arXiv subjects

Brian Punsly

Publications and source records attributed to Brian Punsly.

At least 37 records · Page 2Linked to original sources

arXiv2018

A New Solution to the Plasma Starved Event Horizon Magnetosphere: Application to the Forked Jet in M87

Very Long Baseline Interferometry observations at 86 GHz reveal an almost hollow jet in M87 with a forked morphology. The detailed analysis presented here indicates that the spectral luminosity of the central spine of the jet in M87 is a few percent of that of the surrounding hollow jet $200 -400 μ\rm{as}$ from the central black hole. Furthermore, recent jet models in indicate that a hollow "tubular" jet can explain a wide range of plausible broadband spectra originating from jetted plasma located within $\sim 30μ\rm{as}$ of the central black hole, including the 230 GHz correlated flux detected by the Event Horizon Telescope. Most importantly, these hollow jets from the inner accretion flow have an intrinsic power capable of energizing the global jet out to kiloparsec scales. Thus motivated, this paper considers new models of the event horizon magnetosphere (EHM) in low luminosity accretion systems. Contrary to some models, the spine is not an invisible powerful jet. It is an intrinsically weak jet. In the new EHM solution, the accreted poloidal magnetic flux is weak and the background photon field is weak. It is shown how this accretion scenario naturally results in the dissipation of the accreted poloidal magnetic flux in the EHM not the accumulation of poloidal flux required for a powerful jet. The new solution indicates less large scale poloidal magnetic flux (and jet power) in the EHM than in the surrounding accretion flow and cannot support significant EHM driven jets.

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arXiv2017

A Jet Source of Event Horizon Telescope Correlated Flux in M87

Event Horizon Telescope (EHT) observations at 230 GHz are combined with Very Long Baseline Interferometry (VLBI) observations at 86 GHz and high resolution Hubble Space Telescope optical observations in order to constrain the broadband spectrum of the emission from the base of the jet in M87. The recent VLBI observations of Hada et al provide much stricter limits on the 86 GHz luminosity and component acceleration in the jet base than was available to previous modelers. They reveal an almost hollow jet on sub-mas scales. Thus, tubular models of the jet base emanating from the innermost accretion disk are considered within the region responsible for the EHT correlated flux. There is substantial synchrotron self absorbed opacity at 86 GHz. A parametric analysis indicates that the jet dimensions and power depend strongly on the 86 GHz flux density and the black hole spin, but weakly on other parameters such as jet speed, 230 GHz flux density and optical flux. The entire power budget of the M87 jet, $\lesssim 10^{44}\rm{ergs/sec}$, can be accommodated by the tubular jet. No invisible, powerful spine is required. Even though this analysis never employs the resolution of the EHT, the spectral shape implies a dimension transverse to the jet direction of 12-21 $μ\rm{as}$ ($\sim$24-27$\, μ\rm{as}$) for $0.99 > a/M > 0.95$ ($a/M\sim 0.7 $), where $M$ is the mass and $a$ is the angular momentum per unit mass of the central black hole.

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arXiv2017

The Kinetically Dominated Quasar 3C~418

The existence of quasars that are kinetically dominated, where the jet kinetic luminosity, $Q$, is larger than the total (IR to X-ray) thermal luminosity of the accretion flow, $L_{\rm{bol}}$, provides a strong constraint on the fundamental physics of relativistic jet formation. Since quasars have high values of $L_{\rm{bol}}$ by definition, only $\sim 10$ kinetically dominated quasars (with $\overline{Q}/L_{\rm{bol}}>1$) have been found, where $\overline{Q}$ is the long term time averaged jet power. We use low frequency (151 MHz$-$1.66 GHz) observations of the quasar 3C\,418 to determine $\overline{Q}\approx 5.5 \pm 1.3 \times 10^{46} \rm{ergs~s^{-1}}$. Analysis of the rest frame ultraviolet spectrum indicates that this equates to $0.57 \pm 0.28$ times the Eddington luminosity of the central supermassive black hole and $\overline{Q}/L_{\rm{bol}} \approx 4.8 \pm 3.1$, making 3C\,418 one of the most kinetically dominated quasars found to date. It is shown that this maximal $\overline{Q}/L_{\rm{bol}}$ is consistent with models of magnetically arrested accretion of jet production in which the jet production reproduces the observed trend of a decrement in the extreme ultraviolet continuum as the jet power increases. This maximal condition corresponds to an almost complete saturation of the inner accretion flow with vertical large scale magnetic flux (maximum saturation).

