SMARTS OPTICAL AND INFRARED MONITORING OF 12 GAMMA-RAY BRIGHT BLAZARS

We present multiwavelength data for 12 blazars observed from 2008 to 2010 as part of an ongoing optical–infrared photometric monitoring project. Sources were selected to be bright, southern (δ < 20◦) blazars observed by the Fermi Gamma-Ray Space Telescope. Light curves are presented for the 12 blazars in BVRJK at near-daily cadence. We find that optical and infrared fluxes are well correlated in all sources. Gamma-ray bright flat spectrum radio quasars (FSRQs) in our sample have optical/infrared emission correlated with gamma-rays consistent with inverse Compton-scattering models. In FSRQs, variability amplitude increases toward IR wavelengths, consistent with the presence of a thermal accretion disk varying on significantly longer timescales than the jet. In BL Lac objects, variability is mainly constant, or increases toward shorter wavelength. FSRQs have redder optical–infrared colors when they are brighter,whileBLLac objects showno such trend. Several objects showcomplicated color–magnitude behavior: AO 0235+164 appears in two different states depending on its gamma-ray intensity. OJ 287 and 3C 279 show some hysteresis tracks in their color–magnitude diagrams. Individual flares may be achromatic or otherwise depart from the trend, suggesting different jet components becoming important at different times. We present a time-dependent spectral energy distribution of the bright FSRQ 3C 454.3 during its 2009 December flare, which is well fit by an external Compton model in the bright state, although day-to-day changes pose challenges to a simple one-zone model. All data from the SMARTS monitoring program are publicly available on our Web site

Stellar Kinematics in the Complicated Inner Spheroid of M31: Discovery of Substructure Along the Southeastern Minor Axis and its Relationship to the Giant Southern Stream

We present the discovery of a kinematically-cold stellar population along the SE minor axis of the Andromeda galaxy (M31) that is likely the forward continuation of M31's giant southern stream. This discovery was made in the course of an on-going spectroscopic survey of red giant branch (RGB) stars in M31 using the DEIMOS instrument on the Keck II 10-m telescope. Stellar kinematics are investigated in eight fields located 9-30 kpc from M31's center (in projection). A likelihood method based on photometric and spectroscopic diagnostics is used to isolate confirmed M31 RGB stars from foreground Milky Way dwarf stars: for the first time, this is done without using radial velocity as a selection criterion, allowing an unbiased study of M31's stellar kinematics. The radial velocity distribution of the 1013 M31 RGB stars shows evidence for the presence of two components. The broad (hot) component has a velocity dispersion of 129 km/s and presumably represents M31's virialized spheroid. A significant fraction (19%) of the population is in a narrow (cold) component centered near M31's systemic velocity with a velocity dispersion that decreases with increasing radial distance, from 55.5 km/s at R_proj=12 kpc to 10.6 km/s at R_proj=18 kpc. The spatial and velocity distribution of the cold component matches that of the "Southeast shelf" predicted by the Fardal et al. (2007) orbital model of the progenitor of the giant southern stream. The metallicity distribution of the cold component matches that of the giant southern stream, but is about 0.2 dex more metal rich on average than that of the hot spheroidal component. We discuss the implications of our discovery on the interpretation of the intermediate-age spheroid population found in this region in recent ultra-deep HST imaging studies.Comment: 23 pages, 16 figures, 2 tables, accepted for publication in the Astrophysical Journal. Changes from previous version: expanded discussion in sections 4.2 and 7.2, removal of section 7.1.4 and associated figure (discussion moved to section 7.1.2

The Time-Domain Spectroscopic Survey: Understanding the Optically Variable Sky with SEQUELS in SDSS-III

The Time-Domain Spectroscopic Survey (TDSS) is an SDSS-IV eBOSS subproject primarily aimed at obtaining identification spectra of ~220,000 optically-variable objects systematically selected from SDSS/Pan-STARRS1 multi-epoch imaging. We present a preview of the science enabled by TDSS, based on TDSS spectra taken over ~320 deg^2 of sky as part of the SEQUELS survey in SDSS-III, which is in part a pilot survey for eBOSS in SDSS-IV. Using the 15,746 TDSS-selected single-epoch spectra of photometrically variable objects in SEQUELS, we determine the demographics of our variability-selected sample, and investigate the unique spectral characteristics inherent in samples selected by variability. We show that variability-based selection of quasars complements color-based selection by selecting additional redder quasars, and mitigates redshift biases to produce a smooth quasar redshift distribution over a wide range of redshifts. The resulting quasar sample contains systematically higher fractions of blazars and broad absorption line quasars than from color-selected samples. Similarly, we show that M-dwarfs in the TDSS-selected stellar sample have systematically higher chromospheric active fractions than the underlying M-dwarf population, based on their H-alpha emission. TDSS also contains a large number of RR Lyrae and eclipsing binary stars with main-sequence colors, including a few composite-spectrum binaries. Finally, our visual inspection of TDSS spectra uncovers a significant number of peculiar spectra, and we highlight a few cases of these interesting objects. With a factor of ~15 more spectra, the main TDSS survey in SDSS-IV will leverage the lessons learned from these early results for a variety of time-domain science applications.Comment: 17 pages, 14 figures, submitted to Ap

