ReadingTimeMachine/rtm-sgt-ocr-v1 · Datasets at Hugging Face

source stringlengths 1 2.05k ⌀	target stringlengths 1 11.7k
Adaptive stepping poses no threat to momentum conservation. provided (hat the steps are chosen in a wav which respects (he svmuuetries in (he continuous mechanical problem.	Adaptive stepping poses no threat to momentum conservation, provided that the steps are chosen in a way which respects the symmetries in the continuous mechanical problem.
Unfortunatelv. adaptive stepping does pose a threat to svinplecticitv.	Unfortunately, adaptive stepping does pose a threat to symplecticity.
With a Gimestep function h(n.qequU.4»). the expression for dS (see eqrekl5)) gets additional ternis: , . ∐∐∐↲⊳∖⊽∩↲↕↽≻⊳∖⇁⋅⊔∐↲↕⋅≼↲↕⋝∖⊽∐∪↥∖∖⊽∪−↓⋟∪↕⋅∐↓∪∐⊔∐↲⊳∖⊽↥≀↧↴∥↲⋝∖⊽↕↽≻≀↧↴≺∢≼↲∖∖↽∐↕≺∢∐↕⋝∖⊽≺∢∪∐⊳∖⇁≼↲↕⋅∖↽≼↲≼⇂∪∖⇁≼↲↕⋅≀↧↴∐⇀↸≼↲≼⇂∐∏↕∐∣↽≻≼↲↕⋅∪↓≯⋅⋅ JA ⋅⊳ ∏∐↲⋟∖⊽≼↲≼↲⇀↸⊔⋅≀↧↴∩↲↕⋅∐↓⋟∖⊽↕↽≻↕⋅≼↲∖↽≼↲↕∐∏⋟∖⊽∐⋅∪∐⊔∖⊽↕⋅↕⊔∐≸↽↔↴↙∣−↺∶∩≀↧⊔∖⊽⊔∐↲≼∐∐≼↲↕⋅≼↲∐≺∢↩∪↓↥∖∖⇁∪↓∪↕⋅	With a timestep function $h\left( q_1, q'_1, \ldots, q_1^{(n)}, q_2 \right)$, the expression for $d \mathcal{S}$ (see ) gets additional terms: These extra terms prevent us from writing $d^2\mathcal{S} = 0$ as the difference of two forms, one of which is the pushforward of the other, as we did in equation.
∐↓⋟∖⊽⋅∪∐≼↲ ∪↓⋟∖∖↽∐↥≺∢∐↕⊳∖⇁⊔∐↲↕↽≻∏⊳∖⇁∐↓≯∪↕⋅∖∖↽≀↧↴↕⋅≼⇂∪↓≯⊔∐↲∪⊔∐↲↕⋅⋅≀↧↴⊳∖⊽∖∖↽≼↲≼∐≼⊔∐≼↲≺⇂∏≀↧↴∐∪∐≼⋝∏⋅⋅∖∖⊽↕⊔↥↖≺↽↔↴≼↲∐≼↲↕⋅≀↧↴↥≀↧↴≼⇂≀↧↴↕↽≻∐∖↽≼↲ sleps.	With general adaptive timesteps, there is no two-form on the state space which is conserved over a fixed number of steps.
VAL1	$^{-1}$.
The mass model determined from the X-ray data may be compared to the mass implied by the observed. lensing configuration in the cluster (Section 1).	The mass model determined from the X-ray data may be compared to the mass implied by the observed lensing configuration in the cluster (Section 1).
Since only a single. putative gravitational arc is seen. and to be consistent with the X-ray analysis. we have only carried out a simple. spherically-svnimetric analysis of the lensing data.	Since only a single, putative gravitational arc is seen, and to be consistent with the X-ray analysis, we have only carried out a simple, spherically-symmetric analysis of the lensing data.
For a spherical mass distribution. the projected mass within the tangential critical radius. which we assume to be equal to the are vraclius. r0=15 aresee (071.8 kpe). is given by where Dene. Dave and Dareons are respectively the angular diameter distances from. the observer to the cluster. the observer to the lensed object. and the cluster to the Iensed object.	For a spherical mass distribution, the projected mass within the tangential critical radius, which we assume to be equal to the arc radius, $r_{\rm arc}= 15$ arcsec (71.8 kpc), is given by where $D_{\rm clus}$, $D_{\rm arc}$ and $D_{\rm arc-clus}$ are respectively the angular diameter distances from the observer to the cluster, the observer to the lensed object, and the cluster to the lensed object.
Fig.	Fig.
4 shows the projected mass within the critical radius as a function of the redshift of the are (solid curve).	4 shows the projected mass within the critical radius as a function of the redshift of the arc (solid curve).
The horizontal dashed. ancl dotted. lines mark the best fit (projected) mass measurement and 90 per cent confidence limits determined. from the X-ray data. within the same radius (3.8"Lot? )).	The horizontal dashed and dotted lines mark the best fit (projected) mass measurement and 90 per cent confidence limits determined from the X-ray data, within the same radius $3.8^{+1.0}_{-0.6} \times 10^{13}$ ).
We see that the X-ray and lensing mass measurements are consistent for any are redshift zi20.7.	We see that the X-ray and lensing mass measurements are consistent for any arc redshift $z_{\rm arc} > 0.7$.
The best match between the N-rayv and lensing mass measurements is obtained for an are recdshift of 1.5.	The best match between the X-ray and lensing mass measurements is obtained for an arc redshift of 1.5.
The ROSAT URL image of the powerful raclio galaxy 4€155.16 shows extended X-ray emission. peaking at the radio galaxy indicating cluster enmüssion with a strong cooling Low.	The ROSAT HRI image of the powerful radio galaxy 4C+55.16 shows extended X-ray emission peaking at the radio galaxy indicating cluster emission with a strong cooling flow.
A spectral study of the ASCA data suggests the N- emitting gas to be multi-phase.	A spectral study of the ASCA data suggests the X-ray emitting gas to be multi-phase.
An absorbed. cool component is found in the spectrum.	An absorbed, cool component is found in the spectrum.
The muti-phase spectral analysis indicates that the temperature of the ambient. cluster medium is στ5.4 keV. A single-phase mocel fitted to the data gives a temperature lower by ~1 keV. typical of a cooling How cluster.	The muti-phase spectral analysis indicates that the temperature of the ambient cluster medium is $kT \simeq 5.4$ keV. A single-phase model fitted to the data gives a temperature lower by $\sim 1$ keV, typical of a cooling flow cluster.
The mass deposition rate of the cooling low. 110021544. ver+. derived from the spectral analysis is consistent with that (070.το ver1 0) estimated: from⋅ the image. analysis. when corrected [or excess absorption.	The mass deposition rate of the cooling flow, $1100^{+240}_{-410}$ $^{-1}$, derived from the spectral analysis is consistent with that $970^{+270}_{-450}$ $^{-1}$ ) estimated from the image analysis when corrected for excess absorption.
Agreements between mass deposition rates derived from the two methods have been found for other distant cooling-How clusters (Allen 1998b).	Agreements between mass deposition rates derived from the two methods have been found for other distant cooling-flow clusters (Allen 1998b).
The optical spectrum of 4€155.16. (Lawrence ct al 1996) is indeed very similar to the other cooling Low galaxies (Crawford et al L999).	The optical spectrum of 4C+55.16 (Lawrence et al 1996) is indeed very similar to the other cooling flow galaxies (Crawford et al 1999).
The La luminosity is about S810K ((Lawrence et al 1996).	The $\alpha $ luminosity is about $8\times 10^{42}$ (Lawrence et al 1996).
The relatively laree Balmer decriment. (La 11:32 5.5) suggests a significant reddening. which is often observed in cooling flows.	The relatively large Balmer decriment $\alpha $ $\beta \simeq 5.5$ ) suggests a significant reddening, which is often observed in cooling flows.
The inferred absorption column density is slightly smaller than observed in the X-ray. spectrum.	The inferred absorption column density is slightly smaller than observed in the X-ray spectrum.
The absorption-corrected. 2.10. keV. and. bolometric Iumiosities. computed from the multi-phase model. are 8.010tere st. and 2.2«LOMerela respectively == 50 aan == 0.5).	The absorption-corrected 2–10 keV and bolometric lumiosities, computed from the multi-phase model, are $8.0\times 10^{44}$ , and $2.2\times 10^{45}$, respectively = 50 and = 0.5).
About 60 per cent of the bolometric luminosity is due to the cooling How.	About 60 per cent of the bolometric luminosity is due to the cooling flow.
The bolometric luminosity execeds that predicted. for the single-phase temperature of4 keV from the correlation between emission-weighted cluster temperature ancl luminosity (Mushotzky 1984: Eclee Stewart 1991: David ct al 1998: Fabian οἱ al 1994: Alushotzky Sharl 1997: White ct al 1997).	The bolometric luminosity exceeds that predicted for the single-phase temperature of 4 keV from the correlation between emission-weighted cluster temperature and luminosity (Mushotzky 1984; Edge Stewart 1991; David et al 1993; Fabian et al 1994; Mushotzky Sharf 1997; White et al 1997).