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arXiv2017

The Relativistic Jet-Accretion Flow-Wind Connection in Mrk\,231

Long term radio monitoring of the broad absorption line quasar, Mrk\,231, at 17.6~GHz detected a strong flare in 2015. This triggered four epochs of Very Long Baseline Array (VLBA) observations from 8.4 GHz to 43 GHz as well as three epochs of X-ray observations with NuSTAR and two with XMM over a 15 week period. Two ejected components were detected by the VLBA observations. A conservative lower bound on the apparent speed of the first ejection is attained by assuming that it was ejected when the flare began, $v_{\rm{app}}>3.15$c. Serendipitous far UV Hubble Space Telescope observations combined with our long term radio monitoring seem to indicate that episodes of relativistic ejections suppress flux that is emitted at wavelengths shortward of the peak of the far UV spectral energy distribution, similar to what has been observed in radio loud quasars. Episodes of strong jet production also seem to suppress the high ionization broad absorption line wind seen in weak jet states. We found a statistically significant increase ($\sim 25\%$) of the 3-12 keV flux during the radio flare relative to a quiescent radio state. This is explained by an ultra-fast ($\sim 0.06$c) X-ray absorbing photo-ionized wind that is significantly detected only in the low radio state (similar to Galactic black holes). Mrk~231 is becoming more radio loud. We found that the putative parsec scale radio lobe doubled in brightness in 9 years. Furthermore, large flares are more frequent with 3 major flares occurring at $\sim 2$ year intervals.

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arXiv2016

The Detection of Diffuse Extended Structure in 3C~273: Implications for Jet Power

We present deep Very Large Array imaging of 3C~273 in order to determine the diffuse, large scale radio structure of this famous radio-loud quasar. Diffuse extended structure (radio lobes) is detected for the first time in these observations as a consequence of high dynamic range in the 327.5 and 1365 MHz images. This emission is used to estimate a time averaged jet power, $7.2 \times 10^{43} \rm{~ergs~s^{-1}} < \overline{Q} < 3.7 \times 10^{44} \rm{~ergs~s^{-1}}$. Brightness temperature arguments indicate consistent values of the time variability Doppler factor and the compactness Doppler factor for the inner jet, $δ\gtrsim 10$. Thus, the large apparent broadband bolometric luminosity of the jet, $\sim 3 \times 10^{46}\rm{~ergs~s^{-1}}$, corresponds to a modest intrinsic luminosity $\gtrsim 10^{42}\rm{~ergs~s^{-1}}$, or $\sim 1\%$ of $\overline{Q}$. In summary, we find that 3C~273 is actually a "typical" radio loud quasar contrary to suggestions in the literature. The modest $\overline{Q}$ is near the peak of the luminosity distribution for radio loud quasars and it is consistent with the current rate of dissipation emitted from millimeter wavelengths to gamma rays. The extreme core-jet morphology is an illusion from a near pole-on line of sight to a highly relativistic jet that produces a Doppler enhanced glow that previously swamped the lobe emission. 3C~273 apparently has the intrinsic kpc scale morphology of a classical double radio source, but it is distorted by an extreme Doppler aberration.

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arXiv2016

Riemann Solvers and Alfven Waves in Black Hole Magnetospheres

In the magnetosphere of a rotating black hole, an inner Alfven critical surface (IACS) must be crossed by inflowing plasma. Inside the IACS, Alfven waves are inward directed toward the black hole. The majority of the proper volume of the active region of spacetime (the ergosphere) is inside of the IACS. The charge and the totally transverse momentum flux (the momentum flux transverse to both the wave normal and the unperturbed magnetic field) are both determined exclusively by the Alfven polarization. Thus, it is important for numerical simulations of black hole magnetospheres to minimize the dissipation of Alfven waves. Elements of the dissipated wave emerge in adjacent cells regardless of the IACS, there is no mechanism to prevent Alfvenic information from crossing outward. Thus, numerical dissipation can affect how simulated magnetospheres attain the substantial Goldreich-Julian charge density associated with the rotating magnetic field. In order to help minimize dissipation of Alfven waves in relativistic numerical simulations we have formulated a one-dimensional Riemann solver, called HLLI, which incorporates the Alfven discontinuity and the contact discontinuity. We have also formulated a multidimensional Riemann solver, called MuSIC, that enables low dissipation propagation of Alfven waves in multiple dimensions. The importance of higher order schemes in lowering the numerical dissipation of Alfven waves is also catalogued.

