HEASARC Staff Scientist Position - Applications are now being accepted for a Staff Scientist with significant experience and interest in the technical aspects of astrophysics research, to work in the High Energy Astrophysics Science Archive Research Center (HEASARC) at NASA Goddard Space Flight Center (GSFC) in Greenbelt, MD. Refer to the AAS Job register for full details.
Proposal Number: 16500286 PI Last Name: Halpern Title: The Energetic Magnetar in HESS J1713-381/CTB 37B Abstract: The spin-down power of the 3.82 s AXP in the SNR CTB 37B is among the largest of magnetars, and it may be the youngest one as well. We propose to continue to monitor its spin-down rate, which varies by a factor of 2. Magnetars with the largest spin-down power are SGRs, and a marked increase in their spin-down torque often precedes an outburst. In this regard, CXOU J171405.7-381031 is very similar to SGR/AXP 1E 1547.0-5408, the magnetar with the largest spin-down power. By analogy with 1E 1547.0-5408, we may be observing the behavior of an SGR before its outburst. The pulse profiles show a change in shape above 8 keV, which suggests that a separate high-energy spectral component is present. We will examine the high-energy spectrum and pulse with NuSTAR.
Proposal Number: 16400577 PI Last Name: Neilsen Title: An Integrated Approach to Winds, Jets, and State Transitions Abstract: We propose a large multiwavelength campaign (120 ks Chandra HETGS, NuSTAR, INTEGRAL, JVLA/ATCA, Swift) on a black hole transient to study the influence of ionized winds on relativistic jets and state transitions. With a reimagined observing strategy based on new results on integrated RMS variability and a decade of radio/X-ray monitoring, we will search for winds before the state transition to test their influence on and track their coevolution with the disk and the jet over the next ~2 months.
Proposal Number: 17200180 PI Last Name: Guenther Title: How hot can flares from young stars be? Abstract: The most energetic events on cool stars are coronal flares. There is initial evidence that flares on pre-main sequence stars differ from their main-sequence counterparts. As the hard X-rays generated in rare, but energetic flares can penetrate deep into the circumstellar disk, they strongly influence the disk chemistry with decisive consequences for star formation. Thus, we need an accurate and complete census of flare rates and flare energies from young stars. We propose 90 ks of simultaneous Chandra and NuStar observations of the Orion Nebular Cloud (ONC). NuStar allows us to directly measure the high energy tail of the flare distribution above 10 keV, while Chandra will resolve the sources in the dense core of the ONC to pin-point the origin of the flares.
Proposal Number: 17400281 PI Last Name: Neilsen Title: An Integrated Approach to Winds, Jets, and State Transitions Abstract: We propose a large multiwavelength campaign (120 ks Chandra HETGS, NuSTAR, INTEGRAL, JVLA/ATCA, Swift) on a black hole transient to study the influence of ionized winds on relativistic jets and state transitions. With a reimagined observing strategy based on new results on integrated RMS variability and a decade of radio/X-ray monitoring, we will search for winds before the state transition to test their influence on and track their coevolution with the disk and the jet over the next ~2 months.
Proposal Number: 17400584 PI Last Name: Reynolds Title: Accretion Disk Winds in the Presence of a Neutron Star with a 1e12 G Magnetic Field Abstract: We propose to obtain a 30 ks Chandra/HETGS and quasi-simultaneous 20 ks NuSTAR ToO observation of the next bright outburst from the Be/X-ray binary 1A0535+262. We will trigger the proposed observation when the source is at a luminosity in excess of 10% Eddington to further constrain the high velocity wind in this source and to probe accretion, at large fractions of the Eddington luminosity, onto the accreting pulsar with the largest known magnetic field (4e12 G). The NuSTAR high energy data will provide constraints on the broadband spectrum, and will accurately constrain the cyclotron line energy at the highest luminosity observed to date and place constraints on the geometry of the accretion column onto the neutron star at high Eddington fractions.
Proposal Number: 17500487 PI Last Name: Kaspi Title: Target-of-Oppurtunity Chandra Observations of Magnetars in Outburst Abstract: Magnetars are highly magnetized young neutron stars that are powered by the decay of their enormous magnetic fields. Magnetars exhibit dramatic variability including major outbursts -- a hallmark of their emission. These outbursts allow us to probe the extreme physics at work in the Universe's largest known magnetic fields. Understanding the evolution of these outbursts will place stringent constraints on physical models of magnetars, including their crusts, cores, atmospheres, coronae, and magnetospheres. In this proposal, we request Chandra and NuSTAR Target-of-Opportunity observations of a major magnetar outburst in AO17 in order to put detailed physical models to the test, and as an anchor for multiwavelength follow-up.
Proposal Number: 17700582 PI Last Name: Brenneman Title: A Long Look at NGC 3783 with Chandra/HETG and NuSTAR Abstract: We propose a simultaneous observation of the Seyfert 1 AGN NGC 3783 with Chandra (160 ks) and NuSTAR (80 ks). Our primary aim is to address the highly disparate measurements of supermassive black hole spin in this source that have been reported in the literature. The high signal-to-noise (S/N), high resolution, broadband X-ray spectra uniquely enabled by this joint observing campaign will allow us to definitively deconvolve the primary continuum, absorption and reprocessed emission components in NGC 3783 for the first time. The signatures of relativistic reflection from the inner disk can then be isolated and the spin of the black hole measured accurately and precisely.
