Keck Spectroscopy of Dwarf Elliptical Galaxies in the Virgo Cluster

Keck spectroscopy is presented for four dwarf elliptical galaxies in the Virgo Cluster. At this distance, the mean velocity and velocity dispersion are well resolved as a function of radius between 100 to 1000 pc, allowing a clear separation between nuclear and surrounding galaxy light. We find a variety of dispersion profiles for the inner regions of these objects, and show that none of these galaxies is rotationally flattened.Comment: 4 pages, 2 figures, to appear in the proceedings of the Yale Cosmology Workshop "The Shapes of Galaxies and their Halos", (ed. P. Natarjan

Dwarf Galaxies with Optical Signatures of Active Massive Black Holes

We present a sample of 151 dwarf galaxies (10^8.5 < M_stellar < 10^9.5 Msun) that exhibit optical spectroscopic signatures of accreting massive black holes (BHs), increasing the number of known active galaxies in this stellar mass range by more than an order of magnitude. Utilizing data from the Sloan Digital Sky Survey Data Release 8 and stellar masses from the NASA-Sloan Atlas, we have systematically searched for active BHs in ~25,000 emission-line galaxies with stellar masses comparable to the Magellanic Clouds and redshifts z<0.055. Using the narrow-line [OIII]/H-beta versus [NII]/H-alpha diagnostic diagram, we find photoionization signatures of BH accretion in 136 galaxies, a small fraction of which also exhibit broad H-alpha emission. For these broad-line AGN candidates, we estimate BH masses using standard virial techniques and find a range of 10^5 < M_BH < 10^6 Msun and a median of M_BH ~ 2 x 10^5 Msun. We also detect broad H-alpha in 15 galaxies that have narrow-line ratios consistent with star-forming galaxies. Follow-up observations are required to determine if these are true type 1 AGN or if the broad H-alpha is from stellar processes. The median absolute magnitude of the host galaxies in our active sample is Mg = -18.1 mag, which is ~1-2 magnitudes fainter than previous samples of AGN hosts with low-mass BHs. This work constrains the smallest galaxies that can form a massive BH, with implications for BH feedback in low-mass galaxies and the origin of the first supermassive BH seeds.Comment: 26 pages, 15 figures, 6 tables. Accepted for publication in The Astrophysical Journa

Monosodium glutamate delivered in a protein-rich soup improves subsequent energy compensation

Previous research suggests that monosodium glutamate (MSG) may have a biphasic effect on appetite, increasing appetite within a meal with its flavour-enhancing effect, but enhancing subsequent satiety due to its proposed role as a predictor of protein content. The present study explored this by assessing the impact of a 450 g soup preload differing in MSG concentration (1 % MSG added (MSG+) or no MSG (MSG-)) and nutrient content (low-energy control or high-energy carbohydrate or high-energy protein) on rated appetite and ad libitum intake of a test meal in thirty-five low-restraint male volunteers using a within-participant design. Protein-rich preloads significantly reduced intake at the test meal and resulted in more accurate energy compensation than did carbohydrate-rich preloads. This energy compensation was stronger in the MSG+ protein conditions when compared with MSG+ carbohydrate conditions. No clear differences in rated appetite were seen in MSG or the macronutrient conditions alone during preload ingestion or 45 min after intake. Overall, these findings indicate that MSG may act to further improve energy compensation when provided in a protein-rich context

Evidence for the disky origin of luminous Virgo dwarf ellipticals from the kinematics of their globular cluster systems

We report evidence for dynamically significant rotation in the globular cluster systems of two luminous Virgo dwarf ellipticals, VCC1261 and VCC1528. Including previous results for VCC1087, the globular cluster systems of all three Virgo dwarf ellipticals studied in detail to date exhibit v_rot/sigma > 1. Taking the rotation seen in the globular clusters as maximal disk rotation, we find all three dEs lie on the r-band Tully-Fisher relation. We argue that these data support the hypothesis that luminous dEs are the remnants of transformed disk galaxies. We also obtained deep, longslit data for the stars in VCC1261 and VCC1528. Both these galaxies show rapid rotation in their inner regions, with spatial scales of ~0.5 kpc. These rotation velocities are similar to those seen in the GC systems. Since our longslit data for Virgo dEs extend out to 1-2 effective radii (typical of deep observations), whereas the globular clusters extend out to 4--7 effective radii, we conclude that non-detections of rotation in many luminous dEs may simply be due to a lack of radial coverage in the stellar data, and that globular clusters represent singularly sensitive probes of the dynamics of dEs. Based on these data, we suggest that gas disks are significant sites of globular cluster formation in the early universe.Comment: To appear in the AJ, corrected typographical errors in Table 1, added a referenc

