AGN Activity and Black Hole Masses in Low Surface Brightness Galaxies (original) (raw)
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Investigating the AGN activity and black hole masses in Low Surface brightness galaxies
We present an analysis of the optical nuclear spectra from the active galactic nuclei (AGN) in a sample of giant low surface brightness (GLSB) galaxies. GLSB galaxies are extreme late type spirals that are large, isolated and poorly evolved compared to regular spiral galaxies. Earlier studies have indicated that their nuclei have relatively low mass black holes. Using data from the Sloan Digital Sky Survey (SDSS), we selected a sample of 30 GLSB galaxies that showed broad H$\alpha$ emission lines in their AGN spectra. In some galaxies such as UGC 6284, the broad component of H$\alpha$ is more related to outflows rather than the black hole. One galaxy (UGC 6614) showed two broad components in H$\alpha$, one associated with the black hole and the other associated with an outflow event. We derived the nuclear black hole (BH) masses of 29 galaxies from their broad H$\alpha$ parameters. We find that the nuclear BH masses lie in the range 105−107Modot10^{5}-10^{7} M_{\odot}105−107Modot. The bulge stellar veloc...
Active galactic nucleus activity and black hole masses in low surface brightness galaxies
Monthly Notices of the Royal Astronomical Society, 2011
We present medium resolution optical spectroscopy of a sample of nine low surface brightness (LSB) galaxies. For those that show clear signatures of active galactic nucleus (AGN) emission, we have disentangled the AGN component from stellar light and any Fe I and Fe II contribution. We have decomposed the Hα line into narrow and broad components and determined the velocities of the broad components; typical values lie between 900 and 2500 km s −1 . Of the galaxies in our study, UGC 6614, UGC 1922, UGC 6968 and LSBC F568−6 (Malin 2) show clear signatures of AGN activity. We have calculated the approximate black hole (BH) masses for these galaxies from the Hα line emission using the virial approximation. The BH masses are ∼3 × 10 5 M for three galaxies and lie in the intermediate-mass BHs domain rather than the supermassive range. UGC 6614 harbours a BH of mass 3.8 × 10 6 M ; it also shows an interesting feature bluewards of Hα and Hβ implying outflow of gas or a one-sided jet streaming towards us. We have also measured the bulge stellar velocity dispersions using the Ca II triplet lines and plotted these galaxies on the M-σ plot. We find that all the three galaxies UGC 6614, UGC 6968 and F568−6 lie below the M-σ relation for nearby galaxies. Thus, we find that although the bulges of LSB galaxies may be well evolved, their nuclear BH masses are lower than those found in bright galaxies and lie offset from the M-σ correlation.
Towards a Complete Census of AGNs in Nearby Galaxies: The Incidence of Growing Black Holes
We investigate the local supermassive black hole (SMBH) density function and relative mass accretion rates of all active galactic nuclei (AGNs) identified in a volume-limited sample of infrared (IR) bright galaxies (L IR > 3 × 10 9 L ⊙ ) to D < 15 Mpc (Goulding & Alexander 2009). A database of accurate SMBH mass (M BH ) estimates is compiled from literature sources using physically motivated AGN modeling techniques (reverberation mapping, maser mapping and gas kinematics) and well-established indirect M BH estimation methods (the M-σ * and M BH -L K,bul relations). For the three sources without previously published M BH estimates, we use 2MASS K-band imaging and galfit to constrain the bulge luminosities, and hence SMBH masses. In general, we find the AGNs in the sample host SMBHs which are spread over a wide mass range (M BH ≈ (0.1-30) × 10 7 M ⊙ ), but with the majority in the poorly studied M BH ≈ 10 6 -10 7 M ⊙ region. Using sensitive hard X-ray (2-10 keV) and mid-IR constraints we calculate the bolometric luminosities of the AGNs (L Bol,AGN ) and use them to estimate relative mass accretion rates. We use these data to calculate the volume-average SMBH growth rate of galaxies in the local Universe and find that the AGNs hosting SMBHs in the mass range M BH ≈ 10 6 -10 7 M ⊙ are dominated by optically unidentified AGNs. These relatively small SMBHs are acquiring a significant proportion of their mass in the present-day, and are amongst the most rapidly growing in the local Universe (SMBH mass doubling times of ≈ 6 Gyrs). Additionally, we find tentative evidence for an increasing volume-weighted AGN fraction with decreasing SMBH mass in the M BH ≈ 10 6 -10 8 M ⊙ range. Overall, we conclude that significant mass accretion onto small SMBHs may be missed in even the most sensitive optical surveys due to absent or weak optical AGN signatures.
