deletions | additions
diff --git a/Abstract.tex b/Abstract.tex
index 314a47e..7101b5d 100644
--- a/Abstract.tex
+++ b/Abstract.tex
...
foreground cluster suggest that it is entirely plausible that the two
events are {\it spatially} coincident at the source plane, but very
unlikely that they were also {\it temporally} coincident. We find
that {\it Spock} can be explained as a
recurrent nova, a luminous blue variable,
a
recurrent nova, or a stellar caustic crossing event. High-cadence
monitoring of the field could distinguish between these hypotheses by
detecting new transient episodes at or near the \spock locations.
\end{abstract}
diff --git a/Observations.tex b/Observations.tex
index c9fe6de..2be5120 100644
--- a/Observations.tex
+++ b/Observations.tex
...
a more complete description of the operations of the FrontierSN
program, see \citet{Rodney:2015a}.
\subsection{X-ray Non-detections}\label{sec:Xray}
The MACS0416 field was observed by the SWIFT X-Ray Telescope (XRT) and
UltraViolet/Optical Telescope (UVOT) in April 2013. No source was
detected near the locations of the \spock events (N. Gehrels, private
communication). The field was also observed by the Chandra X-ray
space telescope with the ACIS-I instrument for three separate
programs. On June 7, 2009 it was observed for GO program 10800770
(PI: H.\,Ebeling). It was revisited for GTO program 15800052 (PI:
S.\,Murray) on November 20, 2013 and for GO program 15800858 (PI: C.\,
Jones) on June 9, August 31, November 26, and December 17, 2014. These
Chandra images show no evidence for an x-ray emitting point source
near the \spock locations on those dates (S. Murray, private
communication).
\subsection{Photometry}\label{sec:Photometry}
diff --git a/Results.tex b/Results.tex
index 528610e..c104e3b 100644
--- a/Results.tex
+++ b/Results.tex
...
To interpret the observed light curves and the timing of these two
events, we use six independently constructed cluster mass models to
determine the impact of gravitational lensing from the MACS0416
cluster (Methods \ref{sec:LensingModels}).
The lensing scenario that
has been consistently adopted for this cluster is that the arc in
which the \spock events appeared comprises two mirror images of the
host galaxy \citep[labeled 11.1 and 11.2 in
Figure~\ref{fig:SpockDetectionImages};][]{Zitrin:2013a, Jauzac:2014,
Johnson:2014, Richard:2014, Diego:2015a, Grillo:2015a, Hoag:2016,
Sebesta:2016}. This implies that a single critical curve passes
roughly mid-way between the two observed \spock locations.
As reported in Table~\ref{tab:LensModelPredictions},
these our six lens
models predict absolute magnification values between about $\mu=10$
and $\mu=100$ for both events. This wide range is due primarily to
the close proximity of the \spock\ events to the lensing critical
curve (the region of theoretically infinite magnification) for sources
at $z=1$. Note that the magnifications for \spockone\ and
\spocktwo\ are highly correlated. A variation of a given lens model
that moves the critical curve closer to the position of
\spockone\ would drive the magnification of that event much higher
(toward $\mu_1\sim100$), but that would also have the effect of moving
the critical curve farther from \spocktwo\, which would necessarily
drive its magnification downward (toward $\mu_2\sim10$). From each
model we also extract two time delay predictions, given in
Table~\ref{tab:LensModelPredictions}. We report all time delays
relative to the \spockone\ event, which appeared in January 2014 in
host image 11.2.
%\renewcommand{\arraystretch}{1.5}
\begin{deluxetable}{lccccc}\label{tab:LensModelPredictions}
...