High-resolution spectroscopy of extremely metal-poor stars in the least evolved galaxies: Bootes II

We present high-resolution Magellan/MIKE spectra of the four brightest confirmed red giant stars in the ultra-faint dwarf galaxy Bootes II (Boo II). These stars all inhabit the metal-poor tail of the Boo II metallicity distribution function. The chemical abundance pattern of all detectable elements in these stars is consistent with that of the Galactic halo. However, all four stars have undetectable amounts of neutron-capture elements Sr and Ba, with upper limits comparable to the lowest ever detected in the halo or in other dwarf galaxies. One star exhibits significant radial velocity variations over time, suggesting it to be in a binary system. Its variable velocity has likely increased past determinations of the Boo II velocity dispersion. Our four stars span a limited metallicity range, but their enhanced {\alpha}-abundances and low neutron-capture abundances are consistent with the interpretation that Boo II has been enriched by very few generations of stars. The chemical abundance pattern in Boo II confirms the emerging trend that the faintest dwarf galaxies have neutron-capture abundances distinct from the halo, suggesting the dominant source of neutron-capture elements in halo stars may be different than in ultra-faint dwarfs.Comment: 10 pages, 5 figures, 4 tables. Updated to match ApJ accepted versio

Nature as an Impermanent Canvas: An Intergenerational Nature-Based Art Community Engagement Project

The longing for permanence, including an attachment to objects, is a perpetual desire in human beings. In the artistic world, the longing for permanence is reflected in the desire to conserve artworks forever. This has left humans in an existential dilemma of interpersonal and transpersonal conflicts with the world beyond them. A one-day community workshop in nature-based expressive arts was offered to explore the idea of transience and impermanence through creative existential and transpersonal notions. The workshop involved time indoors and outdoors, and activities included self-check-ins and checkouts, a sensory awareness and mindful walking exercise as mover and witness, and locating a resonating space and visually contemplating it. The experience culminated in the creation of a nature-based art installation that evolved out of the participants’ understanding of existence and their experience of the workshop. This community-based project was completed by a multiethnic and multigenerational group including one Caucasian woman, one Latin American woman, and one Middle Eastern man. Participants took part in a three-hour immersive experience where they created an ephemeral art installation in nature, and consequently an impermanent collective art piece. Results indicated that nature-based art therapy is a viable means for exploring existential and transpersonal concepts in a community environment, and that intergenerational presence and connections are valuable and beneficial within this process. More research needs to be done on the benefits of existential and transpersonal expressive-based experiences in nature

Local Group Dwarf Elliptical Galaxies: II. Stellar Kinematics to Large Radii in NGC 147 and NGC 185

We present kinematic and metallicity profiles for the M31 dwarf elliptical (dE) satellite galaxies NGC 147 and NGC 185. The profiles represent the most extensive spectroscopic radial coverage for any dE galaxy, extending to a projected distance of eight half-light radii (8 r_eff = 14'). We achieve this coverage via Keck/DEIMOS multislit spectroscopic observations of 520 and 442 member red giant branch stars in NGC 147 and NGC 185, respectively. In contrast to previous studies, we find that both dEs have significant internal rotation. We measure a maximum rotational velocity of 17+/-2 km/s for NGC 147 and 15+/-5 km/s for NGC 185. The velocity dispersions decrease gently with radius with an average dispersion of 16+/-1 km/s for NGC 147 and 24+/-1 km/s for NGC 185. Both dEs have internal metallicity dispersions of 0.5 dex, but show no evidence for a radial metallicity gradient. We construct two-integral axisymmetric dynamical models and find that the observed kinematical profiles cannot be explained without modest amounts of non-baryonic dark matter. We measure central mass-to-light ratios of ML_V = 4.2+/-0.6 and ML_V = 4.6+/-0.6 for NGC 147 and NGC 185, respectively. Both dE galaxies are consistent with being primarily flattened by their rotational motions, although some anisotropic velocity dispersion is needed to fully explain their observed shapes. The velocity profiles of all three Local Group dEs (NGC 147, NGC 185 and NGC 205) suggest that rotation is more prevalent in the dE galaxy class than previously assumed, but is often manifest only at several times the effective radius. Since all dEs outside the Local Group have been probed to only inside the effective radius, this opens the door for formation mechanisms in which dEs are transformed or stripped versions of gas-rich rotating progenitor galaxies.Comment: 16 pages, 7 figures. accepted to A