Merge branch 'master' into LSSTScienceCollaborations#630

whitepaper/AGN/AGN_BELR.tex

@@ -68,6 +68,8 @@ \subsubsection{Target measurements and discoveries}
 %parameters, we can anticipate some of the sensitivity of the
 %photometric RM method to observing strategy.}
 
+% LSST Review by Niel Brandt: how to address selection bias towards high line strength systems?
+
 The PRM method is very sensitive to the sampling in each band,
 therefore the ability to derive reliable time delays can be affected
 significantly by the LSST cadence. The best results will be obtained
@@ -142,7 +144,7 @@ \subsubsection{Metrics}
 % \item[Q1:] {\it Does the science case place any constraints on the
 % tradeoff between the sky coverage and coadded depth? For example, should
 % the sky coverage be maximized (to $\sim$30,000 deg$^2$, as e.g., in
-% Pan-STARRS) or the number of detected galaxies (the current baseline 
+% Pan-STARRS) or the number of detected galaxies (the current baseline
 % of 18,000 deg$^2$)?}
 %
 % \item[A1:] ...

whitepaper/AGN/AGN_Census.tex

@@ -20,7 +20,7 @@ \section{AGN Selection and Census}\label{sec:AGNCensus}
 \credit{AstroVPK},
 \credit{ScottAnderson}
 
-The basic figure of merit for AGN science is the total number of AGNs
+One basic figure of merit for AGN science is the total number of AGNs
 discovered in the entire LSST survey, as a function of luminosity and
 redshift. The main goal is therefore to adjust the Observing Strategy
 in order to maximize this number.
@@ -52,9 +52,9 @@ \subsection{Target measurements and discoveries}
 observations using two different filters for a particular LSST field. This will
 eventually determine the AGN $L-z$ distribution and, in particular, may affect
 the identification of quasars at $z\gtsim 6$ if, for example, $Y$-band exposures
-will not be sufficiently deep.
+are not sufficiently deep.
 
-{\bf Variability:} AGNs can be effectively distinguished from (variable)
+{\bf Variability:} some AGNs can be effectively distinguished from (variable)
 stars, and from quiescent galaxies, by exhibiting certain characteristic
 variability patterns (e.g., \citealt{ButlerandBloom2011}). Picking the
 right cadence can increase the effectiveness of AGN selection. Ultimately,
@@ -69,7 +69,7 @@ \subsection{Target measurements and discoveries}
 {\bf Astrometry:} In cases where selection by color and variability is
 insufficient for a reliable identification, AGNs can be further selected
 among sources having zero proper motion, within the uncertainties. The
-LSST cadence may affect the level of this uncertainty in each band, and
+LSST cadence may affect the level of this uncertainty in each band, and certainly the temporal baseline for proper motion measurement, and
 may therefore affect the ability to identify (mostly fainter) AGN.
 %
 Differential chromatic refraction (DCR), making use of the astrometric offset a
@@ -78,7 +78,7 @@ \subsection{Target measurements and discoveries}
 photometric redshifts \citep{KaczmarczikEtal2009}. The DCR effect is more
 pronounced at higher airmasses. Therefore, it could be advantageous to have at
 least one visit, per source, at airmass greater than about 1.4 (though of course
-there are trade-offs versus the additional extinction, for faint sources). AGN
+there is a trade-off with the additional extinction, for faint sources). AGN
 selection and photometric redshift confirmation may be affected since the LSST
 cadence will affect the airmass distribution, in each band, for each AGN
 candidate.
@@ -116,7 +116,7 @@ \subsection{Metrics}
 
 2) Estimate the {\bf number of quasars at $z>6$ that LSST can discover}
 during a single visit, as well as in the entire survey, and verify that
-these numbers do not fall short of the original predictions. This
+these numbers do not fall short of the original predictions. To first order this
 simply requires computing the maximum depth in the $Y$-band (for both
 single visits and the coadd), averaged across the sky for the nominal
 OpSim, as well as assessing the ability to reject L and T dwarfs via astrometry.
@@ -131,9 +131,11 @@ \subsection{Metrics}
 The aim is to assess the sizes of the ellipses and how these sizes could be
 minimized by perturbing the current cadence.
 
-4) Asses how the sampling affects the selection of AGN by variability (e.g.,
+4) Assess how the sampling affects the selection of AGN by variability (e.g.,
 interactions with red-noise power spectrum).
 