Proposal Number: 17700625 PI Last Name: Chartas Title: The Wide-Angle Outflow of the z=1.51 AGN HS 0810+2554 Abstract: Massive and ultrafast wide-angle outflows from AGN are one of the proposed feedback mechanisms that may provide the coupling of kinetic energy between quasars and their host galaxies. To further our understanding of the AGN's role in this process we propose joint Chandra and NuSTAR observations of the relativistic outflow of the z=1.5 AGN HS 0810+2554. The factor of 120 lensing magnification of HS 0810 makes this source exceptionally bright compared to other quasars with detected outflows at similar distances. The joint observations will provide constraints on both the opening angle of the wind and the inclination angle of the disk by combined modeling of the P-Cygni profile of the outflow and the disk/wind reflection. We will also study the variability of the properties of the outflow.
Proposal Number: 18500288 PI Last Name: Rea Title: PROMPT STUDY OF MAGNETAR OUTBURSTS WITH CHANDRA AND NUSTAR Abstract: The discovery of transient magnetars has opened a new perspective in the field confirming that a relatively large number of members of this class has not been discovered yet, and suggesting that others would manifest themselves in the future through outbursts. This proposal is aimed at gathering new insights on the physics of magnetars through the study of their outbursts. In particular, we are asking for 85ks of Chandra time divided in 4 observations throughout the outburst from a known or still unknown magnetar candidate, as well as 85ks of NuSTAR time to monitor the hard X-ray emission during the outburst decay.
Proposal Number: 18500371 PI Last Name: Kaspi Title: Target-of-Oppurtunity Chandra Observations of Magnetars in Outburst Abstract: Magnetars are highly magnetized young neutron stars that are powered by the decay of their enormous magnetic fields. Magnetars exhibit dramatic variability including major outbursts - a hallmark of their emission. These outbursts allow us to probe the extreme physics at work in the Universe's largest known magnetic fields. Understanding the evolution of these outbursts will place stringent constraints on physical models of magnetars, including their crusts, cores, atmospheres, coronae, and magnetospheres. In this proposal, we request Chandra and NuSTAR Target-of-Opportunity observations of a major magnetar outburst in AO18 in order to put detailed physical models to the test, and as an anchor for multiwavelength follow-up.
Proposal Number: 18500379 PI Last Name: Margutti Title: Mapping extreme mass loss from evolved massive stars with coordinated Chandra-NuSTAR observations Abstract: Contrary to expectations from current stellar evolutionary models, recent observations uncovered the ejection of shells of material by massive stars in the years before the supernova (SN) explosion. The physical mechanism behind the impulsive mass ejection synchronized with the stellar core-collapse is unclear. Here we propose a coordinated Chandra-NuSTAR effort to map the evolution of the broad-band X-ray spectrum of 1 nearby (d<50 Mpc) strongly interacting SN and enable progress. Our program is designed to characterize the medium around strongly interacting SN, which originate from stellar progenitors with the most extreme mass loss before explosion. The overarching goal is to constrain the nature of the physical process responsible for mass loss in evolved massive stars.
Proposal Number: 18700375 PI Last Name: Satyapal Title: WISE Discovery of the Largest Sample of Obscured Dual AGNs: A Chandra and NuSTAR Follow-up Abstract: Despite decades of searching, confirmed cases of dual AGNs are extremely rare, and most have been dis- covered serendipitously. Using the all-sky WISE survey, we identified a population of over one hundred advanced mergers that display mid-IR colors suggestive of AGNs despite having no signatures of activity in the optical. Expanding on our pilot program, which confirmed dual AGNs in 5 targets, we propose 1) longer exposure Chandra observations of 4 of the duals to confirm all tentative detections and obtain sufficient counts for a spectral analysis, and 2) NuSTAR observations of the one dual with sufficient counts for which our current Chandra observations show a prominent Fe K alpha line, consistent with a Compton-thick source.
Proposal Number: 18700471 PI Last Name: Perlman Title: The 3C111 Jet: X-ray Variability, Spectrum & Broadband SED Abstract: The discovery of X-ray emission from AGN jets is a touchstone of the Chandra mission. Their X-ray emission processes have become the source of much debate, with implications for both jet physics and cluster feedback models. 3C111 has an extraordinary 2-arcminute long jet that is seen in X-ray, near-IR and radio. At least 8 knots, plus both approaching and receding hotspots and lobes, are seen in the Chandra image. We request additional Chandra, HST and NuSTAR observations, to follow up on possible evidence of variability in two knots, pin down the knots' X-ray spectrum and SED, detect the jet above 10 keV, and study the morphology and X-ray spectrum of the extended lobes. These observations will place the tightest constraints yet on the physics of this fascinating system.
Proposal Number: 18700575 PI Last Name: Brightman Title: A Deep broadband study of the diverse population of X-ray sources in M51 with Chandra and NuSTAR Abstract: We propose simultaneous 40-ks Chandra and 100-ks NuSTAR observations of the interacting galaxies of M51 that will shed light on a range of unique X-ray sources with diverse astrophysical implications. The nucleus of the spiral galaxy contains a Compton-thick AGN in a luminosity regime where the AGN torus is predicted to vanish. Intense Fe Kalpha emission revealed by deep Chandra observations contradicts this prediction, but a deep NuSTAR observation will uncover the true covering factor of the torus through observation of the Compton hump. A ULX in M51a shows the properties of an IMBH in the low/hard state, but only the combined broadband coverage from Chandra and NuSTAR can confirm if the hard spectrum continues above 10 keV, indicative of an Eddington-limited accretor.
