We examine stellar population gradients in ~100 massive early type galaxies spanning 180 < sigma* < 370 km/s and M_K of -22.5 to -26.5 mag, observed as part of the MASSIVE survey (Ma et al. 2014). Using integral-field spectroscopy from the Mitchell S
pectrograph on the 2.7m telescope at McDonald Observatory, we create stacked spectra as a function of radius for galaxies binned by their stellar velocity dispersion, stellar mass, and group richness. With excellent sampling at the highest stellar mass, we examine radial trends in stellar population properties extending to beyond twice the effective radius (~2.5 R_e). Specifically, we examine trends in age, metallicity, and abundance ratios of Mg, C, N, and Ca, and discuss the implications for star formation histories and elemental yields. At a fixed physical radius of 3-6 kpc (the likely size of the galaxy cores formed at high redshift) stellar age and [alpha/Fe] increase with increasing sigma* and depend only weakly on stellar mass, as we might expect if denser galaxies form their central cores earlier and faster. If we instead focus on 1-1.5 R_e, the trends in abundance and abundance ratio are washed out, as might be expected if the stars at large radius were accreted by smaller galaxies. Finally, we show that when controlling for sigmastar, there are only very subtle differences in stellar population properties or gradients as a function of group richness; even at large radius internal properties matter more than environment in determining star formation history.
We explore the warm molecular and ionized gas in the centers of two megamaser disk galaxies using K-band spectroscopy. Our ultimate goal is to determine how gas is funneled onto the accretion disk, here traced by megamaser spots on sub-pc scales. We
present NIR IFU data with a resolution of ~50 pc for two galaxies: NGC 4388 with VLT/SINFONI and NGC 1194 with Keck/OSIRIS+AO. The high spatial resolution and rich spectral diagnostics allow us to study both the stellar and gas kinematics as well as gas excitation on scales only an order of magnitude larger than the maser disk. We find a drop in the stellar velocity dispersion in the inner ~100 pc of NGC 4388, a common signature of a dynamically cold central component seen in many active nuclei. We also see evidence for non-circular gas motions in the molecular hydrogen on similar scales, with the gas kinematics on 100-pc scales aligned with the megamaser disk. In contrast, the high ionization lines and Br-gamma trace outflow along the 100 pc-scale jet. In NGC 1194, the continuum from the accreting black hole is very strong, making it difficult to measure robust two-dimensional kinematics, but the spatial distribution and line ratios of the molecular hydrogen and Br-gamma have consistent properties between the two galaxies.
We examine the alignment between H_2O megamaser disks on sub-pc scales with circumnuclear disks and bars on <500 pc scales observed with HST/WFC3. The HST imaging reveals young stars, indicating the presence of gas. The megamaser disks are not well a
ligned with the circumnuclear bars or disks as traced by stars in the HST images. We speculate on the implications of the observed misalignments for fueling supermassive black holes in gas-rich spiral galaxies. In contrast, we find a strong preference for the rotation axes of the megamaser disks to align with radio continuum jets observed on >50 pc scales, in those galaxies for which radio continuum detections are available. Sub-arcsecond observations of molecular gas with ALMA will enable a more complete understanding of the interplay between circumnuclear structures.
SDSS J1356+1026 is a pair of interacting galaxies at redshift z=0.123 that hosts a luminous obscured quasar in its northern nucleus. Here we present two long-slit Magellan LDSS-3 spectra that reveal a pair of symmetric ~10 kpc-size outflows emerging
from this nucleus, with observed expansion velocities of ~250 km/s in projection. We present a kinematic model of these outflows and argue that the deprojected physical velocities of expansion are likely ~1000 km/s and that the kinetic energy of the expanding shells is likely 10^44-10^45 erg/s, with an absolute minimum of >10^42 erg/s. Although a radio counterpart is detected at 1.4GHz, it is faint enough that the quasar is considered to be radio-quiet by all standard criteria, and there is no evidence of extended emission due to radio lobes, whether aged or continuously powered by an ongoing jet. We argue that the likely level of star formation is probably insufficient to power the observed energetic outflow and that SDSS J1356+1026 makes a strong case for radio-quiet quasar feedback. In further support of this hypothesis, polarimetric observations show that the direction of quasar illumination is coincident with the direction of the outflow.
It is now possible to estimate black hole masses across cosmic time, using broad emission lines in active galaxies. This technique informs our views of how galaxies and their central black holes coevolve. Unfortunately, there are many outstanding unc
ertainties associated with these virial mass estimates. One of these comes from using the accretion luminosity to infer a size for the broad-line region. Incorporating the new sample of low-luminosity active galaxies from our recent monitoring campaign at Lick Observatory, we recalibrate the radius-luminosity relation with tracers of the accretion luminosity other than the optical continuum. We find that the radius of the broad-line region scales as the square root of the X-ray and Hbeta luminosities, in agreement with recent optical studies. On the other hand, the scaling appears to be marginally steeper with narrow-line luminosities. This is consistent with a previously observed decrease in the ratio of narrow-line to X-ray luminosity with increasing total luminosity. The radius of the broad-line region correlates most tightly with Hbeta luminosity, while the X-ray and narrow-line relations both have comparable scatter of a factor of two. These correlations provide useful alternative virial BH masses in objects with no detectable optical/UV continuum emission, such as high-redshift galaxies with broad emission lines, radio-loud objects, or local active galaxies with galaxy-dominated continua.
