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Additioially. the cooperaion of the technical teams at boh LaveΠΜ ludustries i1 Russia aud ISITE iu Tnclia facilitated t10 testingc» at various stagesOo and the easy aud oefficieit integration of the FAL wi↕↓≺∶≋∡≚⊺∟↓
Additionally, the cooperation of the technical teams at both Lavotchkin Industries in Russia and ISITE in India facilitated the testing at various stages and the easy and efficient integration of the FM with GSAT-4.
∙ With an eve to the future, the Indian and. Isracli science teams expect ISA and ISRO to reach ali agreement very soon to allow a full-recovered TAUVENE to be launched and perform its original mission in a timely manner.
With an eye to the future, the Indian and Israeli science teams expect ISA and ISRO to reach an agreement very soon to allow a fully-recovered TAUVEX to be launched and perform its original mission in a timely manner.
In particular, the science team proposed to refurbish and recoat the nirrors: this is expected to recover the original seusitivitv of TAUVEN.
In particular, the science team proposed to refurbish and recoat the mirrors; this is expected to recover the original sensitivity of TAUVEX.
Iowever. when this paper was completed no such decision. or indeed
However, when this paper was completed no such decision, or indeed
Iowever. when this paper was completed no such decision. or indeed.
However, when this paper was completed no such decision, or indeed
αἱ all.
at all.
Postponing for a moment seeking a correlation with more subtle statistical tools (han the human eve. we will first (av to find a plot which gives something more obvious.
Postponing for a moment seeking a correlation with more subtle statistical tools than the human eye, we will first try to find a plot which gives something more obvious.
Perhaps the problem lies in using blue Iuminosities.
Perhaps the problem lies in using blue luminosities.
Ht is well known that starbursts can skew the mass-to-light ratio in this band. drastically: the nearby dwarl IC 10 is nearly as luminous as (he spiral M32 in D. but much fainter in (he infrared.
It is well known that starbursts can skew the mass-to-light ratio in this band drastically; the nearby dwarf IC 10 is nearly as luminous as the spiral M33 in $B$, but much fainter in the infrared.
Using A-band luminosity. which should be a much better measure of the actual mass of the galaxies. we arrive al the right panel of Figure (2)).
Using $K$ -band luminosity, which should be a much better measure of the actual mass of the galaxies, we arrive at the right panel of Figure \ref{scatter1}) ).
There is. again. no visible correlation.
There is, again, no visible correlation.
There are significantly fewer galaxies with A photometry (o contribute to the synthetic gravity. field. but the effect of the unmeasured objects should be slight: none are as bright as the Magellanic Clouds in D. and so the combined effect of all of them is less than about that of one giant galaxy.
There are significantly fewer galaxies with $K$ photometry to contribute to the synthetic gravity field, but the effect of the unmeasured objects should be slight: none are as bright as the Magellanic Clouds in $B$, and so the combined effect of all of them is less than about that of one giant galaxy.
Recalling that the anisotropic model was calculated to bea better fit to the data. we tum to the peculiar velocities based on that model for Figure (2)).
Recalling that the anisotropic model was calculated to be a better fit to the data, we turn to the peculiar velocities based on that model for Figure \ref{hscatter1}) ).
Again (here is no improvement apparent.
Again there is no improvement apparent.
Perhaps the uncertainties in (he various quantiües are large enough to obscure any correlation: that is. perhaps the data are simply not good enough vet to see a signal.
Perhaps the uncertainties in the various quantities are large enough to obscure any correlation; that is, perhaps the data are simply not good enough yet to see a signal.
Adding (he uncertainties in svnthetic eravitv and peculiar velocitv as error bars eives Figure (4)).
Adding the uncertainties in synthetic gravity and peculiar velocity as error bars gives Figure \ref{scatter2}) ).
Some points on the plots are clearly very uncertain indeed.
Some points on the plots are clearly very uncertain indeed.
Though it appears that there are enough good data to delineate a (rend. if it existed. including all the errors serves {ο obscure the matter more than it helps.