A similar deserepancy is found for the other strong cooling How clusters (e.g Fabian ct al 1994: Allen Fabian 19982: Alarkevich 1998).	A similar descrepancy is found for the other strong cooling flow clusters (e.g., Fabian et al 1994; Allen Fabian 1998a; Markevich 1998).
Taking the temperature derived from the multi-phase spectral analwsis. 4€155.16 fits well the &7x Lia correlation obtained from a similar analysis of other luminous (Ly.1OMere t)) clusters for which the cllect of cooling Lows is included. (Allen Fabian 1998a). and is consistent with LpxS expected. [rom simple eravitational collapses for formation of clusters (Ixaiser 1986: Navarro. Frenk White 1995).	Taking the temperature derived from the multi-phase spectral analysis, 4C+55.16 fits well the $kT_{\rm X}$ $L_{\rm Bol}$ correlation obtained from a similar analysis of other luminous $L_{\rm Bol}>10^{45}$ ) clusters for which the effect of cooling flows is included (Allen Fabian 1998a), and is consistent with $L_{\rm Bol}\propto T_{\rm X}^2$ expected from simple gravitational collapses for formation of clusters (Kaiser 1986; Navarro, Frenk White 1995).
As shown in Section 6 (and Lig.	As shown in Section 6 (and Fig.
4). the mass estimated using the tentatively-identified. lensing are and the eravitational mass derived from the X-ray deprojection	4), the mass estimated using the tentatively-identified lensing arc and the gravitational mass derived from the X-ray deprojection
rate due to ms needs to be be comparable to the resonant effect but of opposite sigu.	rate due to $m_2$ needs to be be comparable to the resonant effect but of opposite sign.
Cousidering the precession rate of meo. we estimate that i5 corresponds to TO orbits iu the prograde seuse while the resonant terii corresponds to 70/2 orbits in the retrograde sense.	Considering the precession rate of $m_2,$ we estimate that $\omega_{pr2}$ corresponds to $70$ orbits in the prograde sense while the resonant term corresponds to $70/2$ orbits in the retrograde sense.
Thus the combined effect produces a precession period of 70 orbits iu the retrograde seuse as seen in the simulation.	Thus the combined effect produces a precession period of $70$ orbits in the retrograde sense as seen in the simulation.
Iu sunuuary our simulation gives plasuble eccentricity values for the two plauets that can be uuderstood in outline bv use of a simplified analytic theory and are consistent with the current observatious.	In summary our simulation gives plasuble eccentricity values for the two planets, that can be understood in outline by use of a simplified analytic theory and are consistent with the current observations.
Iun addition. to the analytic model preseuted im section (2)) aud the lvdrodvuaimic simulations prescuted in section (27)). we lave also performed three-body orbit iutegratious using a fifth-order Runge-Kutta scheme (e.g. Press et al.	In addition to the analytic model presented in section \ref{mod}) ) and the hydrodynamic simulations presented in section \ref{simulation}) ), we have also performed three-body orbit integrations using a fifth-order Runge-Kutta scheme (e.g. Press et al.
1993).	1993).
The basic assunptious of the model are that the wo plauets exist Wiun the imuer cavitv of a tically runcaed dise that lies exterior to the outer planet.	The basic assumptions of the model are that the two planets exist within the inner cavity of a tidally truncated disc that lies exterior to the outer planet.
Tidal interaction with this dise causes inwards migration of the outer planet. and also leads to eccentricity damping of he outer plauet.	Tidal interaction with this disc causes inwards migration of the outer planet, and also leads to eccentricity damping of the outer planet.
It is further assumed that as he plancts uierate dwards and approach their final semi-major axes. he disc isperses on Some prescribed tine scale f45;,,. Iu our nunerical calculations. a torque was applied to the outermost plauet such that it nierated inwards on a time scale of ting local orbital periods as defined iu sectiou(2}). and a damping force was applied iu the radial direction ο dap the eccentricity on a ine scale of f. local orbital yeriods also as defined iu section (2)).	It is further assumed that as the planets migrate inwards and approach their final semi-major axes, the disc disperses on some prescribed time scale $t_{disp}.$ In our numerical calculations, a torque was applied to the outermost planet such that it migrated inwards on a time scale of $t_{mig}$ local orbital periods as defined in \ref{mod}) ), and a damping force was applied in the radial direction to damp the eccentricity on a time scale of $t_c$ local orbital periods also as defined in section \ref{mod}) ).
These integrations used initial conditions corresponding to the more nassive. outermost planct reine located initially at 5 AU. with the lighter inuex-most λαο located initially at 2.5 AU.	These integrations used initial conditions corresponding to the more massive, outermost planet being located initially at 5 AU, with the lighter inner-most planet located initially at 2.5 AU.
The planct niasses adopted for the orbit integrations are the same as the uinimuuni masses reported for the planets im the svsteus around CJsT6 by Marcy et al. (2001)) (	The planet masses adopted for the orbit integrations are the same as the minimum masses reported for the planets in the system around GJ876 by Marcy et al. \cite{Marcy4}) ) (
ie. Lae M; ancl 0.56 NL;).	i.e. 1.87 $_{J}$ and 0.56 $_{J}$ ).
The stellar mass is taken to be 0.32 AL...	The stellar mass is taken to be 0.32 $_{\odot}$.
Whülst these caleulatious provide onlv a crude approximation to the detailed plysics of disecompanion iuteractions. their simplicity allows us to perform many calculations. covering a wide area of parameter space. and also to run for much longer time scales than is possible for sinulatious of the type described in section(? ?)).	Whilst these calculations provide only a crude approximation to the detailed physics of disc–companion interactions, their simplicity allows us to perform many calculations, covering a wide area of parameter space, and also to run for much longer time scales than is possible for simulations of the type described in \ref{simulation}) ).
A qnunber of calculations have been performed to examine the relationship between the final values of ey. ey. and their ratio ο ουν to the various input parameters fig te ANC των.	A number of calculations have been performed to examine the relationship between the final values of $e_1$, $e_2$, and their ratio $e_1/e_2$ , to the various input parameters $t_{mig}$, $t_c$, and $t_{disp}$.
The results of some of these caleulations are preseuted in table Ἐν, aud are discussed below.	The results of some of these calculations are presented in table \ref{tab1}, and are discussed below.
The unit of time used iu the abscissa of the figures 3. to 5. is the orbital period for au object at 1 AU in orbit around a star with mass 0.32 Li and is denoted as P(1 AU).	The unit of time used in the abscissa of the figures \ref{fig3} to \ref{fig5} is the orbital period for an object at 1 AU in orbit around a star with mass $0.32$ $_{\odot}$, and is denoted as P(1 AU).