+5) Check how overall survey length affects proper motion measurements and consequently AGN selection.
+
 %4) Estimate the number of low-luminosity AGN (LLAGN) that can be
 %identified during the entire survey.
 
@@ -154,6 +156,7 @@ \subsection{OpSim Analysis}
 \label{fig:zgt6}
 \end{figure}
 
+% LSST Review from Niel Brandt: check for updates needed to this figure, as it is over a decade old. Also, add a plot comparing LSST and WFIRST for high-z AGN selection
 
 For assessing the limitations of DCR on the $L-z$ plane of LSST AGNs,
 one needs to obtain from OpSim the current maximal airmasses for each band,
@@ -199,6 +202,7 @@ \subsection{OpSim Analysis}
 As for general AGN selection, the effects of the sampling on variability selection
 should be assessed, and the amplitudes of the uncertainties in color-color space
 and how these depend on the cadence should be simulated.
+The combination of LSST photometry with that from WFIRST and/or Euclid data should also be considered, both for extending the upper limit in detectable redshift to $\sim10$, but also improving the completeness and purity of the sample at lower redshifts.
 
 % % --------------------------------------------------------------------
 %
@@ -222,7 +226,7 @@ \subsection{Conclusions}
 \item[Q1:] {\it Does the science case place any constraints on the
 tradeoff between the sky coverage and coadded depth? For example, should
 the sky coverage be maximized (to $\sim$30,000 deg$^2$, as e.g., in
-Pan-STARRS) or the number of detected galaxies (the current baseline 
+Pan-STARRS) or the number of detected galaxies (the current baseline
 of 18,000 deg$^2$)?}
 
 \item[A1:] The main FoM for AGN science is maximizing the number of AGNs
@@ -242,7 +246,7 @@ \subsection{Conclusions}
 the relative selection completeness and efficiency for OpSim outputs
 with different uniformity/frequency of sampling. The same can be said
 for constraining the fraction of observing time in each band (where $u$
-is the most important for $z<\sim3$ and $Y$ is most important for $z>\sim6$)
+is the most important for $z\lesssim3$ and $Y$ is most important for $z\gtrsim6$)
 and for determining whether nightly
 visits should be in the same band or not, and for the trade-off of
 single-visit depth and number of visits. However, the AGN census is
@@ -252,7 +256,7 @@ \subsection{Conclusions}
 Galactic plane coverage (spatial coverage, temporal sampling, visits per
 band)?}
 
-\item[A4:] Given the desire for maximal area, added Galactic plane
+\item[A4:] Given the desire for maximal extragalactic area, added Galactic plane
 coverage would be detrimental to AGN science.
 
 \item[Q6:] {\it Does the science case place any constraints on the
@@ -292,5 +296,7 @@ \subsection{Conclusions}
 
 \end{description}
 
+% LSST Review from Niel Brandt: survey must span full 10 years to enable good astrometry / propoer motion measurements to aid in selection. PJM: doesn't fit in the 10 questions, but leaving a note here for the future!
+
 
 \navigationbar

whitepaper/AGN/AGN_Disk_Extrinsic.tex

@@ -84,7 +84,7 @@ \subsection{Target measurements and discoveries}
 low-level microlensing that will far exceed previous efforts.
 
 Note, however, that the larger the apparent magnification, the more stringent are
-the constraints on the geometric information that can be obtained about the source.
+the constraints on the geometric properties of the source.
 \citet{MosqueraandKochanek2011} studied the expected microlensing
 timescales for all known lensed quasars at the time. They found that the median
 Einstein crossing time scales, which can statistically be interpreted as the
@@ -99,7 +99,7 @@ \subsection{Target measurements and discoveries}
 that, statistically, in every system, one (for doubles) or two (for quads) high
 magnification events should be observed in 10~yr of LSST monitoring.
 