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arXiv2016

The Extreme Ultraviolet Variability of Quasars

We study the extreme ultraviolet (EUV) variability (rest frame wavelengths 500 - 920 $Å$) of high luminosity quasars using HST (low to intermediate redshift sample) and SDSS (high redshift sample) archives. The combined HST and SDSS data indicates a much more pronounced variability when the sampling time between observations in the quasar rest frame is $> 2\times 10^{7}$ sec compared to $< 1.5\times 10^{7}$ sec. Based on an excess variance analysis, for time intervals $< 2\times 10^{7}$ sec in the quasar rest frame, $10\%$ of the quasars (4/40) show evidence of EUV variability. Similarly, for time intervals $>2\times 10^{7}$ sec in the quasar rest frame, $55\%$ of the quasars (21/38) show evidence of EUV variability. The propensity for variability does not show any statistically significant change between $2.5\times 10^{7}$ sec and $3.16\times 10^{7}$ sec (1 yr). The temporal behavior is one of a threshold time interval for significant variability as opposed to a gradual increase on these time scales. A threshold time scale can indicate a characteristic spatial dimension of the EUV region. We explore this concept in the context of the slim disk models of accretion. We find that for rapidly spinning black holes, the radial infall time to the plunge region of the optically thin surface layer of the slim disk that is responsible for the preponderance of the EUV flux emission (primarily within 0 - 7 black hole radii from the inner edge of the disk) is consistent with the empirically determined variability time scale.

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arXiv2016

The Accretion Flow - Discrete Ejection Connection in GRS 1915+105

The microquasar GRS~1915+105 is known for its spectacular discrete ejections. They occur unexpectedly, thus their inception escapes direct observation. It has been shown that the X-ray flux increases in the hours leading up to a major ejection. In this article, we consider the serendipitous interferometric monitoring of a modest version of a discrete ejection described in Reid et al. (2014) that would have otherwise escaped detection in daily radio light curves. The observation begins $\sim 1$ hour after the onset of the ejection, providing unprecedented accuracy on the estimate of the ejection time. The astrometric measurements allow us to determine the time of ejection as $\rm{MJD}\, 56436.274^{+0.016}_{-0.013}$, i.e., within a precision of 41 minutes (95\% confidence). Just like larger flares, we find that the X-ray luminosity increases in last 2 - 4 hours preceding ejection. Our finite temporal resolution indicates that this elevated X-ray flux persists within $21.8^{+22.6}_{-19.1}$ minutes of the ejection with 95\% confidence, the highest temporal precision of the X-ray - superluminal ejection connection to date. This observation provides direct evidence that the physics that launches major flares occurs on smaller scales as well (lower radio flux and shorter ejection episodes). The observation of a X-ray spike prior to a discrete ejection, although of very modest amplitude suggests that the process linking accretion behavior to ejection is general from the smallest scales to high luminosity major superluminal flares.