Equation Ls shows that the eccentricity of the outer plauet. ej. depeuds ou the ratio of f./f,,;4.	Equation \ref{e1} shows that the eccentricity of the outer planet, $e_1$, depends on the ratio of $t_c/t_{mig}$.
Mere we preseut results of simulations that explore how the ecceutricitv ratio ¢y/e, depends ou f. aud τω. Figure 3.Pa shows the evolution of the sonimajor axes and eccentricities for the rum R1. whose model parameters are described iu table 1..	Here we present results of simulations that explore how the eccentricity ratio $e_2/e_1$ depends on $t_c$ and $t_{mig}.$ Figure \ref{fig3} shows the evolution of the semi–major axes and eccentricities for the run R1, whose model parameters are described in table \ref{tab1}.
This figure shows the invard uueration of the outer plauct that subsequeutlv locks to the iuuer planet as it reaches the 2:1 conuuensurability.	This figure shows the inward migration of the outer planet that subsequently locks to the inner planet as it reaches the 2:1 commensurability.
The subsequent evolution is such that the two planets. nowresonautly locked. migrate wards.	The subsequent evolution is such that the two planets, nowresonantly locked, migrate inwards.
The eccentricities	The eccentricities
Type I AGN (20).	Type I AGN $2\sigma$ ).
The ratio of Type I quasars to Type II AGN increases for both bright and dim equasars with decreasing scale. but less dramatically as the ratio to Tvpe E AGN.	The ratio of Type I quasars to Type II AGN increases for both bright and dim quasars with decreasing scale, but less dramatically as the ratio to Type I AGN.
The ratio between dimmer Type I quasars and Tvpe II AGN is approximately consistent with unitv lor scales 150hlkpeSR<2.0Alpe: the ratio between brighter Type I quasars aud Type I AGN is 1.3 CZ 26) for scales RZ500hz!kpe.	The ratio between dimmer Type I quasars and Type II AGN is approximately consistent with unity for scales $150\kpchseventy \lesssim R \leqslant 2.0\Mpchseventy$; the ratio between brighter Type I quasars and Type II AGN is 1.3 $\gtrsim2\sigma$ ) for scales $R\gtrsim500\kpchseventy$.
On smaller scales. both ratios increase.	On smaller scales, both ratios increase.
At scales 2zz150hlkpe. the ratio of brighter Type I quasars to Type II AGN is 1.6 (220). and the ratio of dimmer Type I quasars to Type IL AGN is 1.3 (>Lo).	At scales $R\approx150\kpchseventy$, the ratio of brighter Type I quasars to Type II AGN is 1.6 $\approx2\sigma$ ), and the ratio of dimmer Type I quasars to Type II AGN is 1.3 $>1\sigma$ ).
This scale dependeney could be evidence for (he merger origin of quasars. since one would expect (o see a higher density of environment galaxies al small scales where merger events are likely to take place (Ilopkinsetal.2008).	This scale dependency could be evidence for the merger origin of quasars, since one would expect to see a higher density of environment galaxies at small scales where merger events are likely to take place \citep{Hopkins2007}.
. Evidence (hat dimuner quasars and lower-Iuminosity AGN are located in environments wilh similar overclensitv might suggest that cdimmer quasars could be a transition population between low-liminosity AGN (likely fueled in dry mergers. close encounters. or secular processes) and high-Iuminositv AGN (likely fueled in major mergers).	Evidence that dimmer quasars and lower-luminosity AGN are located in environments with similar overdensity might suggest that dimmer quasars could be a transition population between low-luminosity AGN (likely fueled in dry mergers, close encounters, or secular processes) and high-luminosity AGN (likely fueled in major mergers).
Rather than disparate populations of merger-fueled and secularlv fueled AGN. there may be a continuum of galaxy interactions from major mergers to close encounters or harassment that cause AGN Iuninosityv differences.	Rather than disparate populations of merger-fueled and secularly fueled AGN, there may be a continuum of galaxy interactions from major mergers to close encounters or harassment that cause AGN luminosity differences.
Alternatively. a mix of mergers and secular processes could drive the AGN population near (he quasar-Sevlert divide (GV;2005b).	Alternatively, a mix of mergers and secular processes could drive the AGN population near the quasar-Seyfert divide \citep[$M_{i}.
We have compared the AGN samples without redshilt cuts. but we note that in Section ?? we demonstrated (hat evolution of quasar environments with redshift is negligible.	We have compared the AGN samples without redshift cuts, but we note that in Section \ref{redshiftsubsec} we demonstrated that evolution of quasar environments with redshift is negligible.
The significant dillerence in (he environments of bright Type I quasars aud (he environments ol both Type I and Type II AGN could imply that these populations have different fueling mechanisms.	The significant difference in the environments of bright Type I quasars and the environments of both Type I and Type II AGN could imply that these populations have different fueling mechanisms.
This result is consistent with results presented by Lietal.(2006.2008).. who find that there is only a weak link between nearby neighbors of narrow-line AGN and their nuclear activily.	This result is consistent with results presented by \citet{Li2006, Li2008}, who find that there is only a weak link between nearby neighbors of narrow-line AGN and their nuclear activity.
Finally. we combine our analysis of tvpe. redshift and luminosity effects on environment overdensitv in Figures 11.. 12.. and 13..	Finally, we combine our analysis of type, redshift and luminosity effects on environment overdensity in Figures \ref{scale_spectargs_Mandz_higherz}, \ref{scale_spectargs_Mandz_lowerz}, and \ref{scale_qso_newMzcompare}.
Our ὃς cuts on the photometric galaxies around the spectroscopic targets as well as around the random positions to which they are compared (as described in Section ??)) allow us to make meaningful comparisons of objects in different	Our $\delta z$ cuts on the photometric galaxies around the spectroscopic targets as well as around the random positions to which they are compared (as described in Section \ref{deltazcutsection}) ) allow us to make meaningful comparisons of objects in different
absorbed mid-IR emissiou re-radiated in the FIR docs not exceed the observed poiuts.	absorbed mid-IR emission re-radiated in the FIR does not exceed the observed points.
If the FIR emission is powered bv the ACN this is UV radiation re-processed by dust.	If the FIR emission is powered by the AGN this is UV radiation re-processed by dust.
However. if the AGN emits —2«JUL. im UV photons. high excitation gas chussiou lines should also be observed.	However, if the AGN emits $\sim 2\xten{10}\Lo$ in UV photons, high excitation gas emission lines should also be observed.
The abseuce of high ionization lines like rur\|A5007.LO59A (CMoorwood c al. 1996a})	The absence of high ionization lines like $\lambda 5007,4959$ (Moorwood et al. \cite{moorwood96a}) )
or [NeVJALL3pau (Genzelet al. 1998))	or $\lambda 14.3\MIC$ (Genzel et al. \cite{genzel98}) )
aud the low excitation observed in the wind-blown cone strongly argues that uo ioniziug UV photous (ie. 13.6<hr 00ο) escape frou the inuer region.	and the low excitation observed in the wind-blown cone strongly argues that no ionizing UV photons (i.e. $13.6\le \HNU < 500\EV$ ) escape from the inner region.