Though it appears that there are enough good data to delineate a trend, if it existed, including all the errors serves to obscure the matter more than it helps.
Using only the 63 points with the best svnthetie gravity uncertainties. we have Figure (5)).
Using only the 63 points with the best synthetic gravity uncertainties, we have Figure \ref{scatter3}) ).
As one would expect. points have been preferentially removed at synthetic eravilies of large (positive and negative) magnitude. since these are most subject to distance errors in nearby. galaxies: and there is a bit of structure due to small-number statistics.
As one would expect, points have been preferentially removed at synthetic gravities of large (positive and negative) magnitude, since these are most subject to distance errors in nearby galaxies; and there is a bit of structure due to small-number statistics.
However. no real trend is visible. and the errors here are certainly small enough to show one.
However, no real trend is visible, and the errors here are certainly small enough to show one.
] have claimed that there is no correlation on anv of the plots presented: however. it is very difficult to prove the absence ofany correlation. (
I have claimed that there is no correlation on any of the plots presented; however, it is very difficult to prove the absence of correlation. (
In [act there could be a very. strong correlation of a particular kind. sav a high-[requency sine wave. which would be entirely masked by the errors.
In fact there could be a very strong correlation of a particular kind, say a high-frequency sine wave, which would be entirely masked by the errors.
But we are looking lor something less general. à monotonic function.)
But we are looking for something less general, a monotonic function.)
The [act that none is evident in the plots here presented is a strong indication in that direction. the human eve being very good at detecting correlations amidst noise (indeed. even when none exists): but we would like something quantitative.
The fact that none is evident in the plots here presented is a strong indication in that direction, the human eye being very good at detecting correlations amidst noise (indeed, even when none exists); but we would like something quantitative.
Consikler a linear relation.
Consider a linear relation.
While we expect the Local Volume to be nonlinear as [ar as eravilational elfects are concerned. we should certainly be able to approximate il wilh a
While we expect the Local Volume to be nonlinear as far as gravitational effects are concerned, we should certainly be able to approximate it with a
Figure 2. shows the light curves of models 3.4 while the inset provides the light curves of model 2. for the same set of parameters.
Figure \ref{fig2} shows the light curves of models 3, while the inset provides the light curves of model 2, for the same set of parameters.
In. model 3. the peak of the light curves for Oo.2Oy is flatter compared to model 2. and is obtained at a somewhat latter time.
In model 3, the peak of the light curves for $\theta_{\rm obs}>\theta_0$ is flatter compared to model 2, and is obtained at a somewhat latter time.
The rise before the peak is not as sharp as in models | or 2. since in model 3 there is some material at the sides of the jet with a moderate Lorentz factor (Granot et al.
The rise before the peak is not as sharp as in models 1 or 2, since in model 3 there is some material at the sides of the jet with a moderate Lorentz factor (Granot et al.
2001; Piran Granot 2001).
2001; Piran Granot 2001).
The emission from this slower material tends to dominate the observed flux at early times for observers at (i.My. resulting 1n a gentler rise before the peak.
The emission from this slower material tends to dominate the observed flux at early times for observers at $\theta_{\rm obs}>\theta_0$, resulting in a gentler rise before the peak.
The light curves for 0,4,>(Aj peak at a later time compared to model 2. and the flux during the decay stage grows faster with @,,),.. since in model 3 the curvature of the shock front is larger and the emission occurs within a shell of finite width. resulting in a larger photon arrival time. and implying that smaller radi contribute to a given observer time.
The light curves for $\theta_{\rm obs}>\theta_0$ peak at a later time compared to model 2, and the flux during the decay stage grows faster with $\theta_{\rm obs}$, since in model 3 the curvature of the shock front is larger and the emission occurs within a shell of finite width, resulting in a larger photon arrival time, and implying that smaller radii contribute to a given observer time.
The light-curves for model 2 3 are quantitatively similar for ην<(y.
