Paschen Emission Lines Research Articles

Physical properties of strong 1 < z < 3 Balmer and Paschen line emitters observed with JWST

Context. The ultraviolet continuum traces young stars while the near-infrared unveils older stellar populations and dust-obscured regions. Balmer emission lines provide insights into gas properties and young stellar objects but are highly affected by dust attenuation. The near-infrared Paschen lines suffer less dust attenuation and can be used to measure star formation rates (SFRs) in star-forming regions obscured by dust clouds. Aims. We present a new way of combining spectro-photometric data in order to test the robustness of the SFRs and stellar mass estimates of star-forming sources observed with JWST. We also aim to quantify the amount of differential attenuation between the interstellar medium and the birth clouds with the use of Paschen emission lines. Methods. We select 13 sources between redshifts 1 and 3 observed with HST, JWST/NIRCam and NIRSpec based on the availability of at least one Balmer and one Paschen line with S/N ≥ 5. With a newly developed version of CIGALE, we fit their hydrogen line equivalent widths (EWs) and photometric data. We assess the impacts of the removal of spectroscopic data by comparing the quality of the fits of the spectro-photometric data to those with photometric data only. We compare the single (BC03) vs binary (BPASS) stellar population models in the fitting process of spectro-photometric data. We derive the differential attenuation and explore different attenuation recipes by fitting spectro-photometric data with BC03. For each stellar model and for each input dataset (with and without EWs), we quantify the deviation on the SFRs and stellar masses from the “standard” choice. Results. The combination of spectro-photometric data provides robust constraints on the physical properties of galaxies, with a significant reduction in the uncertainties compared to using only photometric data. On average, the SFRs are overestimated and the stellar masses are underestimated when EWs are not included as input data. We find a major contribution of the Hα emission line to the broadband photometric measurements of our sources, and a trend of increasing contribution with specific SFR. Using the BPASS models has a significant impact on the derived SFRs and stellar masses, with SFRs being higher by an average of 0.13 dex and stellar masses being lower by an average of 0.18 dex compared to BC03. We show that a flexible attenuation recipe provides more accurate estimates of the dust attenuation parameters, especially the differential attenuation. Finally, we reconstruct the total effective attenuation curves of the most dust-obscured galaxies in our sample.

The Paschen Jump as a Diagnostic of the Diffuse Nebular Continuum Emission in Active Galactic Nuclei*

Abstract Photoionization modeling of active galactic nuclei (AGN) predicts that diffuse continuum (DC) emission from the broad-line region makes a substantial contribution to the total continuum emission from ultraviolet through near-infrared wavelengths. Evidence for this DC component is present in the strong Balmer jump feature in AGN spectra, and possibly from reverberation measurements that find longer lags than expected from disk emission alone. However, the Balmer jump region contains numerous blended emission features, making it difficult to isolate the DC emission strength. In contrast, the Paschen jump region near 8200 Å is relatively uncontaminated by other strong emission features. Here, we examine whether the Paschen jump can aid in constraining the DC contribution, using Hubble Space Telescope Space Telescope Imaging Spectrograph spectra of six nearby Seyfert 1 nuclei. The spectra appear smooth across the Paschen edge, and we find no evidence of a Paschen spectral break or jump in total flux. We fit multicomponent spectral models over the range 6800–9700 Å and find that the spectra can still be compatible with a significant DC contribution if the DC Paschen jump is offset by an opposite spectral break resulting from blended high-order Paschen emission lines. The fits imply DC contributions ranging from ∼10% to 50% at 8000 Å, but the fitting results are highly dependent on assumptions made about other model components. These degeneracies can potentially be alleviated by carrying out fits over a broader wavelength range, provided that models can accurately represent the disk continuum shape, Fe ii emission, high-order Balmer line emission, and other components.