-Strong lensing events are also our best chance investigate anomalies in accretion
+Strong lensing events also provide our best chance of investigating anomalies in accretion
 disk geometries. For example, warps due to multiple accretion events or magnetic
 fields, fragmentation due to gravitational instability, and hot spots due to
 embedded star formation can all result in deviations from smooth temperature profiles.
@@ -219,7 +219,7 @@ \subsection{Metrics}
 \item ��Macro'' lens model parameters on top of lensed quasar images: Surface mass density $\kappa$ and shear $\gamma$.
 \end{itemize}
 
-\noindent In its current state, the tool assumes simple face-on concentric Gaussian emission regions for the accretion disk. An example of such a curve is shown in figure \ref{microsimcurve}. To recover the figure of merit, (measurement accuracy of $\alpha$ and $\sigma_0$), light curves generated with this tool for a given realistic lensed quasar system ($\kappa$, $\gamma$, s and velocity dispersion of the lensing galaxy as well as time delays between lensed images) for every region in the sky need to analyzed using the above mentioned statistical analyses to recover the input accretion disk parameters.
+\noindent In its current state, the tool assumes simple face-on concentric Gaussian emission regions for the accretion disk. An example of such a curve is shown in figure \ref{microsimcurve}. To recover the figure of merit, (measurement accuracy of $\alpha$ and $\sigma_0$), light curves generated with this tool for a given realistic lensed quasar system ($\kappa$, $\gamma$, $s$ and velocity dispersion of the lensing galaxy as well as time delays between lensed images) for every region in the sky need to analyzed using the above mentioned statistical analyses to recover the input accretion disk parameters.
 
 
 % microlensing - convolve microlensing timescales for QSOs we already know
@@ -280,7 +280,7 @@ \subsection{Conclusions}
 \item[Q1:] {\it Does the science case place any constraints on the
 tradeoff between the sky coverage and coadded depth? For example, should
 the sky coverage be maximized (to $\sim$30,000 deg$^2$, as e.g., in
-Pan-STARRS) or the number of detected galaxies (the current baseline 
+Pan-STARRS) or the number of detected galaxies (the current baseline
 of 18,000 deg$^2$)?}
 
 \item[A1:] Given that lensed quasars are rare, maximizing the area

whitepaper/AGN/AGN_Disk_Intrinsic.tex

@@ -30,7 +30,9 @@ \section{Disc Intrinsic AGN Variability}\label{sec:AGNContinuum}
 LSST band to the continuum flux in another, will be one of the main themes of
 AGN science in the LSST era (e.g., \citealt{Chelouche2013};
 \citealt{CheloucheandZucker2013}; \citealt{EdelsonEtal2015};
-\citealt{FausnaughEtal2015}). Such measurements can test accretion disk models
+\citealt{FausnaughEtal2015}).
+% LSST Review by Niel Brandt: Add Jiang et al? Sentences below are vague: what can be learned _specifically_ about accretion disk models?
+Such measurements can test accretion disk models
 in a robust manner for a considerably larger number of AGNs than is currently
 feasible with microlensing (see section~\ref{sec:agn:microlensing}).
 
@@ -119,20 +121,24 @@ \subsection{Target measurements and discoveries}
 periodic AGNs. Correlation analyses will search for relations between AGN
 variability properties and their basic physical parameters. In the DDFs, such
 analyses will enable probing deeper and more frequently, resulting in
-higher-quality data that will provide stronger constraints; the only drawback is
+higher-quality data that will provide stronger constraints on AGN variability propertie; the only drawback is
 the relatively smaller number of sources available at the high-luminosity end.
 
 A key measurement enabled by the DDFs is a high-quality PSD, in six bands,
 for the largest number of AGNs to date. These PSDs, which are rich
-in diagnostic power, will be used to search for `features' such as QPOs
+in diagnostic power, will be used to search for ``features'' such as QPOs
 and breaks, as well as power-law slopes, that can help constrain SMBH masses
-and accretion rates. Additionally, the PSDs can serve as selection
+and accretion rates.
+% LSST Review from Niel Brandt: describe current optical/NIR PSD results, add refs.
+Additionally, the PSDs can serve as selection
 tools, to more effectively distinguish AGNs from variable stars, as
 well as a basis to propose cadence perturbations to further enhance
 AGN selection.
 