The light-curves for model 2 3 are quantitatively similar for $\theta_{\rm obs}<\theta_0$.
The main advantage of this model ts a reliable and rigorous treatment of the jet dynamics. which provides insight on the behavior of the Jet and the corresponding light curves.
The main advantage of this model is a reliable and rigorous treatment of the jet dynamics, which provides insight on the behavior of the jet and the corresponding light curves.
Its main drawback ts the long computational time it requires.
Its main drawback is the long computational time it requires.
While the afterglow emission from a spherical outflow is expected to exhibit little or no linear polarization. as the polarization from the different parts of the afterglow image cancel out. a jetted outflow breaks the circular symmetry of the afterglow image and may exhibit a polarization of up to <20% (Ghisellint Lazatti 1999; Sart 1999).
While the afterglow emission from a spherical outflow is expected to exhibit little or no linear polarization, as the polarization from the different parts of the afterglow image cancel out, a jetted outflow breaks the circular symmetry of the afterglow image and may exhibit a polarization of up to $\lesssim 20\%$ (Ghisellini Lazatti 1999; Sari 1999).
One might therefore expect an even larger polarization for an observer at 0,4,7Oy.
One might therefore expect an even larger polarization for an observer at $\theta_{\rm obs}>\theta_0$.
An isotropic magnetic field configuration in the local rest frame will produce no linear polarization.
An isotropic magnetic field configuration in the local rest frame will produce no linear polarization.
However. as the magnetic field is most likely produced at the shock itself. one might expect the magnetic field perpendicular (231) and parallel to the shock direction. to have different magnitudes (Gruzinov(4) 1999: Sari 1999).
However, as the magnetic field is most likely produced at the shock itself, one might expect the magnetic field perpendicular $B_\perp$ ) and parallel $B_\parallel$ ) to the shock direction, to have different magnitudes (Gruzinov 1999; Sari 1999).
We calculate the linear polarization for model 2 following Ghisellini Lazatti and using their notations.
We calculate the linear polarization for model 2 following Ghisellini Lazatti and using their notations.
They assume the magnetic field is strictly in the plane of the shock (5=D, ).
They assume the magnetic field is strictly in the plane of the shock $B=B_{\perp}$ ).
Figure 3. shows the polarization as a function of time for different 0,4, in terms of Py.
Figure \ref{fig3} shows the polarization as a function of time for different $\theta_{\rm obs}$ in terms of $P_{60}$.
For Pyy«0 the polarization is along the plane containing the line of sight and the jet axis. wile for Pay>O itis rotated by 907 (for (51520D5 this is reversed. e.g. Sart 1999).
For $P_{60}<0$ the polarization is along the plane containing the line of sight and the jet axis, wile for $P_{60}>0$ it is rotated by $90^\circ$ (for $\langle B_{\perp}\rangle < 2\langle B_{\parallel}\rangle$ this is reversed, e.g. Sari 1999).
A more isotropic magnetic field configuration would result in à smaller degree of polarization. so the value of the polarization in Figure 1. (<lo%) may be viewed as a rough upper limit.
A more isotropic magnetic field configuration would result in a smaller degree of polarization, so the value of the polarization in Figure \ref{fig1} $\lesssim 40\%$ ) may be viewed as a rough upper limit.
For 0.3<μυ1.1 the polarization vanishes and reappears rotated by 907 around tie.
For $0.3 \lesssim \theta_{\rm obs}/\theta_0 \lesssim 1.1$ the polarization vanishes and reappears rotated by $90^\circ$ around $t_{\rm jet}$.
This behavior may occur again at a later time. but the subsequent polarization is very low.
This behavior may occur again at a later time, but the subsequent polarization is very low.
For 1.1<04,76091.6 the polarization has two peaks. the first higher than the second.
For $1.1 \lesssim \theta_{\rm obs}/\theta_0 \lesssim 1.6$ the polarization has two peaks, the first higher than the second.