Discovery of Metastable He I* λ10830 Mini-broad Absorption Lines and Very Narrow Paschen α Emission Lines in the ULIRG Quasar IRAS F11119+3257

Abstract IRAS F11119+3257 is a quasar-dominated ultraluminous infrared galaxy, with a partially obscured narrow-line Seyfert 1 nucleus. In this paper, we present the near-IR (NIR) spectroscopy of F11119+3257, in which we find unusual Paschen emission lines and metastable He i* λ10830 absorption associated with the previously reported atomic sodium and molecular OH mini-BAL (broad absorption line) outflow. Photoionization diagnosis confirms previous findings that the outflows are at kiloparsec scales. Such large-scale outflows should produce emission lines. We indeed find that high-ionization emission lines ([O III], [Ne III], and [Ne V]) are dominated by blueshifted components at similar speeds to the mini-BALs. The blueshifted components are also detected in some low-ionization emission lines, such as [O II] λ3727 and some Balmer lines (Hα, Hβ, and Hγ), even though their cores are dominated by narrow (FWHMNEL = 570 ± 40 km s−1) or broad components at the systemic redshift of z = 0.18966 ± 0.00006. The mass flow rate (230–730 M ⊙ yr−1) and the kinetic luminosity ( erg s−1) are then inferred jointly from the blueshifted emission and absorption lines. In the NIR spectrum of F11119+3257, we also find that the Paschen emission lines are unique, in which a very narrow (FWHM = 260 ± 20 km s−1) component is shown in only Paα. This narrow component most probably comes from heavily obscured star formation. Based on the Paα and Paβ emissions, we obtain an extinction at the H band, A H > 2.1 (or a reddenning of > 3.7), and a star formation rate of SFR > 130 M ⊙ yr−1 that resembles the estimates inferred from the far-IR emissions (SFRFIR = 190 ± 90 M ⊙ yr−1).

CXOGBS J174954.5−294335: a new deeply eclipsing intermediate polar

We present the results of a photometric and spectroscopic analysis of the Galactic Bulge Survey X-ray source CXOGBS J174954.5-294335 (hereafter, referred to as CX19). CX19 is a long period, eclipsing intermediate polar type cataclysmic variable with broad, single-peaked Balmer and Paschen emission lines along with HeII $\lambda4686$ and Bowen blend emission features. With coverage of one full and two partial eclipses and archival photometry, we determine the ephemeris for CX19 to be HJD(eclipse) = 2455691.8581(5) + 0.358704(2)$\times$N. We also recovered the white dwarf spin period of P$_{\rm spin}$ = 503.32(3) seconds which gives a P$_{\rm spin}$/P$_{\rm orb}$ = 0.016(6), comparable to several confirmed, long period intermediate polars. CX19 also shows a clear X-ray eclipse in the 0.3-8.0 keV range observed with Chandra. Two optical outbursts were observed lasting between 6-8 hours (lower limits) reaching $\sim$1.3 mags in amplitude. The outbursts, both in duration and magnitude, the accretion disc dominated spectra and hard X-ray emission are reminiscent of the intermediate polar V1223 Sgr sharing many of the same characteristics. If we assume a main sequence companion, we estimate the donor to be an early G-type star and find a minimum distance of $d \approx$ 2.1 kpc and a 0.5-10.0 keV X-ray luminosity upper limit of 2.0 $\times$ 10$^{33}$ erg s$^{-1}$. Such an X-ray luminosity is consistent with a white dwarf accretor in a magnetic cataclysmic variable system. To date, CX19 is only the second deeply-eclipsing intermediate polar with X-ray eclipses and the first which is optically accessible.

On the black hole mass of the γ-ray emitting narrow-line Seyfert 1 galaxy 1H 0323+342

Narrow-line Seyfert 1 galaxies have been identified by the Fermi Gamma-Ray Space Telescope as a rare class of gamma-ray emitting active galactic nuclei (AGN). The lowest-redshift candidate among them is the source 1H 0323+342. Here we present quasi-simultaneous Gemini near-infrared and Keck optical spectroscopy for it, from which we derive a black hole mass based on both the broad Balmer and Paschen emission lines. We supplement these observations with a NuSTAR X-ray spectrum taken about two years earlier, from which we constrain the black hole mass based on the short timescale spectral variability. Our multiwavelength observations suggest a black hole mass of ~2x10^7 solar masses, which agrees well with previous estimates. We build the spectral energy distribution and show that it is dominated by the thermal and reprocessed emission from the accretion disc rather than the non-thermal jet component. A detailed spectral fitting with the energy-conserving accretion disc model of Done et al. constrains the Eddington ratio to L/L_Edd ~ 0.5 for a (non-rotating) Schwarzschild black hole and to L/L_Edd ~ 1 for a Kerr black hole with dimensionless spin of a*=0.8. Higher spin values and so higher Eddington ratios are excluded, since they would strongly overpredict the observed soft X-ray flux.