\colhead{$\mu_3$}\\ \colhead{} & \colhead{(days)} &
\colhead{(years)} & \colhead{} & \colhead{} & \colhead{} }
\startdata
Bradac &
42 $^{+13}_{-9}$ & -3.7 $\pm0.3$ & 90 $^{+61}_{-27}$ & 32 $^{+8}_{-10}$ & 3.6 $^{+0.2}_{-0.5}$\\[0.5em]
Bradac-v3 & \nodata & \nodata & 38 $\pm8$ & 12.8 $\pm0.8$ & 2.9 $\pm0.1$\\[0.5em]
Diego & -48$\pm$10 & 0.8 & 35$\pm$20 & 30$\pm$20
&\\[0.5em]
Jauzac-A &
29 $\pm3$ \nodata\\[0.5em]
%Jauzac-A & 29$\pm3$ &
-2.2 $\pm0.1$ -2.2$\pm0.1$ & 36 $^{+4}_{-3}$ & 17 $\pm1$ & 4.5 $\pm0.1$\\[0.5em]
Jauzac-B Jauzac &
28 $^{+5}_{-7}$ 28$^{+5}_{-7}$ &
-2.2 $^{+0.1}_{-0.2}$ -2.2$^{+0.1}_{-0.2}$ & 37 $\pm3$ & 18 $\pm2$ & 4.6 $\pm0.1$\\[0.5em]
Jauzac-C %Jauzac-C &
2.5 $^{+0.8}_{-1.0}$ 2.5$^{+0.8}_{-1.0}$ &
-3.0 $\pm0.1$ -3.0$\pm0.1$ & 37 $^{+4}_{-3}$ & 16 $^{+1}_{-2}$ & 3.2 $\pm0.05$\\[0.5em]
Kawamata &
4.1 $^{+5.5}_{-3.4}$ 4.1$^{+5.5}_{-3.4}$ &
-5.0 $^{+0.5}_{-0.6}$ -5.0$^{+0.5}_{-0.6}$ & 29 $^{+43}_{-10}$ & 84 $^{+103}_{-38}$ & 3.0 $^{+0.2}_{-0.2}$\\[0.5em]
Williams &
-10 $^{+1}_{-7}$ -10$^{+1}_{-7}$ &
-2.5 $^{+1.0}_{-3.1}$ -2.5$^{+1.0}_{-3.1}$ & 13 $^{+11}_{-6}$ & 12 $^{+9}_{-5}$ & 3.1 $^{+2.2}_{-0.9}$\\[0.5em]
Zitrin &
42 $^{+13}_{-9}$ 42$^{+13}_{-9}$ &
-3.7 $\pm0.3$ -3.7$\pm0.3$ & 90 $^{+61}_{-27}$ & 32 $^{+8}_{-10}$ & 3.6 $^{+0.2}_{-0.5}$\\
%% New Jauzac model predictions
%$\mu_{\rm NW}$ = 0.2 $^{+0.1}_{-0.1}$
%$\mu_{\rm SE}$ = 0.4 $^{+0.4}_{-0.1}$
...
\end{deluxetable}
%\renewcommand{\arraystretch}{1.}
\subsection{Microlensing}\label{sec:MicroLensing}
In the presence of strong gravitational lensing it is possible to
generate a transient event from lensing effects alone. In this case
the background source has a steady luminosity but the relative motion
of the source, lens, and observer causes the magnification of that
source (and therefore the apparent brightness) to change rapidly with
time. An isolated strong lensing event with a rapid timescale can be
generated when a background star crosses over a lensing critical
curve. In the case of a star crossing the caustic of a smooth lensing
potential, the amplification of the source flux would increase
(decrease) with a characteristic $t^{-1/2}$ profile as it moves toward
(away from) the caustic. This slowly evolving light curve then
transitions to a very sharp decline (rise) when the star has moved to
the other side of the caustic \citep{Schneider:1986,
MiraldaEscude:1991}. With a more complex lens comprising many
compact objects, the light curve would exhibit a superposition of many
such sharp peaks \citep{Lewis:1993}.
The peculiar transient {\it Icarus}, observed behind the Hubble
Frontier Fields cluster MACS J1149.6+2223, has been proposed as the
first observed example of such a stellar caustic crossing event
(P. Kelly et al., in prep). Kelly et al. find that such events may be
expected to appear more frequently in strongly lensed galaxies that
have small angular separation from the center of a massive cluster. In
such a situation, our line of sight to the lensed background galaxy
passes through a dense web of overlapping micro-lenses caused by the
intracluster stars distributed around the center of the cluster. This
has the effect of ``blurring'' the magnification profile across the
cluster critical curve, making it more likely that a single (and rare)
massive star in the background galaxy gets magnified by the required
factor of $\sim10^5$ to become visible as a transient caustic crossing
event. On this basis the \spock host galaxy images are suitably
positioned for caustic crossing transients, as they are seen through a
relatively high density of intracluster stars---comparable to that
observed for the {\it Icarus} transient (Methods \ref{sec:ICL}).
The characteristic timescale of a canonical caustic crossing event
would be on the order of hours or days (Methods
\ref{sec:Microlensing}), which is comparable to the timescales
observed for the \spock events. Furthermore, since gravitational
lensing is achromatic, the color of a caustic crossing transient will
be constant. Using simplistic linear interpolations of the observed
light curves (Methods \ref{sec:LightCurves}) we find that the inferred
color curves for both \spock events are marginally consistent with
this expectation of an unchanging color (Methods
\ref{sec:ColorCurves}).