For 0,,,/0,ο1.1 the polarization is largest near the peakin the light curve. and decreases quite slowly with time. while the peak polarization shows a very weak dependence on 0,,,. and is about a factor of 2 larger than for 0,4,=6.
For $\theta_{\rm obs}/\theta_0\gtrsim 1.1$ the polarization is largest near the peakin the light curve, and decreases quite slowly with time, while the peak polarization shows a very weak dependence on $\theta_{\rm obs}$, and is about a factor of $2$ larger than for $\theta_{\rm obs}=\theta_0$.
If GRB jets have well defined edges. the prompt gamma-ray flux drops very sharply outside the opening of the jet. and the prompt burst will be very hard to detect from ην.>0j.
If GRB jets have well defined edges, the prompt gamma-ray flux drops very sharply outside the opening of the jet, and the prompt burst will be very hard to detect from $\theta_{\rm obs}>\theta_0$.
On the other hand. the afterglow emission may be detected out to Oia~afewOy. where the exact value of 01,4. depends on the jet parameters (including its redshift). the observed band and the limiting flux for detection.
On the other hand, the afterglow emission may be detected out to $\theta_{\rm det}\sim\ {\rm a\ few}\ \theta_0$, where the exact value of $\theta_{\rm det}$ depends on the jet parameters (including its redshift), the observed band and the limiting flux for detection.
Jetted GRBs with 0,<do.Oi are expected to be orphan afterglows (1.e. detectable in the optical but not in gamma-rays).
Jetted GRBs with $\theta_0<\theta_{\rm obs}<\theta_{\rm det}$ are expected to be orphan afterglows (i.e. detectable in the optical but not in gamma-rays).
It has been argued by Dalal et al. (
It has been argued by Dalal et al. (
2002) that 0,4,/Ó7:coust for (y«&1. so that the detection rate of orphan afterglows NU (associated with off-axis jets) will be a constant [namely (044/04)?] times the GRB detection rate Nds and thereby a comparison between these two rates will not constrain (; or the true rate of GRBs NUR
2002) that $\theta_{\rm det}/\theta_0\approx{\rm const}$ for $\theta_0\ll 1$, so that the detection rate of orphan afterglows $\dot{\rm N}_{\rm orph}^{\rm det}$ (associated with off-axis jets) will be a constant [namely $(\theta_{\rm det}/\theta_0)^2$ ] times the GRB detection rate $\dot{\rm N}_{\rm GRB}^{\rm det}$, and thereby a comparison between these two rates will not constrain $\theta_0$ or the true rate of GRBs $\dot{\rm N}_{\rm GRB}^{\rm true}$.
This result was obtained assuming a constant flux. Fy,(tyr). at ty for 0,;,,=0.
This result was obtained assuming a constant flux, $F_\nu(t_{\rm jet})$, at $t_{\rm jet}$ for $\theta_{\rm obs}=0$.
However. afterglow observations suggest that the total energy in the jet. £i. is roughly constant (Frail et al.
However, afterglow observations suggest that the total energy in the jet, $E_{\rm jet}$, is roughly constant (Frail et al.
2001. Panaitescu Kumar 2001. Piran et al.
2001, Panaitescu Kumar 2001, Piran et al.
2001) while F,(7;.4) varies over a wider range.
2001) while $F_{\nu}(t_{\rm jet})$ varies over a wider range.
In fact. for Lj.= coust. simple jet models (R-SPH99) predict that the hydrodynamical evolution of the jet (and therefore the light curves for all 0,4,.) becomes independent of Jy once
In fact, for $E_{\rm jet}={\rm const}$ , simple jet models (R-SPH99) predict that the hydrodynamical evolution of the jet (and therefore the light curves for all $\theta_{\rm obs}$ ) becomes independent of $\theta_0$ once
Asstronomy.1.Introduction The nature of interstellar dust has implications for interstellar extinction. scattering of starlight. interstellar chemistry. the heating of diffuse clouds. the deposition of interstellar ices. and the dynamics of star formation.
