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Register a new userThe relation between globular cluster systems and supermassive black holes in spiral galaxies. The case study of NGC 4258
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Rosa Amelia Gonzalez-Lopez Lira
Publication date
2016
fields
Physics
and research's language is
English
Authors
Rosa A. Gonzalez-Lopezlira
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We aim to explore the relationship between globular cluster total number, $N_{rm GC}$, and central black hole mass, $M_bullet$, in spiral galaxies, and compare it with that recently reported for ellipticals. We present results for the Sbc galaxy NGC 4258, from Canada France Hawaii Telescope data. Thanks to water masers with Keplerian rotation in a circumnuclear disk, NGC 4258 has the most precisely measured extragalactic distance and supermassive black hole mass to date. The globular cluster (GC) candidate selection is based on the ($u^* - i^prime$) vs. ($i^prime - K_s$) diagram, which is a superb tool to distinguish GCs from foreground stars, background galaxies, and young stellar clusters, and hence can provide the best number counts of GCs from photometry alone, virtually free of contamination, even if the galaxy is not completely edge-on. The mean optical and optical-near infrared colors of the clusters are consistent with those of the Milky Way and M 31, after extinction is taken into account. We directly identify 39 GC candidates; after completeness correction, GC luminosity function extrapolation and correction for spatial coverage, we calculate a total $N_{rm GC} = 144pm31^{+38}_{-36}$ (random and systematic uncertainties, respectively). We have thus increased to 6 the sample of spiral galaxies with measurements of both $M_bullet$ and $N_{rm GC}$. NGC 4258 has a specific frequency $S_{rm N} = 0.4pm0.1$ (random uncertainty), and is consistent within 2$sigma$ with the $N_{rm GC}$ vs. $M_bullet$ correlation followed by elliptical galaxies. The Milky Way continues to be the only spiral that deviates significantly from the relation.
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We present new Space Telescope Imaging Spectrograph (STIS) observations of three spiral galaxies, NGC 4303, NGC 3310 and NGC 4258. The bright optical emission lines H$alpha$ $lambda$ $6564 AA$, [NII] $lambda$$lambda$ $6549,6585 AA$ and [SII] $lambda$$lambda$ $ 6718,6732 AA$ were used to study the kinematics of the ionized gas in the nuclear region of each galaxy with a $sim 0.07arcsec$ spatial resolution. In NGC 3310, the observed gas kinematics is well matched by a circularly rotating disk model but we are only able to set an upper limit to the BH mass which, taking into account the allowed disk inclinations, varies in the range $5.0 times 10^{6} - 4.2 times 10^{7} M_{odot}$ at the 95% confidence level. In NGC 4303 the kinematical data require the presence of a BH with mass $M_{BH}=(5.0)^{+0.87}_{-2.26}times 10^{6}M_{odot}$ (for a disk inclination $i=70$ deg).In NGC 4258, the observed kinematics require the presence of a black hole with $M_{BH}= (7.9)^{+6.2}_{-3.5} times 10^{7}M_{odot}$ ($i=60$ deg). This result is in good agreement with the published value $(3.9 pm 0.1) times 10^{7} M_{odot}$, derived from $H_{2}O$-maser observations. Our attempt at measuring BH masses in these 3 late type Sbc spiral galaxies has shown that these measurements are very challenging and at the limit of the highest spatial resolution currently available. Nonetheless our estimates are in good agreement with the scaling relations between black holes and their host spheroids suggesting that (i) they are reliable and (ii) black holes in spiral galaxies follows the same scaling relations as those in more massive early-type galaxies. A crucial test for the gas kinematical method, the correct recovery of the known BH mass in NGC 4258, has been successful. [abridged]
