اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدThe Small Scatter in BH-Host Correlations & The Case for Self-Regulated BH Growth
328
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Supermassive black holes (BHs) obey tight scaling relations between their mass and their host galaxy properties such as total stellar mass, velocity dispersion, and potential well depth. This has led to the development of self-regulated models for BH growth, in which feedback from the central BH halts its own growth upon reaching a critical threshold. However, models have also been proposed in which feedback plays no role: so long as a fixed fraction of the host gas supply is accreted, relations like those observed can be reproduced. Here, we argue that the scatter in the observed BH-host correlations, and its run with scale, presents a demanding constraint on any model for these correlations, and that it favors self-regulated models of BH growth. We show that the scatter in the stellar mass fraction within a radius R in observed ellipticals and spheroids increases strongly at small R. At fixed total stellar mass (or host velocity dispersion), on very small scales near the BH radius of influence, there is an order-of-magnitude scatter in the amount of gas that must have entered and formed stars. In short, the BH appears to know more about the global host galaxy potential on large scales than the stars and gas supply on small scales. This is predicted in self-regulated models; however, models where there is no feedback would generically predict order-of-magnitude scatter in the BH-host correlations. Likewise, models in which the BH feedback in the bright mode does not regulate the growth of the BH itself, but sets the stellar mass of the galaxy by inducing star formation or blowing out a mass in gas much larger than the galaxy stellar mass, are difficult to reconcile with the scatter on small scales.
قيم البحث
اقرأ أيضاً
Strong scaling relations between host galaxy properties (such as stellar mass, bulge mass, luminosity, effective radius etc) and their nuclear supermassive black holes mass point towards a close co-evolution. In this work, we first review previous ef
forts supporting the fundamental importance of the relation between supermassive black hole mass and stellar velocity dispersion ($M_{rm BH}$-$sigma_{rm e}$). We then present further original work supporting this claim via analysis of residuals and principal component analysis applied to some among the latest compilations of local galaxy samples with dynamically measured supermassive black hole masses. We conclude with a review of the main physical scenarios in favour of the existence of a $M_{rm BH}$-$sigma_{rm e}$ relation, with a focus on momentum-driven outflows.
The LIGO/Virgo collaboration has reported 50 BH-BH mergers and 8 additional candidates recovered from digging deeper into the detectors noise. Majority of these mergers have low effective spins pointing toward low BH spins and efficient angular momen
tum transport in massive stars as proposed by several models (e.g., Tayler-Spruit magnetic dynamo or Fuller model). However, out of these 58 mergers, 7 are consistent with having high effective spin parameter (chi_eff>0.3). Additionally, 2 out of these 7 events seem to have high effective spins sourced from the high spin of a primary (more massive) BH. The most extreme merger has very high primary BH dimensionless spin (a_1=0.9). These particular observations may be potentially used to discriminate between the isolated binary and dynamical globular cluster BH-BH formation channels. It may seem that high BH spins point to the dynamical origin if stars have efficient angular momentum transport and form low-spinning BHs. Then dynamical formation is required to produce second and third generations of BH-BH mergers that typically produce high-spinning BHs. Here we show that isolated binary BH-BH formation channel can naturally reproduce such highly spinning BHs. Our models start with efficient angular momentum transport in massive stars that is needed to reproduce majority of BH-BH mergers with low effective spins. However, some massive binaries are subject to strong tidal spin-up allowing for the formation of moderate fraction (~10%) of BH-BH mergers with high effective spins (chi_eff>0.4-0.5). Moreover, binary evolution can produce small fraction (~1%) of BH-BH mergers with almost maximally spinning primary BHs ($a_1>0.9$). Therefore, the formation scenario of those unusual BH-BH mergers remains unresolved.
The gravitational-wave detection by the LIGO-Virgo scientific collaboration shows that the black hole and neutron star (BH-NS) or BH-BH systems with a BH mass of tens of solar masses widely exist in the universe. Two main types of scenarios have been
invoked for the formation of BH-NS/BH systems, including isolated binary evolution in galactic fields and dynamical interactions in dense environments. Here we propose that if the BH-NS/BH systems are formed from isolated binary evolution, the supernova (SN) signal associated with the second core collapse would show some identifiable features, due to the accretion feedback from the companion BH. Depending on the binary properties, we show that the SN lightcurve could present a sharp peak around $sim10$ days, with luminosity even at the level of the super luminous SNe ( e.g. $sim10^{44}~rm erg~s^{-1}$) or present a plateau feature lasting for several tens of days with regular luminosity of core collapse SNe. Comparing the event rate density of these special SN signals with the event rate density of LIGO-Virgo detected BH-NS/BH systems could help to distinguish the BH-NS/BH formation channel.
While an axion-clouded black hole (BH) encounters a pulsar (PSR) or has a PSR companion, a gravitational molecule can be formed. In such a system, the axion cloud evolves at the binary hybrid orbitals, as it happens at microscopic level to electron c
loud in a chemical molecule. To demonstrate this picture, we develop a semi-analytical formalism using the method of linear combination of atomic orbitals with an adiabatic approximation. An oscillating axion-cloud profile and a perturbed binary rotation, together with unique and novel detection signals, are then predicted. Remarkably, the proposed PSR timing and polarization observables, namely the oscillation of periastron time shift and the birefringence with multiple modulations, correlate in pattern, and thus can be properly combined to strengthen the detection.
[Abridged] We investigate the nature of the relations between black hole (BH) mass ($M_{rm BH}$) and the central velocity dispersion ($sigma$) and, for core-Sersic galaxies, the size of the depleted core ($R_{rm b}$). Our sample of 144 galaxies with
dynamically determined $M_{rm BH}$ encompasses 24 core-Sersic galaxies, thought to be products of gas-poor mergers, and reliably identified based on high-resolution HST imaging. For core-Sersic galaxies -- i.e., combining normal-core ($R_{rm b} < 0.5 $ kpc) and large-core galaxies ($R_{rm b} gtrsim 0.5$ kpc), we find that $M_{rm BH}$ correlates remarkably well with $R_{rm b}$ such that $M_{rm BH} propto R_{rm b}^{1.20 pm 0.14}$ (rms scatter in log $M_{rm BH}$ of $Delta_{rm rms} sim 0.29$ dex), confirming previous works on the same galaxies except three new ones. Separating the sample into Sersic, normal-core and large-core galaxies, we find that Sersic and normal-core galaxies jointly define a single log-linear $M_{rm BH}-sigma$ relation $M_{rm BH} propto sigma^{ 4.88 pm 0.29}$ with $Delta_{rm rms} sim 0.47$ dex, however, at the high-mass end large-core galaxies (four with measured $M_{rm BH}$) are offset upward from this relation by ($2.5-4) times sigma_{rm s}$, explaining the previously reported steepening of the $M_{rm BH}-sigma$ relation for massive galaxies. Large-core spheroids have magnitudes $M_{V} le -23.50$ mag, half-light radii Re $>$ 10 kpc and are extremely massive $M_{*} ge 10^{12}M_{odot}$. Furthermore, these spheroids tend to host ultramassive BHs ($M_{rm BH} ge 10^{10}M_{odot}$) tightly connected with their $R_{rm b}$ rather than $sigma$. The less popular $M_{rm BH}-R_{rm b}$ relation exhibits $sim$ 62% less scatter in log $M_{rm BH}$ than the $M_{rm BH}- sigma$ relations.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
