BL Lacertae object
Active galactic nuclei with rapid variability and featureless spectra.
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A BL Lacertae object is a type of active galactic nucleus named after its prototype, BL Lacertae.[1] BL Lacs are a subtype of blazar, and in the unified scheme their observed features come from a relativistic jet aligned with the observer's line of sight.[2] BL Lac objects exhibit swift, substantial changes in flux and notable optical polarization, setting them apart from other active galactic nuclei.[1]
Quick Facts
- Field
- Astronomy
- Prototype
- BL Lacertae
- Host galaxy type
- Massive elliptical galaxies
- Classification
- Blazar subtype
Facts from the source article.
Key facts and history
The object class was formally suggested by Peter Albert Strittmatter in 1972, who also included four additional objects.[3] By the year 1976, the count of known objects had reached 30.[3] BL Lac objects display a spectrum largely composed of a featureless non-thermal continuum, which made it difficult to determine their nature and distance in the past.[4] Massive elliptical galaxies are the hosts for these active nuclei.[2]
What the research sources say
The Hubble Space Telescope survey of 132 BL Lac objects in 2000 studied the morphologies of possible host galaxies.[5][6] That survey concluded that two-thirds of the images showed detected host galaxies, and a de Vaucouleurs profile was significantly preferred for 58 of the 72 resolved hosts.[5][6] The survey established an upper limit of 8% for disk systems, which aligns with the idea that all BL Lac host galaxies might be elliptical.[7][6]
References
- Wikipedia, "BL Lacertae object" (CC BY-SA 4.0), which cites: Padovani, "A Sample-Oriented Catalogue of BL Lacertae Objects", Monthly Notices of the Royal Astronomical Society, 15 December 1995, p. 1477–1490 (we also read that source) en.wikipedia.org
- Wikipedia, "BL Lacertae object" (CC BY-SA 4.0), which cites: Marscher, "The inner jet of an active galactic nucleus as revealed by a radio-to-gamma-ray outburst", Nature, 24 April 2008, p. 966–969 (we also read that source) en.wikipedia.org
- Wikipedia, "BL Lacertae object" (CC BY-SA 4.0), which cites: Stein, "The BL Lacertae Objects", Annual Review of Astronomy and Astrophysics, September 1976, p. 173–195 (we also read that source) en.wikipedia.org
- Wikipedia, "BL Lacertae object" (CC BY-SA 4.0), which cites: Falomo, "An Optical View of BL Lacertae Objects", The Astronomy and Astrophysics Review, 2014, p. 44; Falomo, "An Optical View of BL Lacertae Objects", The Astronomy and Astrophysics Review, 2014, p. 44 (original not read by us) en.wikipedia.org
- Wikipedia, "BL Lacertae object" (CC BY-SA 4.0), which cites: Urry, "The Hubble Space Telescope Survey of BL Lacertae Objects", The Astrophysical Journal, 2000, p. 816–829; Sparke, "Galaxies in the Universe: An Introduction", Cambridge University Press, 2007, p. 244 (we also read that source) en.wikipedia.org
- Claudia Megan Urry, "TheHubble Space TelescopeSurvey of BL Lacertae Objects. II. Host Galaxies", The Astrophysical Journal (2000), doi:10.1086/308616. OpenAlex metadata CC0; paper not read. doi.org
- Wikipedia, "BL Lacertae object" (CC BY-SA 4.0), which cites: Urry, "The Hubble Space Telescope Survey of BL Lacertae Objects", The Astrophysical Journal, 2000, p. 816–829 (we also read that source) en.wikipedia.org
Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article BL Lacertae object (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.
More in Galaxies And Their Properties
Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: BL Lacertae object (CC BY-SA 4.0).
- Word definitions: the Codexery glossary, each quoted from its Wikipedia article.
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