The Host Galaxies and Black Holes of Typical z ∼0.5–1.4 AGNs
The Astrophysical Journal, 2008
We study the stellar and star formation properties of the host galaxies of 58 X-ray selected AGN in the GOODS portion of the Chandra Deep Field South (CDF-S) region at z ∼ 0.5 − 1.4. The AGN are selected such that their rest-frame UV to near-infrared spectral energy distributions (SEDs) are dominated by stellar emission, i.e., they show a prominent 1.6 µm bump, thus minimizing the AGN emission 'contamination'. This AGN population comprises approximately 50% of the X-ray selected AGN at these redshifts. Using models of stellar and dust emission we model their SEDs to derive stellar masses (M * ) and total (UV+IR) star formation rates (SFR). We find that AGN reside in the most massive galaxies at the redshifts probed here. Their characteristic stellar masses (M * ∼ 7.8 × 10 10 M ⊙ and M * ∼ 1.2×10 11 M ⊙ at median redshifts of 0.67 and 1.07, respectively) appear to be representative of the X-ray selected AGN population at these redshifts, and are intermediate between those of local type 2 AGN and high redshift (z ∼ 2) AGN. The inferred black hole masses (M BH ∼ 2 × 10 8 M ⊙ ) of typical AGN are similar to those of optically identified quasars at similar redshifts. Since the AGN in our sample are much less luminous (L 2−10keV < 10 44 erg s −1 ) than quasars, typical AGN have low Eddington ratios (η ∼ 0.01 − 0.001). This suggests that, at least at intermediate redshifts, the cosmic AGN 'downsizing' is due to both a decrease in the characteristic stellar mass of typical host galaxies, and less efficient accretion. Finally there is no strong evidence in AGN host galaxies for either highly suppressed star formation (expected if AGN played a role in quenching star formation) or elevated star formation when compared to mass selected (i.e., IRAC-selected) galaxies of similar stellar masses and redshifts. This may be explained by the fact that galaxies with M * ∼ 5 × 10 10 − 5 × 10 11 M ⊙ are still being assembled at the redshifts probed here.
Relations between Massive Black Holes in AGN and their Host Galaxies
Massive black holes detected in the centers of many nearby galaxies are linearly correlated with the luminosity of the host bulge, the black hole mass being about 0.1% of the bulge mass. An even stronger relation exists between the BH mass (Mbh) and the stellar velocity dispersion in the host bulge. We show that massive BHs of AGNs (measured by reverberation mapping) and their bulge luminosity (measured by using a bulge/disk decomposition) follow the same relations as ordinary (inactive) galaxies, with the exeption of narrow line AGN which apparently have significantly lower BH/bulge ratios. Narrow line AGNs seem to be outstanding also in the Mbh-velocity dispersion relation: the small number of Seyfert galaxies with measured velocity dispersion indicate that narrow line Seyfert 1 galaxies have a smaller BH mass/velocity dispersion than quiescent galaxies and broad line Syferts. Estimating the velocity dispersion for from the bulge luminosity with the Faber-Jackson relation more than doubles the sample and supports these results.
Astronomy & Astrophysics, 2013
Context. Active galactic nuclei (AGN) are thought to play an important role in galaxy evolution. It has been suggested that AGN feedback could be partly responsible for quenching star-formation in the hosts, leading to transition from the blue cloud to the red sequence. The transition seems to occur faster for the most massive galaxies, where traces of AGN activity have been already found as early as at z < 0.1. The correlation between AGN activity, aging of the stellar populations and stellar mass still needs to be fully understood, especially at high redshifts. Aims. Our aim is to investigate the link between AGN activity, star-formation, and stellar mass of the host galaxy at 0 < z < 1, looking for spectroscopic traces of AGN and aging of the host. This work provides an extension of the existing studies at z < 0.1 and contributes to shed light on galaxy evolution at intermediate redshifts.
