (Alam, S., et al.: Astrophys. J. Suppl. Ser. 219, 12, 2015). We use the 1.4 GHz fluxes from the FIRST (Becker R.H., White R.L., & Helfand D.J.: 1995, ApJ, 450, 559) and NVSS (Condon, J.J., Cotton, W.D., Greisen, E.W., et al.: 1998, AJ, 115, 1693) catalogues. The fluxes of the thermal component at 1.4 GHz are derived from the extinction- and aperture-corrected fluxes of the Hβ emission line in the SDSS spectra following to (Caplan, J., & Deharveng, L.: 1986, A&A, 155, 297) and are compared with the total fluxes in radio continuum. The distribution of the fraction of thermal emission A at 1.4 GHz is similar to the log-normal one. Its median values of 6 % and 14 % are derived respectively with the Hβemission line fluxes which are non-corrected and corrected for aperture. We consider these values as lower and upper limits and discuss their uncertainties introduced by aperture corrections. The derived fractions of thermal emission are similar to those found previously for different types of star-forming galaxies. We study the dependence of A on various parameters and find strong correlation with the equivalent width of the Hβ emission line W and the gr colour index I. The A value increases with increasing of the equivalent width W at a fixed colour index I or with increasing of the colour index I at a fixed equivalent width W. Additionally, we find that the fraction of thermal emission at 1.4 GHz is lower for older starbursts.

Key words
Star-forming galaxies, continuum radio emission, thermal emission

References

Sullivan, M., Mobasher, B., Chan, B. et al. 2001, Astrophys. J., 558, 72
Baldwin, J.A., Phillips, M.M., Terlevich, R. 1981, PASP, 93, 551, 5
Becker, R.H., White, R.L., Helfand, D.J. 1995, Astrophys. J., 450, 559
Bell, E.F. 2003, Astrophys. J., 586, 2, 794
Bicay, M.D., Helou, G. 1990, Astrophys. J. 362, 59
Calzetti, D. 2013, Secular Evolution of Galaxies, by Jesús Falcón-Barroso, and Johan H. Knapen, Cambridge
Caplan, J., Deharveng, L. 1986, Astron. Astrophys., 155, 297
Colgate, S.A. 1984, Advances in Space Research, 4, 2–3, 367
Lee, J.C., Gil de Paz, A., Tremonti, C. et al. 2009, Astrophys. J., 706, 1, 599
Condon, J.J., Anderson, M.L., Helou, G. 1991, Astrophys. J., 376, 95
Condon, J.J. 1992, Ann. Rev. Astron. Astrophys., 30, 575
Battisti, A.J., Calzetti, D., Johnson, B.D., Elbaz, D. 2015, Astrophys. J., 800, 2, Id. 143
Izotov, I.Y., Guseva, N.G., Fricke, K.J. et al. 2014, Astron. Astrophys., 570, Id. A97
Kennicutt, Jr. R.C., C.-N., Hao, Calzetti, D. et al. 2009, Astrophys. J., 703, 2, 1672
Hao, C.-N., Kennicutt, R.C., Johnson, B.D. et al. 2011, Astrophys. J. 741, 2, Id. 124
Fisher, R.A. 1950, L.
Forsythe, G. 1957, Journal of the Society for Industrial and Applied Mathematics, 5 (2), 74
Salim, S., Lee, J.C., Janowiecki, S. et al. 2016, Astrophys. J. Suppl. Ser., 227, 1, id. 2
Hirashita, H., Tajiri, Y.Y., Kamaya, H. 2002, Astron. and Astrophys., 388, 439
Hopkins, A.M. 2004, Astrophys. J., 615, 1, 209
Hopkins, A.M., Schulte-Labreck, R.E., Drozdovsky, I.O. 2002, Astron. J. 124, 2, 862
Hunter, D.A., Elmegreen, B.G. 2004, Astron. J., 128, 5, 2170
Izotova, I., Parnovsky, S.L., Izotov, Yu. 2000, New Astronomy Reviews, 44, 283
Izotova,  I.Y., Parnovsky,  S.L. 2008, Kinematics and Physics of Celestial Bodies, 24, 4, 183
Izotova, I.Y., Parnovsky, S.L., Tyutyunnyk, A.A. 2006, Kinematika i Fizika Nebesnykh Tel, 22, 3, 187
Izotova, I.Y., Izotov, Y.I. 2018, Astrophysics and Space Science, 363, 3, Id. 47
Kennicutt, R. 1983, Astron. Astrophys, 120, 219
Kennicutt, R.C.Jr. 1998, Ann. Rev. Astron. Astrophys, 36, 189
Kimball, A.E., Ivezić, Ž. 2008, Astron. J., 136, 2, 684
Lee, J.C., Hwang, H.S., Ko, J. 2013, Astrophys. J. 774, 1, Id. 62
Leitherer, C., Schaerer, D., Goldader, J.D. et al. 1999, Astrophys. J. Suppl. Ser. 123, 1, 3
Schmitt, H.R., Calzetti, D., Armus, L. et al. 2006, Astrophys. J. Suppl. Ser. 164, 1, 52
Izotov, I.Y., Guseva, N.G., Fricke, K.J., Henkel, C. 2014, Astron. Astrophys., 561, Id. A33
Parnovsky, S.L., Izotova, I.Yu. 2013, Astrophysics and Space Science, 348, 199
Parnovsky, S.L., Izotova, I.Y. 2014, Bull. Kyiv National Taras Shevchenko University.Astronomy, 51, 18
Parnovsky, S.L., Izotova, I.Yu., Izotov, Y.I. 2013, Astrophysics and Space Science, 343, 361
Parnovsky, S.L., Izotova, I.Yu. 2016, Astrophysics and Space Science, 361, 3, Id. 111
Parnovsky, S.L., Izotova, I.Y. 2015, Astronomische Nachrichten, Astronomical Notes, 336, 3, 276
Schaerer, D., Vacca, W.D. 1998, Astrophys. J., 497, 2, 618
Iglesias-Paramo, J., Buat, V., et al. 2006, Astrophys. J. Suppl. Ser., 164, № 1, 38
Hopkins, A.M., Miller, C.J., Nichol, R.C. et al. 2003, Astrophys. J., 599, 971
Stasinska, G., Leitherer, C. 1996, Astrophys. J. Suppl., 107, 2, 661
Izotov, I.Y., Guseva, N.G., Fricke, K.J., Henkel, C. 2016, Mon. Not. R. Astron. Soc. 462, 4, 4427
Calzetti, D., Wu, S.-Y., Hong, S.et al. 2010, Astrophys. J., 714, 2, 1256
Murphy, E.J., Helou, G., Braun, R. et al. 2006, Astrophys. J., 651, 2, L111
Alam, S., Albareti, F.D., Allende, P. et al. 2015, Astrophys. J. Suppl. Ser., 219, 1, Id. 12
Condon, J.J., Cotton, W.D., Greisen, E.W. et al. 1998, Astron. J., 115, 5, 1693
Boquien, M., Kennicutt, R., Calzetti, D. et al. 2016, Astron. Astrophys., 591, Id. A6

Full text PDF

DOI: https://doi.org/10.17721/BTSNUA.2018.57.41-47