The lensing scenario that has been consistently adopted for this host
galaxy \todo{add references} is that a single critical curve passes
roughly mid-way between the two observed \spock locations. Each event
then belongs to one of two images (11.1 and 11.2 in
Figure~\ref{fig:SpockDetectionImages}) that comprise the long arc of
the host galaxy. In this case, the \spock events can not plausibly be
explained as stellar caustic crossings, because neither transient is
close enough to the single critical curve to reach the required
magnifications of $\mu\sim10^6$.
Some lens models can, however, be modified so that instead of just two
host images, the lensed galaxy arc is made up of many more images of
the host, with multiple critical curves subtending the arc where the
\spock events appeared. By tuning the assumed masses of cluster
galaxies near the \spock host, those multiple critical curves can be
made to pass very close to the positions of the two \spock transient
events. In the {\it Kawamata} and {\it Diego} lens models, this
alternative lensing scenario requires that the masses of the two
nearest cluster galaxies are increased by $30-60\%$. With this
adjustment, both models can reproduce the observed morphology of the
HFF14Spo host galaxy as a smooth, unbroken arc. These model
realizations imply magnifications on the order of $\mu\sim1000$ for
both \spock transients. If this alternative lensing scenario is
correct, then similar microlensing transients would be expected to
appear at different locations along the host galaxy arc, instigated by
new caustic crossing episodes from different stars in the host galaxy.
\subsection{Ruling Out Common Astrophysical Transients}
Instead of relying on lensing effects alone to explain the rise and
fall of the \spock events, we might instead invoke some astrophysical
transient source in the host galaxy. There are several categories of
astrophysical transients that cannot accommodate the light curve
characteristics of the \spock transients. We may first dismiss any of
the category of {\it periodic} sources (e.g. Cepheids, RR Lyrae, or
...
% require substantial fine-tuning of the lens models in order to
% accommodate multiple critical curves that still map the spock events
% back to the same location on the source plane.
\subsection{Microlensing}\label{sec:MicroLensing}
In the presence of strong gravitational lensing it is possible to
generate a transient event from lensing effects alone. In this case
the background source has a steady luminosity but the relative motion
of the source, lens, and observer causes the magnification of that
source (and therefore the apparent brightness) to change rapidly with
time. An isolated strong lensing event with a rapid timescale can be
generated when a background star crosses over a lensing critical
curve. In the case of a star crossing the caustic of a smooth lensing
potential, the amplification of the source flux would increase
(decrease) with a characteristic $t^{-1/2}$ profile as it moves toward
(away from) the caustic. This slowly evolving light curve then
transitions to a very sharp decline (rise) when the star has moved to
the other side of the caustic \citep{Schneider:1986,
MiraldaEscude:1991}. With a more complex lens comprising many
compact objects, the light curve would exhibit a superposition of many
such sharp peaks \citep{Lewis:1993}.
The peculiar transient {\it Icarus}, observed behind the Hubble
Frontier Fields cluster MACS J1149.6+2223, has been proposed as the
first observed example of such a stellar caustic crossing event
(P. Kelly et al., in prep). Kelly et al. find that such events may be
expected to appear more frequently in strongly lensed galaxies that
have small angular separation from the center of a massive cluster. In
such a situation, our line of sight to the lensed background galaxy
passes through a dense web of overlapping micro-lenses caused by the
intracluster stars distributed around the center of the cluster. This
has the effect of ``blurring'' the magnification profile across the
cluster critical curve, making it more likely that a single (and rare)
massive star in the background galaxy gets magnified by the required
factor of $\sim10^5$ to become visible as a transient caustic crossing
event. On this basis the \spock host galaxy images are suitably
positioned for caustic crossing transients, as they are seen through a
relatively high density of intracluster stars---comparable to that
observed for the {\it Icarus} transient (Methods \ref{sec:ICL}).
The characteristic timescale of a canonical caustic crossing event
would be on the order of hours or days (Methods
\ref{sec:Microlensing}), which is comparable to the timescales
observed for the \spock events. Furthermore, since gravitational
lensing is achromatic, the color of a caustic crossing transient will
be constant. Using simplistic linear interpolations of the observed
light curves (Methods \ref{sec:LightCurves}) we find that the inferred
color curves for both \spock events are marginally consistent with
this expectation of an unchanging color (Methods
\ref{sec:ColorCurves}).
