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Open Access
Issue
A&A
Volume 695, March 2025
Article Number A120
Number of page(s) 10
Section Extragalactic astronomy
DOI https://doi.org/10.1051/0004-6361/202451840
Published online 12 March 2025

© The Authors 2025

Licence Creative CommonsOpen Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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1. Introduction

It is now well established that the nuclei of active galaxies, called active galactic nuclei (AGNs), host supermassive black holes (SMBHs) that actively accrete material through a disc and generate electromagnetic radiation (e.g. Rees 1984). Evidence of highly collimated relativistic outflows, or jets, has been detected in a fraction (∼10 − 20%) of AGNs, known as jetted-AGNs, using high-resolution radio imaging and multi-wavelength observations (e.g. Blandford et al. 2019). The formation, acceleration, and collimation of these relativistic jets are still not fully understood. Models available in the literature for jet production assume that they originate in the vicinity of the BHs and extract their power mainly from (a) the BH spin (Blandford & Znajek 1977), and/or (b) the accretion disc (Blandford & Payne 1982). Both of these basic models expect a connection between the relativistic jet and the accretion disc. The disc-jet connection in accreting systems is one of the most important unresolved issues in astrophysics and has been the focus of many studies (e.g. Maraschi & Tavecchio 2003; Livio et al. 2003; Sbarrato et al. 2014; Mukherjee et al. 2019).

Active galactic nuclei that have relativistic jets closely aligned to the observer are known as blazars (e.g. Padovani et al. 2017). Based on the equivalent widths (EWs) of emission lines in their optical spectra, Stocke et al. (1991) classified them as flat spectrum radio quasars (FSRQs; EWrest > 5 Å) and BL Lacertae objects (BLLs; EWrest < 5 Å). The absence of strong emission lines in BLLs could be due to the presence of a radiatively inefficient disc (Ghisellini et al. 2011).

The first identified quasar, 3C 273, is a nearby (z = 0.158; Schmidt 1963) highly luminous FSRQ. It is extremely variable across all the electromagnetic (EM) frequencies (e.g. Soldi et al. 2008); however, unlike most other FSRQs, it shows a low (on average <  1%) degree of optical polarization (Valtaoja et al. 1991; Hutsemékers et al. 2018). Due to its high luminosity and proximity, it has been intensively monitored for flux and spectral variability over the entire (that is, from radio to γ rays) EM spectrum (e.g. Xie et al. 1999; Türler et al. 2000; Sambruna et al. 2001; Kataoka et al. 2002; Fan et al. 2009, 2014; Abdo et al. 2010; Kalita et al. 2015; Madsen et al. 2015; Chidiac et al. 2016; Fernandes et al. 2020).

The submillimetre-to-radio emission of 3C 273 is characterized by strong flux variations that are produced by the synchrotron emission of relativistic electrons within the jet (Türler et al. 2000; Soldi et al. 2008). At optical-to-UV frequencies, a bright excess (blue bump) is usually found that can be interpreted as the contribution from two differently variable components: a blue component and a red component (Paltani et al. 1998). The blue component, which is mostly variable in the UV, can be attributed to thermal emission from the accretion disc, while the red component, which is significantly variable in the IR, could be due to the jet emission (Soldi et al. 2008).

In the X-ray band, a soft excess is commonly observed in the low energy (below ∼2 keV) spectra of 3C 273, which can be explained by the thermal Comptonization of UV disc photons in a hot corona above the disc (Grandi & Palumbo 2004). A correlation between low-energy X-ray and UV emission has been found in a few observations that support the Comptonization scenario (e.g. Walter & Courvoisier 1992; Kalita et al. 2015). However, such a correlation was not detected in certain studies (e.g. Chernyakova et al. 2007; Soldi et al. 2008) that question this interpretation.

