As mentioned in Rory's comment, an object in space must at some point in time acquire spin. Any object has gravity, and with a rotational rate of zero it would have no spin, as soon as it contacts another object spin is imparted on it.
While it is true, but unlikely, that it could be struck by another object that exactly cancelled out its spin it's only a matter of time before yet another object comes along - therefore objects in space are far more likely to spin than not.
See for example the SXS Collaboration video: "Inspiral and merger of binary black hole GW151226":
Angular momentum is the rotational equivalent of linear momentum and a conserved quantity — the total angular momentum of a closed system remains constant. The greater the density the faster the spin of the object, to conserve its angular momentum.
For anyone seeking additional information I'll include these references:
"Inferring black hole spins and probing accretion/ejection flows in AGNs with the Athena X-ray Integral Field Unit" (Jun 6 2019), by Didier Barret (IRAP) and Massimo Cappi (INAF-OAS):
"Context. Active Galactic Nuclei (AGN) display complex X-ray spectra which exhibit a variety of emission and absorption features, that are commonly interpreted as a combination of i) a relativistically smeared reflection component, resulting from the irradiation of an accretion disk by a compact hard X-ray source, ii) one or several warm/ionized absorption components produced by AGN-driven outflows crossing our line of sight, and iii) a non relativistic reflection component produced by more distant material. Disentangling these components via detailed model fitting can thus be used to constrain the black hole spin, the geometry and characteristics of the accretion flow, as well as of the outflows and surroundings of the black hole.
Aims. We investigate how a high throughput high resolution X-ray spectrometer, such as the Athena X-ray Integral Field Unit (X-IFU)
can be used to this aim, using the state of the art reflection model relxill in a lamp post geometrical configuration.
Methods. We simulate a representative sample of AGN spectra, including all necessary model complexities, as well as a range of
model parameters going from standard to more extreme values, and considered X-ray fluxes that are representative of known AGN
and Quasars (QSOs) populations. We also present a method to estimate the systematic errors related to the uncertainties in the
calibration of the X-IFU.
Results. In a conservative setting, in which the reflection component is computed self consistently by the relxill model from the preset geometry and no iron over abundance, the mean errors on the spin and height of the irradiating source are < 0.05 and ∼ 0.2 R$_g$ (in units of gravitational radius). Similarly the absorber parameters (column density, ionization parameter, covering factor and velocity)
are measured to an accuracy typically less than ∼ 5% over their allowed range of variations. Extending the simulations to include
blue shifted ultra fast outflows, we show that X-IFU could measure their velocity with statistical errors < 1%, even for high redshift
objects (e.g. at redshifts ∼ 2.5).
Conclusions. The simulations presented here demonstrate the potential of the X-IFU to understand how black holes are powered and
how they shape their host galaxies. The accuracy to recover the physical model parameters encoded in their X-ray emission is reached
thanks to the unique capability of X-IFU to separate and constrain, narrow and broad, emission and absorption components.".
"Observing Black Holes Spin" (Mar 27 2019), by Christopher S. Reynolds:
"... black holes are nature’s simplest objects, defined solely by their electrical charge (which is neutralized to zero in realistic astrophysical settings), mass, and angular momentum.
In this Review, I will survey the current state and future promise of black hole spin measurements. For much of the past 20 years, quantitative measures of spin have been the domain of X-ray astronomy, and these techniques continue to be refined as the quality of the data improves. With the recent advent of gravitational wave astronomy, we now have a completely new and complementary window on spinning black holes. Furthermore, we stand on the threshold of anothernmajor breakthrough, the direct imaging of the shadow of the event horizon by global mm-band Very Long Baseline Interferometry, aka, the Event Horizon Telescope (EHT). We are truly entering a goldenbage for the study of black hole physics and black hole spin.
While the original Penrose process may be hard to realise in nature, Roger Blandford and Roman Znajek showed that magnetic fields can similarly extract rotational energy from the ergosphere. Magnetic spin-extraction is the.leading theoretical model for the driving of relativistic jets from black hole systems.
To be more quantitative, we consider a black hole with mass $M$ and angular momentum $J$. We can define the unitless “spin parameter” by $a = cJ/GM^2$ where $c$ is the speed of light and $G$ is Newton’s
constant of Gravitation. The Kerr solution tells us that the structure of the spacetime around a spinning black hole depends only on $M$ and $a$. As well as greatly simplifying any GR treatments of
black hole astrophysics, this provides a route to observational explorations of gravity theories beyond GR — once the mass and spin of an astrophysical black hole has been measured, we can in principle
search for deviations of the inferred gravitational field (including any gravitational radiation) from the predictions of GR.
If one were to spin a planet or a star too quickly, it would fly apart as the centrifugal forces overwhelm the gravity that binds the object together. There is an equivalent situation for a black
hole. The Kerr solution shows that, if $|a| > 1$, there is no longer an event horizon. GR would then predict a naked spacetime singularity, an outcome that is abhorrant to physical law and the notion of predictability and thus forbidden by the Cosmic Censorship Hypothesis. Of course, it is of great interest to physicists to test whether nature respects this Kerr limit.".
Figure 1: Location of some special orbits in the equatorial plane of a Kerr black hole as a function of spin parameter. Shown here is the innermost stable circular orbit (red line), photon circular orbit (blue line), static limit (dashed white line), and event horizon (bounding the grey shade). Positive/negative spin parameter corresponds to spin that is prograde/retrograde, respectively, relative to the orbiting matter (or photons). The vertical dashed red line separates the prograde and retrograde cases. Circular orbits are stable outside of the innermost stable orbit but become unstable inside of this radius (region denoted by light red shading). Circular orbits do not exist interior to the photon circular orbit (region denoted by solid red shading). For concreteness, a 10 solar mass black hole is assumed. Radii for other masses can be obtained using linear proportionality.