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arXiv2016

The Extreme Ultraviolet Spectra of Low Redshift Radio Loud Quasars

This paper reports on the extreme ultraviolet (EUV) spectrum of three low redshift ($z \sim 0.6$) radio loud quasars, 3C 95, 3C 57 and PKS 0405-123. The spectra were obtained with the Cosmic Origins Spectrograph (COS) of the Hubble Space Telescope. The bolometric thermal emission, $L_{bol}$, associated with the accretion flow is a large fraction of the Eddington limit for all of these sources. We estimate the long term time averaged jet power, $\overline{Q}$, for the three sources. $\overline{Q}/L_{bol}$, is shown to lie along the correlation of $\overline{Q}/L_{bol}$ and $α_{EUV}$ found in previous studies of the EUV continuum of intermediate and high redshift quasars, where the EUV continuum flux density between 1100 Å\, and 700 Å\, is defined by $F_ν \sim ν^{-α_{EUV}}$. The high Eddington ratios of the three quasars extends the analysis into a wider parameter space. Selecting quasars with high Eddington ratios has accentuated the statistical significance of the partial correlation analysis of the data. Namely. the correlation of $\overline{Q}/L_{\mathrm{bol}}$ and $α_{EUV}$ is fundamental and the correlation of $\overline{Q}$ and $α_{EUV}$ is spurious at a very high statistical significance level (99.8\%). This supports the regulating role of ram pressure of the accretion flow in magnetically arrested accretion models of jet production. In the process of this study, we use multi-frequency and multi-resolution Very Large Array radio observations to determine that one of the bipolar jets in 3C 57 is likely frustrated by galactic gas that keeps the jet from propagating outside the host galaxy.

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arXiv2016

General Relativistic Considerations of the Field Shedding Model of Fast Radio Bursts

Popular models of fast radio bursts (FRBs) involve the gravitational collapse of neutron star progenitors to black holes. It has been proposed that the shedding of the strong neutron star magnetic field ($B$) during the collapse is the power source for the radio emission. Previously, these models have utilized the simplicity of the Schwarzschild metric which has the restriction that the magnetic flux is magnetic "hair" that must be shed before final collapse. But, neutron stars have angular momentum and charge and a fully relativistic Kerr Newman solution exists in which $B$ has its source inside of the event horizon. In this letter, we consider the magnetic flux to be shed as a consequence of the electric discharge of a metastable collapsed state of a Kerr Newman black hole. It has also been argued that the shedding model will not operate due to pair creation. By considering the pulsar death line, we find that for a neutron star with $B = 10^{11} - 10^{13}$ G and a long rotation period, $>1$ s this is not a concern. We also discuss the observational evidence supporting the plausibility of magnetic flux shedding models of FRBs that are spawned from rapidly rotating progenitors.

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arXiv2016

A Temporal Analysis Indicates a Mildly Relativistic Compact Jet in GRS~1915+105

Most of our knowledge of the radio morphology and kinematics of X-ray binary partially synchrotron self-absorbed compact jets (hereafter compact jets) is based on the observations of GRS~1915+105 which has the most prominent compact jet. Yet, the compact jet bulk velocity, $v$, is poorly constrained in the literature, $0.07 < v/c < 0.98$. In spite of this uncertainty, compact jets are often unified with relativistic jets in active galactic nuclei. We have estimated $v$ as part of a temporal analysis of GRS~1915+105 jets in "high plateau states" (HPS). We define the HPS as a state showing a hard X-ray spectrum and low level of long-term ($>10$s) X-ray activity associated with 15 GHz flux density $>70$ mJy for $>7$ consecutive days. The radio emission is associated with compact jet emission. Two HPS were monitored at 15 GHz during their termination with e-folding times of 3.8 hrs and 8.6 hrs. We combine this time scale with the scale of spatial variation of the linear source of a VLBA image preceding the fade of one of these HPS in order to estimate the jet speed. Our assumption that the reduction in radio emissivity propagates as an approximate discontinuity down the HPS jet (leaving a weak jet in its wake) indicates $0.17 <v/c< 0.43$. This agrees closely with the only other existing $v$ estimates that are derived directly from radio images, jet asymmetry produced by Doppler enhancement.

