Redshift Evolution In Black Hole-Bulge Relations: Testing C IV-Based Black Hole Masses

We re-examine claims for redshift evolution in black hole-bulge scaling relations based on lensed quasars. In particular, we refine the black hole (BH) mass estimates using measurements of Balmer lines from near-infrared spectroscopy obtained with Triplespec at Apache Point Observatory. In support of previous work, we find a large scatter between Balmer and UV line widths, both Mg II lambda lambda 2796, 2803 and CIV lambda lambda 1548, 1550. There is tentative evidence that C III]lambda 1909, despite being a blend of multiple transitions, may correlate well with Mg II, 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.NASA Hubble Fellowship HF-01196NASA NAS 5-26555Astronom

Strong [O III] Objects Among SDSS Broad-Line Active Galaxies

We present the results of a spectral principal component analysis on 9046 broad-line AGN from the Sloan Digital Sky Survey. We examine correlations between spectral regions within various eigenspectra (e.g., between Fe II strength and H$\beta$ width) and confirm that the same trends are apparent in spectral measurements, as validation of our technique. Because we found that our sample had a large range in the equivalent width of [O III] $\lambda$5007, we divided the data into three subsets based on [O III] strength. Of these, only in the sample with the weakest equivalent width of [O III] were we able to recover the known correlation between [O III] strength and full width at half maximum of H$\beta$ and their anticorrelation with Fe II strength. At the low luminosities considered here ($L_{5100 \AA}$ of $10^{42}-10^{46}$ erg s$^{-1}$), interpretation of the principal components is considerably complicated particularly because of the wide range in [O III] equivalent width. We speculate that variations in covering factor are responsible for this wide range in [O III] strength.Comment: 26 pages, 11 figures, published in Ap

Physical Properties of the Narrow-Line Region of Low-Mass Active Galaxies

We present spectroscopic observations of 27 active galactic nuclei (AGN) with some of the lowest black hole (BH) masses known. We use the high spectral resolution and small aperture of our Keck data, taken with the Echellette Spectrograph and Imager, to isolate the narrow-line regions (NLRs) of these low-mass BHs. We investigate their emission-line properties and compare them with those of AGN with higher-mass black holes. While we are unable to determine absolute metallicities, some of our objects plausibly represent examples of the low-metallicity AGN described by Groves et al. (2006), based on their [N II]/H_alpha ratios and their consistency with the Kewley & Ellison (2008) mass-metallicity relation. We find tentative evidence for steeper far-UV spectral slopes in lower-mass systems. Overall, NLR emission lines in these low-mass AGN exhibit trends similar to those seen in AGN with higher-mass BHs, such as increasing blueshifts and broadening with increasing ionization potential. Additionally, we see evidence of an intermediate line region whose intensity correlates with L/L_Edd, as seen in higher-mass AGN. We highlight the interesting trend that, at least in these low-mass AGN, the [O III] equivalent width (EW) is highest in symmetric NLR lines with no blue wing. This trend of increasing [O III] EW with line symmetry could be explained by a high covering factor of lower ionization gas in the NLR. In general, low-mass AGN preserve many well-known trends in the structure of the NLR, while exhibiting steeper ionizing continuum slopes and somewhat lower gas-phase metallicities.Comment: 46 pages, 14 figures, 7 table

Fe II Emission In Active Galactic Nuclei: The Role Of Total And Gas-Phase Iron Abundance

Active galactic nuclei (AGNs) have Fe II emission from the broad-line region (BLR) that differs greatly in strength from object to object. We examine the role of the total and gas-phase iron abundance in determining Fe II strength. Using AGN spectra from the Sloan Digital Sky Survey (SDSS) in the redshift range of 0.2 < z < 0.35, we measure the Fe/Ne abundance of the narrow-line region (NLR) using the [Fe VII]/[Ne v] line intensity ratio. We find no significant difference in the abundance of Fe relative to Ne in the NLR as a function of Fe II/H beta. However, the [N II]/[S II] ratio increases by a factor of 2 with increasing Fe II strength. This indicates a trend in N/S abundance ratio, and by implication in the overall metallicity of the NLR gas, with increasing Fe II strength. We propose that the wide range of Fe II strength in AGN largely results from the selective depletion of Fe into grains in the low ionization portion of the BLR. Photoionization models show that the strength of the optical Fe II lines varies almost linearly with gas-phase Fe abundance, while the ultraviolet Fe II strength varies more weakly. Interstellar depletions of Fe can be as large as 2 orders of magnitude, sufficient to explain the wide range of optical Fe II strength in AGNs. This picture is consistent with the similarity of the BLR radius to the dust sublimation radius and with indications of Fe II emitting gas flowing inward from the dusty torus.Jane and Roland Blumberg Centennial Professorship in Astronomy at the University of Texas at AustinAlfred P. Sloan FoundationNational Aeronautics and Space AdministrationNational Science FoundationU.S. Department of EnergyJapanese MonbukagakushoMax Planck SocietyAstronom