The low excitation IT, /Pao map. associated with the peak in IH» cluission close to the nucleus location. indicates that ALL ultraviolet photons must be absorbed within R<175. Le. T?30pe along ALL lines of sight.	The low excitation $_2$ $\alpha$ map, associated with the peak in $_2$ emission close to the nucleus location, indicates that ALL ultraviolet photons must be absorbed within $R<1\farcs5$, i.e. $R<30\PC$ along ALL lines of sight.
This is in contrast with the standard unified model of AGN where ionizing radiation escapes along directions close to the torus axis.	This is in contrast with the standard unified model of AGN where ionizing radiation escapes along directions close to the torus axis.
If. the AGNUM is duoenmibedded5B ini a; thickTEM dustydx mediunm then two effects will contribute to its obsewmration.	If the AGN is embedded in a thick dusty medium then two effects will contribute to its obscuration.
First. dust will compete] with the otgas in ‘absorbing© UV. photons which will be directly converted iuto infrared radiation (e.g. Netzer Laor 1993.. Oliva. Marconi AMoorwood 1999a)).	First, dust will compete with the gas in absorbing UV photons which will be directly converted into infrared radiation (e.g. Netzer Laor \cite{netzer93}, Oliva, Marconi Moorwood \cite{oliva99}) ).
Second. emission lines originating πι this. medium. will: be suppressed. by dust absorption.	Second, emission lines originating in this medium will be suppressed by dust absorption.
. To00 ⋅ . ↸∖↴∖↴↑∐⊔⋜↧↑↸∖↑∐↸∖⋜⋯⋯∏∐∪↕↥⋅↸∖≺∣∏∐⋅↸∖≺↸∖⊼↑⋯≼⊳↕∪∐⋅∐∪↑↸∖↑↕⋯↑∐↓↽∙⊽↴∙↴⋅↴∙⋅∙. ⋅∙⋅ ∙ ≼⊲∐⋅↸⊳↕∐∏↴∖↴⊪∖⊽↸∖∖⊳∏↓∙∶≩∕∣⋯⊪∖⊽↸∖∐∫⊔∙≺∖∖∕∣⋯∶∩∙↓≺↸∖↘⊓∐↸⊳↑↕∪∐ coirected) aud iu NGC 1915 0.008 (both ratios are from Cienzel et al. 19908)).	To estimate the amount of required extinction, note that in Circinus $\NeV 14.3\MIC/\NeII 12.8\MIC=0.4$ (extinction corrected) and in NGC 4945 $\le 0.008$ (both ratios are from Genzel et al. \cite{genzel98}) ).
TE NGC1915. has the same iutrinsie ratio as Circinus. then the observed rratiov] requiresui] {οyon)2 L2maeg correspondiug to Ay> LlOmag aud in aereeimeut with the above estimates.	If NGC4945 has the same intrinsic ratio as Circinus, then the observed ratio requires $A(14.3\MIC)>4.2$ mag corresponding to $\AV>110$ mag and in agreement with the above estimates.
We conclude that the ACN can power the FIR cnussion if it is properly obscured.	We conclude that the AGN can power the FIR emission if it is properly obscured.
Inferring the black hole mass from the nunuaser observatious (1.1ον109NI.. Greenhill.	Inferring the black hole mass from the maser observations $1.4\xten{6}\Mo$, Greenhill.
et al. 1997)).	et al. \cite{greenhill}) ),
we find im this scenario that the ACN is eidttine at ~50% of its Eddineton Lumiuosity.	we find in this scenario that the AGN is emitting at $\sim 50\%$ of its Eddington Luminosity.
As discussed above. if an ACN powers the FIR cuission of NGC 1915. it aust be hidden up to midIR wavelengths aud does not fitJ inH the standard uuifedf model.	As discussed above, if an AGN powers the FIR emission of NGC 4945, it must be hidden up to mid-IR wavelengths and does not fit in the standard unified model.
The possible: existence: of: such a class of: Active: Nuelei.-: detectable onlv at >10keV. would have important cousequeuces ou the interpretation of IR huuinous objects whose power source is still debated.	The possible existence of such a class of Active Nuclei, detectable only at $>10\KEV$, would have important consequences on the interpretation of IR luminous objects whose power source is still debated.
Genzel et al. (1998))	Genzel et al. \cite{genzel98}) )
and Lutz et al (1998)	and Lutz et al. \cite{lutz98}) )
compared iiid-IR spectra of Ultra Luninous IRAS ealaxies (ULIRGs. see Sanders Mirabel 1996 for a review) with those of AGN aud starburst templates.	compared mid-IR spectra of Ultra Luminous IRAS galaxies (ULIRGs, see Sanders Mirabel \cite{sanders96} for a review) with those of AGN and starburst templates.
They concluded that the absence of high excitation lines (e.g. [Nev]}) and the presence of PAT features undiluted bv strong thermal coutimmun in CLIRGSs spectra strongly Sugeest that the starburst component is dominaut.	They concluded that the absence of high excitation lines (e.g. ) and the presence of PAH features undiluted by strong thermal continuum in ULIRGs spectra strongly suggest that the starburst component is dominant.
They also show that. after a proper extinction correction. the observed star formation activity can power FIR cussion.	They also show that, after a proper extinction correction, the observed star formation activity can power FIR emission.
In their papers. NCC 11915 is classified as a starburst because of its mid-IR properties but. as shown in the previous. section. NGC 1915. could also be powered by a highly obscured AGN aud the same scenario could iu principle apply to all ULIRGs.	In their papers, NGC 4945 is classified as a starburst because of its mid-IR properties but, as shown in the previous section, NGC 4945 could also be powered by a highly obscured AGN and the same scenario could in principle apply to all ULIRGs.
Their bolometric cussion cau be powered by an active nucleus completely obscured even at mil-IR wavelengths.	Their bolometric emission can be powered by an active nucleus completely obscured even at mid-IR wavelengths.
The same aremnent could be used for the sources detected at submillimeter wavelengths by SCUBA which cai be considered as the high redshift counterpart of local ULIRGs.	The same argument could be used for the sources detected at submillimeter wavelengths by SCUBA which can be considered as the high redshift counterpart of local ULIRGs.
If they are powered by hidden active uuclei then their enormous FIR ciission would uot require star formation rates in excess of >LOOMxr.\| (e.g. Hughes et al. 1998)).	If they are powered by hidden active nuclei then their enormous FIR emission would not require star formation rates in excess of $>100\Mo\YR\1$ (e.g. Hughes et al. \cite{hughes98}) ),
and this would have important consequences :for understanding: the history: of. star formationJ: in: hieh: yedshift ealaxies.	and this would have important consequences for understanding the history of star formation in high redshift galaxies.
Iu additiou.⋅⋅ it∙∙ is well known that in⋅ order to explai⋅— he Nav background a huge fraction of obscured ACN0 is required.	In addition, it is well known that in order to explain the X-ray background a large fraction of obscured AGN is required.
However Calli et al. (1999))	However Gilli et al. \cite{gilli99}) )
have shown that. dm order to reconcile the observed Xaay background with ↕⋜⋯∟∖≓⋯⋅↖↸⊳∪∏∐↑↴∖∙⋜⋃⋜∏⋯∐⋅↖↸∖↖∪↕∏∐∶↴∙↻∪↴⋯↕⋜↧↕∪∐∪↕∐⋜⋯↧∙↽∙⊽ ↴ ∙⋅⊽⊽⊽⋅↜ ⋅ ⊳∙ ∙↴⋅⊳ ⊸∖≓⋯⋅↖↴∖≺∏∐∏∖↴∖↕↴∖↥↸∖≺∣∏∐↸∖≼↧∏↻↑∪⊓∖	have shown that, in order to reconcile the observed X-ray background with hard X-ray counts, a rapidly evolving population of hard X-ray sources is required up to redshift $\sim 1.5$.
≼⊔∐⇈∿↓∙⋅⊐∙⋀∖∪↴∖⋯⊳↕ »pulatiou is known at the moment aud the oulv class of objects which are known to undergo such a rapid density evolution are local ULIRGs (iim et al. 1998))	No such population is known at the moment and the only class of objects which are known to undergo such a rapid density evolution are local ULIRGs (Kim et al. \cite{kim98}) )
anc. at higher redshift. the SCUBA sources (Suail ct al. 1997)).	and, at higher redshift, the SCUBA sources (Smail et al. \cite{smail97}) ).