stronomy,\tikzmark{mainBodyEnd0} \tikzmark{mainBodyStart1}Gower\tikzmark{mainBodyEnd1} \tikzmark{mainBodyStart2}Street,\tikzmark{mainBodyEnd2} \tikzmark{mainBodyStart3}London\tikzmark{mainBodyEnd3} \tikzmark{mainBodyStart4}WC1E\tikzmark{mainBodyEnd4} \tikzmark{mainBodyStart5}6BT,\tikzmark{mainBodyEnd5} \tikzmark{mainBodyStart6}UK\tikzmark{mainBodyEnd6} %\textendash\email{dawstar.ucl.ac.uk} \tikzmark{mainBodyStart7}}\tikzmark{mainBodyEnd7} \date{Received 21 April 2008; Accepted 9 June 2008} \abstract % c\tikzmark{mainBodyStart8}context\tikzmark{mainBodyEnd8} \tikzmark{mainBodyStart9}heading\tikzmark{mainBodyEnd9} {}\tikzmark{mainBodyStart10}}\tikzmark{mainBodyEnd10} % aims heading {We explore the relation between the charge state of polycyclic aromatic hydrocarbons (PAHs) and the extinction curve morphology.}\tikzmark{mainBodyStart11}}\tikzmark{mainBodyEnd11} % methods heading {We fit extinction curves with a dust model including core\textendash mantle spherical particles of mixed chemical composition (silicate core, $sp^2$ and $sp^3$ carbonaceous layers), and an additional molecular component. We use exact methods to calculate the extinction due to classical particles and accurate computed absorption spectra of PAHs in different charge states, for the contribution due to the molecular component, along five different lines of sight.}\tikzmark{mainBodyStart12}}\tikzmark{mainBodyEnd12} % results heading {A combination of classical dust particles and mixtures of real PAHs satisfactorily matches the observed interstellar extinction curves. Variations of the spectral properties of PAHs in different charge states produce changes consistent with the varying relative strengths of the bump and non\textendash linear far\textendash UV rise.}\tikzmark{mainBodyStart13}}\tikzmark{mainBodyEnd13} %conclusions heading {}\tikzmark{mainBodyStart14}} The nature of interstellar dust has implications for interstellar extinction, scattering of starlight, interstellar chemistry, the heating of diffuse clouds, the deposition of interstellar ices, and the dynamics of star formation.
Models of interstellar dust take into account a wide range of observational information that constrains the composition and size distribution2003).
Models of interstellar dust take into account a wide range of observational information that constrains the composition and size distribution.
. This includes the pattern of elemental depletions. the variety of observed interstellar extinction. curves. the distribution of the linear polarisation of starlight. the properties of scattered light. absorption and emission features. and broadband emission in the visible and infrared regions.
This includes the pattern of elemental depletions, the variety of observed interstellar extinction curves, the distribution of the linear polarisation of starlight, the properties of scattered light, absorption and emission features, and broadband emission in the visible and infrared regions.
All models involve a significant fraction of dust in the form of solid carbon. some of which may be in the form of erystalline graphite1997).
All models involve a significant fraction of dust in the form of solid carbon, some of which may be in the form of crystalline graphite.
.. Other forms of carbon have been given various names (amorphous. diamond-like. glassy and hydrogenated amorphous carbon. quasi-carbonaceous condensate. soot. yellow stuff...)) yet these all seem manifestations of carbon in which particular valence long-range structures and physical/chemical properties (e.g.. hydrogen content) are emphasised.
Other forms of carbon have been given various names (amorphous, diamond-like, glassy and hydrogenated amorphous carbon, quasi-carbonaceous condensate, soot, yellow ) yet these all seem manifestations of carbon in which particular valence range structures and physical/chemical properties (e.g., hydrogen content) are emphasised.
The strongest interstellar extinction feature 1s the broad absorption bump at 217.5 nm discovered by(1965).. whose carrier Is as yet unknown.
