Spiral DRAGNs or Speca-like galaxies are a type of spiral galaxies which are also radio galaxies or which contain DRAGNs (Double Radio-source Associated with Galactic Nucleus).
Most DRAGNs are associated with elliptical galaxies, as are most double-lobed radio-galaxies. Spiral DRAGNs are inconsistent with currently known galaxy formation processes. As of 2023, there are nearly 36 spiral DRAGNs.
Lenticlular galaxies containing DRAGNs are as rare as spiral DRAGNs, with only 5 known examples as of 2020, including: Centaurus A, NGC 612 and NGC 1534. Nearby Seyfert galaxies containing small or galaxy-scale radio jets/lobes are not accepted as Specas or Spiral DRANGs.
The first spiral-host large radio galaxy, 0313-192, was discovered in 1998 by Michael J. Ledlow, Frazer N. Owen, and William C. Keel. After more than a decade the second case, Speca, was discovered by Ananda Hota and his collaborators in 2011. Since Speca was also episodic, two pairs of radio lobes on either sides of the host, it removed all doubts on possible background galaxy confusing as the host. Hereafter the search for Speca-like galaxy got intensified and by 2023 the total number of such galaxies has increased to three dozens, establishing itself as a new class of radio galaxies.
List Galaxy Identified Date Notes References ESO 0313-192 1998 First known spiral DRAGN, located in Abell 428. It is the first spiral DRAGN with VLBI detection. ESO 248-G10 2000 Second known spiral DRAGN, one of the largest with a scale of 2.51 megaparsecs. Speca 2011 First confirmed case due to its episodic radio jet nature. Hosted in a massive spiral and with giant Mpc-scale radio-lobes. It was the second galaxy shown to have three episodes of periodic activity, the first was an elliptical.SPECA = Spiral-host Episodic radio galaxy tracing Cluster Accretion J2345-0449 2014 Third known spiral DRAGN with two episodic activities, observed at radio wavelengths and measuring about 1.6 megaparsecs in total size. SDSS J1649+2635 2014 Fourth known spiral DRAGN; first located in a grand design spiral galaxy. It was discovered by cross-matching spiral galaxies identified by galaxy zoo volunteers with the Unified Radio Catalog. It was the first systematic search for spiral DRAGNs.J0836+05322015Two clear spiral armsJ1159+58202012/2015Candidate: Disturbed galaxy with signs of a merger.J1352+31262015Candidate: Galaxy was well studied at the time of the discovery by Singh et al. The galaxy was classified as spiral or irregular galaxy.MCG+07-47-102016radio source has a low luminosityNGC 61852022The largest known spiral DRAGN, the scale of the radio lobes is 2.54 Mpc. J0354-13402022spiral host that is a narrow-line Seyfert 1, size of the de-projected jets is 250 kpcJ0209+07502022loose spiral arms, has star-forming clumpsJ0806+06242022several spiral arms and a luminous bar-like featureJ1328+57102022low-mass, low-redshift galaxy with many star-forming regions, at least two prominent arms and a strong bar. One of the few intermediate massive black holes (≤ 105 ) with a strong radio emission and the first with a double-lobed radio emission.J1656+64072022extremely massive star-forming spiral galaxyJ1128+24172022star-forming clumps in the armsJ1646+3832022dust-lane with peculiar arc-like shapeJ0326-06232023two major spiral arms, scale of the radio lobes is 430 kpcJ1110+03212023scale of the radio lobes is 100 kpcJ1134+30462023scale of the radio lobes is 380 kpcNGC 53832023Second spiral DRAGN found to be hosted by a grand design spiral galaxy, scale of the radio lobes is 70 kpc.LEDA 8963252025Similar to Speca and J2345-0449 this is episodic and giant (2Mpc)
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