We study the relations between the mass of the central black hole (BH) $M_{rm BH}$, the dark matter halo mass $M_{rm h}$, and the stellar-to-halo mass fraction $f_starpropto M_star/M_{rm h}$ in a sample of $55$ nearby galaxies with dynamically measured $M_{rm BH}>10^6,{rm M}_odot$ and $M_{rm h}>5times10^{11},{rm M}_odot$. The main improvement with respect to previous studies is that we consider both early- and late-type systems for which $M_{rm h}$ is determined either from globular cluster dynamics or from spatially resolved rotation curves. Independently of their structural properties, galaxies in our sample build a well defined sequence in the $M_{rm BH}$-$M_{rm h}$-$f_star$ space. We find that: (i) $M_{rm h}$ and $M_{rm BH}$ strongly correlate with each other and anti-correlate with $f_star$; (ii) there is a break in the slope of the $M_{rm BH}$-$M_{rm h}$ relation at $M_{rm h}$ of $10^{12},{rm M}_odot$, and in the $f_star$-$M_{rm BH}$ relation at $M_{rm BH}$ of $sim10^7!-!10^8,{rm M}_odot$; (iii) at a fixed $M_{rm BH}$, galaxies with a larger $f_star$ tend to occupy lighter halos and to have later morphological types. We show that the observed trends can be reproduced by a simple equilibrium model in the $Lambda$CDM framework where galaxies smoothly accrete dark and baryonic matter at a cosmological rate, having their stellar and black hole build-up regulated both by the cooling of the available gas reservoir and by the negative feedback from star formation and active galactic nuclei (AGN). Feature (ii) arises as the BH population transits from a rapidly accreting phase to a more gentle and self-regulated growth, while scatter in the AGN feedback efficiency can account for feature (iii).
This work aims at studying the $M_{BH}-M_{dyn}$ relation of a sample of $2<z<7$ quasars by constraining their host galaxy masses through full kinematical modeling of the cold gas kinematics, thus avoiding all possible biases and effects introduced by the rough virial estimates usually adopted so far. For this purpose we retrieved public observations of $72$ quasar host galaxies observed in ${rm [CII]_{158mu m}}$ or ${rm CO}$ transitions with the Atacama Large Millimeter Array (ALMA). We then selected those quasars whose line emission is spatially resolved and performed a kinematic analysis on ALMA observations. We estimated the dynamical mass of the systems by modeling the gas kinematics with a rotating disc taking into account geometrical and instrumental effects. Our dynamical mass estimates, combined with $M_{BH}$ obtained from literature and our own new ${rm CIV}lambda1550$ observations, have allowed us to investigate the $ M_{BH}/M_{dyn}$ in the early Universe. Overall we obtained a sample of $10$ quasars at $zsim2-7$ in which line emission is detected with high S/N ($> 5-10$) and the gas kinematics is spatially resolved and dominated by ordered rotation. The estimated dynamical masses place $6$ out of $10$ quasars above the local relation yielding to a $M_{BH}/M_{dyn}$ ratios $sim10times$ higher than those estimated in low-$z$ galaxies. On the other hand, we found that $4$ quasars at $zsim 4-6$ have dynamical-to-BH mass ratios consistent with what is observed in early-type galaxies in the local Universe.
Using the Next Generation Very Large Array (ngVLA), we will make a comprehensive inventory of intermediate-mass black holes (IMBHs) in hundreds of globular cluster systems out to a distance of 25 Mpc. IMBHs have masses of about 100 to 100,000 solar masses. Finding them in globular clusters would validate a formation channel for seed black holes in the early universe and inform event predictions for gravitational wave facilities. Reaching a large number of globular clusters is key, as Fragione et al. (2018) predict that only a few percent will have retained their gravitational-wave fostering IMBHs.
In the last decades several correlations between the mass of the central supermassive black hole (BH) and properties of the host galaxy - such as bulge luminosity and mass, central stellar velocity dispersion, Sersic index, spiral pitch angle etc. - have been found and point at a coevolution scenario of BH and host galaxy. In this article, I review some of these relations for inactive galaxies and discuss the findings for galaxies that host an active galactic nucleus/quasar. I present the results of our group that finds that active galaxies at $zlesssim 0.1$ do not follow the BH mass - bulge luminosity relation. Furthermore, I show near-infrared integral-field spectroscopic data that suggest that young stellar populations cause the bulge overluminosity and indicate that the host galaxy growth started first. Finally, I discuss implications for the BH-host coevolution.
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