AP Librae

AP Librae
Light curves for AP Librae. Top panel: The long-term variability, plotted from data published by Fan & Lin (2000).[1] Bottom panel: short-timescale variability, adapted from Carini et al. (1991)[2]
Observation data (Epoch J2000)
ConstellationLibra
Right ascension15h 17m 41.814s[3]
Declination−24° 22′ 19.48″[3]
Redshift0.049[4]
Distance700 Mly (215 Mpc)[5]
TypeBL Lac[6]
Apparent dimensions (V)0′.323 × 0′.278[7]
Apparent magnitude (V)14.0[8]
Notable featuresHighly active; emits a one-sided radio jet
Other designations
AP Lib, LEDA 54592, PKS 1514-24, QSO B1514-24[9]
See also: Quasar, List of quasars

AP Librae is a BL Lacertae object[6] located at a distance of 700 million light years[5] in the southern constellation of Libra. In the visual band it is one of the most active blazars known.[10] AP Lib is surrounded by an extended source with a spectrum characteristic of a red-shifted giant elliptical galaxy. The derived visual magnitude of this region is 15.0, and it follows a radially decreasing brightness that is characteristic of an elliptical. Seven fainter galaxies are visible within an angular radius of 9′, suggesting it is the brightest member of a galactic cluster.[6]

This object was first identified as an optical variable by Martha D. Ashbrook in 1942, who noted the brightness changed irregularly from magnitude 15.0 down to 16.0.[11] The source was found to vary chaotically on time scales of days and even hours.[12] Howard E. Bond and Francois Biraud in 1971 noted the coincidence of this object with the position of the radio source PKS 1514–24.[13] In 1965, John G. Bolton and associates identified the latter as a sixteenth magnitude elliptical galaxy.[11] Glenn M. Frye and associates in 1971 suggested that it may be a gamma-ray source.[13] The similarity of this object to BL Lacertae was noted, leading to it being designated as a BL Lac object.[14]

AP Librae emits a synchrotron radiation component to its spectral energy distribution (SED). The peak component of this radiation lies in the infrared band, making this a low-frequency peaked BL Lac (LBL). It is one of the few LBLs known to emit gamma rays. The width of the high energy component of the SED is considered extremely broad for objects of this class, ranging in energy from around 0.1 keV up to the TeV level.[15] In 1998–99, extended radio emission was detected from a one-sided jet that starts in a south-easterly direction from the source before bending to the northeast.[16] This non-thermal jet extends 15″ from AP Lib (equivalent to ~46 kly), and in 2013 was found to emit X-rays.[10] The jet may be the source for the gamma-ray emission in the TeV range.[17]

  1. ^ Cite error: The named reference Fan_2000 was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference Carini_1991 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference GaiaEDR3 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference Roychowdhury_et_al_2022 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Sanchez_et_al_2015 was invoked but never defined (see the help page).
  6. ^ a b c Cite error: The named reference Visvanathan_Griersmith_1977 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Skrutskie_et_al_2006 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Ducati2002 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference Kaufmann_et_al_2013 was invoked but never defined (see the help page).
  11. ^ a b Cite error: The named reference Bond1971 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Hunstead1971 was invoked but never defined (see the help page).
  13. ^ a b Cite error: The named reference Andrews_et_al_1974 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Peterson_et_al_1976 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Fortin_et_al_2010 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference Cassaro_et_al_1999 was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference Zacharias_et_al_2016 was invoked but never defined (see the help page).