Proposal Number: 18700577 PI Last Name: Annuar Title: Towards A Complete Census of the Compton-thick AGN Population in our Cosmic Backyard Abstract: We propose for Chandra and NuSTAR observations of two local AGNs to characterise their obscuring properties. We are using Chandra and NuSTAR to form the first complete measurement of the column density (N H) distribution of AGN at D<15 Mpc. Even at this distance the distribution was only 50% complete. We have recently improved this, and found a Compton-thick (CT) AGN fraction of >35%. We also found that Chandra resolution is key in resolving the AGN from off-nuclear X-ray sources. When combined with NuSTAR, this allow us to accurately characterise the broadband spectrum of the AGN, and identify it as CT. These new observations will provide Chandra data for all D<15Mpc AGNs and boost up the N H distribution up to 85% complete. This will be fully completed with future NuSTAR observations.
Proposal Number: 18500288 PI Last Name: Rea Title: PROMPT STUDY OF MAGNETAR OUTBURSTS WITH CHANDRA AND NUSTAR Abstract: The discovery of transient magnetars has opened a new perspective in the field confirming that a relatively large number of members of this class has not been discovered yet, and suggesting that others would manifest themselves in the future through outbursts. This proposal is aimed at gathering new insights on the physics of magnetars through the study of their outbursts. In particular, we are asking for 85ks of Chandra time divided in 4 observations throughout the outburst from a known or still unknown magnetar candidate, as well as 85ks of NuSTAR time to monitor the hard X-ray emission during the outburst decay.
Proposal Number: 18500371 PI Last Name: Kaspi Title: Target-of-Oppurtunity Chandra Observations of Magnetars in Outburst Abstract: Magnetars are highly magnetized young neutron stars that are powered by the decay of their enormous magnetic fields. Magnetars exhibit dramatic variability including major outbursts - a hallmark of their emission. These outbursts allow us to probe the extreme physics at work in the Universe's largest known magnetic fields. Understanding the evolution of these outbursts will place stringent constraints on physical models of magnetars, including their crusts, cores, atmospheres, coronae, and magnetospheres. In this proposal, we request Chandra and NuSTAR Target-of-Opportunity observations of a major magnetar outburst in AO18 in order to put detailed physical models to the test, and as an anchor for multiwavelength follow-up.
Proposal Number: 18500379 PI Last Name: Margutti Title: Mapping extreme mass loss from evolved massive stars with coordinated Chandra-NuSTAR observations Abstract: Contrary to expectations from current stellar evolutionary models, recent observations uncovered the ejection of shells of material by massive stars in the years before the supernova (SN) explosion. The physical mechanism behind the impulsive mass ejection synchronized with the stellar core-collapse is unclear. Here we propose a coordinated Chandra-NuSTAR effort to map the evolution of the broad-band X-ray spectrum of 1 nearby (d<50 Mpc) strongly interacting SN and enable progress. Our program is designed to characterize the medium around strongly interacting SN, which originate from stellar progenitors with the most extreme mass loss before explosion. The overarching goal is to constrain the nature of the physical process responsible for mass loss in evolved massive stars.
Proposal Number: 18700375 PI Last Name: Satyapal Title: WISE Discovery of the Largest Sample of Obscured Dual AGNs: A Chandra and NuSTAR Follow-up Abstract: Despite decades of searching, confirmed cases of dual AGNs are extremely rare, and most have been dis- covered serendipitously. Using the all-sky WISE survey, we identified a population of over one hundred advanced mergers that display mid-IR colors suggestive of AGNs despite having no signatures of activity in the optical. Expanding on our pilot program, which confirmed dual AGNs in 5 targets, we propose 1) longer exposure Chandra observations of 4 of the duals to confirm all tentative detections and obtain sufficient counts for a spectral analysis, and 2) NuSTAR observations of the one dual with sufficient counts for which our current Chandra observations show a prominent Fe K alpha line, consistent with a Compton-thick source.
Proposal Number: 18700471 PI Last Name: Perlman Title: The 3C111 Jet: X-ray Variability, Spectrum & Broadband SED Abstract: The discovery of X-ray emission from AGN jets is a touchstone of the Chandra mission. Their X-ray emission processes have become the source of much debate, with implications for both jet physics and cluster feedback models. 3C111 has an extraordinary 2-arcminute long jet that is seen in X-ray, near-IR and radio. At least 8 knots, plus both approaching and receding hotspots and lobes, are seen in the Chandra image. We request additional Chandra, HST and NuSTAR observations, to follow up on possible evidence of variability in two knots, pin down the knots' X-ray spectrum and SED, detect the jet above 10 keV, and study the morphology and X-ray spectrum of the extended lobes. These observations will place the tightest constraints yet on the physics of this fascinating system.
