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Study of UV line and continuum variabilities in the Broadline Seyfert 1 Galaxy ESO 141-G55

Mayukh Pahari, Veda Samhita, Harikumar N., Anurag Baruah, Vivek Shinde

Abstract

We present the results from a 3-year-long Ultraviolet monitoring campaign of the broad line Seyfert 1 galaxy ESO 141-G55 using International Ultraviolet Explorer (IUE). By modelling all individual, extinction-corrected UV spectra in 1150-1978 A and 1850-3348 A wavelength range, we have observed a significant variability in both UV continuum and line fluxes. Variabilities due to ionised UV lines like SiIV, CIV and HeII are delayed with respect to the UV continuum by 2.92$^{+0.54}_{-0.61}$, 4.41$^{+0.44}_{-0.54}$, 4.11$^{+0.35}_{-0.81}$ days, respectively. At a distance of $\sim$0.004c, an outer accretion disc can be a possible site for the origin of UV lines.

Study of UV line and continuum variabilities in the Broadline Seyfert 1 Galaxy ESO 141-G55

Abstract

We present the results from a 3-year-long Ultraviolet monitoring campaign of the broad line Seyfert 1 galaxy ESO 141-G55 using International Ultraviolet Explorer (IUE). By modelling all individual, extinction-corrected UV spectra in 1150-1978 A and 1850-3348 A wavelength range, we have observed a significant variability in both UV continuum and line fluxes. Variabilities due to ionised UV lines like SiIV, CIV and HeII are delayed with respect to the UV continuum by 2.92, 4.41, 4.11 days, respectively. At a distance of 0.004c, an outer accretion disc can be a possible site for the origin of UV lines.
Paper Structure (8 sections, 1 equation, 8 figures, 6 tables)

This paper contains 8 sections, 1 equation, 8 figures, 6 tables.

Table of Contents

  1. Introduction
  2. OBSERVATIONS AND DATA REDUCTION
  3. UV SPECTRAL ANALYSIS AND RESULTS
  4. lightcurve extraction and results
  5. Time lag analysis
  6. DISCUSSION
  7. Origin of UV line emissions
  8. Conclusions

Figures (8)

  • Figure 1: Reddening-corrected UV spectra showing the observed (black) and de-reddened (red) flux distributions. There is significant increase in flux levels after the correction. The vertical blue dashed line marks the offset-corrected Civ emission feature at 1550.77 Å.
  • Figure 2: Reddening-corrected UV spectra showing the observed (black) and de-reddened (red) flux distributions. There is significant increase in flux levels after the correction. The vertical blue dashed line marks the offset-corrected Ly$\alpha$ emission feature at 1215.67 Å.
  • Figure 3: UV variability of ESO 141-G55 as observed on 5 June 1980 at 20:56:49 (circles) and 2 October 1980 at 19:58:00 (stars). IUE spectra in the wavelength range of 1550--1670 Å show a substantial change in the flux level.
  • Figure 4: The best-fit SWP UV spectrum (1180-1800 Å) from IUE is shown (top panel) along with the fitted model (red) consisting of continuum and emission features and the residual of the fitting (bottom panel).
  • Figure 5: The best-fit LWP UV spectrum (2000- 3200 Å) from IUE is shown (top panel) along with the fitted model (red) consisting of continuum and emission features and the residual of the fitting (bottom panel).
  • ...and 3 more figures