Physics Commons^™

Large-Scale Outflows In Luminous Qsos Revisited: The Impact Of Beam Smearing On Agn Feedback Efficiencies, Bernd Husemann, Julia Scharwächter, Vardha N. Bennert, V. Manieri, Jong-Hak Woo, Darshan Kakkad

Physics

Context. Feedback from active galactic nuclei (AGN) is thought to play an important role in quenching star formation in galaxies. However, the efficiency with which AGN dissipate their radiative energy into the ambient medium remains strongly debated.

Aims. Enormous observational efforts have been made to constrain the energetics of AGN feedback by mapping the kinematics of the ionized gas on kpc scale. We study how the observed kinematics and inferred energetics are affected by beam smearing of a bright unresolved narrow-line region (NLR) due to seeing.

Methods. We re-analyse optical integral-field spectroscopy of a sample of twelve luminous unobscured quasi-stellar …

Community Outreach With Play-Doh® Electronics, Thomas J. Bensky, William Bensky

Physics

It never fails: you’re in your office and the phone rings. Your department head says, “Hi! Fifty kids are coming to campus in 30 minutes. Can you meet with them and give them a one-hour hands-on activity that will make them excited about physics?” Likely you’ll run to your demonstration room and grab anything that’ll generate a bright light or cause something to explode or levitate, right? In recent years, we’ve taken a more systematic approach to hosting visitors by developing a ready-to-go hands-on activity that provides opportunities for learning about DC electric circuits.

The Close Agn Reference Survey (Cars): Mrk 1018 Returns To The Shadows After 30 Years As A Seyfert 1, R. E. Mcelroy, Bernd Husemann, S. M. Croom, T. A. Davis, Vardha N. Bennert, G. Busch, F. Combes, A. Eckart, M. Perez-Torres, M. Powell, J. Scharwächter, G. R. Tremblay, T. Urrutia

Physics

We report the discovery that the known “changing look” AGN Mrk 1018 has changed spectral type for a second time. New VLT-MUSE data taken in 2015 as part of the Close AGN Reference Survey (CARS) shows that the AGN has returned to its original Seyfert 1.9 classification. The CARS sample is selected to contain only bright type 1 AGN, but Mrk 1018’s broad emission lines and continuum, typical of type 1 AGN, have almost entirely disappeared. We use spectral fitting of the MUSE spectrum and previously available spectra to determine the drop in broad line flux and the Balmer decrement. …

Environmental And Economic Implications Of Alternative Cruise Ship Pathways In Bermuda, Sarah E. Lester, Crow White, Kevin Mayall, Ryan K. Walter

Physics

As the cruise ship industry moves towards ever larger vessels, many tourist destinations are faced with dilemmas about how to accommodate the latest generation of ships, which require deeper and wider shipping pathways. The location of nearshore shipping channels traveled by cruise ships has important environmental and economic implications, as dredging larger lanes damages habitat, ship traffic produces sediment plumes that can smother adjacent sensitive habitats (e.g., coral reefs, seagrass beds), and dredging costs vary spatially. These environmental and economic costs should ideally be evaluated in the context of projected benefits from increased tourism. To inform decision-making on cruise ship …

About Agn Ionization Echoes, Thermal Echoes, And Ionization Deficits In Low Redshift Lyman-Alpha Blobs, Mischa Schirmer, Sangeeta Malhotra, Nancy A. Levenson, Hai Fu, Rebecca L. Davies, William Keel, Paul Torrey, Vardha Nicola Bennert, Anna Pancoast, James E. H. Turner

Physics

We report the discovery of 14 Lyα blobs (LABs) at z ∼ 0.3, existing at least 4–7 billion years later in the Universe than all other LABs known. Their optical diameters are 20–70 kpc, and GALEX data imply Lyα luminosities of (0.4–6.3) × 10⁴³ erg s⁻¹. Contrary to high-z LABs, they live in low-density areas. They are ionized by AGN, suggesting that cold accretion streams as a power source must deplete between z = 2 and 0.3. We also show that transient AGN naturally explain the ionization deficits observed in many LABs. Their Lyα and X-ray …

Broad HΒ Emission-Line Variability In A Sample Of 102 Local Active Galaxies, Jordan Runco, Maren Cosens, Vardha Nicola Bennert, Bryan Scott, S. Komossa, Matthew A. Malkan, Mariana S. Lazarova, Matthew W. Auger, Tommaso Treu, Daeseong Park

Physics

A sample of 102 local (0.02 ≤ z ≤ 0.1) Seyfert galaxies with black hole masses M_BH > 10⁷M_⊙ was selected from the Sloan Digital Sky Survey (SDSS) and observed using the Keck 10 m telescope to study the scaling relations between M_BH and host galaxy properties. We study profile changes of the broad Hβ emission line within the three to nine year time frame between the two sets of spectra. The variability of the broad Hβ emission line is of particular interest, not only because it is used to estimate M_BH, …

Observations Of Nonlinear Internal Waves At A Persistent Coastal Upwelling Front, Ryan K. Walter, Marek Stastna, C. Brock Woodson, Stephen G. Monismith

Physics

We collected high-resolution observations of nonlinear internal waves (NLIWs) at a persistent upwelling front in the shallow coastal environment (~20 m) of northern Monterey Bay, CA. The coastal upwelling front forms between recently upwelled waters and warmer stratified waters that are trapped in the bay (upwelling shadow). The front propagates up and down the coast in the along-shore direction as a buoyant plume front due to modulation by strong diurnal wind forcing. The evolution of the coastal upwelling front, and the subsequent modulation of background environmental conditions, is examined using both individual events and composite day averages. We demonstrate that …

Internal Bore Seasonality And Tidal Pumping Of Subthermocline Waters At The Head Of The Monterey Submarine Canyon, Ryan K. Walter, P. Joe Phelan

Physics

This study utilizes more than a year of observations made in shallow waters (~30 m) at the head of the Monterey Submarine Canyon to assess variability in the physical environment and internal bore field. The interaction of the internal tide with the canyon rim results in a semidiurnal tidal period pumping of cold–water masses (subthermocline waters) onto the adjacent shelf (i.e., internal bores). These internal bores are shown to be significantly coherent with the local sea surface height with minimal spatial variability when comparing two sites near the canyon head region. During the summer months, and periods of strong regional …