Hands-on-Science: Using Education Research to Construct Learner-Centered Classes

Research into the process of learning, and learning astronomy, can be informative for the development of a course. Students are better able to incorporate and make sense of new ideas when they are aware of their own prior knowledge (Resnick et al. 1989; Confrey 1990), have the opportunity to develop explanations from their own experience in their own words (McDermott 1991; Prather et al. 2004), and benefit from peer instruction (Mazur 1997; Green 2003). Students in astronomy courses often have difficulty understanding many different concepts as a result of difficulties with spatial reasoning and a sense of scale. The Hands-on-Science program at UT Austin incorporates these research-based results into four guided-inquiry, integrated science courses (50 students each). They are aimed at pre-service K–5 teachers but are open to other majors as well. We find that Hands-on-Science students not only attain more favorable changes in attitude towards science, but they also outperform students in traditional lecture courses in content gains. Workshop Outcomes: Participants experienced a research-based, guided-inquiry lesson about the motion of objects in the sky and discussed the research methodology for assessing students in such a course

Exploring The Low-Mass End Of The M-Bh-Sigma(*) Relation With Active Galaxies

We present new measurements of stellar velocity dispersions, using spectra obtained with the Keck Echellette Spectrograph and Imager (ESI) and the Magellan Echellette (MagE), for 76 Seyfert 1 galaxies from the recent catalog of Greene & Ho. These objects were selected from the Sloan Digital Sky Survey (SDSS) to have estimated black hole (BH) masses below 2 x 10(6) M-circle dot. Combining our results with previous ESI observations of similar objects, we obtain an expanded sample of 93 galaxies and examine the relation between BH mass and velocity dispersion (the M-BH-sigma(*) relation) for active galaxies with low BH masses. The low-mass active galaxies tend to follow the extrapolation of the M-BH-sigma(*) relation of inactive galaxies. Including results for active galaxies of higher BH mass from the literature, we find a zero point alpha = 7.68 +/- 0.08 and slope of beta = 3.32 +/- 0.22 for the MBH-sigma(*) relation (in the form log M-BH = alpha + beta log(sigma(*)/200 km s(-1))), with intrinsic scatter of 0.46 +/- 0.03 dex. This result is consistent, within the uncertainties, with the slope of the MBH-s* relation for reverberation-mapped active galaxies with BH masses from 10(6) to 10(9) M-circle dot. For the subset of our sample having morphological information from Hubble Space Telescope images, we examine the slope of the M-BH-sigma(*) relation separately for subsamples of barred and unbarred host galaxies, and find no significant evidence for a difference in slope. We do find a mild offset between low-inclination and high-inclination disk galaxies, such that more highly inclined galaxies tend to have larger sigma(*) at a given value of BH mass, presumably due to the contribution of disk rotation within the spectroscopic aperture. We also find that the velocity dispersion of the ionized gas, measured from narrow emission lines including [N II] lambda 6583, [S II] lambda lambda 6716, 6731, and the core of [O III] lambda 5007 (with the blueshifted wing removed), trace the stellar velocity dispersion well for this large sample of low-mass Seyfert 1 galaxies.Chinese Scholarship CouncilNSF AST-0548198W. M. Keck FoundationAlfred P. Sloan FoundationNational Science FoundationU.S. Department of EnergyNational Aeronautics and Space AdministrationJapanese MonbukagakushoMax Planck SocietyHigher Education Funding Council for EnglandAstronom

Strong population structure in a species manipulated by humans since the Neolithic: The European fallow deer (Dama dama dama)

Species that have been translocated and otherwise manipulated by humans may show patterns of population structure that reflect those interactions. At the same time, natural processes shape populations, including behavioural characteristics like dispersal potential and breeding system. In Europe, a key factor is the geography and history of climate change through the Pleistocene. During glacial maxima throughout that period, species in Europe with temperate distributions were forced south, becoming distributed among the isolated peninsulas represented by Anatolia, Italy and Iberia. Understanding modern patterns of diversity depends on understanding these historical population dynamics. Traditionally, European fallow deer (Dama dama dama) are thought to have been restricted to refugia in Anatolia and possibly Sicily and the Balkans. However, the distribution of this species was also greatly influenced by human-mediated translocations. We focus on fallow deer to better understand the relative influence of these natural and anthropogenic processes. We compared modern fallow deer putative populations across a broad geographic range using microsatellite and mitochondrial DNA loci. The results revealed highly insular populations, depauperate of genetic variation and significantly differentiated from each other. This is consistent with the expectations of drift acting on populations founded by small numbers of individuals, and reflects known founder populations in the north. However, there was also evidence for differentiation among (but not within) physically isolated regions in the south, including Iberia. In those regions we find evidence for a stronger influence from natural processes than may be expected for a species with such strong, known anthropogenic influence