| PG 0844+349 | |
|---|---|
 PG 0844+349 and its companion galaxy captured bySDSS | |
| Observation data (J2000epoch) | |
| Constellation | Lynx |
| Right ascension | 08h 47m 42.47s |
| Declination | +34d 45m 04.40s |
| Redshift | 0.064000 |
| Heliocentric radial velocity | 19,187km/s |
| Distance | 849Mly (260.3Mpc) |
| Apparent magnitude (V) | 0.10 |
| Apparent magnitude (B) | 0.13 |
| Surface brightness | 13.5 |
| Characteristics | |
| Type | Sp (d), Sy1, |
| Notable features | Seyfert galaxy containing aquasar |
| Other designations | |
| TON 951, RBS 724,PGC 24702,RX J0847.6+3445, LAMOST J084742.44+344504.4, CSO 204, 2E 2048, 1ES 0844+349, 2PBC J0848.2+3443 | |
PG 0844+349, also known asTON 951 (abbreviation ofTonantzintla 951), is agalaxy in the southern constellationLynx, near the border ofCancer. Itsredshift is 0.064000, putting the galaxy at 849 millionlight-years away fromEarth.[1]
PG 0844+349 was firstdiscovered in 1957 by theTonantzintla Observatory who was searching for blue stellar objects (mainlywhite dwarfs) as quasar candidates.[2] Because quasars were not identified until 1963,[3] the nature of this object was unknown. Studying photographic plates that were taken with the 0.7 m Schmidttelescope, it was discovered PG 0844+349 has a Seyfert 1spectrum, classifying it as a quasar. Mexican astronomers Braulio Iriarte and Enrique Chavira subsequently listed it as the 951st object in theTonantzintla Catalogue.[4] The same case was applied withTON 618.
In 2009, PG 0844+349 was observed again, by theSwift observatory, and it was noted to have a weakX-ray state. Several weeks later, a follow-up observation byXMM-Newton found it showing a spectral hardening and substantialcurvature. This shows that PG 0844+349 is in the phase of reflection-dominated state and itslight bending scenario can be accounted for short-term ( ∼1000 s) spectral variability in its source.[5]
PG 0844+349 has anactive galactic nucleus. It is classified aSeyfert type 1.0 galaxy,[6] containing two sets ofemission lines superimposed onto each other. One set of lines is a low-density (electron densityne 103-106 cm−3)ionized gas that has widths which corresponds tovelocities of several hundredkilometers per second. The other is a set ofbroad lines, with widths as high as 104 km s−1; but the absence of broad forbidden-lineemission indicates that the broad-line gas is of highdensity (ne 109 cm−3 or higher).[7] It can be said PG 0844+349 is a narrow-line Seyfert 1 galaxy considered having all characteristics of type 1 Seyfert galaxies,[8] but it does not have any hardnessratio variations as a single observation finds no strongcorrelation between the hardness ratio and the continuum luminosity.[9]
PG 0844+349 is also aquasar but with lowluminosity.[2] The quasar host is a disturbed face-onbarred spiral galaxy,[10][11] which is foundinteracting with its companion galaxy, 2MASX J08474179+3444405.[12] Both galaxies show signs ofgravitational distortion, in whichtidal tails and a hot blue stellar component can be seen.[2] Through the interaction with 2MASX J08474179+3444405, this causes the activity in the central region of PG 0844+349 to awaken causing it to create morestar formation with itsblack hole mass suppressed by its increasing starburst luminosity.[13] This gives it its quasar appearance.
In a 2002 observation of PG 0844+349, it was found to be in a historically high state compared to the prior observation by X-rays. This shows a featureless spectrum containing a strong soft excess that is over theextrapolation of a hardpower law. From the acceptable descriptions of the spectral continuum, thecomptonization model is represented by its Gamma_{soft} ~ 2.75, Gamma_{hard} ~ 2.25 and a break energy of E_{break} of ~ 1.35 keV, meaning thetemperature is low and have a higheroptical depth than in broad-line Seyfert galaxies. Further observation shows the flux in PG 0844+349 varyingachromatically on its time scale, in relatively few seconds by ~ 25%. This puts constraints on the current models of Comptonizingaccretion disk coronae.[14]
According to observation from theASCA satellite, researchers has found PG 0844+349 has a high state with aphoton index of 1.98 and an Fe Kα line with EW ~ 300 eV. Even its X-ray flux ranging in the 2-10 keV band is considered highly variable. They found that the fastest variation detected reaches up to 2 × 104 s but less than 60%. Given the state of PG 0844+349, the measured excess variance fits well in comparison with theL2-10 keV relation for Seyfert 1 galaxies; the fluxvariability in the 0.5-2.0 keV band has a slightly higheramplitude than in the 2-10 keV band. Researchers noted the optical microvariability of PG 0844+349 is driven by reprocessing of variable X-ray fluxes, provided one-half of its absorbed X-rays are reradiated in the optical-to-ultraviolet band.[15]
Thesupermassive black hole in PG 0844+349 has an estimatedsolar mass of 2.138×107.[16] This makes the galaxy contain one of thelargest black holes, but a lower black holemass putting it betweenMessier 58 andCentaurus A. Only TON 618 has a higher black hole solar mass of 4.07×1010 compared to PG 0844+349.[17]