We re-examine claims of redshift evolution in black hole-bulge scaling relations based on lensed quasars. In particular, we refine the black hole mass estimates using measurements of Balmer lines from near-infrared spectroscopy obtained with Triplesp
ec at Apache Point Observatory. In support of previous work, we find a large scatter between Balmer and UV line widths, both MgII 2796, 2803 and CIV 1548, 1550. There is tentative evidence that CIII] 1909, despite being a blend of multiple transitions, may correlate well with MgII, although a larger sample is needed for a real calibration. Most importantly, we find no systematic changes in the estimated BH masses for the lensed sample based on Balmer lines, providing additional support to the interpretation that black holes were overly massive compared to their host galaxies at high redshift.
We discuss the critical importance of black hole mass indicators based on scaling relations in active galaxies. We highlight outstanding uncertainties in these methods and potential paths to substantial progress in the next decade.
Obscured or narrow-line active galaxies offer an unobstructed view of the quasar environment in the presence of a luminous and vigorously accreting black hole. We exploit the large new sample of optically selected luminous narrow-line active galaxies
from the Sloan Digital Sky Survey at redshifts 0.1 < z < 0.45, in conjunction with follow-up observations with the Low Dispersion Survey Spectrograph (LDSS3) at Magellan, to study the distributions of black hole mass and host galaxy properties in these extreme objects. We find a narrow range in black hole mass (<log M_BH/M_sun> = 8.0 +/- 0.7) and Eddington ratio (<log L/L_Edd> = -0.7 +/- 0.7) for the sample as a whole, surprisingly similar to comparable broad-line systems. In contrast, we infer a wide range in star formation properties and host morphologies for the sample, from disk-dominated to elliptical galaxies. Nearly one-quarter have highly disturbed morphologies indicative of ongoing mergers. Unlike the black holes, which are apparently experiencing significant growth, the galaxies appear to have formed the bulk of their stars at a previous epoch. On the other hand, it is clear from the lack of correlation between gaseous and stellar velocity dispersions in these systems that the host galaxy interstellar medium is far from being in virial equilibrium with the stars. While our findings cast strong doubt on the reliability of substituting gas for stellar dispersions in high luminosity active galaxies, they do provide direct evidence that luminous accreting black holes influence their surroundings on a galaxy-wide scale.
We investigate the relationship between black hole mass and host galaxy properties for active galaxies with the lowest black hole masses currently known in galaxy nuclei. Hubble Space Telescope imaging confirms that the host galaxies have correspondi
ngly low luminosity; they are ~1 mag below L*. In terms of morphology, ~60% of the members of the sample are disk-dominated, and all of these are consistent with containing a bulge or (more likely) pseudobulge, while the remainder are compact systems with no discernible disk component. In general the compact components of the galaxies do not obey the fundamental plane of giant elliptical galaxies and classical bulges, but rather are less centrally concentrated at a given luminosity, much like spheroidal galaxies. Our results strongly confirm that a classical bulge is not a requirement for a nuclear black hole. At the same time, the observed ratio of black hole to bulge mass is nearly an order of magnitude lower in this sample than that seen for classical bulges. While the M-sigma relation appears to continue to low mass, it seems that black hole-galaxy scaling relations do depend on galaxy structure.
We present an expanded sample of low-mass black holes (BHs) found in galactic nuclei. Using standard virial mass techniques to estimate BH masses, we select from the Fourth Data Release of the Sloan Digital Sky Survey all broad-line active galaxies w
ith masses < 2 x 10^6 M_sun. BHs in this mass regime provide unique tests of the relationship between BHs and galaxies, since their late-type galaxy hosts do not necessarily contain classical bulges. Furthermore, they provide observational analogs of primordial seed BHs and are expected, when merging, to provide strong gravitational signals for future detectors such as LISA. From our preliminary sample of 19, we have increased the total sample by an order of magnitude to 174, as well as an additional 55 (less secure) candidates. The sample has a median BH mass of <M_BH> = 1.3 x 10^6 M_sun, and in general the objects are radiating at high fractions of their Eddington limits. We investigate the broad spectral properties of the sample; 55 are detected by rosat, with soft X-ray luminosities in the range 10^40 to 7 x 10^43 ergs/sec. Much like the preliminary sample, these objects are predominantly radio-quiet (R = f_6cm/f_4400A < 10), but 11 objects are detected at 20 cm, with radio powers (10^21-10^23 W/Hz) that may arise from either star formation or nuclear activity; only 1% of the sample is radio-loud. We further confirm that, with <M_g>=-19.3 and <g-r> = 0.7 mag, the host galaxies are low-mass, late-type systems. At least 40% show disk-like morphologies, and the combination of host galaxy colors and higher-order Balmer absorption lines indicate intermediate-age stellar populations in a subset of the sample.