Proposal Number: 18700575 PI Last Name: Brightman Title: A Deep broadband study of the diverse population of X-ray sources in M51 with Chandra and NuSTAR Abstract: We propose simultaneous 40-ks Chandra and 100-ks NuSTAR observations of the interacting galaxies of M51 that will shed light on a range of unique X-ray sources with diverse astrophysical implications. The nucleus of the spiral galaxy contains a Compton-thick AGN in a luminosity regime where the AGN torus is predicted to vanish. Intense Fe Kalpha emission revealed by deep Chandra observations contradicts this prediction, but a deep NuSTAR observation will uncover the true covering factor of the torus through observation of the Compton hump. A ULX in M51a shows the properties of an IMBH in the low/hard state, but only the combined broadband coverage from Chandra and NuSTAR can confirm if the hard spectrum continues above 10 keV, indicative of an Eddington-limited accretor.
Proposal Number: 18700577 PI Last Name: Annuar Title: Towards A Complete Census of the Compton-thick AGN Population in our Cosmic Backyard Abstract: We propose for Chandra and NuSTAR observations of two local AGNs to characterise their obscuring properties. We are using Chandra and NuSTAR to form the first complete measurement of the column density (N H) distribution of AGN at D<15 Mpc. Even at this distance the distribution was only 50% complete. We have recently improved this, and found a Compton-thick (CT) AGN fraction of >35%. We also found that Chandra resolution is key in resolving the AGN from off-nuclear X-ray sources. When combined with NuSTAR, this allow us to accurately characterise the broadband spectrum of the AGN, and identify it as CT. These new observations will provide Chandra data for all D<15Mpc AGNs and boost up the N H distribution up to 85% complete. This will be fully completed with future NuSTAR observations.
Proposal Number: 19200504 PI Last Name: del Palacio Title: A unique opportunity to observe the extreme massive binary HD 93129A near periastron passage Abstract: Colliding-wind binaries are expected to be non-thermal (NT) X-ray sources; however, up to date none has been firmly confirmed as such. With a total mass of 120 Mo, an eccentricity of 0.9, and an orbital period of 120 yr, HD 93129A is one of the most extreme massive binaries in our Galaxy, and it will go through periastron passage in 2018. During that time, the intensity of the wind-collision region (WCR) will greatly enhance, making this a unique opportunity to determine the properties of the shocked plasma and the level of NT hard X-ray emission. This event is a once-in-a-lifetime opportunity which would provide an observational breakthrough in our understanding of shock physics, the hydrodynamics of the WCR, and mechanisms of particle acceleration and magnetic field amplification.
Proposal Number: 19400282 PI Last Name: Neilsen Title: An Integrated Approach to Winds/ Jets/ and State Transitions Abstract: We propose a large multiwavelength campaign (120 ks Chandra HETGS, NuSTAR, INTEGRAL, JVLA/ATCA, Swift, XMM, Gemini) on a black hole transient to study the influence of ionized winds on relativistic jets and state transitions. With a reimagined observing strategy based on new results on integrated RMS variability and a decade of radio/X-ray monitoring, we will search for winds during and after the state transition to test their influence on and track their coevolution with the disk and the jet over the next 2-3 months. Our spectral and timing constraints will provide precise probes of the accretion geometry and accretion/ejection physics.
Proposal Number: 19400584 PI Last Name: Steiner Title: A Test of Black-Hole Disk Truncation: Thermal Disk Emission in the Bright Hard State Abstract: The assumption that a black hole's accretion disk extends inwards to the ISCO is on firm footing for soft spectral states, but has been challenged for hard spectral states where it is often argued that the accretion flow is truncated far from the horizon. This is of critical importance because black-hole spin is measured on the basis of this assumption. The direct detection (or absence) of thermal disk emission associated with a disk extending to the ISCO is the smoking-gun test to rule truncation in or out for the bright hard state. Using a self-consistent spectral model on data taken in the bright hard state while taking advantage of the complementary coverage and capabilities of Chandra and NuSTAR, we will achieve a definitive test of the truncation paradigm.
Proposal Number: 20400577 PI Last Name: Neilsen Title: An Integrated Approach to Winds, Jets, and State Transitions Abstract: We propose a large multiwavelength campaign (120 ks Chandra HETGS, NuSTAR, JVLA/ATCA, NICER, Swift, Gemini) on a black hole transient to study the influence of ionized winds on relativistic jets and state transitions. With a reimagined observing strategy based on new results on integrated RMS variability and a decade of radio/X-ray monitoring, we will search for winds during and after the state transition to test their influence on and track their coevolution with the disk and the jet over the next 2-3 months. Our spectral and timing constraints will provide precise probes of the accretion geometry and accretion/ejection physics.
Proposal Number: 20400601 PI Last Name: Steiner Title: A Test of Black-Hole Disk Truncation: Thermal Disk Emission in the Bright Hard State Abstract: The assumption that a black hole's accretion disk extends inwards to the ISCO is on firm footing for soft spectral states, but has been challenged for hard spectral states where it is often argued that the accretion flow is truncated far from the horizon. This is of critical importance because black-hole spin is measured on the basis of this assumption. The direct detection (or absence) of thermal disk emission associated with a disk extending to the ISCO is the smoking-gun test to rule truncation in or out for the bright hard state. Using a self-consistent spectral model on data taken in the bright hard state while taking advantage of the complementary coverage and capabilities of Chandra and NuSTAR, we will achieve a definitive test of the truncation paradigm.