FORMATION OF RAMAN SCATTERING WINGS AROUND Hα, Hβ, AND PAαIN ACTIVE GALACTIC NUCLEI

Powered by a supermassive black hole with an accretion disk, the spectra of active galactic nuclei (AGNs) are characterized by prominent emission lines including Balmer lines. The unification schemes of AGNs require the existence of a thick molecular torus that may hide the broad emission line region from the view of observers near the equatorial direction. In this configuration, one may expect that the far UV radiation from the central engine can be Raman scattered by neutral hydrogen to reappear around Balmer and Paschen emission lines which can be identified with broad wings. We produce H$\alpha$, H$\beta$ and Pa$\alpha$ wings using a Monte Carlo technique to investigate their properties. The neutral scattering region is assumed to be a cylindrical torus specified by the inner and outer radii and the height. While the covering factor of the scattering region affects the overall strengths of the wings, the wing widths are primarily dependent on the neutral hydrogen column density $N_{\rm HI}$ being roughly proportional to $N_{\rm HI}^{1/2}$. In particular, with $N_{\rm HI}=10^{23}{\rm cm^{-2}}$ the H$\alpha$ wings typically show a width $\sim 2\times 10^4{\rm km s^{-1}}$. We also find that H$\alpha$ and Pa$\alpha$ wing profiles are asymmetric with the red part stronger than the blue part and an opposite behavior is seen for H$\beta$ wings.

The orientation of the η Carinae binary system

We examine a variety of observations that shed light on the orientation of the semimajor axis of the η Carinae massive binary system. Under several assumptions, we study the following observations: the Doppler shifts of some He i P Cygni lines that are attributed to the secondary's wind, of one Fe ΙΙ line that is attributed to the primary's wind and of the Paschen emission lines which are attributed to the shocked primary's wind, are computed in our model and are compared with observations. We compute the hydrogen column density towards the binary system in our model, and find a good agreement with that deduced from X-ray observations. We calculate the ionization of the surrounding gas blobs by the radiation of the hotter secondary star, and compare with observations of a highly excited [Ar ΙΙΙ] narrow line. We find that all of these support an orientation where for most of the time the secondary - the hotter, less-massive star - is behind the primary star. The secondary comes closer to the observer only for a short time near periastron passage in its highly eccentric (e ≃ 0.9) orbit. Further supporting arguments are also listed, followed by a discussion on some open and complicated issues.

Detection of the radial velocity curve of the B5-A0 supergiant companion star of Cir X-1?

In this paper, we report on phase-resolved I-band optical spectroscopic and photometric observations of Cir X-1 obtained with the Very Large Telescope. The spectra are dominated by Paschen absorption lines at nearly all orbital phases except near phase zero (coinciding with the X-ray dip) when the absorption lines are filled in by broad Paschen emission lines. The radial velocity curve of the absorption lines corresponds to an eccentric orbit (e = 0.45) whose period and time of periastron passage are consistent with the period and phase predicted by the most recent X-ray dip ephemeris. We found that the I-band magnitude decreases from 17.6 to ~16.8 near phase 0.9-1.0 this brightening coincides in phase with the X-ray dip. Even though it is likely that the absorption-line spectrum is associated with the companion star of Cir X-1, we cannot exclude the possibility that the spectrum originates in the accretion disc. However, if the spectrum belongs to the companion star, it must be a supergiant of spectral type B5-A0. If we assume that the compact object does not move through the companion star at periastron, the companion star mass is constrained to solar for a 1.4-M solar neutron star, whereas the inclination has to be . Alternatively, the measured absorption lines and their radial velocity curve can be associated with the accretion disc surrounding a 1.4-M solar neutron star and its motion around the centre of mass. An absorption-line spectrum from an accretion disc is typically found when our line of sight passes through the accretion disc rim implying a high inclination. In this scenario, the companion star mass is found to be ~0.4 M solar . However, from radio observations it was found that the angle between the line of sight and the jet axis is smaller than 5°. This would mean that the jet ploughs through the accretion disc in this scenario, making this solution less probable.

