arXiv subjects

S. Geier

Publications and source records attributed to S. Geier.

At least 37 records · Page 2Linked to original sources

arXiv2023

The black widow pulsar J1641+8049 in the optical, radio and X-rays

PSR J1641+8049 is a 2 ms black widow pulsar with the 2.2 h orbital period detected in the radio and $γ$-rays. We performed new phase-resolved multi-band photometry of PSR J1641+8049 using the OSIRIS instrument at the Gran Telescopio Canarias. The obtained data were analysed together with the new radio-timing observations from the Canadian Hydrogen Intensity Mapping Experiment (CHIME), the X-ray data from the Spectrum-RG/eROSITA all-sky survey, and all available optical photometric observations. An updated timing solution based on CHIME data is presented, which accounts for secular and periodic modulations in pulse dispersion. The system parameters obtained through the light curve analysis, including the distance to the source 4.6-4.8 kpc and the orbital inclination 56-59 deg, are found to be consistent with previous studies. However, the optical flux of the source at the maximum brightness phase faded by a factor of $\sim$2 as compared to previous observations. Nevertheless, the face of the J1641+8049 companion remains one of the most heated (8000-9500 K) by a pulsar among the known black widow pulsars. We also report a new estimation on the pulsar proper motion of $\approx$2 mas yr$^{-1}$, which yields a spin down luminosity of $\approx$4.87$\times 10^{34}$ ergs s$^{-1}$ and a corresponding heating efficiency of the companion by the pulsar of 0.3-0.7. The pulsar was not detected in X-rays implying its X-ray-luminosity was <3 $\times$ 10$^{31}$ erg s$^{-1}$ at the date of observations.

astro-ph.HE↗

arXiv2023

Scaling slowly rotating asteroids by stellar occultations

As evidenced by recent survey results, majority of asteroids are slow rotators (P>12 h), but lack spin and shape models due to selection bias. This bias is skewing our overall understanding of the spins, shapes, and sizes of asteroids, as well as of their other properties. Also, diameter determinations for large (>60km) and medium-sized asteroids (between 30 and 60 km) often vary by over 30% for multiple reasons. Our long-term project is focused on a few tens of slow rotators with periods of up to 60 hours. We aim to obtain their full light curves and reconstruct their spins and shapes. We also precisely scale the models, typically with an accuracy of a few percent. We used wide sets of dense light curves for spin and shape reconstructions via light-curve inversion. Precisely scaling them with thermal data was not possible here because of poor infrared data: large bodies are too bright for WISE mission. Therefore, we recently launched a campaign among stellar occultation observers, to scale these models and to verify the shape solutions, often allowing us to break the mirror pole ambiguity. The presented scheme resulted in shape models for 16 slow rotators, most of them for the first time. Fitting them to stellar occultations resolved previous inconsistencies in size determinations. For around half of the targets, this fitting also allowed us to identify a clearly preferred pole solution, thus removing the ambiguity inherent to light-curve inversion. We also address the influence of the uncertainty of the shape models on the derived diameters. Overall, our project has already provided reliable models for around 50 slow rotators. Such well-determined and scaled asteroid shapes will, e.g. constitute a solid basis for density determinations when coupled with mass information. Spin and shape models continue to fill the gaps caused by various biases.

astro-ph.EP↗

arXiv2023

The first massive compact companion in a wide orbit around a hot subdwarf star

We report the discovery of the first hot subdwarf B (sdB) star with a massive compact companion in a wide ($P=892.5\pm60.2\,{\rm d}$) binary system. It was discovered based on an astrometric binary solution provided by the Gaia mission Data Release 3. We performed detailed analyses of the spectral energy distribution (SED) as well as spectroscopic follow-up observations and confirm the nature of the visible component as a sdB star. The companion is invisible despite of its high mass of $M_{\rm comp}=1.50_{-0.45}^{+0.37}\,M_{\rm \odot}$. A main sequence star of this mass would significantly contribute to the SED and can be excluded. The companion must be a compact object, either a massive white dwarf or a neutron star. Stable Roche lobe overflow to the companion likely led to the stripping of a red giant and the formation of the sdB, the hot and exposed helium core of the giant. Based on very preliminary data, we estimate that $\sim9\%$ of the sdBs might be formed through this new channel. This binary might also be the prototype for a new progenitor class of supernovae type Ia, which has been predicted by theory.