Adaptive stepping poses no threat to momentum conservation. provided (hat the steps are chosen in a wav which respects (he svmuuetries in (he continuous mechanical problem.

Adaptive stepping poses no threat to momentum conservation, provided that the steps are chosen in a way which respects the symmetries in the continuous mechanical problem.

Unfortunatelv. adaptive stepping does pose a threat to svinplecticitv.

Unfortunately, adaptive stepping does pose a threat to symplecticity.

With a Gimestep function h(n.qequU.4»). the expression for dS (see eqrekl5)) gets additional ternis: , . ∐∐∐↲⊳∖⊽∩↲↕↽≻⊳∖⇁⋅⊔∐↲↕⋅≼↲↕⋝∖⊽∐∪↥∖∖⊽∪−↓⋟∪↕⋅∐↓∪∐⊔∐↲⊳∖⊽↥≀↧↴∥↲⋝∖⊽↕↽≻≀↧↴≺∢≼↲∖∖↽∐↕≺∢∐↕⋝∖⊽≺∢∪∐⊳∖⇁≼↲↕⋅∖↽≼↲≼⇂∪∖⇁≼↲↕⋅≀↧↴∐⇀↸≼↲≼⇂∐∏↕∐∣↽≻≼↲↕⋅∪↓≯⋅⋅ JA ⋅⊳ ∏∐↲⋟∖⊽≼↲≼↲⇀↸⊔⋅≀↧↴∩↲↕⋅∐↓⋟∖⊽↕↽≻↕⋅≼↲∖↽≼↲↕∐∏⋟∖⊽∐⋅∪∐⊔∖⊽↕⋅↕⊔∐≸↽↔↴↙∣−↺∶∩≀↧⊔∖⊽⊔∐↲≼∐∐≼↲↕⋅≼↲∐≺∢↩∪↓↥∖∖⇁∪↓∪↕⋅

With a timestep function $h\left( q_1, q'_1, \ldots, q_1^{(n)}, q_2 \right)$, the expression for $d \mathcal{S}$ (see ) gets additional terms: These extra terms prevent us from writing $d^2\mathcal{S} = 0$ as the difference of two forms, one of which is the pushforward of the other, as we did in equation.

∐↓⋟∖⊽⋅∪∐≼↲ ∪↓⋟∖∖↽∐↥≺∢∐↕⊳∖⇁⊔∐↲↕↽≻∏⊳∖⇁∐↓≯∪↕⋅∖∖↽≀↧↴↕⋅≼⇂∪↓≯⊔∐↲∪⊔∐↲↕⋅⋅≀↧↴⊳∖⊽∖∖↽≼↲≼∐≼⊔∐≼↲≺⇂∏≀↧↴∐∪∐≼⋝∏⋅⋅∖∖⊽↕⊔↥↖≺↽↔↴≼↲∐≼↲↕⋅≀↧↴↥≀↧↴≼⇂≀↧↴↕↽≻∐∖↽≼↲ sleps.

With general adaptive timesteps, there is no two-form on the state space which is conserved over a fixed number of steps.

VAL1

$^{-1}$.

The mass model determined from the X-ray data may be compared to the mass implied by the observed. lensing configuration in the cluster (Section 1).

The mass model determined from the X-ray data may be compared to the mass implied by the observed lensing configuration in the cluster (Section 1).

Since only a single. putative gravitational arc is seen. and to be consistent with the X-ray analysis. we have only carried out a simple. spherically-svnimetric analysis of the lensing data.

Since only a single, putative gravitational arc is seen, and to be consistent with the X-ray analysis, we have only carried out a simple, spherically-symmetric analysis of the lensing data.

For a spherical mass distribution. the projected mass within the tangential critical radius. which we assume to be equal to the are vraclius. r0=15 aresee (071.8 kpe). is given by where Dene. Dave and Dareons are respectively the angular diameter distances from. the observer to the cluster. the observer to the lensed object. and the cluster to the Iensed object.

For a spherical mass distribution, the projected mass within the tangential critical radius, which we assume to be equal to the arc radius, $r_{\rm arc}= 15$ arcsec (71.8 kpc), is given by where $D_{\rm clus}$, $D_{\rm arc}$ and $D_{\rm arc-clus}$ are respectively the angular diameter distances from the observer to the cluster, the observer to the lensed object, and the cluster to the lensed object.

Fig.

4 shows the projected mass within the critical radius as a function of the redshift of the are (solid curve).

4 shows the projected mass within the critical radius as a function of the redshift of the arc (solid curve).

The horizontal dashed. ancl dotted. lines mark the best fit (projected) mass measurement and 90 per cent confidence limits determined. from the X-ray data. within the same radius (3.8"Lot? )).

The horizontal dashed and dotted lines mark the best fit (projected) mass measurement and 90 per cent confidence limits determined from the X-ray data, within the same radius $3.8^{+1.0}_{-0.6} \times 10^{13}$ ).

We see that the X-ray and lensing mass measurements are consistent for any are redshift zi20.7.

We see that the X-ray and lensing mass measurements are consistent for any arc redshift $z_{\rm arc} > 0.7$.

The best match between the N-rayv and lensing mass measurements is obtained for an are recdshift of 1.5.

The best match between the X-ray and lensing mass measurements is obtained for an arc redshift of 1.5.

The ROSAT URL image of the powerful raclio galaxy 4€155.16 shows extended X-ray emission. peaking at the radio galaxy indicating cluster enmüssion with a strong cooling Low.

The ROSAT HRI image of the powerful radio galaxy 4C+55.16 shows extended X-ray emission peaking at the radio galaxy indicating cluster emission with a strong cooling flow.

A spectral study of the ASCA data suggests the N- emitting gas to be multi-phase.

A spectral study of the ASCA data suggests the X-ray emitting gas to be multi-phase.

An absorbed. cool component is found in the spectrum.

An absorbed, cool component is found in the spectrum.

The muti-phase spectral analysis indicates that the temperature of the ambient. cluster medium is στ5.4 keV. A single-phase mocel fitted to the data gives a temperature lower by ~1 keV. typical of a cooling How cluster.

The muti-phase spectral analysis indicates that the temperature of the ambient cluster medium is $kT \simeq 5.4$ keV. A single-phase model fitted to the data gives a temperature lower by $\sim 1$ keV, typical of a cooling flow cluster.

The mass deposition rate of the cooling low. 110021544. ver+. derived from the spectral analysis is consistent with that (070.το ver1 0) estimated: from⋅ the image. analysis. when corrected [or excess absorption.

The mass deposition rate of the cooling flow, $1100^{+240}_{-410}$ $^{-1}$, derived from the spectral analysis is consistent with that $970^{+270}_{-450}$ $^{-1}$ ) estimated from the image analysis when corrected for excess absorption.

Agreements between mass deposition rates derived from the two methods have been found for other distant cooling-How clusters (Allen 1998b).

Agreements between mass deposition rates derived from the two methods have been found for other distant cooling-flow clusters (Allen 1998b).

The optical spectrum of 4€155.16. (Lawrence ct al 1996) is indeed very similar to the other cooling Low galaxies (Crawford et al L999).

The optical spectrum of 4C+55.16 (Lawrence et al 1996) is indeed very similar to the other cooling flow galaxies (Crawford et al 1999).

The La luminosity is about S810K ((Lawrence et al 1996).

The $\alpha $ luminosity is about $8\times 10^{42}$ (Lawrence et al 1996).

The relatively laree Balmer decriment. (La 11:32 5.5) suggests a significant reddening. which is often observed in cooling flows.

The relatively large Balmer decriment $\alpha $ $\beta \simeq 5.5$ ) suggests a significant reddening, which is often observed in cooling flows.