The spectra of such ‘jetted’ sources can be described using accretion-disc-jet-based models (Wandel & Urry 1991; Zdziarski & Grandi 2001; Grandi & Palumbo 2004; Mondal et al. 2022a; Das & Chatterjee 2023, and references therein), where UV and X-ray emission might come from the vicinity of the accretion disc. These works found the signature of an accretion disc along with the jet in the X-ray spectra of blazars and FSRQs. As 3C 273 is one such candidate, we attempted to further investigate this possibility by fitting simultaneous broad-band X-ray observations from NuSTAR and XMM-Newton using an accretion-ejection-based two-component advective flow (TCAF; Chakrabarti & Titarchuk 1995) model that has been expanded to include jet emission (JeTCAF; Mondal & Chakrabarti 2021). The JeTCAF model takes into account the radiation mechanisms in the disc, corona, and at the base of the jet or outflows, and the effect of bulk motion by the outflowing jet on the emitted spectra. We note that apart from the base of the jet, the rest of the jet can also contribute to the spectrum. In the present model, the jet is only considered up to the sonic surface. If the inclusion of the rest of the jet does not change the overall spectral shape but only the total flux in X-rays, the present model parameters could fit the contribution from the rest of the jet with some changes in the model normalization. This model has six parameters: (i) The mass of the BH (MBH) if it is unknown; (ii) the Keplerian disc accretion rate (ṁd); (iii) the sub-Keplerian halo accretion rate (ṁh); (iv) the size of the dynamic corona or the location of the shock within the accretion flow (Xs in units of rS = 2GMBH/c2; Chakrabarti 1989; v) the shock compression ratio (R), which is the velocity drop across the shock, and therefore the jump in density there; and (vi) the ratio of the solid angle subtended by the outflow to the inflow, fcol(≡Θo/Θin). The final parameter may depend on the jet properties. However, since we do not know these properties before model fitting, we take it as a user-defined parameter. Since the mass of the BH is also a parameter in this model, we can determine its value from spectral analysis (e.g. Mondal et al. 2022b), as was done using the TCAF model fitting within the standard software package, XSPEC (Debnath et al. 2014; Molla et al. 2017). The spectrum of 3C 273 is complex, including disc and power-law components, soft excess, and a reflection signature. The JeTCAF model incorporates both the corona to disc and disc to corona photon interceptions to iteratively compute the spectrum with a modified disc temperature similar to TCAF. In addition, when Comptonized photons from the corona pass through the jet medium, this produces a Compton hump. The combination of these two processes changes the X-ray spectrum significantly by producing a hump above 10 keV, similar to so-called reflection models. However, the current model does not include emission processes and therefore cannot produce the often-observed iron lines.

The structure of this paper is as follows. In Sect. 2 we describe the observations and data reduction procedure. The results and our discussion of them are presented in Sect. 3. Section 4 presents our conclusions.

2. Observation and data analysis

NuSTAR observed the blazar 3C 273 on 32 occasions between 2012 July 1 and 2024 January 7. In this work, we only selected observations with an exposure time greater than 5 ks. Also, on 2012 July 13, out of the six observations of almost equal exposures (∼6 ks), we only used the observation with the longest exposure time. We were left with a total of 16 observations with an exposure time ranging from 6.23 ks to 243.97 ks that were performed between 2012 July 13 and 2024 January 7. A detailed log of these observations is given in Table A.1.

We downloaded the NuSTAR observations of 3C 273 from the HEASARC data archive1. We followed the standard procedures2 to reduce and analyse the NuSTAR datasets using HEASOFT version 6.29 and CALDB version 20210427. We first generated the calibrated, cleaned, and screened event files using the nupipeline script. The source and background spectra were then extracted from these cleaned event files using the nuproducts script. To extract both source and background spectra, we took circular regions with similar radii (30″). The source region was centred at the source position and the background region was on the same focal plane module but away from the source contamination. We rebinned the NuSTAR spectra using the grppha routine to have at least 25 counts per spectral bin.

Additionally, we searched for 3C 273 data in the XMM-Newton data archive. We found ten XMM-Newton observations of 3C 273 that were simultaneous to the NuSTAR observations, as listed in Table A.1. To reduce the XMM-Newton data of 3C 273, we used the Science Analysis System (SAS v. 21.0.0) and followed the standard procedures3. We limited our analysis to the data from the European Photon Imaging Camera (EPIC) pn detector, which is the most sensitive and least impacted by pile-up effects. We started by reprocessing the observation data files (ODFs) to generate the calibrated and concatenated EPIC pn event lists. We then filtered out the periods of high background flares. We chose a circular region of 40″ centred on the source to extract the X-ray spectrum. A background spectrum was also extracted using a circular region of a similar radius from a source-free region. We checked all the observations for pileup using the task epatplot and corrected the affected observations by removing a region of radius 7.5″ from the core of the source PSF. Finally, we rebinned the X-ray spectra so we had at least 25 counts for each background-subtracted spectral bin.