-A high-quality PSD, extending to high frequencies (reaching $\sim 1$ min
-timescales for stacked PSDs), can effectively distinguish AGNs from other
+A high-quality PSD, extending to high frequencies
+% (reaching $\sim 1$ min timescales for stacked PSDs),
+% PJM: commented out followin LSST Review by Niel Brandt: is 1 min really needed?
+can effectively distinguish AGNs from other
 variable sources, assuming AGN light curves are described by a particular
 continuous-time autoregressive moving average model (C-ARMA; \citet{KellyEtal14}),
 i.e., C-ARMA(2,1), corresponding to a damped harmonic oscillator.
@@ -141,8 +147,10 @@ \subsection{Target measurements and discoveries}
 sampling at least as frequent as $\sim1$~d$^{-1}$. Figure~\ref{PSDvsFreq} shows
 the frequency dependence of the spectral index of the PSD for one particular AGN,
 Zw 229-15, observed with {\em Kepler}. The light curve of this source is
-well-described by a C-ARMA(2,1) model. The C-ARMA(2,1) model is a higher order
-random walk than the damped random walk (DRW) model of \citet{Kelly09}, which
+well-described by a C-ARMA(2,1) model. The C-ARMA(2,1) model is a
+% higher order random walk
+damped harmonic oscillator rather
+than the damped random walk (DRW) model of \citet{Kelly09}, which
 corresponds to a C-ARMA(1,0) model. Recent variability studies indicate that
 the simple C-ARMA(1,0) model is insufficient to model AGN variability because
 the spectral index of its PSD is mathematically constrained to be 2
@@ -247,10 +255,12 @@ \subsection{Metrics}
 %with the nominal OpSim, and point out potential perturbations in the
 %cadence to improve the number and quality of such time delays.
 
-While additional work is required for determining the optimal cadence in order
-to fully capture AGN accretion physics and to enhance AGN selection, it is clear
-that even the nominal DDF sampling (\eg in \opsimdbname{enigma\_1189}) is barely sufficient, and
-more frequent sampling would have been ideal. The ability to detect HFQPOs
+While additional quantitative work is required for determining the optimal cadence for
+fully capturing AGN accretion physics and to enhance AGN selection, it is clear
+that even the nominal DDF sampling (\eg in \opsimdbname{db:baseCadence}) is barely sufficient, and
+more frequent sampling would be ideal.
+% LSST Review from Niel Brandt: Haven't connected the hyperparameters to science impacts clearly. What exactly is lost going from 1 day to 3 day cadence?
+The ability to detect HFQPOs
 should also improve by increasing the sampling frequency, the amplitudes of such
 features are quite uncertain, as are the (short) duty cycles. Observations,
 theory and numerical simulations have only suggested that the fractional
@@ -267,7 +277,7 @@ \subsection{Metrics}
 sources with $L \ltsim 10^{42}$~erg~s$^{-1}$, in the DDFs. Such sources are
 likely to be missed by traditional color-variability selection algorithms due to
 a strong host contribution. The metric to be developed should assess how the
-number of selected LLAGN depends on the sampling frequency in each band.
+number of selected LLAGN depends on the sampling frequency in each band, and take into account the host galaxy light contamination.
 
 2) Assessing the standard deviation of the error in recovered time-lag between
 bands, $\tau$, using a cross-correlation analysis. The goal is to minimize
@@ -302,13 +312,14 @@ \subsection{Discussion}
 % made to improve this science project's figure of merit, and mitigate
 % the identified risks?
 
-Overall, the key requirement is to increase the nominal sampling
+While science-driven metric analysis is still to be performed, we expect the key requirement emerging from such an analysis to be to increase the nominal sampling
 frequency in the DDFs by at least a factor of 3, i.e., having at least
 3000 visits, per band, during the entire survey. Alternatively, if this
 sampling is not feasible for all the DDFs, it would be beneficial to
 identify a subset of ``special'' DDFs which would be sampled by this
-frequency. Such DDFs would also benefit from being circumpolar, e.g.,
-the Magellanic Clouds, enabling a more uniform sampling to produce the
+frequency. Such DDFs would also benefit from being circumpolar,
+% e.g., the Magellanic Clouds,
+enabling a more uniform sampling to produce the
 highest quality PSDs.
 
 % ====================================================================
@@ -323,7 +334,7 @@ \subsection{Conclusions}
 \item[Q1:] {\it Does the science case place any constraints on the
 tradeoff between the sky coverage and coadded depth? For example, should
 the sky coverage be maximized (to $\sim$30,000 deg$^2$, as e.g., in
-Pan-STARRS) or the number of detected galaxies (the current baseline 
+Pan-STARRS) or the number of detected galaxies (the current baseline
 of 18,000 deg$^2$)?}
 
 \item[A1:] The disc-intrinsic variability science case places no direct