UM 287

UM 287 known as PHL 868 and LBQS 0049+0045, is a quasar located in the Cetus constellation. Its redshift is 2.267134 estimating the object to be located 10.9 billion light-years away from Earth.^[1]

UM 287
UM 287, as seen by DESI Legacy Survey
Observation data (J2000.0 epoch)
Constellation	Cetus
Right ascension	00h 52m 02.40s
Declination	+01d 01m 29.31s
Redshift	2.267134
Heliocentric radial velocity	679,670 km/s
Distance	10.9 Gly (light travel time distance)
Apparent magnitude (V)	0.073
Apparent magnitude (B)	0.097
Surface brightness	17.6
Characteristics
Type	Quasar
Notable features	Quasar in a Lyman-alpha blob
Other designations
PGC 3048, LBQS 0049+0045, PHL 868, KODIAQ J005202+010129, SDSS J005202.39+010129.3

Observation history

UM 287 was first discovered between 1974 and 1976, where it was observed as a part of the Curtis Schmidt-thin prism survey for extragalactic emission-line objects and possible quasars. The name UM comes from the University of Michigan.^[2]

Characteristics

An image of the nebula (Slug Nebula) extending across two million light-years discovered around UM 287.

UM 287 is classified as a radio-quiet quasar. It has a bolometric brightness of around 10 ^47.3 erg /s (10 ⁴⁰ watts), making it one of the brightest quasars ever observed.^[3] Furthermore, UM 287 has a Lyman-alpha blob structure surrounding the object. Some of these Lyman-alpha blobs have line luminosities up to ~ 10⁴⁴ erg s⁻¹ with their spatial extents exceeding 100 proper kpc.^[4][5] But in this case, the Lyman-alpha blob structure in UM 287 is 1.5 million light-years across making it too big to be contained within the quasar's host galaxy,^[6] which is found to be a massive early-type galaxy.^[7]

Using the 10-meter Keck I telescope in Hawaii,^[8] a team of researchers found there is cold hydrogen emitting Lyman-alpha radiation underneath the spotlight of the quasar's intense ultraviolet beam.^[6] The nebula is dubbed the Slug Nebula,^[9] named after the UCSC’s banana slug mascot.^[10] It is believed to play a major role in powering up the quasar^[11] which the Lyα emission produces from a large population of compact (< 20 pc), dense (n_H & 3 cm⁻³), cool gas clumps.^[12] From a follow-up field observation, a smooth kinematic profile is suggested. This presents a giant, rotating proto-galactic disk for the brightest portion of the filament showing a cold accretion flow around the black hole in UM 287.^[13]

In addition to the Lyman-alpha blob structure, a new dusty star-forming galaxy was found. The galaxy has a 2 mm continuum with its single emission line consistent with the CO(4–3), sitting at a projected distance of 100 kpc southeast from UM 287. The systemic velocity difference is -360 ± 30 km s-1 with respect to UM 287, suggesting the galaxy is a possible contributor to the powering of the Slug Nebula.^[11]