astro-ph.SR↗

arXiv2023

Optical polarization and spectral properties of the H-poor superluminous supernovae SN 2021bnw and SN 2021fpl

New optical photometric, spectrocopic and imaging polarimetry data are combined with publicly available data to study some of the physical properties of the two H-poor superluminous supernovae (SLSN) SN 2021bnw and SN 2021fpl. For each SLSN, the best-fit parameters obtained from the magnetar model with \texttt{MOSFiT} do not depart from the range of parameter obtained on other SLSNe discussed in the literature. A spectral analysis with \texttt{SYN++} shows that SN 2021bnw is a W Type, Fast evolver, while SN 2021fpl is a 15bn Type, Slow evolver. The analysis of the polarimetry data obtained on SN 2021fpl at four epochs (+1.8, +20.6, +34.1 and +43.0 days, rest-frame) shows $> 3σ$ polarization detections in the range 0.8--1 $\%$. A comparison of the spectroscopy data suggests that SN 2021fpl underwent a spectral transition a bit earlier than SN 2015bn, during which, similarly, it could have underwent a polarization transition. The analysis of the polarimetry data obtained on SN 2021bnw do not show any departure from symmetry of the photosphere at an empirical diffusion timescale of $\approx$ 2 (+81.1 days rest-frame). This result is consistent with those on the sample of W Type SLSN observed at empirical diffusion timescale $\le$ 1 with that technique, even though it is not clear the effect of limited spectral windows varying from one object to the other. Measurements at higher empirical diffusion timescale may be needed to see any departure from symmetry as it is discussed in the literature for SN 2017egm.

astro-ph.HE↗

arXiv2023

Hot subdwarfs in close binaries observed from space II: Analysis of the light curves

Hot subdwarfs in close binaries with either M dwarf, brown dwarf or white dwarf companions show unique light variations. In hot subdwarf binaries with M dwarf or brown dwarf companions we can observe the so-called reflection effect and in hot subdwarfs with close white dwarf companions ellipsoidal modulation and/or Doppler beaming. Aims. The analysis of these light variations can be used to derive the mass and radius of the companion and hence determine its nature. Thereby we assume the most probable sdB mass and the radius of the sdB derived by the fit of the spectral energy distribution and the Gaia parallax. In the high signal-to-noise space-based light curves from the Transiting Exoplanet Survey Satellite and the K2 space mission, several reflection effect binaries and ellipsoidal modulation binaries have been observed with much better quality than possible for ground-based observations. The high quality of the light curves allowed us to analyse a large sample of sdB binaries with M dwarf or white dwarf companions using lcurve. For the first time we can constrain the absolute parameters of 19 companions of reflection effect systems covering periods from 2.5 to 19 hours and companion masses from the hydrogen burning limit to early M dwarfs. Moreover, we could determine the mass of eight white dwarf companion to hot subdwarf binaries showing ellipsoidal modulations, covering a so far unexplored period range from 7 to 19 hours. The derived masses of the white dwarf companions show that all but two of the white dwarf companions are most likely helium-core white dwarfs. Combining our results with previously measured rotation velocities allowed us to derive the rotation period of seven sdBs in short-period binaries. In four of those systems the rotation period of the sdB agrees with a tidally locked orbit, in the other three systems the sdB rotates significantly slower.

astro-ph.SR↗

arXiv2022

Panchromatic evolution of three luminous red novae: Forbidden hugs in pandemic times -- IV