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arXiv2015

The Extreme Ultraviolet Deficit - Jet Connection in the Quasar 1442+101

In previous studies, it has been shown that the long term time average jet power, $\overline{Q}$, is correlated with the spectral index in the extreme ultraviolet (EUV), $α_{EUV}$ (defined by $F_ν \sim ν^{-α_{EUV}}$ computed between 700Å\, and 1100Å\,). Larger $\overline{Q}$ tends to decrease the EUV emission. This is a curious relationship because it connects a long term average over $\sim 10^{6}$ years with an instantaneous measurement of the EUV. The EUV appears to be emitted adjacent to the central supermassive black hole and the most straightforward explanation of the correlation is that the EUV emitting region interacts in real time with the jet launching mechanism. Alternatively stated, the $\overline{Q}$ - $α_{EUV}$ correlation is a manifestation of a contemporaneous (real time) jet power, $Q(t)$, correlation with $α_{EUV}$. In order to explore this possibility, this paper considers the time variability of the strong radio jet of the quasar 1442+101 that is not aberrated by strong Doppler enhancement. This high redshift (z = 3.55) quasar is uniquely suited for this endeavor as the EUV is redshifted into the optical observing window allowing for convenient monitoring. More importantly, it is bright enough to be seen through the Lyman forest and its radio flux is strong enough that it has been monitored frequently. Quasi-simultaneous monitoring (five epochs spanning $\sim 40$ years) show that increases in $Q(t)$ correspond to decreases in the EUV as expected.

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arXiv2015

The Extreme Ultraviolet Spectrum of the Kinetically Dominated Quasar 3C 270.1

Only a handful of quasars have been identified as kinetically dominated, their long term time averaged jet power, $\overline{Q}$, exceeds the bolometric thermal emission, $L_{bol}$, associated with the accretion flow. This letter presents the first extreme ultraviolet (EUV) spectrum of a kinetically dominated quasar, 3C 270.1. The EUV continuum flux density of 3C 270.1 is very steep, $F_ν \sim ν^{-α_{EUV}}$, $α_{EUV} =2.98\pm 0.15$. This value is consistent with the correlation of $\overline{Q}/L_{bol}$ and $α_{EUV}$ found in previous studies of the EUV continuum of quasars, the EUV deficit of radio loud quasars. Curiously, although ultraviolet broad absorption line (BAL) troughs in quasar spectra are anti-correlated with $\overline{Q}$, 3C 270.1 has been considered a BAL quasar based on an SDSS spectrum. This claim is examined in terms of the EUV spectrum of OVI 1and the highest resolution CIV spectrum in the archival data and the SDSS spectrum. First, from [OIII]4959,5007 (IR) observations and the UV spectral lines, it is concluded that the correct redshift for 3C 270.1 is 1.5266. It is then found that the standard measure of broad absorption, BALnicity = 0, for MgII 2800, CIV 1549 and OVI 1032 in all epochs.

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arXiv2015

Evidence of the Dynamics of Relativistic Jet Launching in Quasars

Hubble Space Telescope (HST) spectra of the extreme ultraviolet (EUV), the optically thick emission from the innermost accretion flow onto the central supermassive black hole, indicate that RLQs tend to be EUV weak compared to the radio quiet quasars (RQQs); yet the remainder of the optically thick thermal continuum is indistinguishable. The deficit of EUV emission in RLQs has a straightforward interpretation as a missing or a suppressed innermost region of local energy dissipation in the accretion flow. This article is an examination of the evidence for a distribution of magnetic flux tubes in the innermost accretion flow that results in magnetically arrested accretion (MAA) and creates the EUV deficit. These same flux tubes and possibly the interior magnetic flux that they encircle are the source of the jet power as well. In the MAA scenario, islands of large scale magnetic vertical flux perforate the innermost accretion flow of RLQs. The first prediction of the theory that is supported by the HST data is that the strength of the (large scale poloidal magnetic fields) jets in the MAA region is regulated by the ram pressure of the accretion flow in the quasar environment. The second prediction that is supported by the HST data is that the rotating magnetic islands remove energy from the accretion flow as a Poynting flux dominated jet in proportion to the square of the fraction of the EUV emitting gas that is displaced by these islands.