The inferred absorption column density is slightly smaller than observed in the X-ray. spectrum.

The inferred absorption column density is slightly smaller than observed in the X-ray spectrum.

The absorption-corrected. 2.10. keV. and. bolometric Iumiosities. computed from the multi-phase model. are 8.010tere st. and 2.2«LOMerela respectively == 50 aan == 0.5).

The absorption-corrected 2–10 keV and bolometric lumiosities, computed from the multi-phase model, are $8.0\times 10^{44}$ , and $2.2\times 10^{45}$, respectively = 50 and = 0.5).

About 60 per cent of the bolometric luminosity is due to the cooling How.

About 60 per cent of the bolometric luminosity is due to the cooling flow.

The bolometric luminosity execeds that predicted. for the single-phase temperature of4 keV from the correlation between emission-weighted cluster temperature ancl luminosity (Mushotzky 1984: Eclee Stewart 1991: David ct al 1998: Fabian οἱ al 1994: Alushotzky Sharl 1997: White ct al 1997).

The bolometric luminosity exceeds that predicted for the single-phase temperature of 4 keV from the correlation between emission-weighted cluster temperature and luminosity (Mushotzky 1984; Edge Stewart 1991; David et al 1993; Fabian et al 1994; Mushotzky Sharf 1997; White et al 1997).

A similar deserepancy is found for the other strong cooling How clusters (e.g Fabian ct al 1994: Allen Fabian 19982: Alarkevich 1998).

A similar descrepancy is found for the other strong cooling flow clusters (e.g., Fabian et al 1994; Allen Fabian 1998a; Markevich 1998).

Taking the temperature derived from the multi-phase spectral analwsis. 4€155.16 fits well the &7x Lia correlation obtained from a similar analysis of other luminous (Ly.1OMere t)) clusters for which the cllect of cooling Lows is included. (Allen Fabian 1998a). and is consistent with LpxS expected. [rom simple eravitational collapses for formation of clusters (Ixaiser 1986: Navarro. Frenk White 1995).

Taking the temperature derived from the multi-phase spectral analysis, 4C+55.16 fits well the $kT_{\rm X}$ $L_{\rm Bol}$ correlation obtained from a similar analysis of other luminous $L_{\rm Bol}>10^{45}$ ) clusters for which the effect of cooling flows is included (Allen Fabian 1998a), and is consistent with $L_{\rm Bol}\propto T_{\rm X}^2$ expected from simple gravitational collapses for formation of clusters (Kaiser 1986; Navarro, Frenk White 1995).

As shown in Section 6 (and Lig.

As shown in Section 6 (and Fig.

4). the mass estimated using the tentatively-identified. lensing are and the eravitational mass derived from the X-ray deprojection

4), the mass estimated using the tentatively-identified lensing arc and the gravitational mass derived from the X-ray deprojection

rate due to ms needs to be be comparable to the resonant effect but of opposite sigu.

rate due to $m_2$ needs to be be comparable to the resonant effect but of opposite sign.

Cousidering the precession rate of meo. we estimate that i5 corresponds to TO orbits iu the prograde seuse while the resonant terii corresponds to 70/2 orbits in the retrograde sense.

Considering the precession rate of $m_2,$ we estimate that $\omega_{pr2}$ corresponds to $70$ orbits in the prograde sense while the resonant term corresponds to $70/2$ orbits in the retrograde sense.

Thus the combined effect produces a precession period of 70 orbits iu the retrograde seuse as seen in the simulation.

Thus the combined effect produces a precession period of $70$ orbits in the retrograde sense as seen in the simulation.

Iu sunuuary our simulation gives plasuble eccentricity values for the two plauets that can be uuderstood in outline bv use of a simplified analytic theory and are consistent with the current observatious.

In summary our simulation gives plasuble eccentricity values for the two planets, that can be understood in outline by use of a simplified analytic theory and are consistent with the current observations.

Iun addition. to the analytic model preseuted im section (2)) aud the lvdrodvuaimic simulations prescuted in section (27)). we lave also performed three-body orbit iutegratious using a fifth-order Runge-Kutta scheme (e.g. Press et al.

In addition to the analytic model presented in section \ref{mod}) ) and the hydrodynamic simulations presented in section \ref{simulation}) ), we have also performed three-body orbit integrations using a fifth-order Runge-Kutta scheme (e.g. Press et al.

1993).

The basic assunptious of the model are that the wo plauets exist Wiun the imuer cavitv of a tically runcaed dise that lies exterior to the outer planet.

The basic assumptions of the model are that the two planets exist within the inner cavity of a tidally truncated disc that lies exterior to the outer planet.

Tidal interaction with this dise causes inwards migration of the outer planet. and also leads to eccentricity damping of he outer plauet.

Tidal interaction with this disc causes inwards migration of the outer planet, and also leads to eccentricity damping of the outer planet.

It is further assumed that as he plancts uierate dwards and approach their final semi-major axes. he disc isperses on Some prescribed tine scale f45;,,. Iu our nunerical calculations. a torque was applied to the outermost plauet such that it nierated inwards on a time scale of ting local orbital periods as defined iu sectiou(2}). and a damping force was applied iu the radial direction ο dap the eccentricity on a ine scale of f. local orbital yeriods also as defined iu section (2)).

It is further assumed that as the planets migrate inwards and approach their final semi-major axes, the disc disperses on some prescribed time scale $t_{disp}.$ In our numerical calculations, a torque was applied to the outermost planet such that it migrated inwards on a time scale of $t_{mig}$ local orbital periods as defined in \ref{mod}) ), and a damping force was applied in the radial direction to damp the eccentricity on a time scale of $t_c$ local orbital periods also as defined in section \ref{mod}) ).

These integrations used initial conditions corresponding to the more nassive. outermost planct reine located initially at 5 AU. with the lighter inuex-most λαο located initially at 2.5 AU.

These integrations used initial conditions corresponding to the more massive, outermost planet being located initially at 5 AU, with the lighter inner-most planet located initially at 2.5 AU.

The planct niasses adopted for the orbit integrations are the same as the uinimuuni masses reported for the planets im the svsteus around CJsT6 by Marcy et al. (2001)) (

The planet masses adopted for the orbit integrations are the same as the minimum masses reported for the planets in the system around GJ876 by Marcy et al. \cite{Marcy4}) ) (

ie. Lae M; ancl 0.56 NL;).

i.e. 1.87 $_{J}$ and 0.56 $_{J}$ ).

The stellar mass is taken to be 0.32 AL...

The stellar mass is taken to be 0.32 $_{\odot}$.

Whülst these caleulatious provide onlv a crude approximation to the detailed plysics of disecompanion iuteractions. their simplicity allows us to perform many calculations. covering a wide area of parameter space. and also to run for much longer time scales than is possible for sinulatious of the type described in section(? ?)).

Whilst these calculations provide only a crude approximation to the detailed physics of disc–companion interactions, their simplicity allows us to perform many calculations, covering a wide area of parameter space, and also to run for much longer time scales than is possible for simulations of the type described in \ref{simulation}) ).

A qnunber of calculations have been performed to examine the relationship between the final values of ey. ey. and their ratio ο ουν to the various input parameters fig te ANC των.

A number of calculations have been performed to examine the relationship between the final values of $e_1$, $e_2$, and their ratio $e_1/e_2$ , to the various input parameters $t_{mig}$, $t_c$, and $t_{disp}$.

The results of some of these caleulations are preseuted in table Ἐν, aud are discussed below.

The results of some of these calculations are presented in table \ref{tab1}, and are discussed below.

The unit of time used iu the abscissa of the figures 3. to 5. is the orbital period for au object at 1 AU in orbit around a star with mass 0.32 Li and is denoted as P(1 AU).