3. Results and discussion

We first fitted the 0.3–10 keV XMM-Newton spectra of 3C 273 using simple power-law (PL) models with the Galactic absorption component TBABS using XSPEC version v12.11.0. During the fit, we fixed the value of the hydrogen column density to 1.69 × 1020 cm−2 for the Galactic absorption (HI4PI Collaboration 2016). The fits were poor, with χr2 > 10 for all the spectra. We illustrate this by plotting the TBABS(PL) model fit to the data and the ratio of the data/model for each spectrum in Fig. 1. The ratio plots show a clear presence of soft excess below 1.5 keV, which indicates a Seyfert-like feature.

thumbnail Fig. 1.

Sample plots showing TBABS(PL)-fitted 0.3–10 keV spectra of 3C 273 (top panel) and the ratio of data/model (bottom panel). The observation ID is mentioned in each plot. Plots for the remaining XMM-Newton observations are shown in Fig. B.1.

We then fitted joint XMM-Newton and NuSTAR X-ray spectra in the full energy range (0.3–78.0 keV) using the TBABS(DISKBB+PL), model. The fitting results are given in Table 1. The data fitted using this model combination, shown in Fig. 2, returned rather poor fits for all epochs except on MJD 56122. Using the standard relation between DISKBB model normalization and the inner edge of the disc (Rin), one can determine the colour-corrected inner disc radius (Kubota et al. 1998): Rin = [(D/10 kpc)2 Normdiskbb/cos i]1/2κ2 km, where D, i, Normdiskbb, and κ are the source distance, disc inclination, normalization for the DISKBB component, and the colour correction factor, respectively. For the values of D ∼ 750 Mpc and i ∼ 60° (Kriss et al. 1999), MBH ∼ 8 × 108 M⊙ (from this work, see below), κ = 1.6, and the maximum Normdiskbb value (∼3780) estimated on MJD 59036 yield Rin ≲ 1.7 × 106 km ∼ 0.07 rS. Such a low Rin indicates that the inner disc extended well within the innermost stable circular orbit (ISCO), which is non-physical. While we can get estimates of the accretion disc temperature, Tin, and spectral slope of the coronal emission, those quantities are the end product of underlying fundamental physical quantities, that is, the mass accretion rate (Shakura & Sunyaev 1973; Sunyaev & Titarchuk 1980; Chakrabarti & Titarchuk 1995). Since the origin of soft X-ray excess is as yet unclear, we also tested a model with two GAUSSIAN components combined with a PL. However, the fit is still not satisfactory (χr2 > 1.4). The unsatisfactory results of these model fits motivated us to use an accretion-ejection-based JeTCAF model, which was recently developed by Mondal & Chakrabarti (2021).

thumbnail Fig. 2.

Sample plots showing TBABS(DISKBB+PL)-fitted 0.3–78 keV spectra of 3C 273 (top panel) and the ratio of data/model (bottom panel). The observation date (yyyymmdd) is mentioned in each plot. Plots for the remaining simultaneous observations are shown in Fig. C.1.

Table 1.

Best-fitted TBABS(DISKBB+PL) model parameters for all simultaneous XMM-Newton and NuSTAR observations of 3C 273.

We next performed a broad-band (0.3–78.0 keV) X-ray spectral fitting of 3C 273 using simultaneous XMM-Newton and NuSTAR observations with the JeTCAF model. The JeTCAF-model-fitted parameters are shown in Table 2. Along with JeTCAF model, two GAUSSIAN components were also included to take into account the soft excess below the ∼1.5 keV energy range. One component is required between energies 0.2–0.5 keV of width 0.1–0.4 keV and another component at ≲0.1 keV of width ∼0.4 keV. Some representative best fits are shown in Fig. 3. The remaining observations are shown in Fig. D.1. When used in XSPEC, the JeTCAF model incorporates the total spectrum, including all components, to fit the observed data. Consequently, the unfolded spectra do not display individual components. However, in theoretical spectra, the individual components can be separated, as demonstrated by Mondal & Chakrabarti (2021).

thumbnail Fig. 3.

Sample plots showing JeTCAF-model-fitted 0.3–78.0 keV spectra of 3C 273 (top panel) and the ratio of the data/model (bottom panel). The observation date (yyyymmdd) is mentioned in each plot. Best-fit spectra were rebinned for visual clarity. Plots for the remaining observations are shown in Fig. D.1.

Table 2.

Best-fitting TBABS*JeTCAF model parameters for all observations of 3C 273.