Optical Spectropolarimetric Variability Properties in Blazars PKS 0637–75 and PKS 1510–089

Spectropolarimetry is a powerful tool to investigate the central regions of active galactic nuclei (AGNs) as polarization signatures are key to probing magnetic field structure, evolution, and the physics of particle acceleration in jets. Optical linear polarization of blazars is typically greater than a few percent, indicating the emission is dominated by nonthermal synchrotron radiation, while polarization less than a few percent is common for other type 1 AGNs. We present a spectropolarimetric study of PKS 0637–75 and PKS 1510–089 to determine how the head-on orientation of a jet and dominant emission processes influence polarimetric variations in the broad lines and continuum. Observations were obtained biweekly from the Robert Stobie Spectrograph on the Southern African Large Telescope. Variability in the continuum polarization is detected for both PKS 0637–75 and PKS 1510–089, with a total average level of 2.5% ± 0.1% and 7.5% ± 0.1%, respectively. There is no clear polarization in the broad Balmer emission lines and weak polarization in Mg ii as the average level across all observations is 0.2% ± 0.1% for H β , 0.2% ± 0.3% for H γ , and 0.6% ± 0.2% for Mg ii . We find that polarization measurements confirm the conclusions drawn from spectral energy distribution modeling of the disk–jet contributions to the emission as optical polarization and time variability for PKS 0637–75 are shown to be dominated by accretion disk emission while those of PKS 1510–089 are due to both disk and jet emission, with greater jet contribution during flaring states

Defining the Flow—Using an Intersectional Scientific Methodology to Construct a VanguardSTEM Hyperspace

#VanguardSTEM is an online community and platform that centers the experiences of women, girls, and non-binary people of color in science, technology, engineering, and mathematics (STEM) fields. We publish original and curated content, using cultural production, to include a multiplicity of identities as worthy of recognition and thus redefine STEM identity and belonging. #VanguardSTEM is rooted firmly in Queer, Black feminisms which delineate that the experiences and critiques of Black women matter and that these insights can foster a restorative and regenerative construction of the cultures in which we exist. In describing how #VanguardSTEM descended from counterspaces, we draw on speculative fiction to define a #VanguardSTEM hyperspace as a fluid “place-time” that is born digital and enabled by social media, but materializes in the physical world for specific purposes. As Black women in STEM, we consider how our situated knowledges and scientific expertise inform our process. We propose an intersectional scientific methodology to address the influence of embodied observation, embedded context and collective impact on scientific inquiry. Through #VanguardSTEM, we assert, without apology, the right of Black, Indigenous, women of color and non-binary people of color to self-advocate by fully representing ourselves and our STEM identities and interests, without assimilation

Defining the Flow—Using an Intersectional Scientific Methodology to Construct a VanguardSTEM Hyperspace

#VanguardSTEM is an online community and platform that centers the experiences of women, girls, and non-binary people of color in science, technology, engineering, and mathematics (STEM) fields. We publish original and curated content, using cultural production, to include a multiplicity of identities as worthy of recognition and thus redefine STEM identity and belonging. #VanguardSTEM is rooted firmly in Queer, Black feminisms which delineate that the experiences and critiques of Black women matter and that these insights can foster a restorative and regenerative construction of the cultures in which we exist. In describing how #VanguardSTEM descended from counterspaces, we draw on speculative fiction to define a #VanguardSTEM hyperspace as a fluid “place-time” that is born digital and enabled by social media, but materializes in the physical world for specific purposes. As Black women in STEM, we consider how our situated knowledges and scientific expertise inform our process. We propose an intersectional scientific methodology to address the influence of embodied observation, embedded context and collective impact on scientific inquiry. Through #VanguardSTEM, we assert, without apology, the right of Black, Indigenous, women of color and non-binary people of color to self-advocate by fully representing ourselves and our STEM identities and interests, without assimilation