We present photometric and spectroscopic data on three extragalactic luminous red novae (LRNe): AT2018bwo, AT2021afy, and AT2021blu. AT2018bwo was discovered in NGC45 (at 6.8 Mpc) a few weeks after the outburst onset. During the monitoring period, the transient reached a peak luminosity of 10^40 erg/s. AT2021afy, hosted by UGC10043 (49.2 Mpc), showed a double-peaked light curve, with the two peaks reaching a similar luminosity of 2.1(+-0.6)x10^41 erg/s. For AT2021blu in UGC5829, (8.6 Mpc), the pre-outburst phase was well-monitored by several photometric surveys, and the object showed a slow luminosity rise before the outburst. The light curve of AT2021blu was sampled with an unprecedented cadence until the object disappeared behind the Sun, and it was then recovered at late phases. The light curve of AT2021blu shows a double peak, with a prominent early maximum reaching a luminosity of 6.5x10^40 erg/s, which is half of that of AT2021afy. The spectra of AT2021afy and AT2021blu display the expected evolution for LRNe: a blue continuum dominated by prominent Balmer lines in emission during the first peak, and a redder continuum consistent with that of a K-type star with narrow absorption metal lines during the second, broad maximum. The spectra of AT2018bwo are markedly different, with a very red continuum dominated by broad molecular features in absorption. As these spectra closely resemble those of LRNe after the second peak, AT2018bwo was probably discovered at the very late evolutionary stages. This would explain its fast evolution and the spectral properties compatible with that of an M-type star. From the analysis of deep frames of the LRN sites years before the outburst, and considerations of the light curves, the quiescent progenitor systems of the three LRNe were likely massive, with primaries ranging from 13Mo for AT2018bwo, to 13-18Mo for AT2021blu, and over 40Mo for AT2021afy.

astro-ph.SR↗

arXiv2022

Laser Guide Star uplink beam: scattering and Raman emission measurements with the 10.4m Gran Telescopio CANARIAS

Laser Guide Star Adaptive Optics (LGS-AO) is becoming routine in several astronomical observatories. The use of powerful lasers generates sensible Raman emissions on the uplink laser beam path, plus secondary Rayleigh scattering from atmospheric molecules and Mie scattering from aerosols. This paper reports the results of a campaign done with the 10.4m Gran Telescopio CANARIAS (GTC); this campaign was undertaken to assess the spectral and photometric contamination coming from a 589 nm laser uplink beam scattering and Raman emission induced on the GTC spectro-imager OSIRIS by laser launched about 1 km off-axis. The photometric contamination is due to primary and secondary scattering of the uplink photons, as well by the Raman inelastic scattering. We have propagated the laser beam creating a mesospheric LGS, then pointed and focused the GTC telescope toward the uplink laser beam, at different heights and up to the LGS, taking into account the observing geometry. In our observations, the Raman emissions for O2 and N2 vibrational lines are visible at 20 km, weakening with altitude and becoming undetectable above 30 km. The scattering of the focused uplink beam is detectable at less than +/-0.2 arcmin from the center of the beam, while for the focused LGS the scattering is narrower, being detectable at less than +/-0.1 arcmin around the plume. Recommendations for Laser Traffic Control Systems (LTCS) are given accordingly.

astro-ph.IM↗

arXiv2022

Sub-stellar Companions of Intermediate-mass Stars with CoRoT: CoRoT-34b, CoRoT-35b, and CoRoT-36b

