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Register a new userPopulating the low-mass end of the $M_{rm BH}-sigma_{ast}$ relation
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Added by
Vivienne Baldassare
Publication date
2020
fields
Physics
and research's language is
English
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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.
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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.
We present a re-calibration of the $M_{BH}-sigma_{star}$ relation, based on a sample of 16 reverberation-mapped galaxies with newly determined bulge stellar velocity dispersions ($sigma_{star}$) from integral-field spectroscopy (IFS), and a sample of 32 quiescent galaxies with publicly available IFS. For both samples, $sigma_{star}$ is determined via two different methods that are popular in the literature, and we provide fits for each sample based on both sets of $sigma_{star}$. We find the fit to the AGN sample is shallower than the fit to the quiescent galaxy sample, and that the slopes for each sample are in agreement with previous investigations. However, the intercepts to the quiescent galaxy relations are notably higher than those found in previous studies, due to the systematically lower $sigma_{star}$ measurements that we obtain from IFS. We find that this may be driven, in part, by poorly constrained measurements of bulge effective radius ($r_{e}$) for the quiescent galaxy sample, which may bias the $sigma_{star}$ measurements low. We use these quiescent galaxy parameterizations, as well as one from the literature, to recalculate the virial scaling factor $f$. We assess the potential biases in each measurement, and suggest $f=4.82pm1.67$ as the best currently available estimate. However, we caution that the details of how $sigma_{star}$ is measured can significantly affect $f$, and there is still much room for improvement.
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.
The $M_{BH}$ - $sigma_{star}$ relation is considered a result of co-evolution between the host galaxies and their super-massive black holes. For elliptical-bulge hosting inactive galaxies, this relation is well established, but there is still a debate whether active galaxies follow the same relation. In this paper, we estimate black hole masses for a sample of 19 local luminous AGNs (LLAMA) in order to test their location on the $M_{BH}$ - $sigma_{star}$ relation. Super-massive black hole masses ($M_{BH}$) were derived from the broad-line based relations for H$alpha$, H$beta$ and Pa$beta$ emission line profiles for the Type 1 AGNs. We compare the bulge stellar velocity dispersion ($sigma_{star}$) as determined from the Ca II triplet (CaT) with the dispersion measured from the near-infrared CO (2-0) absorption features for each AGN and find them to be consistent with each other. We apply an extinction correction to the observed broad line fluxes and we correct the stellar velocity dispersion by an average rotation contribution as determined from spatially resolved stellar kinematic maps. The H$alpha$-based black hole masses of our sample of AGNs were estimated in the range 6.34 $leq$ $log{M_{BH}}$ $leq$ 7.75 M$_odot$ and the $sigma_{star CaT}$ estimates range between 73 $leq$ $sigma_{star CaT}$ $leq$ 227 km s$^{-1}$. From the so-constructed $M_{BH}$ - $sigma_{star}$ relation for our Type 1 AGNs, we estimate the black hole masses for the Type 2 AGNs and the inactive galaxies in our sample. In conclusion, we find that our sample of local luminous AGNs is consistent with the $M_{BH}$ - $sigma_{star}$ relation of lower luminosity AGNs and inactive galaxies, after correcting for dust extinction and the rotational contribution to the stellar velocity dispersion.
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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