arXiv subjects

Max North

Publications and source records attributed to Max North.

6 recordsLinked to original sources

arXiv2026

Winds Versus Jets in Active Galactic Nuclei

The well-established anti-correlation between disk winds and relativistic jets in X-ray binaries is often interpreted in a scale-invariant black hole accretion context. If so, active galactic nuclei (AGN) should exhibit a direct mass-scaled analog. We test this prediction across FRII radio quasars, radio-quiet quasars, and jetted and non-jetted Narrow Line Seyfert 1 galaxies (NLS1) in spirals, among others. They exclude simple scale invariance. The highest-velocity winds occur exclusively in radio-quiet quasars, while powerful FRII quasars host systematically weaker winds despite equally large black hole masses. Jetted NLS1s show strong wind suppression consistent with X-ray binary behavior, whereas FRII quasars occupy a distinct regime in which jets and winds coexist. Black hole mass and spin magnitude alone cannot account for this dichotomy. We argue that the angular momentum direction of the disk relative to that of the black hole (aligned versus anti-aligned or co-rotation versus counter-rotation) is the critical parameter: secularly fueled spiral systems and most post-merger systems favor co-rotation, which is associated with compact ISCO radii, high radiative efficiency, strong winds, and jet suppression, while the counter-rotating subset of merger-influenced ellipticals can sustain powerful jets alongside moderate winds. Moreover, while spiral AGN and merger-driven radio-quiet quasars experience similar strong jet/wind anti-correlation, they cannot be treated as strict scaled analogs of X-ray binaries, which undergo rapid state transitions involving magnetic flux redistribution absent in AGN. At least two distinct wind-jet regimes therefore operate across the mass scale. We identify the details of this behavior across AGN subclasses.

astro-ph.HE↗

arXiv2025

Why Jet Power and Star Formation Are Uncorrelated in Active Galaxies

Jet luminosity from active galaxies and the rate of star formation have recently been found to be uncorrelated observationally. We show how to understand this in the context of a model in which powerful AGN jets enhance star formation for up to hundreds of millions of years while jet power decreases in time, followed by a longer phase in which star formation is suppressed but coupled to jet power increasing with time. We also highlight characteristic differences depending on environment richness in a way that is also compatible with the observed SEDs of high redshift radio galaxies. While the absence of a direct correlation between jet power and star formation rate emerges naturally, our framework allows us to also predict the environment richness, range of excitation and redshift values of radio AGN in the jet power-star formation rate plane.

astro-ph.GA↗

arXiv2023

M-$\sigma$ relations across space and time

Feedback from active galactic nuclei (AGN) has long been invoked to explain the correlation between black hole mass and stellar velocity dispersion (M-$\sigma$) discovered in low redshift galaxies. We describe the time evolution of AGN in the M-$\sigma$ plane based on our gap model (Garofalo, Evans \& Sambruna 2010) for black hole accretion and jet formation illustrating a fundamental difference between jetted and non-jetted AGN. While the latter tend to evolve diagonally upward with black hole mass increasing along with stellar dispersion, we show that jetted AGN tend on average to move initially more upwards because their effect on velocity dispersion is weaker than for non-jetted AGN. But this initial phase is followed by a shift in the nature of the feedback, from positive to negative, a transition that is more dramatic on average in denser cluster environments. The feedback gets its kick from tilted jets which shut down star formation but increase velocity dispersion values. As this change in the nature of the feedback takes tens of millions to hundreds of millions of years, these cluster, merger-triggered jetted AGN, will evolve more upwards for up to order $10^{8}$ years, followed by an extremely long phase in which low excitation progressively slows black hole growth but dramatically affects stellar dispersion. As a result, powerful jetted AGN evolve for most of their lives almost horizontally on the M-$\sigma$ plane. The prediction is that strongest AGN feedback on stellar dispersion is a late universe phenomenon with M87 a good example. We show how jetted and non-jetted AGN parallel the Sersic and core-Sersic galaxy paths in the M-$\sigma$ plane found by Sahu et al (2019) and to a prediction that jetted quasars are not core-Sersic galaxies as found for lower redshift jetted AGN.

astro-ph.GA↗

arXiv2021

The black hole-star formation connection over cosmic time

Observations at low redshift have begun to tease out the star formation rate in active galaxies (AGN), which marks the beginning of the black hole-star formation connection over cosmic time. Star formation appears to depend on AGN type, cluster richness, and black hole accretion, but in ways that are not direct and have yet to be understood. Much of the confusion is that while some AGN appear to enhance star formation, others seem to suppress it. By implementing simplified, yet informed assumptions about AGN feedback on star formation, we show how AGN with jets might be dominated by two phases in which star formation is first enhanced, then suppressed. With this new element incorporated into our model, we make sense of radio and quasar mode behavior in the star formation rate-stellar mass (SFR-SM) plane for AGN. Due to jet feedback on star formation, jetted AGN tend to move upwards and rightward in the SFR-SM plane and then downward and to the right, past both the star-forming main sequence (SFMS) as well as the radio-quiet AGN. This picture allows us to predict the black hole connection to star formation as a function of the environment over the history of the universe.

astro-ph.HE↗

arXiv2020

Why radio quiet quasars are preferred over radio loud quasars regardless of environment and redshift

Evidence has accumulated suggesting the clustering of radio loud quasars is greater than for radio quiet quasars. We interpret these results in a context in which the fraction of radio loud quasar formation is less than or equal to that for radio quiet quasars for all environments and redshift. Because we assume that post-merger cold gas onto large black holes produces either a radio loud or a radio quiet quasar, we show that for largest black hole masses that live in largest dark matter halos, fRLQ approaches 0.5 from below but does not exceed it, such that in rich clusters the formation of a radio loud quasar tends to be equally likely to occur as a radio quiet quasar. In dark matter halos with smaller mass, by contrast, radio quiet quasars are more likely to form and the likelihood increases inversely with dark matter halo mass. As a result, averaging over a population of radio loud and radio quiet quasars will necessarily generate lower average black hole masses for the radio quiet subgroup. Hence, despite the fact that the formation of radio quiet quasars is preferred over radio loud quasars in any environment, at any mass scale, at any luminosity, or redshift, averaging over a range of radio loud quasars will give the appearance they are preferred in cluster environments over radio quiet quasars. We show how this also accounts for the order of magnitude difference in the total number of jetted active galaxies compared to non-jetted counterparts.

astro-ph.HE↗

arXiv2019

A unified framework for X-shaped radio galaxies

We propose a radically different picture for X-shaped radio galaxies compared to existing models as transition objects between cold mode accreting low spinning retrograde black holes and low spinning prograde black holes. The model explains their smaller average black hole masses, their general aversion for cluster compared to isolated environments, the negligible difference in spectral index between primary and secondary jets despite a time difference in their formation, their absence among the most powerful radio quasars and radio galaxies, and their connection to the elusive FRI quasar class, among others. The key to their formation is cold gas accretion onto Schwarzschild black holes.

astro-ph.HE↗