Theories of planet formation give contradicting results of how frequent close-in giant planets of intermediate mass stars (IMSs; $\rm 1.3\leq M_{\star}\leq 3.2\,M_{\rm \odot}$) are. Some theories predict a high rate of IMSs with close-in gas giants, while others predict a very low rate. Thus, determining the frequency of close-in giant planets of IMSs is an important test for theories of planet formation. We use the CoRoT survey to determine the absolute frequency of IMSs that harbour at least one close-in giant planet and compare it to that of solar-like stars. The CoRoT transit survey is ideal for this purpose, because of its completeness for gas-giant planets with orbital periods of less than 10 days and its large sample of main-sequence IMSs. We present a high precision radial velocity follow-up programme and conclude on 17 promising transit candidates of IMSs, observed with CoRoT. We report the detection of CoRoT-34b, a brown dwarf close to the hydrogen burning limit, orbiting a 1.1 Gyr A-type main-sequence star. We also confirm two inflated giant planets, CoRoT-35b, part of a possible planetary system around a metal-poor star, and CoRoT-36b on a misaligned orbit. We find that $0.12 \pm 0.10\,\%$ of IMSs between $1.3\leq M_{\star}\leq 1.6 M_{\rm \odot}$ observed by CoRoT do harbour at least one close-in giant planet. This is significantly lower than the frequency ($0.70 \pm 0.16\,\%$) for solar-mass stars, as well as the frequency of IMSs harbouring long-period planets ($\rm \sim 8\,\%$).

astro-ph.EP↗

arXiv2022

Hot subdwarfs in close binaries observed from space I: orbital, atmospheric, and absolute parameters and the nature of their companions

About a third of the hot subdwarfs of spectral type B, which are mostly core-helium burning objects on the extreme horizontal branch, are found in close binaries with cool, low-mass stellar, substellar, or white dwarf companions. They can show light variations due to different phenomena. We used light curves from the Transiting Exoplanet Survey Satellite and the \textit{K2} space mission to look for more sdB binaries. Their light curves can be used to study the hot subdwarf primaries and their companions and get orbital, atmospheric, and absolute parameters for those systems. By classifying the light variations and combining this with the fit of the spectral energy distribution, the distance derived by the parallaxes obtained by \textit{Gaia} and the atmospheric parameters, we could derive the nature of the primary and secondary in 122 (75\%) of the known sdB binaries and 82 newly found reflection effect systems. We derive absolute masses, radii, and luminosities for a total of 39 hot subdwarfs with cool, low-mass companions, as well 29 known and newly found sdBs with white dwarf companions. The mass distribution of hot subdwarfs with cool, low-mass stellar and substellar companions differs from those with white dwarf companions, implying they come from different populations. By comparing the period and minimum companion mass distributions, we find that there are several different populations of hot subdwarfs with white dwarf binaries. We also derive the first orbital period distribution for hot subdwarfs with cool, low-mass stellar or substellar systems selected from light variations instead of radial velocity variations. It shows a period distribution from 1.5 hours to 35 hours compared to the distribution of hot subdwarfs with white dwarfs, which ranges from 1 hour to 30 days. These period distributions can be used to constrain the previous common envelope phase.

astro-ph.SR↗

arXiv2022

Likely optical counterpart of the cool middle-aged pulsar J1957+5033

The 840 kyr old pulsar PSR J1957+5033, detected so far only in $γ$- and X-rays, is a nearby and rather cool neutron star with a temperature of 0.2--0.3 MK, a distance of $\la$1 kpc, and a small colour reddening excess $E(B-V) \approx 0.03$. These properties make it an ideal candidate to detect in the optical to get additional constraints on its parameters. We thus performed the first deep optical observations of the pulsar with the 10.4-meter Gran Telescopio Canarias in the $g'$ band and found its possible counterpart with $g'=27.63\pm 0.26$. The counterpart candidate position is consistent with the X-ray coordinates of the pulsar within the 0.5 arcsec accuracy. Assuming that this is the real counterpart, we analysed the pulsar X-ray spectrum together with the derived optical flux density. As a result, we found that the thermal emission from the bulk surface of the cooling neutron star can significantly contribute to its optical flux. Our multi-wavelength spectral analysis favours the pulsar nature of the detected optical source, since it provides physically adequate parameters of the pulsar emission. We show that the optical data can provide new constraints on the pulsar temperature and distance.

astro-ph.HE↗

arXiv2022

Discovery and analysis of three magnetic hot subdwarf stars: evidence for merger-induced magnetic fields