In the baseline lensing scenario adopted above---where a single
critical curve subtends the \spock host galaxy arc---these events can
not plausibly be explained as stellar caustic crossings, because
neither transient is close enough to the single critical curve to
reach the required magnifications of $\mu\sim10^6$. Some lens models
can, however, be modified so that instead of just two host images, the
lensed galaxy arc is made up of many more images of the host, with
multiple critical curves subtending the arc where the \spock events
appeared. By tuning the assumed masses of cluster galaxies near the
\spock host, those multiple critical curves can be made to pass very
close to the positions of the two \spock transient events. In the
{\it Kawamata} and {\it Diego} lens models, this alternative lensing
scenario requires that the masses of the two nearest cluster galaxies
are increased by $30-60\%$. With this adjustment, both models can
reproduce the observed morphology of the HFF14Spo host galaxy as a
smooth, unbroken arc. These model realizations imply magnifications
on the order of $\mu\sim1000$ for both \spock transients. If this
alternative lensing scenario is correct, then similar microlensing
transients would be expected to appear at different locations along
the host galaxy arc, instigated by new caustic crossing episodes from
different stars in the host galaxy.
diff --git a/bibliography/biblio.bib b/bibliography/biblio.bib
index ae69a86..1ad18c1 100644
--- a/bibliography/biblio.bib
+++ b/bibliography/biblio.bib
...
%% This BibTeX bibliography file was created using BibDesk.
%% http://bibdesk.sourceforge.net/
%% Created for rodney at
2017-01-22 11:15:41 2017-01-23 10:12:15 -0500
%% Saved with string encoding Unicode (UTF-8)
@article{Hoag:2016,
Author = {{Hoag}, A. and {Huang}, K.-H. and {Treu}, T. and {Brada{\v c}}, M. and {Schmidt}, K.~B. and {Wang}, X. and {Brammer}, G.~B. and {Broussard}, A. and {Amorin}, R. and {Castellano}, M. and {Fontana}, A. and {Merlin}, E. and {Schrabback}, T. and {Trenti}, M. and {Vulcani}, B.},
Journal = {\apj},
Month = nov,
Pages = {182},
Title = {{The Grism Lens-Amplified Survey from Space (GLASS). VI. Comparing the Mass and Light in MACS J0416.1-2403 Using Frontier Field Imaging and GLASS Spectroscopy}},
Volume = 831,
Year = 2016}
@article{Eliasdottir:2007,
Author = {{El{\'{\i}}asd{\'o}ttir}, {\'A}. and {Limousin}, M. and {Richard}, J. and {Hjorth}, J. and {Kneib}, J.-P. and {Natarajan}, P. and {Pedersen}, K. and {Jullo}, E. and {Paraficz}, D.},
Journal = {ArXiv e-prints},
...
Volume = {arXiv:1509.08914},
Year = 2015}
@article{Diego:2015b, @article{Diego:2015c,
Author = {{Diego}, J.~M. and {Broadhurst}, T. and {Chen}, C. and {Lim}, J. and {Zitrin}, A. and {Chan}, B. and {Coe}, D. and {Ford}, H.~C. and {Lam}, D. and {Zheng}, W.},
Journal = {ArXiv e-prints},
Month = apr,
...
Volume = 91,
Year = 2015}
@article{Diego:2015, @article{Diego:2015b,
Author = {{Diego}, J.~M. and {Broadhurst}, T. and {Molnar}, S.~M. and {Lam}, D. and {Lim}, J.},
Journal = {\mnras},
Month = mar,
diff --git a/layout.md b/layout.md
index 50fc999..5f0bed4 100644
--- a/layout.md
+++ b/layout.md
...
figures/composite_lens_model_contours/composite_lens_model_contours.png
LensingModels.tex
Microlensing.tex Xray.tex
figures/light_curve_linear_fits/light_curve_linear_fits.png
figures/spock_colorcurves_observerframe/spock_colorcurves_observerframe.png
LightCurves.tex
ColorCurves.tex
figures/spock_hostgalaxy_properties/spock_hostgalaxy_properties.png
figures/muse_oii_sequence/muse_oii_sequence.png
HostGalaxy.tex
...
figures/recurrent_nova_recurrence_comparison/recurrent_nova_recurrence_comparison.png
RN.tex
Microlensing.tex
ColorCurves.tex
diff --git a/spock_localbuild.pdf b/spock_localbuild.pdf
index e867787..c251d3f 100644
Binary files a/spock_localbuild.pdf and b/spock_localbuild.pdf differ