The variation in model-fitted parameters with observations is shown in Fig. 4. During the combined model fitting, we used BH mass (MBH) as a parameter and kept it free from epoch to epoch. The MBH parameter varies between (7.2–8.1) × 108 M⊙ and the resulting error-weighted average value is (7.8 ± 0.3) × 108 M⊙.

thumbnail Fig. 4.

Temporal variation of best-fitting JeTCAF model parameters: (a) BH mass, (b) disc accretion rate, (c) halo accretion rate, (d) size of the corona, (e) shock compression ratio, and (f) jet collimation factor.

Different estimates of the BH mass of 3C 273 span a broad range of values that were obtained using various methods. Using the reverberation mapping (RM) technique, Laor (1998) estimated a BH mass of 7.4 × 108 M⊙. Kriss et al. (1999) applied the accretion disc models to broad-band (UV to X-ray) data of 3C 273 to get MBH in a range (7.1–12) × 108 M⊙. Kaspi et al. (2000) calculated a BH mass of 2 . 35 − 0.33 + 0.37 × 10 8 M ⊙ $ 2.35_{-0.33}^{+0.37} \times 10^8\,M_\odot $ from the RMS spectra and 5 . 50 − 0.79 + 0.89 × 10 8 M ⊙ $ 5.50_{-0.79}^{+0.89} \times 10^8\,M_\odot $ from average spectra using RM of Balmer lines. Paltani & Türler (2005) obtained a substantially higher value of M BH = 6 . 6 − 0.9 + 1.6 × 10 9 M ⊙ $ _{\mathrm{BH}}=6.6_{-0.9}^{+1.6} \times 10^9\,M_\odot $ using RM of broad UV (Lyα and C IV) lines. A BH mass of only 2.6 ± 1.1 × 108 M⊙ was measured using the GRAVITY observations (GRAVITY Collaboration 2018). In a recent study, Zhang et al. (2019) estimated a BH mass of 4 . 1 − 0.4 + 0.3 × 10 8 M ⊙ $ 4.1_{-0.4}^{+0.3} \times 10^8\,M_\odot $ using a Hβ RM campaign carried out from 2008 to 2018. Our MBH value lies within this range.

Among the other JeTCAF model parameters, the disc mass accretion rate (ṁd) varies between 0.010 ± 0.002 to 0.022 ± 0.003 ṁEdd, where ṁEdd is the Eddington accretion rate. However, the halo, or sub-Keplerian rate (ṁh), varies between 0.36 ± 0.01 to 0.86 ± 0.06 ṁEdd, with its value always being higher than ṁd. This implies that the spectra are dominated by the hot flow, which indicates that it is hard in nature. As both the mass accretion rates vary from epoch to epoch, the size of the dynamic corona (Xs) also changes significantly from 8.5 ± 1.0 to 28.6 ± 2.4 rS. It is worth noting that, during MJD 57930, both Xs and ṁh were at minima while ṁd was at its maximum. Such a negative correlation is expected in the JeTCAF framework as the increased accretion rate increases the cooling of the corona and therefore the shock moves inwards (Chakrabarti & Titarchuk 1995; Mondal & Chakrabarti 2013).

The shock compression ratio (R), the ratio of the velocity of the flow inside the corona to that outside the corona, also changes significantly, from 1.9 ± 0.2 to 3.8 ± 0.3. The jet collimation factor (fcol) variation ranges from a well-collimated outflow (the lowest value: 0.006) to almost a wind-like outflow (the highest value: 0.35). When ṁd is high and fcol is near a minimum, we can understand why the outflow is weakest: a cooler corona may not have enough pressure to drive the outflow (Chakrabarti 1999).