Magnetic fields can play an important role in stellar evolution. Among white dwarfs, the most common stellar remnant, the fraction of magnetic systems is more than 20 per cent. The origin of magnetic fields in white dwarfs, which show strengths ranging from 40 kG to hundreds of MG, is still a topic of debate. In contrast, only one magnetic hot subdwarf star has been identified out of thousands of known systems. Hot subdwarfs are formed from binary interaction, a process often associated with the generation of magnetic fields, and will evolve to become white dwarfs, which makes the lack of detected magnetic hot subdwarfs a puzzling phenomenon. Here we report the discovery of three new magnetic hot subdwarfs with field strengths in the range 300-500 kG. Like the only previously known system, they are all helium-rich O-type stars (He-sdOs). We analysed multiple archival spectra of the three systems and derived their stellar properties. We find that they all lack radial velocity variability, suggesting formation via a merger channel. However, we derive higher than typical hydrogen abundances for their spectral type, which are in disagreement with current model predictions. Our findings suggest a lower limit to the magnetic fraction of hot subdwarfs of 0.147 (+0.143/-0.047) per cent, and provide evidence for merger-induced magnetic fields which could explain white dwarfs with field strengths of 50-150 MG, assuming magnetic flux conservation.

astro-ph.SR↗

arXiv2022

Properties and applications of a predicted population of runaway He-sdO/B stars ejected from single degenerate He-donor SNe

This study builds on previous works, producing the most extensive prediction of the properties of such a hypothetical population to date, taking into account both Chandrasekhar and non-Chandrasekhar mass events. These results are then used to define criteria for membership of this population and characterise putative subpopulations This study contains 6x10^6 individual ejection trajectories out of the Galactic plane calculated with the stellar kinematics framework SHyRT, which are analysed with regard to their bulk observational properties. These are then put into context with the only previously identified population member US\,708 and applied to a number of other possible candidate objects. We find that two additional previously observed objects possess properties to warrant a designation as candidate objects. Characterisation of these object with respect to the predicted population finds all of them to be extreme in at least one astrometric observable. We find that current observations support a Galactic SN rate on the order of ~3x10^-7/yr to ~2x10^-6/yr, three orders of magnitude below the inferred Galactic SN Ia rate and two orders of magnitude below the formation rate of predicted He-donor progenitors. The number of currently observed population members suggests that the He-donor scenariois not a dominant contributor to the number of observed SNe Ia. However, we find that, even at the low event rate suggested, the majority of possibly detectable population members is still undetected. The extreme nature of current population members suggests that a still larger number of objects has simply evaded detection up to this point, hinting at a higher contribution than is currently supported by observation. - abridged -

astro-ph.SR↗

arXiv2022

Microwave-engineering of programmable XXZ Hamiltonians in arrays of Rydberg atoms

We use the resonant dipole-dipole interaction between Rydberg atoms and a periodic external microwave field to engineer XXZ spin Hamiltonians with tunable anisotropies. The atoms are placed in 1D and 2D arrays of optical tweezers, allowing us to study iconic situations in spin physics, such as the implementation of the Heisenberg model in square arrays, and the study of spin transport in 1D. We first benchmark the Hamiltonian engineering for two atoms, and then demonstrate the freezing of the magnetization on an initially magnetized 2D array. Finally, we explore the dynamics of 1D domain wall systems with both periodic and open boundary conditions. We systematically compare our data with numerical simulations and assess the residual limitations of the technique as well as routes for improvements. The geometrical versatility of the platform, combined with the flexibility of the simulated Hamiltonians, opens exciting prospects in the field of quantum simulation, quantum information processing and quantum sensing.