Kinematics of the Circumnuclear Region of NGC 3351

AbstractUsing high-resolution blue and far red spectra from the William Herschel Telescope, we have mapped the velocity field along three different slits in the central kiloparsec of the spiral galaxy NGC 3351. We have measured ionized gas (Hβ and [Oiii]) and stellar (near-IR Ca triplet) velocity dispersions for five individual Circumnuclear Star Forming Regions (CNSFRs) and the nucleus. Velocities and velocity dispersions in the red range were obtained using the cross-correlation technique of Tonry & Davis (1979AJ.84.1511) with a set of eleven templates, following the work by Nelson & Whittle (1995.ApJSS.99.67) with the variations introduced by Palacios et al. (1997.A & A.323.749). The gas velocities and velocity dispersions have been measured by fitting gaussians to the emission lines (Hβ and [OIII] λ5007Å) using three different suitable continua chosen by visual inspection and taking the average of the three results (Jiménez-Benito et al., 2000.MNRAS.317.907).The rotation velocities derived for gas and stars are in very good agreement, although in some cases the gas seems to rotate slightly faster than stars. The turnover points of the rotational curves seem to be located at the same position than the star forming ring as found in other galaxies (Díaz, R. et al., 1999ApJ.512.623). The derived values are consistent with those previously obtained for the systemic velocity of NGC 3351 (Planesas et al., 1997.A & A.325.81).The velocity dispersions of the stars are always larger (by between 10 and 25 km/sec) than those derived from Hβ emission lines. In the cases in which it has been possible to use the Paschen emission lines, the results obtained are similar. The twice ionized oxygen, on the other hand, shows velocity dispersions comparable to the stellar ones or, in some cases, even larger. It is however important to point out that in these metal rich regions the [Oiii] lines are very weak and they have a poor signal to noise ratio, then it is more difficult to accurately estimate the global kinematic behaviour from this emission line.The difference between the behavior of ionized hydrogen and stars could be interpreted by assuming that the gas is confined to the disc and supported by rotation while the stars are mostly supported by dynamical pressure (see Pizzella et al., 2004.A & A.424.447). However, the kinematics of ionized gas as mapped by [Oiii], as we mentioned above, is similar to that of the stellar component.We have applied the virial theorem to estimate the dynamical masses of the clusters and the galactic nucleus, assuming that the systems are gravitationally bound and spherically symmetric, and using sizes measured from the HST-WFPC2 image in the F606W filter (sizes between 2.6 and 5.1 pc). These values of the masses, estimated from stellar velocity dispersion measurements as mapped by the CaT lines, are in the range between 5.1×106 and 5.0×107 M⊙ for the five studied CNSFRs and 3.6×107 M⊙ for the nucleus of the galaxy, in the inner 23.4 pc.

N88: The physical properties of a compact star-forming region and its neighbourhood in the SMC

This paper, the second in a series of papers on the conspicuous compact HII region N88A in the Small Magellanic Cloud, emphasizes the properties of the H2 emission as well as of the surrounding stellar content of the entire Henize region N88. Using VJK photometry and stellar evolutionary models our analysis of N88 reveals a miscellaneous population of evolved stars of low and intermediate masses (1.2–8 ) in an age range of 40 Myr to 6 Gyr. The majority of these stars are found in the cluster HW 82 which also contains several main sequence stars. AV in N88A is revisited using near-IR Pδ, Pγ and Pβ Paschen emission lines. Spectroscopic measurements of the H2 emission in Z, J, H and K bands allow, in conjunction with measurements in the visible, a full spectral coverage from 0.37 μm to 2.45 μm. Long slit spectroscopy through N88 and the nebulosity to the east clearly distinguishes the ionization zone in N88 characterized by H I and He I emission with pure H2 emission clearly delineated in the cloud nearby. The principal excitation mechanism for H2 is through fluorescent excitation in a photodissociation region associated with N88A.

An electrograph for measurement of macroscopic electric fields in prominences and flares

We describe an ‘electrograph’ instrument designed for measurement of macroscopic electric fields in solar plasmas, using the polarization dependence of line width in Stark-broadened hydrogen Paschen emission lines. Observations of quiescent prominences and limb chromosphere with our electrograph at the NSO/Sac Peak Evans Coronal Facility provide upper limits of 5–10 V cm−1 for transverse macroscopic electric fields in these structures, averaged over an area of about 5 × 7 arc sec. Random thermal motions of hydrogen ions across magnetic field lines generate a quasi-static electric field, which should be distinguishable from pressure broadening in the intensely magnetized chromosphere over a sunspot, given an electrograph sensitivity a factor 2–3 better than that achieved here. Future electrograph measurements of limb flares, post-flare loops and eruptive prominences, even at 5 V cm−1 sensitivity, could provide a useful new test of reconnection and discharge effects in such dynamic structures.