Proposal Number: 20500323 PI Last Name: Margutti Title: Continued Chandra-NuSTAR monitoring of the unprecedented metamorphosis of SN2014C at t>1500 days since explosion Abstract: Mass loss in evolved massive stars is one of the least understood yet fundamental aspects of stellar evolution. HOW and WHEN do massive stars lose their H-envelopes? This central question motivates this proposal. We request a continuation of our successful Chandra-NuSTAR campaign that led to the first detection of a H-poor extragalactic SN in the hard X-rays. We request Chandra-NuSTAR observations to map the unique situation of the interaction of the H-stripped SN2014C with a H-rich shell ejected by its progenitor star, as part of our approved gamma-ray to radio follow up. Our goal is to complete the mapping of the density profile of the H-rich material at R>7d17 cm to determine its location and total mass, and hence the mass-loss history of the progenitor in the years before stellar death
Proposal Number: 20700113 PI Last Name: Elvis Title: THE TORUS AND THE HOST: Extended Hard Emission in Compton Thick AGN with NuSTAR Spectra Abstract: We propose a survey of 7 Compton Thick Active Galactic Nuclei (CTAGN) with NuSTAR spectra to find or set limits at the 5% level on their extended hard (2-7 keV) continuum and Fe-K emission. The Chandra discovery that >= 30% of the 2-7 keV continuum and Fe-K line emission from CTAGN can be extended on scales from #100 pc up to #2 kpc affect the structure of the obscuring torus determined from NuSTAR spectra, and demonstrate the impact on the host galaxy, i.e. AGN feedback. By completing a well-defined sample of BASS CTAGN the CTAGN feedback duty cycle can be estimated on #1000 year timescales.
Proposal Number: 21400516 PI Last Name: Mori Title: Follow-up TOO Chandra and NuSTAR observations of Swift X-ray transients in the Galactic Center Abstract: We propose Chandra and NuSTAR follow-up observations of new X-ray transients and recurrent outbursts from the known VFXTs (very faint X-ray transients), detected by Swift-XRT, at r < 50 pc from the Galactic Center. The accurate source localization by Chandra and broad-band spectral/timing data with NuSTAR provide the useful diagnostic tools of understanding the nature of X-ray transients in the Galactic Center, as demonstrated by four Swift transients followed up by Chandra and NuSTAR including the transient magnetar SGR J1745-2900, one VFXT and two new X-ray transients. Detecting and characterizing new X-ray transients, together with the quiescent X-ray binaries recently discovered by Chandra (Hailey et al. 2018) will probe the population and formation of X-ray binaries near Sgr A*.
Proposal Number: 21400565 PI Last Name: Nowak Title: Distinguishing between Circumbinary and Interstellar Medium Dust Signatures in GX 5-1 Abstract: Dust is a major component of ISM absorption. Chandra-HETG spectroscopy has revealed detailed signatures of this dust, specifically near the Si edge as seen in spectra of bright X-ray binary systems behind large neutral columns. Understanding these signatures helps reveal the composition and structure of dust in the ISM. This is complicated by the fact that some fraction of this absorption and dust may be local to the binary system, and thus the dust signatures will respond to the local radiative environment. Here we propose to revisit one such system, GX 5-1, with simultaneous Chandra-HETG/NuSTAR observations. Chandra-HETG will provide detailed spectroscopic descriptions of the dust signatures, while NuSTAR will provide descriptions of the hard X-ray continua affecting the dust.
Proposal Number: 21400587 PI Last Name: Bozzo Title: Hunting for cyclotron lines in the faint symbiotic X-ray binary Sct X-1 with Chandra and NuSTAR Abstract: Symbiotic X-ray binaries (SyXBs) are rare low mass X-ray binaries hosting a red giant and a neutron star (NS). Observations suggest that the NS is young and strongly magnetized, a fact that is difficult to reconcile with the several Gyr age of the system (to allow evolution to the red giant phase). Measuring cyclotron lines in SyXBs thus challenges theories of the NS magnetic field decay or demonstrate that highly magnetized white dwarfs exist and can collapse to strongly magnetized NS. A cyclotron line has been recently discovered from a SyXB, thus calling for a systematic search in other sources of this class. We propose a 30 ks-long observation with Chandra+NuSTAR of the faint SyXB Sct X-1, which faintness requires low background and high sensitivity instruments.
Proposal Number: 21700573 PI Last Name: Walton Title: Is J1042+1641 the First Example of a Gravitationally Lensed, Compton-Thick Quasar? Abstract: Previous X-ray observations of the quadruply lensed quasar J1042+1641 (z=2.517) with Swift XRT reveal evidence for strong obscuration, unusual among the lensed quasar population. However, the current data are not sufficient to robustly determine the level of the absorption. Both Compton-thick and Compton-thin solutions provide equivalent fits, meaning J1042+1641 is potentially the first example of a gravitationally lensed, Compton-thick quasar. We request a coordinated broadband X-ray observation of this remarkable source with Chandra and NuSTAR (50+50ks). This will enable us to robustly determine the nature of the obscuration (Compton-thick vs Compton-thin), a key step towards determining the intrinsic power of J1042+1641, and also obtain the first high-resolution image of this system.