quant-ph↗

arXiv2022

Radial velocity variability and evolution of hot subdwarf stars

Hot subdwarf stars represent a late and peculiar stage in the evolution of low-mass stars, because they are likely formed by close binary interactions. Here we performed a radial velocity (RV) variability study of a sample of 646 hot subdwarfs with multi-epoch radial velocities from Sloan Digital Sky Survey (SDSS) and Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) spectra [...] As diagnostics we used the fraction of RV-variable stars and the distribution of the maximum RV variations $ΔRV_{\rm max}$. Both indicators turned out to be quite inhomogeneous across the studied parameter ranges. A striking feature is the completely different behaviour of He-poor and He-rich hot subdwarfs. While the former have a high fraction of close binaries, almost no significant RV variations could be detected for the latter. This led us to the conclusion that there likely is no evolutionary connection between these subtypes. Intermediate He-rich- and extreme He-rich sdOB/Os on the other hand are likely related. We conclude further that the vast majority of this population is formed via one or several binary merger channels. Hot subdwarfs with temperatures cooler than $\sim24\,000\,{\rm K}$ tend to show less and smaller RV-variations. These objects might constitute a new subpopulation of binaries with longer periods and late-type or compact companions. The RV-variability properties of the extreme horizontal branch (EHB) and corresponding post-EHB populations of the He-poor hot subdwarfs match and confirm the predicted evolutionary connection between them. Stars found below the canonical EHB at somewhat higher surface gravities show large RV-variations and a high RV-variability fraction, which is consistent with most of them being low-mass EHB stars or progenitors of low-mass helium white dwarfs in close binaries.

astro-ph.SR↗

arXiv2022

Post maximum light and late time optical imaging polarimetry of type I superluminous supernova 2020znr

Optical imaging polarimetry was conducted on the hydrogen poor superluminous supernova 2020znr during 3 phases after maximum light (approximately +34 days, +288 days and +289 days). After instrumental and interstellar polarization correction, all measurements are consistent with null-polarization detection. Modelling the light curve with a magnetar spin-down model shows that SN 2020znr has similar magnetar and ejecta parameters to other SLSNe. A comparison of the best-fit values discussed in the literature on SN 2017egm and SN 2015bn, two hydrogen poor SLSNe showing an increase of polarization after maximum light, suggests that SN 2020znr has higher mass ejecta that may prevent access to the geometry of the inner ejecta with optical polarimetry. The combined information provided by spectroscopy and light curve analysis of type I SLSNe may be an interesting avenue to categorize the polarization properties of this class of transients. This approach would require to expand the sample of SLSNe polarimetry data currently available with early and late time epochs new measurements.

astro-ph.HE↗

arXiv2022

Discovery of a highly magnetic He-sdO star from a double-degenerate binary merger

Helium-rich hot subdwarf stars of spectral type O (He-sdO) are considered prime candidates for stellar merger remnants. Such events should lead to the generation of strong magnetic fields. However, no magnetic He-sdO has yet been unambiguously discovered despite the high magnetic rate (20%) among white dwarf stars, the progeny of hot subdwarfs. Here we present the discovery of a strong magnetic field (B = 353 $\pm$ 10 kG) from Zeeman-split hydrogen, helium, and metal lines in the optical X-SHOOTER spectrum of an He-sdO and present the first spectroscopic analysis of any magnetic hot subdwarf. For this we used line-blanketed Tlusty non-local thermodynamic equilibrium models and assumed a simple homogeneous magnetic field. The derived atmospheric parameters $T_\mathrm{eff}$ = 44900 $\pm$ 1000 K and log g = 5.93 $\pm$ 0.15 are typical for He-sdO stars, while the star is less hydrogen-poor than most He-sdOs at log n(He)/n(H) = +0.28 $\pm$ 0.10. The star is a slow rotator ($v_\mathrm{rot}\sin i$ < 40 km s$^{-1}$). Its chemical composition is N-rich and C- and O-poor, and the Si and S abundances are close to solar. Combining the atmospheric parameters with Gaia parallax and photometry, the stellar radius and luminosity are found to be typical for He-sdOs and place the star on the helium main sequence in the Hertzsprung-Russell diagram. Its mass of $0.93^{+0.44}_{-0.30}$ $M_\odot$, although uncertain, appears to be remarkably high. The strong magnetic field along with the atmospheric parameters and metal abundances provide overwhelming evidence for the double-degenerate merger scenario.

