Do Super Massive Blackholes Shape the Galaxy which they reside in?
AGN’s or Active Galactic Nuclei are Galaxies that have Active Blackholes. Active Blackholes are those that accrete on the gas and around it. They swallow ionized gas which heats up as it comes nearer to the Blakhhole. Some of the ionized gas is emitted in a direction parallel to the magnetic field of the Blackhole. Some of the Supermassive Blackholes are in the form of AGN.
In a recent study on the nearby galaxy NGC 7582, Astronomers have discovered that there is a connection between the Supermassive Blackhole and the galactic structure of the galaxy. The feedback of AGN i.e. the gas which is emitted can have effects on the Star-Forming regions in a Galaxy. The results of this feedback are varying with some studies showing negative Star-Formation i.e. impression in the Star Formation in Galaxies due to AGN feedback.
The object under study, NGC 7582 is a nearby barred-spiral galaxy, with an AGN at its core. To reveal the structure they observed the galaxy under various wavelengths using the MUSE instrument. Using the MUSE instrument, they took the spectra of the galaxies and then fitted the spectra to some previously known models.
The stellar kinematics of NGC7582 exhibits a regular rotation pattern on the largest scales probed by MUSE. The presence of KDC is supported by the drop in velocity dispersion.
They found a kinematically distinct core (KDC) in NGC7582, which is corotating with the large-scale galactic disk but with faster relative velocities and limited to a diameter around 600–700 pc.
The KDC could be either a disk or a ring of stars and gas corotating with the main disk but with a differential, faster velocity.
Other observational results include the case of the Circinus galaxy, which was reported to have AGN collimation due to a ∼10pc dust lane structure rather than a subparsec-scale torus. There could also be an interesting parallel with NGC 1266, whose molecular gas outflows seem to originate from a ∼120 pc-scale nuclear gaseous disk and yet be AGN powered. The remaining sources of uncertainties to assess how galactic structure affects AGN feedback include the possible contribution from starburst-driven winds, which can be concurrent with AGN-driven winds.
This feature makes it unlikely that the outflows have a starburst origin. There are lines of evidence showing the presence of AGN obscuration at several scales as well.
KDCs have been observed in the center of several galaxies and exhibit various sizes and properties, including counterrotating, corotating, or nonrotating cores. The physical origin of such distinct kinematics in the cores of galaxies is usually associated with the effect of a tidal interaction or with the resulting perturbation of the galaxy kinematics.
The colocation of the stellar and warm molecular gas components sharing similar kinematics is consistent with a scenario where a KDC can include both stars and gas in the same physical structure as we posit is also the case for NGC7582.
The elliptical galaxy NGC1407 and found that it contains a KDC on a comparable physical scale of ∼0.6 kpc as what we find for NGC7582. Large-and small-scale KDCs may originate from different types of gravitational interactions with other galaxies or instabilities.
NGC7582 is a member of the Grus Quartet, a group of four spiral galaxies that have been observed to be experiencing some gravitational interactions based on tidal features seen in HI emission.
The large-scale stellar and nebular gas velocity fields reveal the presence of large-scale disk rotation, a KDC, and conical bipolar outflows. The kinematics of the stellar KDCis reported here for the first time and is attributed to a ∼600pc diameter ring (or disk) of stars, gas, and dust.
The morphology and kinematics of the ionized cones are consistent with the collimation taking place at the scale of the 600pc ring. The accretion disk must be oriented with a low inclination angle, while the ring and cones have a significant inclination. Thus, they postulated that the ring might also deflect AGN-driven winds. If this scenario is true, there is a broader implication is that galaxy substructure can play a role in how AGN feedback affects galaxies.
