J2345−0449
Galaxy in the constellation of Aquarius
From Wikipedia, the free encyclopedia
J2345−0449 or 2MASX J23453268−0449256, is a spiral galaxy located 947 million light-years away in the constellation of Aquarius.[1] It contains an active galactic nucleus and is classified as a radio galaxy, containing relativistic jets that are projected out from its spiral host by ~1.6 Mpc, making these jets the largest and rarest known.[2][3] It was discovered in 2014 by amateur astronomers, making it the third spiral DRAGN after ESO 0313-192 and Speca.[2]
| J2345−0449 | |
|---|---|
J2345−0449 imaged by the Hubble Space Telescope | |
| Observation data (J2000 epoch) | |
| Constellation | Aquarius |
| Right ascension | 23h 45m 32.7347s[1] |
| Declination | −04° 49′ 25.367″[1] |
| Redshift | 0.075566[1] |
| Heliocentric radial velocity | 22,654 km/s[1] |
| Distance | 947 Mly (290.3 Mpc) |
| Apparent magnitude (V) | 0.086 |
| Apparent magnitude (B) | 0.113 |
| Surface brightness | 16.19 |
| Characteristics | |
| Size | ~237,000 ly (72.67 kpc) (estimated)[1] |
| Apparent size (V) | 0.62′ × 0.31′ |
| Notable features | One of the most massive spiral galaxies containing a radio jet |
| Other designations | |
| PGC 1052974, GRS J2345−0449, 2MASX J23453268−0449256, 6dF J2345327−044925 | |
Physical Properties
Mentioned as a megaparsec-scale object at redshift 0.0757,[4] J2345−0449 is one of the largest and most massive spiral galaxies found in the local universe.[5][6] It is also one of the largest radio sources discovered since the galaxy exhibits two sets of radio lobes found in near alignment and spanning a width of ~387.2 kpc (~452) and ~1.63 Mpc (~191).[2] According to Very Large Array 6 cm imaging, the inner radio lobes are categorized either Fanaroff-Riley Class I or FR II morphology.[7] A further study in 2025, showed these inner radio lobes extend right up to 387.2 kiloparsecs (Kpc).[8]
J2345−0449 contains a fast rotation speed of Vrot = 371/sin (i) = 429 ± 30 km s−1 that is r ≥ 10 kpc away from its galactic center.[9] It has a mass of Mstellar = 4 × 1011 M☉ and a surrounding ring of molecular gas measured 24 kpc wide in diameter. The galaxy has a star formation rate with a surface density measured to be ΣSFR = 1.8 × 10−3 M☉ yr−1 kpc−2.[10] However it has a low factor between 30 and 70 as expected according to the Kennicutt-Schmidt law.[11]
Black hole mass
The black hole mass estimation is challenging since J2345−0449 has no classic bulge structure. According to Bagchi, the black hole has a mass of 2.5 ± 0.5 × 108 M☉. Further observations shows it has a mass of 1.4× 109 M☉ when calculating the MBH–σ relation proposed by Gültekin.[12] However, according to researchers obtaining the M–σ relation from McConnell & Ma,[13] the actual mass of J2345−0449 is 5 × 109 M☉.[9]