The strongest interstellar extinction feature is the broad absorption bump at 217.5 nm discovered by, whose carrier is as yet unknown.
It has been attributed to a plasmon resonance associated with 7— x* transitions of electrons in graphite1965).. despite some difficulties with this interpretation1993).
It has been attributed to a plasmon resonance associated with $\pi \to \pi^\star$ transitions of electrons in graphite, despite some difficulties with this interpretation.
. Others have tried to associate the bump with amorphous carbon1998).. although the peak and the width of the feature do not seem to be simultaneously well reproduced.
Others have tried to associate the bump with amorphous carbon, although the peak and the width of the feature do not seem to be simultaneously well reproduced.
It has also been suggested that defect sites at the surface of the silicate material could carry the feature1987).
It has also been suggested that defect sites at the surface of the silicate material could carry the feature.
. The intensity of the bump is known to be unrelated to the far-UV rise of the interstellar extinction curve1983).. while its FWHM shows an extremely loose relation to the strength of the nonlinear far-UV curvatureFMO7)maimBodyCitationEnd313|FMO7. although with an intrinsic scatter much greater than the observational errors.
The intensity of the bump is known to be unrelated to the UV rise of the interstellar extinction curve, while its FWHM shows an extremely loose relation to the strength of the nonlinear UV curvature, although with an intrinsic scatter much greater than the observational errors.
Leaving aside specialised. hypotheses. almost all the proposed carriers of the bump seem to require some form of aromatic carbon. either as size-restricted. graphite pieces or as single or stacked Polycyclic Aromatic Hydrocarbons (PAHs)2006).
Leaving aside specialised hypotheses, almost all the proposed carriers of the bump seem to require some form of aromatic carbon, either as restricted graphite pieces or as single or stacked Polycyclic Aromatic Hydrocarbons (PAHs).
. The possible quantitative relation between the bump and PAHs was suggested by(1992).. who compared laboratory spectra of mixtures of neutral PAHs and the mean galactic ISEC. showing them to be compatible in spectral shape.
The possible quantitative relation between the bump and PAHs was suggested by, who compared laboratory spectra of mixtures of neutral PAHs and the mean galactic ISEC, showing them to be compatible in spectral shape.
Subsequent papers compared theoretical spectra of mixtures of PAHs in different charge states.
Subsequent papers compared theoretical spectra of mixtures of PAHs in different charge states.
Recent models have a significant fraction of carbon in PAH molecules or clusters. described using approximate average properties2004).
Recent models have a significant fraction of carbon in PAH molecules or clusters, described using approximate average properties.
. In this work we incorporate PAHs with their real extinction properties in the evolutionary model of interstellar dust proposed by(1990).
In this work we incorporate PAHs with their real extinction properties in the evolutionary model of interstellar dust proposed by.
. In the latter model. carbonaceous material is in the form of mantles on the surfaces of silicate cores. forming through deposition processes conceptually similar to the grain core and icy mantle model of dust grains in dark clouds.
In the latter model, carbonaceous material is in the form of mantles on the surfaces of silicate cores, forming through deposition processes conceptually similar to the grain core and icy mantle model of dust grains in dark clouds.
The core-mantle structure and chemical composition of dust particles result from the history of the environmental conditions they experienced. and responded to. so that the observed extinction along any line of sight is an integration of components at different stages of their evolution1998).
The mantle structure and chemical composition of dust particles result from the history of the environmental conditions they experienced, and responded to, so that the observed extinction along any line of sight is an integration of components at different stages of their evolution.
. Different core-mantle models propose different accretion schemes for the carbonaceous mantles. either through the cyclic processing of ices or through direct. condensation1990).
Different mantle models propose different accretion schemes for the carbonaceous mantles, either through the cyclic processing of ices or through direct condensation.
.. Within such a framework. PAHs must also respond to the same environmental conditions. with chemical changes possibly related to observable effects.
Within such a framework, PAHs must also respond to the same environmental conditions, with chemical changes possibly related to observable effects.