The unit of time used in the abscissa of the figures \ref{fig3} to \ref{fig5} is the orbital period for an object at 1 AU in orbit around a star with mass $0.32$ $_{\odot}$, and is denoted as P(1 AU).

Equation Ls shows that the eccentricity of the outer plauet. ej. depeuds ou the ratio of f./f,,;4.

Equation \ref{e1} shows that the eccentricity of the outer planet, $e_1$, depends on the ratio of $t_c/t_{mig}$.

Mere we preseut results of simulations that explore how the ecceutricitv ratio ¢y/e, depends ou f. aud τω. Figure 3.Pa shows the evolution of the sonimajor axes and eccentricities for the rum R1. whose model parameters are described iu table 1..

Here we present results of simulations that explore how the eccentricity ratio $e_2/e_1$ depends on $t_c$ and $t_{mig}.$ Figure \ref{fig3} shows the evolution of the semi–major axes and eccentricities for the run R1, whose model parameters are described in table \ref{tab1}.

This figure shows the invard uueration of the outer plauct that subsequeutlv locks to the iuuer planet as it reaches the 2:1 conuuensurability.

This figure shows the inward migration of the outer planet that subsequently locks to the inner planet as it reaches the 2:1 commensurability.

The subsequent evolution is such that the two planets. nowresonautly locked. migrate wards.

The subsequent evolution is such that the two planets, nowresonantly locked, migrate inwards.

The eccentricities

Type I AGN (20).

Type I AGN $2\sigma$ ).

The ratio of Type I quasars to Type II AGN increases for both bright and dim equasars with decreasing scale. but less dramatically as the ratio to Tvpe E AGN.

The ratio of Type I quasars to Type II AGN increases for both bright and dim quasars with decreasing scale, but less dramatically as the ratio to Type I AGN.

The ratio between dimmer Type I quasars and Tvpe II AGN is approximately consistent with unitv lor scales 150hlkpeSR<2.0Alpe: the ratio between brighter Type I quasars aud Type I AGN is 1.3 CZ 26) for scales RZ500hz!kpe.

The ratio between dimmer Type I quasars and Type II AGN is approximately consistent with unity for scales $150\kpchseventy \lesssim R \leqslant 2.0\Mpchseventy$; the ratio between brighter Type I quasars and Type II AGN is 1.3 $\gtrsim2\sigma$ ) for scales $R\gtrsim500\kpchseventy$.

On smaller scales. both ratios increase.

On smaller scales, both ratios increase.

At scales 2zz150hlkpe. the ratio of brighter Type I quasars to Type II AGN is 1.6 (220). and the ratio of dimmer Type I quasars to Type IL AGN is 1.3 (>Lo).

At scales $R\approx150\kpchseventy$, the ratio of brighter Type I quasars to Type II AGN is 1.6 $\approx2\sigma$ ), and the ratio of dimmer Type I quasars to Type II AGN is 1.3 $>1\sigma$ ).

This scale dependeney could be evidence for (he merger origin of quasars. since one would expect (o see a higher density of environment galaxies al small scales where merger events are likely to take place (Ilopkinsetal.2008).

This scale dependency could be evidence for the merger origin of quasars, since one would expect to see a higher density of environment galaxies at small scales where merger events are likely to take place \citep{Hopkins2007}.

. Evidence (hat dimuner quasars and lower-Iuminosity AGN are located in environments wilh similar overclensitv might suggest that cdimmer quasars could be a transition population between low-liminosity AGN (likely fueled in dry mergers. close encounters. or secular processes) and high-Iuminositv AGN (likely fueled in major mergers).

Evidence that dimmer quasars and lower-luminosity AGN are located in environments with similar overdensity might suggest that dimmer quasars could be a transition population between low-luminosity AGN (likely fueled in dry mergers, close encounters, or secular processes) and high-luminosity AGN (likely fueled in major mergers).

Rather than disparate populations of merger-fueled and secularlv fueled AGN. there may be a continuum of galaxy interactions from major mergers to close encounters or harassment that cause AGN Iuninosityv differences.

Rather than disparate populations of merger-fueled and secularly fueled AGN, there may be a continuum of galaxy interactions from major mergers to close encounters or harassment that cause AGN luminosity differences.

Alternatively. a mix of mergers and secular processes could drive the AGN population near (he quasar-Sevlert divide (GV;2005b).

Alternatively, a mix of mergers and secular processes could drive the AGN population near the quasar-Seyfert divide \citep[$M_{i}.

We have compared the AGN samples without redshilt cuts. but we note that in Section ?? we demonstrated (hat evolution of quasar environments with redshift is negligible.

We have compared the AGN samples without redshift cuts, but we note that in Section \ref{redshiftsubsec} we demonstrated that evolution of quasar environments with redshift is negligible.

The significant dillerence in (he environments of bright Type I quasars aud (he environments ol both Type I and Type II AGN could imply that these populations have different fueling mechanisms.

The significant difference in the environments of bright Type I quasars and the environments of both Type I and Type II AGN could imply that these populations have different fueling mechanisms.

This result is consistent with results presented by Lietal.(2006.2008).. who find that there is only a weak link between nearby neighbors of narrow-line AGN and their nuclear activily.

This result is consistent with results presented by \citet{Li2006, Li2008}, who find that there is only a weak link between nearby neighbors of narrow-line AGN and their nuclear activity.

Finally. we combine our analysis of tvpe. redshift and luminosity effects on environment overdensitv in Figures 11.. 12.. and 13..

Finally, we combine our analysis of type, redshift and luminosity effects on environment overdensity in Figures \ref{scale_spectargs_Mandz_higherz}, \ref{scale_spectargs_Mandz_lowerz}, and \ref{scale_qso_newMzcompare}.

Our ὃς cuts on the photometric galaxies around the spectroscopic targets as well as around the random positions to which they are compared (as described in Section ??)) allow us to make meaningful comparisons of objects in different

Our $\delta z$ cuts on the photometric galaxies around the spectroscopic targets as well as around the random positions to which they are compared (as described in Section \ref{deltazcutsection}) ) allow us to make meaningful comparisons of objects in different

absorbed mid-IR emissiou re-radiated in the FIR docs not exceed the observed poiuts.

absorbed mid-IR emission re-radiated in the FIR does not exceed the observed points.

If the FIR emission is powered bv the ACN this is UV radiation re-processed by dust.

If the FIR emission is powered by the AGN this is UV radiation re-processed by dust.

However. if the AGN emits —2«JUL. im UV photons. high excitation gas chussiou lines should also be observed.

However, if the AGN emits $\sim 2\xten{10}\Lo$ in UV photons, high excitation gas emission lines should also be observed.

The abseuce of high ionization lines like rur|A5007.LO59A (CMoorwood c al. 1996a})

The absence of high ionization lines like $\lambda 5007,4959$ (Moorwood et al. \cite{moorwood96a}) )

or [NeVJALL3pau (Genzelet al. 1998))

or $\lambda 14.3\MIC$ (Genzel et al. \cite{genzel98}) )

aud the low excitation observed in the wind-blown cone strongly argues that uo ioniziug UV photous (ie. 13.6<hr 00ο) escape frou the inuer region.

and the low excitation observed in the wind-blown cone strongly argues that no ionizing UV photons (i.e. $13.6\le \HNU < 500\EV$ ) escape from the inner region.

The low excitation IT, /Pao map. associated with the peak in IH» cluission close to the nucleus location. indicates that ALL ultraviolet photons must be absorbed within R<175. Le. T?30pe along ALL lines of sight.

The low excitation $_2$ $\alpha$ map, associated with the peak in $_2$ emission close to the nucleus location, indicates that ALL ultraviolet photons must be absorbed within $R<1\farcs5$, i.e. $R<30\PC$ along ALL lines of sight.

This is in contrast with the standard unified model of AGN where ionizing radiation escapes along directions close to the torus axis.