Proposal Number: 22400400 PI Last Name: Mori Title: Follow-up TOO Chandra and NuSTAR observations of Swift X-ray transients in the Galactic Center Abstract: We propose Chandra and NuSTAR follow-up observations of new X-ray transients and recurrent outbursts from the known VFXTs (very faint X-ray transients), detected by Swift-XRT, at r < 50 pc from the Galactic Center. The accurate source localization by Chandra and broad-band spectral/timing data with NuSTAR provide the useful diagnostic tools of understanding the nature of X-ray transients in the Galactic Center, as demonstrated by four Swift transients followed up by Chandra and NuSTAR including the transient magnetar SGR J1745-2900, one VFXT and two new X-ray transients. Detecting and characterizing new X-ray transients, together with the quiescent X-ray binaries recently discovered by Chandra (Hailey et al. 2018) will probe the population and formation of X-ray binaries near Sgr A*.
Proposal Number: 22400529 PI Last Name: Bachetti Title: Timing the M82 X-2 pulsar with Chandra and NuSTAR Abstract: The galaxy M82 harbors two notable ultraluminous X-ray sources (ULX): M82 X-2, the archetipal pulsating ultraluminous X-ray source (PULX), and M82 X-1, a IMBH candidate. The extreme luminosity of ULXs, and the observation of strong winds from these sources, suggests that these sources are undergoing strongly super-Eddington accretion. The supply of matter that powers these accreting systems is likely to come from Roche Lobe overflow from a more massive companion star, and should produce changes of orbital period observable in time scales of ~years. We have recently detected such orbital period derivative thanks to NuSTAR. This program aims at following up on this orbital period derivative through pulsar timing in M82 X-2, using Chandra to select the ideal observing times.
Proposal Number: 22500172 PI Last Name: Scholz Title: Simultaneous Chandra, NuSTAR and Radio Observations of CHIME-discovered repeating FRBs Abstract: Fast Radio Bursts (FRBs) are a new class of astrophysical transient of unknown origins. The CHIME/FRB project is now operational and discovering several FRBs per day. A fraction of the sources are repeating and can potentially be localized to arcsecond precision using radio interferometers. These precise localizations will enable a deep search for X-ray counterparts of the radio bursts. Some models, notably those involving magnetars, predict X-ray bursts along with FRBs which may be detectable with Chandra or NuSTART for nearby sources. We therefore propose for 54 ks of Chandra ToO observations to be scheduled along with 15 hr of Effelsberg and 27 ks of NuSTAR observations on a well-localized CHIME/FRB repeater.
Proposal Number: 22500192 PI Last Name: Matthews Title: Chandra-NuSTAR Observations of Rapid, Luminous, and Blue Stellar Explosions Abstract: We propose an in-depth X-ray study of fast blue optical transients (FBOTs), a new class of transients with luminosities and time scales that challenge traditional SN models. Alternative scenarios include a failed SN of a stripped star, He-shell detonation on a white dwarf, and a SN shock breaking through a dense medium. FBOTs have mostly been studied in the optical/UV regime, which is of thermal origin and it is not sensitive to the nature of the underlying energy source. Here we propose to capitalize on our recent discovery of X-rays with unprecedented properties from the FBOTs AT2018cow and CSS161010, and start the first broad-band X-ray monitoring campaign of FBOTs. The primary goal is to test for the presence of engines driving the explosions and constrain their nature.
Proposal Number: 22700176 PI Last Name: Fabbiano Title: The Young Radio Jet - Galaxy Interaction in B2 0258+35/NGC 1167 Abstract: We propose a high-resolution study of the interaction of the emerging radio jets of the low-luminosity young radio galaxy B2 0258+35 with the host galaxy NGC 1167. Given the proximity of NGC 1167 (z=0.06, ~70 Mpc; 1''~300 pc), and the signal to noise that we will achieve with the proposed 200 ks ACIS-S observations, we will be able to investigate the X-ray emission associated with the emerging jets both spatially and spectrally. With sub-pixel binning of Chandra ACIS S data, we will be able to characterize structures on spatial scale of ~100pc, comparable to the resolution provided by the radio maps. Of the sample of known young radio galaxies, our target is the only one that can be resolved with Chandra. With a NuSTAR observation, we will constrain the debated presence of a CT AGN.
Proposal Number: 22700429 PI Last Name: Elvis Title: THE TORUS AND THE HOST -2: Extended Hard Emission in Heavily Obscured AGN Abstract: We propose a survey of 7 highly obscured Active Galactic Nuclei (logNh>23) to find or set limits at the 10% level on their extended hard (2-7 keV) continuum and Fe-K emission. The Chandra discovery that 10-30% of the 2-7 keV continuum from high Nh AGN can be extended on scales from ~100 pc up to ~2 kpc affects the structure of the obscuring torus determined from NuSTAR spectra, and demonstrates the AGN impact on the host galaxy, i.e. AGN feedback. By completing a sample of 20 BASS high Nh AGN we can look for predictors of hard extent; their feedback duty cycle may also be estimated on ~1000 year timescales.