We investigate the relation between the optical properties of PAHs in different tonisation states with the ISEC.
We investigate the relation between the optical properties of PAHs in different ionisation states with the ISEC.
We take advantage of the recent availability of state-of-the-art absorption spectra of PAHs in several charge states
We take advantage of the recent availability of art absorption spectra of PAHs in several charge states
lower plasma temperature. source (e.g. with Lx=10°" aand KT=2—4 keV) is hidden behind 500 mag of extinction. then our observation ts not sensitive enough to detect such a source (see reffig:limLx)).
lower plasma temperature, source (e.g. with $L_{\rm X} = 10^{30}$ and $kT = 2 - 4$ keV) is hidden behind 500 mag of extinction, then our observation is not sensitive enough to detect such a source (see \\ref{fig:limLx}) ).
Of course. we cannot exclude the possibility that an X-ray emitting source with properties similar to the ones of source 60 is hiding beneath a column of absorbing material higher than 40x1077 em7 or that these Class 0 sources are weaker sources.
Of course, we cannot exclude the possibility that an X-ray emitting source with properties similar to the ones of source 60 is hiding beneath a column of absorbing material higher than $40\times 10^{22}$ $^{-2}$ or that these Class 0 sources are weaker sources.
I order to derive à more sensitive upper limit for the typical Class 0 source in the Serpens Cloud Core. we registered and co-added the X-ray photons from 200x pixels (98x98 aresec) regions around each of the sources. centered on the coordinates given in reftab:cO..
In order to derive a more sensitive upper limit for the typical Class 0 source in the Serpens Cloud Core, we registered and co-added the X-ray photons from $200 \times 200$ pixels $98\times 98$ arcsec) regions around each of the sources, centered on the coordinates given in \\ref{tab:c0}.
Since there are six such regions. the result of this operation is equivalent (under the assumption that the six Class 0 sources are all similar to each other) to an observation of a single Class 0 source for an integration time six times longer than our original observation. ~540 ks.
Since there are six such regions, the result of this operation is equivalent (under the assumption that the six Class 0 sources are all similar to each other) to an observation of a single Class 0 source for an integration time six times longer than our original observation, $\sim 540$ ks.
The image of the "coadded" event list. resulting from this operation. 15 shown in reffig:coadd for the two energy intervals ΔΕ=0.5-8.0 keV and AE=4.0-8.0keV".
The image of the “coadded” event list, resulting from this operation, is shown in \\ref{fig:coadd} for the two energy intervals $\Delta E = 0.5 - 8.0$ keV and $\Delta E = 4.0 - 8.0$.
o source appears to be present in the centre of the coadded image. within a 5” radius. corresponding to the positional uncertainties of the mm/submm objects.
No source appears to be present in the centre of the coadded image, within a $5''$ radius, corresponding to the positional uncertainties of the mm/submm objects.
The total number of counts within the 3qe radius central area is 15 (a 3” radius being typical of source extraction regions for ACIS data). completely consistent with the background level for the coadded event list.
The total number of counts within the $3''$ -radius central area is 15 (a $3''$ radius being typical of source extraction regions for ACIS data), completely consistent with the background level for the coadded event list.
The measured average background level in the coadded event file is 0.5 cts arcsec7, 1444 counts in a circular area with a 3 radius.
The measured average background level in the coadded event file is $0.5$ cts $^{-2}$, $14\pm 4$ counts in a circular area with a $3''$ radius.
This agrees well with the level of background in the original image. 0.083 cts aresec. indicating that the "coadded" image does not suffer from significant systematics.
This agrees well with the level of background in the original image, 0.083 cts $^{-2}$, indicating that the “coadded” image does not suffer from significant systematics.
In the coadded image. a source at 6c above the background would have implied 41 counts within a 3PEZ) -radius area. corresponding to a source count rate of 0.04 cts/ks.
In the coadded image, a source at $\sigma$ above the background would have implied 41 counts within a $3''$ -radius area, corresponding to a source count rate of 0.04 cts/ks.