If. the AGNUM is duoenmibedded5B ini a; thickTEM dustydx mediunm then two effects will contribute to its obsewmration.

If the AGN is embedded in a thick dusty medium then two effects will contribute to its obscuration.

First. dust will compete] with the otgas in ‘absorbing© UV. photons which will be directly converted iuto infrared radiation (e.g. Netzer Laor 1993.. Oliva. Marconi AMoorwood 1999a)).

First, dust will compete with the gas in absorbing UV photons which will be directly converted into infrared radiation (e.g. Netzer Laor \cite{netzer93}, Oliva, Marconi Moorwood \cite{oliva99}) ).

Second. emission lines originating πι this. medium. will: be suppressed. by dust absorption.

Second, emission lines originating in this medium will be suppressed by dust absorption.

. To00 ⋅ . ↸∖↴∖↴↑∐⊔⋜↧↑↸∖↑∐↸∖⋜⋯⋯∏∐∪↕↥⋅↸∖≺∣∏∐⋅↸∖≺↸∖⊼↑⋯≼⊳↕∪∐⋅∐∪↑↸∖↑↕⋯↑∐↓↽∙⊽↴∙↴⋅↴∙⋅∙. ⋅∙⋅ ∙ ≼⊲∐⋅↸⊳↕∐∏↴∖↴⊪∖⊽↸∖∖⊳∏↓∙∶≩∕∣⋯⊪∖⊽↸∖∐∫⊔∙≺∖∖∕∣⋯∶∩∙↓≺↸∖↘⊓∐↸⊳↑↕∪∐ coirected) aud iu NGC 1915 0.008 (both ratios are from Cienzel et al. 19908)).

To estimate the amount of required extinction, note that in Circinus $\NeV 14.3\MIC/\NeII 12.8\MIC=0.4$ (extinction corrected) and in NGC 4945 $\le 0.008$ (both ratios are from Genzel et al. \cite{genzel98}) ).

TE NGC1915. has the same iutrinsie ratio as Circinus. then the observed rratiov] requiresui] {οyon)2 L2maeg correspondiug to Ay> LlOmag aud in aereeimeut with the above estimates.

If NGC4945 has the same intrinsic ratio as Circinus, then the observed ratio requires $A(14.3\MIC)>4.2$ mag corresponding to $\AV>110$ mag and in agreement with the above estimates.

We conclude that the ACN can power the FIR cnussion if it is properly obscured.

We conclude that the AGN can power the FIR emission if it is properly obscured.

Inferring the black hole mass from the nunuaser observatious (1.1ον109NI.. Greenhill.

Inferring the black hole mass from the maser observations $1.4\xten{6}\Mo$, Greenhill.

et al. 1997)).

et al. \cite{greenhill}) ),

we find im this scenario that the ACN is eidttine at ~50% of its Eddineton Lumiuosity.

we find in this scenario that the AGN is emitting at $\sim 50\%$ of its Eddington Luminosity.

As discussed above. if an ACN powers the FIR cuission of NGC 1915. it aust be hidden up to midIR wavelengths aud does not fitJ inH the standard uuifedf model.

As discussed above, if an AGN powers the FIR emission of NGC 4945, it must be hidden up to mid-IR wavelengths and does not fit in the standard unified model.

The possible: existence: of: such a class of: Active: Nuelei.-: detectable onlv at >10keV. would have important cousequeuces ou the interpretation of IR huuinous objects whose power source is still debated.

The possible existence of such a class of Active Nuclei, detectable only at $>10\KEV$, would have important consequences on the interpretation of IR luminous objects whose power source is still debated.

Genzel et al. (1998))

Genzel et al. \cite{genzel98}) )

and Lutz et al (1998)

and Lutz et al. \cite{lutz98}) )

compared iiid-IR spectra of Ultra Luninous IRAS ealaxies (ULIRGs. see Sanders Mirabel 1996 for a review) with those of AGN aud starburst templates.

compared mid-IR spectra of Ultra Luminous IRAS galaxies (ULIRGs, see Sanders Mirabel \cite{sanders96} for a review) with those of AGN and starburst templates.

They concluded that the absence of high excitation lines (e.g. [Nev]}) and the presence of PAT features undiluted bv strong thermal coutimmun in CLIRGSs spectra strongly Sugeest that the starburst component is dominaut.

They concluded that the absence of high excitation lines (e.g. ) and the presence of PAH features undiluted by strong thermal continuum in ULIRGs spectra strongly suggest that the starburst component is dominant.

They also show that. after a proper extinction correction. the observed star formation activity can power FIR cussion.

They also show that, after a proper extinction correction, the observed star formation activity can power FIR emission.

In their papers. NCC 11915 is classified as a starburst because of its mid-IR properties but. as shown in the previous. section. NGC 1915. could also be powered by a highly obscured AGN aud the same scenario could iu principle apply to all ULIRGs.

In their papers, NGC 4945 is classified as a starburst because of its mid-IR properties but, as shown in the previous section, NGC 4945 could also be powered by a highly obscured AGN and the same scenario could in principle apply to all ULIRGs.

Their bolometric cussion cau be powered by an active nucleus completely obscured even at mil-IR wavelengths.

Their bolometric emission can be powered by an active nucleus completely obscured even at mid-IR wavelengths.

The same aremnent could be used for the sources detected at submillimeter wavelengths by SCUBA which cai be considered as the high redshift counterpart of local ULIRGs.

The same argument could be used for the sources detected at submillimeter wavelengths by SCUBA which can be considered as the high redshift counterpart of local ULIRGs.

If they are powered by hidden active uuclei then their enormous FIR ciission would uot require star formation rates in excess of >LOOMxr.| (e.g. Hughes et al. 1998)).

If they are powered by hidden active nuclei then their enormous FIR emission would not require star formation rates in excess of $>100\Mo\YR\1$ (e.g. Hughes et al. \cite{hughes98}) ),

and this would have important consequences :for understanding: the history: of. star formationJ: in: hieh: yedshift ealaxies.

and this would have important consequences for understanding the history of star formation in high redshift galaxies.

Iu additiou.⋅⋅ it∙∙ is well known that in⋅ order to explai⋅— he Nav background a huge fraction of obscured ACN0 is required.

In addition, it is well known that in order to explain the X-ray background a large fraction of obscured AGN is required.

However Calli et al. (1999))

However Gilli et al. \cite{gilli99}) )

have shown that. dm order to reconcile the observed Xaay background with ↕⋜⋯∟∖≓⋯⋅↖↸⊳∪∏∐↑↴∖∙⋜⋃⋜∏⋯∐⋅↖↸∖↖∪↕∏∐∶↴∙↻∪↴⋯↕⋜↧↕∪∐∪↕∐⋜⋯↧∙↽∙⊽ ↴ ∙⋅⊽⊽⊽⋅↜ ⋅ ⊳∙ ∙↴⋅⊳ ⊸∖≓⋯⋅↖↴∖≺∏∐∏∖↴∖↕↴∖↥↸∖≺∣∏∐↸∖≼↧∏↻↑∪⊓∖

have shown that, in order to reconcile the observed X-ray background with hard X-ray counts, a rapidly evolving population of hard X-ray sources is required up to redshift $\sim 1.5$.

≼⊔∐⇈∿↓∙⋅⊐∙⋀∖∪↴∖⋯⊳↕ »pulatiou is known at the moment aud the oulv class of objects which are known to undergo such a rapid density evolution are local ULIRGs (iim et al. 1998))

No such population is known at the moment and the only class of objects which are known to undergo such a rapid density evolution are local ULIRGs (Kim et al. \cite{kim98}) )

anc. at higher redshift. the SCUBA sources (Suail ct al. 1997)).

and, at higher redshift, the SCUBA sources (Smail et al. \cite{smail97}) ).