Monthly Notices of the Royal Astronomical Society, 2015
The isolated galaxies are the ideal astrophysical laboratory for distinguishing the properties of other galaxies passed the evolution in environment. The host isolated galaxies with AGNs are unique in this sense due to recognize their internal multi-wavelength properties as well as the physical parameters of accretion on the central supermassive black holes outside of the environment effects.
2009
We present the results of Spitzer IRS infrared 5-35 micron low-resolution spectroscopic energy diagnostics of ultraluminous infrared galaxies (ULIRGs) at z > 0.15, classified optically as non-Seyferts. Based on the equivalent widths of polycyclic aromatic hydrocarbon emission and the optical depths of silicate dust absorption features, we searched for signatures of intrinsically luminous, but optically elusive, buried AGNs in these optically non-Seyfert ULIRGs. We then combined the results with those of non-Seyfert ULIRGs at z < 0.15 and non-Seyfert galaxies with infrared luminosities L(IR) < 10^12Lsun. We found that the energetic importance of buried AGNs clearly increases with galaxy infrared luminosity, becoming suddenly discernible in ULIRGs with L(IR) > 10{12}Lsun. For ULIRGs with buried AGN signatures, a significant fraction of infrared luminosities can be accounted for by detected buried AGN and modestly-obscured (Av < 20 mag) starburst activity. The implied masses of spheroidal stellar components in galaxies for which buried AGNs become important roughly correspond to the value separating red massive and blue, less-massive galaxies in the local universe. Our results may support the widely-proposed AGN-feedback scenario as the origin of galaxy downsizing phenomena, where galaxies with currently larger stellar masses previously had higher AGN energetic contributions and star-formation-originating infrared luminosities, and have finished their major star-formation more quickly, due to stronger AGN feedback.
Arxiv preprint astro-ph/ …, 2003
We examine the properties of the host galaxies of 22,623 narrow-line AGN with 0.02 < z < 0.3 selected from a complete sample of 122,808 galaxies from the Sloan Digital Sky Survey. We focus on the luminosity of the [OIII]λ5007 emission line as a tracer of the strength of activity in the nucleus. We study how AGN host properties compare to those of normal galaxies and how they depend on L[OIII]. We find that AGN of all luminosities reside almost exclusively in massive galaxies and have distributions of sizes, stellar surface mass densities and concentrations that are similar to those of ordinary early-type galaxies in our sample. The host galaxies of low-luminosity AGN have stellar populations similar to normal early-types. The hosts of high-luminosity AGN have much younger mean stellar ages. The young stars are not preferentially located near the nucleus of the galaxy, but are spread out over scales of at least several kiloparsecs. A significant fraction of high-luminosity AGN have strong Hδ absorptionline equivalent widths, indicating that they experienced a burst of star formation in the recent past. We have also examined the stellar populations of the host galaxies of a sample of broad-line AGN. We conclude that there is no significant difference in stellar content between type 2 Seyfert hosts and QSOs with the same [OIII] luminosity and redshift. This establishes that a young stellar population is a general property of AGN with high [OIII] luminosities.
An Improved Black Hole Mass - Bulge Luminosity Relationship for AGNs
Two effects have substantially increased the scatter in the AGN black hole mass - host galaxy bulge luminosity relationship derived from SDSS spectra. The first is that at a fixed black hole mass, the SDSS spectrum depends strongly on redshift because an SDSS fiber sees a larger fraction of the total light of more distant galaxies. The second is that at a given redshift, the fraction of host-galaxy light in the fiber increases with decreasing galaxy luminosity. We illustrate the latter effect using the Kormendy et al. (2009) light profiles of Virgo ellipticals. With allowance for the two effects, we obtain a black hole mass - bulge luminosity relationship for AGNs which has a scatter of only +/- 0.23 dex in mass. This is less than the scatter found for inactive galaxies, and is consistent with the measuring errors. We show that there is a correspondingly tight linear relationship between the fraction of host galaxy light in AGN spectra and the Eddington ratio. This linearity implies...