The fact that there 1s no such a source sets à more stringent upper limit on the typical level of X-ray emission from these Class 0 sources of Ly<0.4xI0ere s7'(in the above assumption of N(OD)=40x107 em? and KT.=2.3 keV).
The fact that there is no such a source sets a more stringent upper limit on the typical level of X-ray emission from these Class 0 sources of $L_{\rm X} < 0.4 \times 10^{30}$ (in the above assumption of $\nh = 40\times 10^{22}$ $^{-2}$ and $kT = 2.3$ keV).
The median luminosity of the YSOs for which spectra have been studied in the present work (32 out of 35 — às three were undergoing a strong flare) is 0.4xI0?"eres7'.. the same as the upper limit on the typical X-ray luminosity of the Class 0 sources. implying that 1f the Class 0 sources in the Serpens cloud are indeed X-ray sources. then they have luminosities below the level typical of the other YSO in the region (or they are hidden behind an absorbing column density higher than 40x10-- 7).
The median luminosity of the YSOs for which spectra have been studied in the present work (32 out of 35 – as three were undergoing a strong flare) is $0.4 \times 10^{30}$, the same as the upper limit on the typical X-ray luminosity of the Class 0 sources, implying that if the Class 0 sources in the Serpens cloud are indeed X-ray sources, then they have luminosities below the level typical of the other YSO in the region (or they are hidden behind an absorbing column density higher than $40 \times 10^{22}$ $^{-2}$ ).
A spectral and timing analysis was carried out on all sufficiently bright sources (count rate >0.5 ets/ks).
A spectral and timing analysis was carried out on all sufficiently bright sources (count rate $> 0.5$ cts/ks).
The spectra and light curves of all the sources brighter than 2.0 cts/ks are shown in reffig:le and reffig:lc2.. the results of the spectral analysis for these source are summarised in reftab:psfit..
The spectra and light curves of all the sources brighter than 2.0 cts/ks are shown in \\ref{fig:lc} and \\ref{fig:lc2}, the results of the spectral analysis for these source are summarised in \\ref{tab:psfit}.
The results of the spectral analysis for some of the sources with count rate between 0.5 and 2.0 ets/ks are also summarised in reftab:psfit..
The results of the spectral analysis for some of the sources with count rate between 0.5 and 2.0 cts/ks are also summarised in \\ref{tab:psfit}.
For these weaker sources. only the results for the sources with cclassification are reported.
For these weaker sources, only the results for the sources with classification are reported.
In the sample of sources stronger than 0.5 cts/ks. there are no sources with a ISO counterpart but no ddata. while there is a number of sources observed by ffor which there are no ISO counterparts. so in reftab:psfit we used only the classification derived from the oobservation.
In the sample of sources stronger than 0.5 cts/ks, there are no sources with a ISO counterpart but no data, while there is a number of sources observed by for which there are no ISO counterparts, so in \\ref{tab:psfit} we used only the classification derived from the observation.
The sources are subdivided in the table according to their classification,
The sources are subdivided in the table according to their classification.
The foreground absorption toward the Serpens complex can be estimated using the galactic extinction law of Baheall&Soneira (1980). where aj=O.15/sinb. z=10Ηsind. b being the galactic latitude and DM the distance modulus.
The foreground absorption toward the Serpens complex can be estimated using the galactic extinction law of \citet{bs80}, where $\alpha_{\rm inf} = 0.15/\sin b$, $z = 10^{((DM+5)/5)}\sin b$, $b$ being the galactic latitude and $DM$ the distance modulus.
Using the distance to Serpens of 260 pe (DM= 7) and its latitude (b= 5.39) one derives à minimum value of Ay=0.3 or N(H)=0.06x1077 em-7.
Using the distance to Serpens of 260 pc $DM = 7$ ) and its latitude $b=5.39$ ) one derives a minimum value of $A_V = 0.3$ or $N({\rm H}) = 0.06 \times 10^{22}$ $^{-2}$.