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arXiv2014

The Extreme Ultraviolet Deficit and Magnetically Arrested Accretion in Radio Loud Quasars

The Hubble Space Telescope composite quasar spectra presented in Telfer et al. show a significant deficit of emission in the extreme ultraviolet (EUV) for the radio loud component of the quasar population (RLQs), compared to the radio quiet component of the quasar population (RQQs). The composite quasar continuum emission between 1100 Å\, and $\sim$580 Å\, is generally considered to be associated with the innermost regions of the accretion flow onto the central black hole. The deficit between 1100 Å\, and 580 Å\, in RLQs has a straightforward interpretation as a missing or a suppressed innermost region of local energy dissipation in the accretion flow. It is proposed that this can be the result of islands of large scale magnetic flux in RLQs that are located close to the central black hole that remove energy from the accretion flow as Poynting flux (sometimes called magnetically arrested accretion). These magnetic islands are natural sites for launching relativistic jets. Based on the Telfer et al. data and the numerical simulations of accretion flows in Penna et al., the magnetic islands are concentrated between the event horizon and an outer boundary of $<2.8 M$ (in geometrized units) for rapidly rotating black holes and $< 5.5M$ for modestly rotating black holes.

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arXiv2014

Evidence of Elevated X-Ray Absorption Before and During Major Flare Ejections in GRS 1915+105

We present time resolved X-ray spectroscopy of the microquasar GRS1915+105 with the MAXI observatory in order to study the accretion state just before and during the ejections associated with its major flares. Radio monitoring with the RATAN-600 radio telescope from 4.8 - 11.2 GHz has revealed two large steep spectrum major flares in the first eight months of 2013. Since, the RATAN receives one measurement per day, we cannot determine the jet forming time without more information. Fortunately, this is possible since a distinct X-ray light curve signature that occurs preceding and during major ejections has been determined in an earlier study. The X-ray luminosity spikes to very high levels in the hours before ejection then becomes variable (with a nearly equal X-ray luminosity when averaged over the duration of the ejection) during a brief 3 to 8 hour ejection process. By comparing this X-ray behavior to MAXI light curves, we can estimate the beginning and end of the ejection episode of the strong 2013 flares to within $\sim$3 hours. Using this estimate in conjunction with time resolved spectroscopy from the data in the MAXI archives allows us to deduce that the X-ray absorbing hydrogen column density increases significantly in the hours preceding the ejections and remains elevated during the ejections responsible for the major flares. This finding is consistent with an out-flowing wind or enhanced accretion at high latitudes.

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arXiv2013

A Blazar-Like Radio Flare in Mrk 231

Radio monitoring of the broad absorption line quasar (BALQSO) Mrk 231 from 13.9 GHz to 17.6 GHz detected a strong flat spectrum flare. Even though BALQSOs are typically weak radio sources, the 17.6 GHz flux density doubled in ~150 days, from ~135 mJy to ~270 mJy. It is demonstrated that the elapsed rise time in the quasar rest frame and the relative magnitude of the flare is typical of some of the stronger flares in blazars that are associated with the ejection of discrete components on parsec scales. The decay of a similar flare was found in a previous monitoring campaign at 22 GHz. We conclude that these flares are not rare and indicate the likely ejection of a new radio component that can be resolved from the core with Very Long Baseline Interferometry. The implication is that Mrk 231 seems to be a quasar in which the physical mechanism that produces the BAL wind is in tension with the emergence of a fledgling blazar.

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arXiv2013

Calibrated Estimates of the Energy in Major Flares of GRS 1915+105

We analyze the energetics of the major radio flare of October 8 2005 in GRS 1915+105. The flare is of particular interest because it is one of the most luminous and energetic radio flares from a Galactic black hole that has ever been observed. The motivation is two-fold. One, to learn more about the energetics of this most extreme phenomenon and its relationship to the accretion state. The second is to verify if the calibrated estimates of the energy of major radio flares (based on the peak low frequency optically thin flux) derived from flares in the period 1996-2001 in Punsly & Rodriguez (2013), PR13 hereafter, can be used to estimate plasmoid energy beyond this time period. We find evidence that the calibrated curves are still accurate for this strong flare. Furthermore, the physically important findings of PR13 are supported by the inclusion of this flare: the flare energy is correlated with both the intrinsic bolometric X-ray luminosity, $L_{\mathrm{bol}}$, $\sim 1$ hour before ejection and $L_{\mathrm{bol}}$ averaged over the duration of the ejection of the plasmoid and $L_{\mathrm{bol}}$ is highly elevated relative to historic levels just before and during the ejection episode. A search of the data archives reveal that only the October 8 2005 flare and those in PR13 have adequate data sampling to allow estimates of both the energy of the flare and the X-ray luminosity before and during flare launch.

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