A technique for estimation of starburst masses and ages in luminous compact galaxies

Abstract

We propose a technique for estimation of the mass m of the young stellar population and the starburst age T in luminous compact galaxies (LCGs). For this purpose we use LCG Hα emission line luminosities from the Sloan Digital Sky Survey (SDSS) spectra and Galaxy Evolution Explorer (GALEX) FUV and NUV continuum luminosities. The method is intended for quick estimation of m and T in large galaxy samples and does not require spectral energy distribution (SED) fitting. Estimated m and T for the sample of about 550 LCGs are compared with the same values derived from the SED fitting in the wavelength range λλ 3800 -9200Å. We obtain the average differences in log m and T of 0.27 and 0.87 Myr, respectively. This technique could be used for selection of galaxies with desired ranges of m and T or for reducing a range of parameter variations in SED fitting.

Radio emission at 1.4 GHz from luminous compact galaxies

“…We study the temporal evolution of the radio emission at 1.4 GHz for the sample of 52 LCG galaxies. Earlier, the temporal evolution of the Hα and UV luminosities in these galaxies was studied by Parnovsky et al (2013). We estimate the luminosities of the thermal component of the radio emission from the luminosities of the Hα line emission and the luminosities of the non-thermal component.…”

“…The mean redshift of the 1.4 GHz subsample is z = 0.074. Parnovsky et al (2013) showed that L Hα /m and L UV /m behave similarly with the starburst age T and are described by Eqs. (1) and (2) -they are constant at T ≤ T 0 and decline exponentially at T > T 0 .…”

“…To find the temporal trends in Fig. 3, we adopt the value T 0 = 3.2 Myr by Parnovsky et al (2013) and calculate the values and errors of the parameters of the simple linear dependence log(L 1.4 GHz /m) = a + bT using the least-squares method (LSM). We derive b = 0.016 ± 0.075 Fig.…”

“…Corresponding author: par@observ.univ.kiev.ua The coefficients C and p in Eqs. (1) and (2) are different for the Hα line and the FUV and NUV ranges and were derived by Parnovsky et al (2013) and . On the other hand, the value T 0 is the same for all wavelength ranges and is estimated to be T 0 = 3.2 Myr, which is close to the lifetime of the most massive stars born during the starburst.…”

“…In this paper we consider the radio emission at 1.4 GHz which is a good star formation indicator (Bell 2003;Condon et al 1991;Hopkins, Schulte-Ladbeck & Drozdovsky 2002;Hopkins et al 2003;Klein, Wielebinski & Thuan 1984;Klein, Weiland & Brinks 1991;Mobasher et al 1999;Sargsyan & Weedman 2009;Schmitt et al 2006), in addition to star-formation indicators mentioned in a previous paper by Parnovsky et al (2013). To study the properties of 1.4 GHz radiation we address the following questions: i) Is there any dependence of L 1.4 GHz /m on T ?…”