UW SALT Science UpdateSALT Science DayNovember 2012

Megaflares on tiny stars with SALTM-dwarf brightens by factor of 100. Spectra taken every 15-30 sec. 70x faster than VLT!Papers in prep now; second semester of YZ CMi observations starting Dec 2012.Jan 13, 2012[]

A project on accreting and hydrogen burning white dwarfs:Emission lines are diagnostics of accretion, irradiation, nebular physics, hydrogen burning a number of lines in U and optical range are extremely useful.Upper panel shows how with SALT we zoom in the region of [Fe X] 6375 and follow its intensity during the orbital period of SMC 3, symbiotic star in the SMC with super-hot WD (~450,000 K), in order to monitor the temperature of the central source and the persistence of hydrogen burning.We measure radial velocity of right lines to determine masses. Lines must be produced very close to WD, but often the strongest ones are not good indicators of radial velocity. Good indicators can be quite faint, hard to measure.Most quiescent novae, symbiotic binaries, supersoft X-ray sources are observed at large distances and a large mirror increases possibilities and statistics of objects, allowing a new horizon for these studies

NGC 1377: S0 galaxy, weak nuclear emission (Palomar 5-m) , but lies off galaxy far infrared-radio luminosity correlation by factor of 30+ (no radio continuum detection, deep 10 micron absorption, strong FIR). What gives???CO nuclear outflowAalto+ 2012 A&A, 546: SMA

Na D[NII][NII]H[SII]Deep H absorption-> post-starburst Strong [NII]-LINERGas kinematics!: absorption -emissionNGC 1377:Optical Perspectives: SALT-RSS to the rescue:Emission line data-LINER nuclear spectrum;Na I vs. HII kinematics-compare CO (ALMA); postburstPaper in Preparation

J. GallagherJ. RyonWisconsin

S. AaltoChalmers USweden+.

Rotation of gas off the plane of ESO 435-G25Arthur Eigenbrot, Matt Bershady, Andrew Schechtman-Rook[OIII] gas rotation50074959 Longslit data at 4 different heights (2 extremes shown above Total exposure time: 8.8 hr (P1 + P2)Target galaxy

Rotation of gas off the plane of ESO 435-G25Arthur Eigenbrot, Matt Bershady, Andrew Schechtman-Rook XV diagrams at all heights Data out to ~8 scale lengths!

Tidal Tail and Main Body Abundances in NGC 1140Jenna Ryon (PI), Jay Gallagher

The Nature of an Unusual Post-Starburst Galaxy with Extremely Strong [Ne V] EmissionJohn Chisholm, Christy Tremonti and Tenzin ChoedakSDSS Optical Spectra in black, error in green and a stellar population fit in red. Important emission and absorption lines are labeled in blue

Spectroscopic follow-up of UV-selected Ly emitters

Properties of Quasar Host GalaxiesGreg Mosby, Marsha Wolf, Christy Tremonti, and Eric Hooper

Above: A schematic showing the observation technique using SALTs RSS and an ideal pair of spectra that would be used at input to a stellar population modeling code developed by Mosby to determine host galaxy properties.The goal of this work is to understand connections between galaxies and the supermassive black holes at their centers, in the context of galaxy formation and evolution. We study this through the properties of luminous quasar host galaxies, objects in which the galaxy is actively feeding its black hole. This proposal focuses on a carefully selected sample of SDSS quasars, chosen over well-defined ranges of black hole mass, redshift and Eddington ratio in order to draw robust conclusions about these objects.

Short:

With SALT we've been able to do very fast (~10-30sec exposures) spectral studies of flaring M-dwarf stars. Shown are spectra from a megaflare on YZ CMi with pre-flare (blue), peak flare (red) and post-flare (light blue) spectra. These are single, 15 sec exposures with SALT/RSS. These observations were crippled by a mechanical failure and in future runs we should be able to do about 10 times better. We're doing this to learn the spectral characteristics of white-light emission in these stars (and in the Sun). Fast exposures are critical because the flare evolves on minute timescales, while NUV throughput is critical to determine the source of the white-light (optical) flare emission. The competing models are either balmer emission or hot blackbody emission (T~10,000K). Our observations currently favor both, but at different times during the flare, which previously couldn't be temporally resolved. Following these observations, we have conducted observations of Proxima Centauri (April 2012) and have an upcoming campaign of observations on YZ CMi this winter (Dec 2012).

More details:

Three spectra are shown, giving stellar emission at quiescence before the flare (lowest; dark blue), at peak emission at the peak of the flare (topmost; pink). In this still frame version, the middle spectra shows the star late in the decay phase of the flare (middle line; light blue; time indicated by black dot on inset).All three spectra are colored according to simultaneous photometry (inset box, showing narrow band photometry of 2 flares [second one is 100x flux increase from quiescence]), with dark tones corresponding to low total flux and bright tones corresponding to enhanced emission during the flare and post-flare decay.

All spectra are single exposures with SALT/RSS. Quiescent and peak spectra have 30 second exposures, while moving middle spectra has 30second exposures before time 0.6 and 15 second exposures after that. Youll see the spectra update more quickly in the movie when the shorter cadence is hit.

In future observations, we can do at least another factor of 10 better, as these observations were subject to some unexpected mechanical failures at SALT that reduced the near-UV flux by about a factor of 10. These observations rely on SALTs large NUV throughput, fast imaging capabilities and on decent spectrophotometric calibration (as best as we can do).

*Lya emission is a primary tool for studying the highest redshift (z>6) galaxies, but we need to study lower redshift Lya emitters to understand their physical properties. Lya emitters with luminosities comparable to those of the highest redshift galaxies are first seen at z~1, though the sample of such galaxies obtained from the pipeline reductions of GALEX grism data is very small. We have discovered many more LAEs at z~1 using a novel three-dimensional data cube search method that we developed for GALEX grism data. The LAEs found by the GALEX pipeline were limited to the pipeline magnitude limit of NUV=22, but the new LAEs extend to much fainter magnitudes and are a flux-limited sample. Here we show examples of follow-up spectra obtained with SALT-RSS. All sources were confirmed to have redshifts consistent with our UV measurements. The lack of detected [NeV] is consistent with these sources being star-forming galaxies rather than AGNs. This project will allow us to construct the Lya luminosity function in this poorly studied redshift range.

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