Proposal Number: 23200093 PI Last Name: Pillitteri Title: The Magnetosphere of the fast spinning B star HR5907 Abstract: Strong magnetism and fast rotation among early type stars produce copious emission in radio and X-rays bands coming from different regions of the spinning magnetosphere. We propose a joint and simultaneous observation of HR 5907 with Chandra and NuSTAR in order to acquire its spectrum from soft (~0.5 keV) to hard (~80 keV) X-rays. HR 5907 is a B2.5V star, it is an extreme rotator with a strong magnetic field. This unique target allows us to test the Oblique Rotator Model in such a regime of fast rotation and magnetism.
Proposal Number: 232000246 PI Last Name: del Placio Title: Evolution of the X-ray emission from the colliding-wind binary HD 93129A after its periastron passage Abstract: Colliding-wind binaries (CWBs) are expected to be non-thermal (NT) X-ray sources; however, until now only one has been confirmed as such. The extreme CWB HD 93129A went through periastron passage in 2018. This system is in a highly eccentric and long-period orbit, making this a unique opportunity to monitor its X-ray emission during the most determining orbital phases. The intensity of its wind-collision region was expected to peak during periastron and decrease as the stars separate. A potential detection of NT hard X-rays from HD 93129A was recently reported close to its periastron. An observation in the post-periastron epoch will probe the variability of the source, helping identify potential orbital-related effects, and provide insight of the properties of the shocks of CWBs.
Proposal Number: 23400247 PI Last Name: Neilsen Title: Searching for Winds and Jets in Black Hole State Transitions Abstract: We propose a large multiwavelength campaign (120 ks Chandra HETGS, NuSTAR, JVLA/ATCA, NICER, Swift, Gemini) on a black hole transient to study the influence of ionized winds on relativistic jets and state transitions. With a new observing strategy based on integrating radio/X-ray monitoring and timing studies, we will search for winds during and after the state transition to test their influence on and track their coevolution with the disk and the jet over the next 2-3 months. Our spectral and timing constraints will provide precise probes of the accretion geometry and accretion/ejection physics.
Proposal Number: 23500541 PI Last Name: Chornock Title: A broad-band view of Extreme Mass Loss events from Evolved Massive Stars with Chandra+NuSTAR Abstract: Contrary to expectations from stellar evolutionary models, recent observations uncovered the ejection of shells of material massive stars in the years before the supernova (SN) explosion. The physical mechanism behind the impulsive mass ejection synchronized with the stellar core-collapse is unclear. Here we propose a coordinated Chandra-NuSTAR effort to map the evolution of the broad-band X-ray spectrum of 1 nearby (d<50 Mpc) strongly interacting SN and enable progress. Our program is designed to characterize the medium around strongly interacting SN, which originate from stellar progenitors with the most extreme mass loss before explosion. The overarching goal is to constrain the nature of the physical process responsible for mass loss in evolved massive stars.
Proposal Number: 23700282 PI Last Name: Wong Title: Opening a New Chapter in Hard X-rays of the M87 AGN Abstract: M87 hosts a 3-6 billion solar mass black hole with an exceptional relativistic jet. It has been regularly monitored in radio to TeV bands, but little has been done in hard X-rays >10 keV. Since the launch of NuSTAR, for the first time, X-rays up to 40 keV from its X-ray core have been detected with joint Chandra observations, providing important insights to the X-ray origins: from the unresolved jet or the accretion flow. The hard X-ray emission is significantly lower than that predicted by synchrotron self-Compton models introduced to explain emission above a GeV. To further understand these high energy processes, we propose to constrain the X-rays from 0.3 keV to 78 keV over two orders of magnitudes and study its variability with Chandra and NuSTAR.
Proposal number: 24200128 PI Last name: Huenemoerder Title: Characterizing the Energetics and Dynamics of V750 Ara, a gamma Cas-type Star Abstract: We propose to obtain high resolution spectra with HETG of the gamma Cas-type star, V750 ara. These stars, of which about 25 are known, are Oe/Be stars which have very hard and strong X-ray emission. Their nature is enigmatic with several proposed explanations, one of which is that they have an He-star companion with a strong wind. With a 200 ks HETGS spectrum, we will characterize plasma temperatures from emission lines of Fe, Si, Mg, and S, and determine dynamical parameters from line widths and centroids. We also request a NuSTAR observation of 100 ks which is necessary to constrain the high temperature plasma, via the spectral energy distribution between 10 and 30 keV.
Proposal number: 24400072 PI last name: Mori Title: Chandra and NuSTAR ToO observations of Swift X-ray transients in the Galactic Center Abstract: We propose Chandra and NuSTAR follow-up observations of new X-ray transients and recurrent outbursts from the known VFXTs (very faint X-ray transients), detected by Swift-XRT, at r < 50 pc from the Galactic Center. The accurate source localization by Chandra and broad-band spectral/timing data with NuSTAR provide the useful diagnostic tools of understanding the nature of X-ray transients in the Galactic Center, as demonstrated by four Swift transients followed up by Chandra and NuSTAR including the transient magnetar SGR J1745-2900, one VFXT and two new black hole transients. Detecting and characterizing new X-ray transients, together with investigating quiescent X-ray binaries, will probe the population and formation of X-ray binaries near Sgr A*.