Nova Ophiuchi 1988: 0.9–1.35 μm Spectroscopy

Near IR grating spectrophotometric observations (λ / Δλ ≃ 400 ) of Nova Ophiuchi 1988 between 0.9 and 1.35 μm on September 22.2, 1988 UT (J.D. = 2447426.7) are reported. We observed the nova with the Lick Observatory 3–meter Shane telescope using the Aerospace cooled grating spectrometer. A 7.5 arc sec aperture was used. The detector was a germanium photodiode, cooled to 77 K and used in conjunction with a charge integrating amplifier. These are the first IR observations ever made of a slow nova.Figure 1 shows the spectrum which contains Paschen emission lines β, γ δ, ε, ζ, η, He I λ1.083 μm, and a very weak continuum, all consistent with a post-maximum, early nebular phase. Figure 1 also shows a number of possible weak lines including [ Fe II ] and He I as well as an unidentified feature at 1.01 μm in the far red wing of Paδ. The line to continuum ratio for He I λ1.083 is about 300. The emission lines are resolved in the stronger features ( Paδ Paζ, Paβ, and He I λ1.083) and show a mean FWHM of 900 ± 150 km/sec.

A P Cygni Profile for the He 10830 A line of CI Cyg in Eclipse

AbstractInfrared spectroscopic observations of CI Cyg in eclipse show a P Cygni profile for He I 10830 Å, with a wind velocity of the order of 150 km/s, not seen in hydrogen Brackett and Paschen emission lines, which are single peaked.

Paschen Decrements in Be Stars

We searched for the general properties of the Be stars with Paschen emission lines. First, we obtained a relation between the infrared excess of the Be stars and the presence of emission in the Paschen lines. Until now, these emission excesses could be related to no physical characteristics of classical Be stars. Then, the measures of Paschen decrements of 12 stars whose spectral types range from B0e to B5e allowed us to check several theoretical calculations about the formation of emission lines in the envelopes of Be stars. Thus we can see the prominent part played by the electronic collisions in the Sobolev theory. Indeed, only with calculations taking the electronic collisions into account, can we obtain theoretical values agreeing with both measured Paschen and Balmer decrements for the hottest stars of our sample. However, no theoretical values agree with the observed decrements for the cooler stars.

Physical Conditions in the Nucleus of M82

view Abstract Citations (64) References (39) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Physical Conditions in the Nucleus of M82 Peimbert, Manuel ; Spinrad, Hyron Abstract Narrow-band photoelectric photometry of the nucleus and a bright region northeast of the center of M82 was carried out with the 120-inch telescope at Lick Observatory. The intensity of several emission lines in the nucleus, as well as of the continuum in both regions at different wavelengths, was obtained. From the Balmer and Paschen emission lines of hydrogen, an interstellar absorption of 4.23 mag at Hfl was derived for the nucleus. Collisions by thermal electrons are not responsible for the ionization in the nuclear region: this result and the observed Balmer decrement led to the adoption of radiation as the principal mechanism of ionization. The thermal contribution to the radio flux is smaller than 10 percent in the most favorable wavelengths. By extrapolating the radio spectrum to below the Lyman limit on the basis of a model of a single electron reservoir, synchrotron radiation fails by at least two orders of magnitude for the excitation of Ha in the nucleus; furthermore, the synchrotron contribution to the visible region of the spectrum is negligible. The N(He+)/N(H+) ratio is 0.065; however, a large fraction of the helium atoms is neutral, and the N(He)/N(H) ratio is about 0.13. The observed Balmer jump is smaller in the nucleus than in the region northeast of it. It is found that the spectral type of the galaxy becomes progressively later from the center outward. Publication: The Astrophysical Journal Pub Date: May 1970 DOI: 10.1086/150444 Bibcode: 1970ApJ...160..429P full text sources ADS | data products SIMBAD (7) NED (1)