Overall, the data fitted this model quite well, which returned reduced χ2 ≃ 1 − 1.1 except for MJDs 57216 and 57565. The best JeTCAF model fits to the 0.3–78.0 keV spectra of 3C 273, as well as the ratios of the data/model check use of ‘/’, are shown in Fig. 3. The best-fitted spectra were rebinned for visual clarity, which does not affect the fitted parameters. After achieving the best fit, we estimated the corona flux (Fcorona) and jet flux (Fjet) using the lowest model normalization method (see Jana et al. 2017; Mondal et al. 2022a). The best-fitting model gives the total flux (Ftotal) and, after replacing the best-fitted model norm by the lowest value obtained from MJD 60046 for this source, this gives the Fcorona. Subtracting Fcorona from Ftotal yields Fjet. Therefore, on MJD 60046 there is essentially no jet contribution. On this observation date, the R parameter was maximal (∼5), yielding a much lower outflow rate (which is only a function of R), and therefore a much lower flux, which is consistent with the observed spectrum. All JeTCAF model parameters and their variation with MJD are shown in Fig. 4. We note that the JeTCAF model includes the base of the jet, extending from above the corona up to the sonic surface; however, large-scale highly collimated jets (Marshall et al. 2001) cannot be taken into account using this model. The radius of the sonic surface is estimated using the relation rc = f0Xs/2 (Chakrabarti 1999), where f0 = R2/R − 1, which yields rc ∼ 2.5 × Xs (in rS) for the strong shock case.

In γ-rays, 3C 273 evinces a blazer-like beamed emission component produced by the relativistic jets, so some of the flux is Doppler boosted. Such emission would include photons produced in the jet by the inverse Compton process of thermal and synchrotron X-ray photons from the disc and corona. The present version of the JeTCAF model does not include relativistic beaming effects, and the Fjet is calculated as the total jet flux, which may include contributions from other physical processes. The estimated Fjet is significantly higher than Fcorona in almost all epochs. Grandi & Palumbo (2004) reported quite similar results while comparing the jet flux with the Seyfert (non-jetted) type flux using reflection-based models. Moreover, previous estimates of Fjet in other jetted sources also showed that Fjet is moderately higher or comparable to Fcorona when the jet was active or moderately weak, respectively, using the TCAF model (Jana et al. 2017; Mondal et al. 2022a). However, for the present source, the jet flux was always higher, which could be due to the effect of Doppler boosting. In such a case, the estimated flux can be used as a tool to estimate the Doppler boosting factor δ (as discussed in Britzen et al. 2007; Hovatta et al. 2009). Assuming that the lowest jet flux, which was observed on MJD 59318, is the base flux and any excess above that is due to the Doppler boosting δ4. Then the minimum and maximum δ estimated for MJD 59374 and 57565 are 1.6 and 2.2, respectively. This also explains the anti-correlation between fcol and Fjet. Our estimated δ is in agreement with the lowest limit reported by Abraham & Romero (1999).

As a further consistency check of the analysis method and to verify the jet signature in the observed spectra, we redid the fitting using only the TCAF model. For all epochs where only NuSTAR data are available, TCAF returned good fits that are similar to JeTCAF-model-fitted statistics. The joint broad-band spectral fitting with TCAF along with GAUSSIAN components for soft-excess also returns satisfactory fits, although with marginally higher fit statistics compared to the JeTCAF, Δχr2 ≳ 0.1. The improvement in fit statistics is due to the presence of two additional components in JeTCAF: (1) some excess at the shoulder of the blackbody (∼2 − 5 keV); and (2) excess above ∼50 keV. Keeping in mind that 3C 273 is a ‘jetted source’, we compared the parameters of both models and find that the TCAF model fits require a higher ṁd and R for all epochs. Noticeably, the R values obtained from TCAF fits are high, falling in the > 4 range. However, in the TCAF scenario, jets or outflows are significant and are launched for intermediate values of R (∼2 − 3; Chakrabarti 1999) and when the disc accretion rate is low. These are closely consistent with JeTCAF- model-fitted parameters. The ṁh and Xs obtained from both models are nearly similar. This comparison shows that the contribution of the jet to the observed spectra is robust in the model fitting.

4. Conclusions

The extremely bright nearby quasar 3C 273 has shown properties typical of both jetted-AGNs and Seyfert galaxies, which makes it a perfect source for examining the disc-jet interactions in AGNs. In this work, we fitted the broad-band (0.3–78.0 keV) X-ray data of 3C 273 from XMM-Newton and NuSTAR using combined accretion-ejection and jet-based models. We summarize the main findings of our investigation below:

  • A simple PL fit left significant X-ray excess at energies below ∼1.5 keV, which suggests emission from the accretion disc-corona system.

  • The accretion disc model that was added to the PL did not yield an acceptable fit.

  • The accretion-ejection-based JeTCAF model provided the best fits along with sensible accretion flow parameters.

  • The value of the model parameter MBH remains consistent for all the observations. The weighted-mean value of MBH is (7.77 ± 0.30) × 108 M⊙, which falls in the range of MBH values estimated using RM and other accretion-based models in the literature.

