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Register a new userAn evolving and mass dependent ${rm sigma_{text{sSFR}}}$-${rm M_{star}}$ relation for galaxies
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The scatter (${rmsigma_{text{sSFR}}}$) of the specific star formation rates (sSFRs) of galaxies is a measure of the diversity in their star formation histories (SFHs) at a given mass. In this paper we employ the EAGLE simulations to study the dependence of the ${rm sigma_{text{sSFR}}}$ of galaxies on stellar mass (${rm M_{star}}$) through the ${rm sigma_{text{sSFR}}}$-${rm M_{star}}$ relation in $ {rm z sim 0-4}$. We find that the relation evolves with time, with the dispersion depending on both stellar mass and redshift. The models point to an evolving U-shape form for the ${rm sigma_{text{sSFR}}}$-${rm M_{star}}$ relation with the scatter being minimal at a characteristic mass $M^{star}$ of ${rm 10^{9.5}}$ ${rm M_{odot}}$ and increasing both at lower and higher masses. This implication is that the diversity of SFHs increases towards both at the low- and high-mass ends. We find that active galactic nuclei feedback is important for increasing the ${rm sigma_{text{sSFR}}}$ for high mass objects. On the other hand, we suggest that SNe feedback increases the ${rm sigma_{text{sSFR}}}$ of galaxies at the low-mass end. We also find that excluding galaxies that have experienced recent mergers does not significantly affect the ${rm sigma_{text{sSFR}}}$-${rm M_{star}}$ relation. Furthermore, we employ the combination of the EAGLE simulations with the radiative transfer code SKIRT to evaluate the effect of SFR/stellar mass diagnostics in the ${rm sigma_{text{sSFR}}}$-${rm M_{star}}$ relation and find that the ${rm SFR/M_{star}}$ methodologies (e.g. SED fitting, UV+IR, UV+IRX-$beta$) widely used in the literature to obtain intrinsic properties of galaxies have a large effect on the derived shape and normalization of the ${rm sigma_{text{sSFR}}}$-${rm M_{star}}$ relation.
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We present high resolution spectroscopy taken with the Keck Echellete Spectrograph and Imager to measure stellar velocity dispersions for eight active dwarf galaxies ($M_{ast}<3times10^{9}~M_{odot}$) with virial black hole masses. We double the number of systems in this stellar mass regime with measurements of both black hole mass ($M_{rm BH}$) and stellar velocity dispersion ($sigma_{ast}$), and place them on the $M_{rm BH}-sigma_{ast}$ relation. The tight relation between $M_{rm BH}$ and $sigma_{ast}$ for higher mass galaxies is a strong piece of evidence for the co-evolution of BHs and their host galaxies, but it has been unclear whether this relation holds in the dwarf galaxy regime. Our sample is in good agreement with the extrapolation of the $M_{rm BH}-sigma_{ast}$ relation to low BH/galaxy masses, suggesting that the processes which produce $M_{rm BH}-sigma_{ast}$ can also operate in dwarf galaxies. These results provide important constraints for massive black hole seed formation models and models exploring the impact of AGN feedback in dwarf galaxies.
We revisit the possibility of redshift evolution in the $M_{rm{BH}}-sigma_*$ relation with a sample of 22 Seyfert 1 galaxies with black holes (BHs) in the mass range $10^{6.3}-10^{8.3}~M_odot$ and redshift range $0.03<z<0.57$ with spectra obtained from spatially resolved Keck/Low-Resolution Imaging Spectrometer observations. Stellar velocity dispersions were measured directly from the Mg Ib region, taking into consideration the effect of Fe II contamination, active galactic nucleus (AGN) dilution, and host-galaxy morphology on our measurements. BH masses are estimated using the H$beta$ line width, and the luminosity at 5100 $overset{lower.5emcirc}{mathrm{A}}$ is estimated from surface brightness decomposition of the AGN from the host galaxy using high-resolution imaging from the Hubble Space Telescope. Additionally, we investigate the use of the [O III]$lambda5007$ emission line width as a surrogate for stellar velocity dispersion, finding better correlation once corrected for Fe II contamination and any possible blueshifted wing components. Our selection criteria allowed us to probe lower-luminosity AGNs and lower-mass BHs in the non-local universe than those measured in previous single-epoch studies. We find that any offset in the $M_{rm{BH}}-sigma_*$ relation up to $zsim0.6$ is consistent with the scatter of local BH masses, and address the sources of biases and uncertainties that contribute to this scatter.
[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.
We analyze the emission line profiles detected in deep optical spectra of quasars to derive the mass of their super-massive black holes (SMBH) following the single-epoch virial method. Our sample consists in 6 radio-loud quasars and 4 radio-quiet quasars. We carefully fit a broad and narrow Gaussian component for each emission line in both the H$beta$ (10 objects) and H$alpha$ regions (5 objects). A very good agreement of the derived SMBH masses, $M_{rm SMBH}$, is found using the fitted broad H$beta$ and H$alpha$ emission lines. We compare our $M_{rm SMBH}$ results with those found by previous studies. We study the relationship between the $M_{rm SMBH}$ of the quasar and the stellar velocity dispersion, $sigma_{*}$, of the host galaxy. We use the measured $M_{rm SMBH}$ and $sigma_{*}$ to investigate the $M_{rm SMBH}$ - $sigma_{*}$ relation for both the radio-loud and radio-quiet subsamples. Besides the scatter, we find a good agreement between radio-quiet quasars and AGN+quiescent galaxies and between radio-loud quasars and AGN. Our analysis does not support the hypothesis of using $sigma$([O III] $lambda$5007) as a surrogate for stellar velocity dispersions in high-mass, high-luminosity quasars. We also investigate the relationship between the 5 GHz radio-continuum luminosity, $L_{rm~5,GHz}$, of the quasar host galaxy with both $M_{rm SMBH}$ and $sigma_{*}$. We do not find any correlation between $L_{rm 5,GHz}$ and $M_{rm SMBH}$, although we observe a trend that galaxies with larger stellar velocity dispersions have larger $L_{rm 5,GHz}$. Using the results of our fitting for the narrow emission lines of [O III] $lambda$5007 and [N II] $lambda$6583 we estimate the gas-phase oxygen abundance of six quasars, being sub-solar in all cases.
Strong scaling relations between host galaxy properties (such as stellar mass, bulge mass, luminosity, effective radius etc) and their nuclear supermassive black holes mass point towards a close co-evolution. In this work, we first review previous efforts supporting the fundamental importance of the relation between supermassive black hole mass and stellar velocity dispersion ($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.
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