Proposal number: 24400242 PI last name: Neilsen Title: Searching for Winds and Jets in Black Hole State Transitions Abstract: We propose a large multiwavelength campaign (120 ks Chandra HETGS, NuSTAR, JVLA/ATCA, NICER, Swift, Gemini) on a black hole transient to study the influence of ionized winds on relativistic jets and state transitions. With a new observing strategy based on integrating radio/X-ray monitoring and timing studies, we will search for winds during and after the state transition to test their influence on and track their coevolution with the disk and the jet over the next 2-3 months. Our spectral and timing constraints will provide precise probes of the accretion geometry and accretion/ejection physics.
Proposal last name: 24500203 PI last name: Brethauer Title: Mapping extreme mass loss from evolved massive stars with coordinated Chandra-NuSTAR observations Abstract: Contrary to expectations from stellar evolutionary models, recent observations uncovered the ejection of shells of material massive stars in the years before the supernova (SN) explosion. The physical mechanism behind the impulsive mass ejection synchronized with the stellar core-collapse is unclear. Here we propose a continuation of our coordinated Chandra-NuSTAR effort to map the evolution of the broad-band X-ray spectrum of 1 nearby (d<50 Mpc) strongly interacting SN and enable progress. Our program is designed to characterize the medium around strongly interacting SN, which originate from stellar progenitors with the most extreme mass loss before explosion. The overarching goal is to constrain the nature of the physical process responsible for mass loss in evolved massive stars.
Proposal number: 24500280 PI last name: Matthews Title: Mining the Transient Sky: Chandra-NuSTAR Observations of the Fastest Explosions Abstraact: We propose an in-depth X-ray study of fast blue optical transients (FBOTs), a new class of transients with luminosities and time scales that challenge traditional SN models. Alternative scenarios include a failed SN of a stripped star, He-shell detonation on a white dwarf, and a SN shock breaking through a dense medium. FBOTs have mostly been studied in the optical/UV regime, which is of thermal origin and it is not sensitive to the nature of the underlying energy source. Here we propose to capitalize on the recent discovery of X-rays from the FBOT AT2018cow with unprecedented properties, and start the first broad-band X-ray monitoring campaign of FBOTs. The primary goal is to test for the presence of engines driving the explosions and constrain their nature.
Proposal number: 25400276 PI last name: Kosec Title: Resolving Powerful Outflows in a Nearby Transient Ultraluminous X-ray Source Abstract: In recent years, high resolution spectroscopy revealed the presence of radiatively driven ultrafast outflows in super-Eddington ultraluminous X-ray sources. Unfortunately, because most ULXs are at Mpc distances, the low signal-to-noise of these spectra limit our ability to probe the plasma properties and their evolution in time. Here we present a unique opportunity to obtain the highest quality high-resolution spectra of a ULX by targeting a transient ULX in the Magellanic Clouds. The quality of these three 25 ks ToO observations (joint with NuSTAR) will rival in statistics the future ATHENA spectra of bona fide ULXs. These observations will easily detect fast outflows in absorption (or place deep limits on their presence), as well as allow us to study the properties of the ionized plasma in emission, commonly seen in regular ULXs. We will accurately measure the ionized outflow properties, estimate its energetics and study both its short-term and long-term evolution with key ULX parameters.
Proposal number: 25400338 PI last name: Neilsen Title: Searching for Winds and Jets in Black Hole State Transitions Abstract: We propose a large multiwavelength campaign (120 ks Chandra HETGS, NuSTAR, JVLA/ATCA, NICER, Swift, Gemini) on a black hole transient to study the influence of ionized winds on relativistic jets and state transitions. With a new observing strategy based on integrating radio/X-ray monitoring and timing studies, we will search for winds during and after the state transition to test their influence on and track their coevolution with the disk and the jet over the next 2-3 months. Our spectral and timing constraints will provide precise probes of the accretion geometry and accretion/ejection physics.
Proposal number: 25500335 PI last name: Margutti Title: Mining the transient sky: Chandra-NuSTAR Observations of the fastest explosions Abstract: We propose an in-depth X-ray study of fast blue optical transients (FBOTs), a new class of transients with luminosities and time scales that challenge traditional SN models. Alternative scenarios include a failed SN of a stripped star, He-shell detonation on a white dwarf, and a SN shock breaking through a dense medium. FBOTs have mostly been studied in the optical/UV regime, which is of thermal origin and it is not sensitive to the nature of the underlying energy source. Here we propose to capitalize on the recent discovery of X-rays from the FBOT AT2018cow with unprecedented properties, and continue the first broad-band X-ray monitoring campaign of FBOTs. The primary goal is to test for the presence of engines driving the explosions and constrain their nature.
Proposal number: 25700436 PI last name: Maksym Title: Resolving Hot Feedback and Iron UFOs in Mrk 34 Abstract: Mrk 34 is a low-redshift Seyfert 2 galaxy with powerful kinematic outflows which provide one of the best targets to spatially resolve the role of hot X-ray winds in AGN feedback. Such winds may entrain the observed kpc-scale [O III] emitting gas in the extended narrow line region. Existing Chandra observations point to a more complex picture than a simple termination shock, with multi-temperature gas spatially segregated at Chandra resolution. Deeper observations are needed to confirm the presence of extended ~10^8 K gas contributing to hard (2-8 keV) emission, resolve complex nuclear structure in this band, and study recently-reported iron emission from spatially resolved ultrafast outflows.
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