  • A broad range in the fcol parameter indicates the presence of both collimated and wind-like outflows from the system.

  • For all observations ṁh>ṁd and Xs were relatively high, a combination associated with the hard spectra from the corona region, and consistent with the PL-model-fitted Γ, < 1.8.

  • If the estimated jet flux is used to estimate the Doppler boosting factor, we obtain values between 1.6–2.2, which are consistent with the lowest value found in the literature.

Acknowledgments

We sincerely thank the referee for their insightful comments and suggestions. The project was partially supported by the Polish Funding Agency National Science Centre, project 2017/26/A/ST9/00756 (MAESTRO 9). AP acknowledges funding from the Chinese Academy of Sciences President’s International Fellowship Initiative (PIFI), Grant No. 2024PVC0088. SM acknowledges the Ramanujan Fellowship (RJF/2020/000113) by DST-SERB, Govt. of India for this research.

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Appendix A: Observation log

Table A.1.

Log of simultaneous NuSTAR and XMM-Newton observations.

Appendix B: Plots showing PL fitting to 0.3-10 keV spectra of 3C 373

thumbnail Fig. B.1.

Simple PL fitted 0.3-10 keV spectra of 3C 273. The ratio of data/model is plotted in the bottom portion of each panel.

thumbnail Fig. B.1.

Continued.

Appendix C: Plots showing TBABS(DISKBB+PL) fitting to 0.3-78 keV spectra of 3C 273

thumbnail Fig. C.1.

TBABS(DISKBB+PL) model fitted 0.3-78 keV spectra of 3C 273. The ratio of data/model is plotted in the bottom portion of each panel.

thumbnail Fig. C.1.

Continued.

Appendix D: Plots showing the JeTCAF model fitted 0.3-78.0 keV spectra of 3C 273

thumbnail Fig. D.1.

JeTCAF model fitted 0.3−78.0 keV spectra of 3C 273. The ratio of data/model is plotted in the bottom portion of each panel.

thumbnail Fig. D.1.

Continued.

All Tables

Table 1.

Best-fitted TBABS(DISKBB+PL) model parameters for all simultaneous XMM-Newton and NuSTAR observations of 3C 273.

In the text
Table 2.

Best-fitting TBABS*JeTCAF model parameters for all observations of 3C 273.

In the text
Table A.1.

Log of simultaneous NuSTAR and XMM-Newton observations.

In the text

All Figures

thumbnail Fig. 1.

Sample plots showing TBABS(PL)-fitted 0.3–10 keV spectra of 3C 273 (top panel) and the ratio of data/model (bottom panel). The observation ID is mentioned in each plot. Plots for the remaining XMM-Newton observations are shown in Fig. B.1.
In the text
thumbnail Fig. 2.

Sample plots showing TBABS(DISKBB+PL)-fitted 0.3–78 keV spectra of 3C 273 (top panel) and the ratio of data/model (bottom panel). The observation date (yyyymmdd) is mentioned in each plot. Plots for the remaining simultaneous observations are shown in Fig. C.1.
In the text
thumbnail Fig. 3.

Sample plots showing JeTCAF-model-fitted 0.3–78.0 keV spectra of 3C 273 (top panel) and the ratio of the data/model (bottom panel). The observation date (yyyymmdd) is mentioned in each plot. Best-fit spectra were rebinned for visual clarity. Plots for the remaining observations are shown in Fig. D.1.
In the text
thumbnail Fig. 4.

Temporal variation of best-fitting JeTCAF model parameters: (a) BH mass, (b) disc accretion rate, (c) halo accretion rate, (d) size of the corona, (e) shock compression ratio, and (f) jet collimation factor.
In the text
thumbnail Fig. B.1.

Simple PL fitted 0.3-10 keV spectra of 3C 273. The ratio of data/model is plotted in the bottom portion of each panel.
In the text
thumbnail Fig. B.1.

Continued.
In the text
thumbnail Fig. C.1.

TBABS(DISKBB+PL) model fitted 0.3-78 keV spectra of 3C 273. The ratio of data/model is plotted in the bottom portion of each panel.
In the text
thumbnail Fig. C.1.

Continued.
In the text
thumbnail Fig. D.1.

JeTCAF model fitted 0.3−78.0 keV spectra of 3C 273. The ratio of data/model is plotted in the bottom portion of each panel.
In the text
thumbnail Fig. D.1.

Continued.
In the text

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