astro-ph.SR↗

arXiv2021

Properties of slowly rotating asteroids from the Convex Inversion Thermophysical Model

Results from the TESS mission showed that previous studies strngly underestimated the number of slow rotators, revealing the importance of studying those asteroids. For most slowly rotating asteroids (P > 12), no spin and shape model is available because of observation selection effects. This hampers determination of their thermal parameters and accurate sizes. We continue our campaign in minimising selection effects among main belt asteroids. Our targets are slow rotators with low light-curve amplitudes. The goal is to provide their scaled spin and shape models together with thermal inertia, albedo, and surface roughness to complete the statistics. Rich multi-apparition datasets of dense light curves are supplemented with data from Kepler and TESS. In addition to data in the visible range, we also use thermal data from infrared space observatories (IRAS, Akari and WISE) in a combined optimisation process using the Convex Inversion Thermophysical Model (CITPM). This novel method has so far been applied to only a few targets, and in this work we further validate the method. We present the models of 16 slow rotators. All provide good fits to both thermal and visible data. The obtained sizes are on average accurate at the 5% precision, with diameters in the range from 25 to 145 km. The rotation periods of our targets range from 11 to 59 hours, and the thermal inertia covers a wide range of values, from 2 to <400 SI units, not showing any correlation with the period. With this work we increase the sample of slow rotators with reliable spin and shape models and known thermal inertia by 40%. The thermal inertia values of our sample do not display a previously suggested increasing trend with rotation period, which might be due to their small skin depth.

astro-ph.EP↗

arXiv2021

Modeling the unresolved NIR-MIR SEDs of local ($z<0.1$) QSOs

To study the nuclear ($\lesssim1\,$kpc) dust of nearby ($z<0.1$) type 1 Quasi Stellar Objects (QSOs) we obtained new near-infrared (NIR) high angular resolution ($\sim0.3$ arcsec) photometry in the H and Ks bands, for 13 QSOs with available mid-infrared (MIR) high angular resolution spectroscopy ($\sim7.5-13.5\,μ$m). We find that in most QSOs the NIR emission is unresolved. We subtract the contribution from the accretion disk, which decreases from NIR ($\sim35\%$) to MIR ($\sim2.4\%$). We also estimate these percentages assuming a bluer accretion disk and find that the contibution in the MIR is nearly seven time larger. We find that the majority of objects ($64\%$, 9/13) are better fitted by the Disk+Wind H17 model \citep[][]{Hoenig17}, while others can be fitted by the Smooth F06 \citep[$14\%$, 2/13,][]{Fritz06}, Clumpy N08 \citep[$7\%$, 1/13,][]{Nenkova08a,Nenkova08b}, Clumpy H10 \citep[$7\%$, 1/13,][]{Hoenig10b}, and Two-Phase media S16 \citep[$7\%$, 1/13,][]{Stalev16} models. However, if we assume the bluer accretion disk, the models fit only 2/13 objects. We measured two NIR to MIR spectral indexes, $α_{NIR-MIR(1.6,8.7\,μ\text{m})}$ and $α_{NIR-MIR(2.2,8.7\,μ\text{m})}$, and two MIR spectral indexes, $α_{MIR(7.8, 9.8\,μ\text{m})}$ and $α_{MIR(9.8, 11.7\,μ\text{m})}$, from models and observations. From observations, we find that the NIR to MIR spectral indexes are $\sim-1.1$ and the MIR spectral indexes are $\sim-0.3$. Comparing the synthetic and observed values, we find that none of the models simultaneously match the measured NIR to MIR and $7.8-9.8\,μ$m slopes. However, we note that measuring the $α_{MIR(7.8, 9.8\,μ\text{m})}$ on the starburst-subtracted {\it Spitzer}/IRS spectrum, gives values of the slopes ($\sim-2$) that are similar to the synthetic values obtained from the models.

astro-ph.GA↗