P ospec s o using quasa o cosmology
LOI Code: Pol-NCB-6
B. Cze ny, V. K. Jaiswal, A. Mandal, S. Panda, F. Pozo Nunez
1. Cen e o Theo e ical Physics, Wa saw, Poland
2. In e na ional Gemini Obse a o y/NSF NOIRLab, La Se ena, Chile
3.As oin o ma ics, Heidelbe g Ins i u e o Theo e ical S udies, Heidelbe g, Ge many
1. In oduc ion
Quasa s a e he b igh es pe sis en objec s in he Uni e se, seen
om la ge cosmological dis ances ( edshi s up o 10). Toge he wi h
hei ain e cousins – Ac i e Galac ic Nuclei (AGN) – loca ed in he
local Uni e se hey c ea e a po en ially in e es ing ool o s udy he
expansion o he Uni e se. They show no s ong ends in he
me allici y despi e he b oad edshi ange which may pose a
p oblem o o he p obes. AGN a e no s anda d candles, bu hey can
be s anda dized – knowing hei physical p ope ies we can es ablish he
dis ance o each indi idual objec , i we ha e he equi ed da a a ou
disposal.
A numbe o me hods was de eloped o use quasa s o cosmology.
Some o he me hods do no equi e ex a calib a ions and can be used
di ec ly o measu e he Hubble cons an .
The cu en ly de eloped me hods based o ha ype include:
■ S ong quasa lensing [1]
■ Wa e mase [2]
■ Emission line ime delay combined wi h in e e ome y [3]
■ Con inuum ime delays
Con ac : Bożena Cze ny
Cen e o Theo e ical Physics PAN
bcz@c .edu.pl
REFERENCES
[1] Bi e , S. e al., 2025, a Xi :2506.03023
[2] Ba ua, S., Ramak ishnan, V., Desai, S., 2025, ApSS, 370, 62
[3] Li, Y.-R. E al., 2025, ApJ, 988, 42
[4] Hönig, S. F. e al., 2017, MNRAS, 464, 1693
[5] Wa son, D. e al., 2011, ???
[6] Haas, M. e al. 2011, ???
[7] Cze ny, B, e al., 2023, A&A675, A163
[8] Cao, S, e al., 2024, MNRAS 528, 6444
[9] Collie , S.J. e al., 1988, ApJ, 500, 162
[10] Cacke , E.M. e al., 2007, MNRAS, 380, 669
Two o he me hods (emission line ime delays and UV/X- ay luminosi y
a io) do no gi e he Hubble cons an as hey equi e calib a ion o he
me hod o a combina ion wi h o he me hods. Dus con inuum me hod may
e en ually be calib a ed wi hou ex e nal calib a ion, a he basis o he dus
sublima ion empe a u e [4].
LSST will b ing he de ec ion o abou 10 million AGN om he Main Su ey
(MS) and abou 4000 AGN om he Deep D illing Field (DDF). In ou wo k
we concen a ed on he p ospec s o using he ligh echo measu emen s o
AGN.
3. Two ep oceso s
The ep ocessing akes place bo h in he acc e ion disk and in he
su ounding B oad Line Region (BLR). BLR size in u n is
de e mined by ou heo y [12,13]: assump ion ha emission lines
like Hbe a o m in he wind pushed by he adia ion p essu e ac ing
on dus y disk a mosphe e Thus size is ela ed o he dus
sublima ion empe a u e (1500 K) and he sou ce luminosi y. We
used a 3-D s uc u e o he egion om he model, and he emi ed
spec um om adia i e ans e compu a ions (no jus lines, bu
also con inuum is p oduced in hose clouds, [14]).
4. Resul s o NGC 5548
We we e able o model he spec um and he de ails o he ime delay
measu emen s a ailable in he li e a u e o he objec NGC 5548
[15,16].
NGC 5548
5. P ospec s o con inuum
ime delay measu emen om
LSST
The me hod can be only applied o DDF, as he
MS does no ha e he high enough cadence. We
pe o med some es s o con inuum ime delay
based on uni o m cadence e . [19] and o likely
DDF cadence [18]. The esul s om uni o m
cadence we e oo op imis ic bu e en wi h
expec ed cadence he e a e p ospec s o
measu e he con inuum ime delay o sou ces
con aining he black hole mass abo e 2 x 108
Msun.
We can es ima e he ac ion o AGN sui able o
con inuum e e be a ion mapping a he basis o
he [17] who es ima ed he s ella mass in h ee
o he DDFs. Assuming he black hole mass o
s ella mass o 1%, we conclude ha 84% o he
black hole masses in de ec ed quasa s wi h be
highe han he limi om [18].
Measu ing he con inuum ime delays o 3000
objec s and assuming 50% e o in an indi idual
measu emen we would be able o es ima e he
Hubble cons an wi h accu acy 0.9 %, i no
sys ema ic e ec s bias ou measu emen s. We
can also y o dec ease he indi idual
measu emen e o using he me hodology using
a combined spec al/ ime delay i we es ed o
NGC 5548 which ga e 10 % e o .
REFERENCES - con inua ion
[11] Jaiswal, V.K. e al., 2025, A&A (in p ess), a Xi :2410.03597
[12] Cze ny, B,. H yniewicz, K., 2011, A&A, 525, L8
[13] Nadda , M.H., Cze ny, B., Szcze ba, R., 2021, ApJ, 920, 30
[14] Ko is a, K.T., Goad, M.R., 2001, ApJ, 553, 695
[15] Mehdipou , M. e al. 2015, A&A, 575, A22
[16] Fausnaugh, M. M. e al. 2016, ApJ, 821, 56
[17] Zou, F. e al., 2022, ApJS, 262, 15
[18] Pozo Nunez, F. e al., 2024, Res. No es AAS 8 47
[19] Pozo Nunez F.e al., 2023, MNRAS, 522, 2002
2. Con inuum ime delays - me hod
This is he me hod which allows di ec ly o measu e he Hubble
cons an , wi hou addi ional calib a ion. De e mina ion o he Hubble
cons an is s ill unde igo ous discussion since he e seems o be a
ension be ween he me hods based on Ea ly Uni e se measu emen s
(Cosmic Mic owa e Backg ound) and La e Uni e se measu emen s
(dis ances in edshi om ze o o 10).
A numbe o me hods we e de eloped so a wi h he aim o ge a
Hubble cons an p oposed a long ime ago [9,10] bu i was inally
success ully used by ou eam [11].
Cu en bes esul s o H0 based on AGN:
71.6+3.9-3.3 km-1s-1Mpc-1(TDCOSMO 2025) [1]
73.9+3.0-3.0 km-1s-1Mpc-1(MCP 2025) [2]
69+12-10 km-1s-1Mpc-1(SARM 2025) [3]
The me hod basically elies on measu emen o he ligh echo om he
a iable compac sou ce i adia ing he AGN su ounding. The heo y
is connec ing he ime delay be ween a ious spec al bands wi h he
objec absolu e luminosi y (b igh e sou ces a e la ge ). The idea
based on jus a con inuum ime delay om he acc e ion disk was no
wo king [9,10] since he delays we e oo long. Bu ecen ly he e we e
be e obse a ions co e ing he delays a a ious wa eleng hs and
hese delays showed a speci ic ea u es clea ly sugges ing he a omic
ea u es. So ou model is based on wo ep ocesso s.
Cu en bes esul s H0 om ou me hod:
66.9+10.6-2.1 km-1s-1Mpc-1(NGC 5548) [11]
2. Line emission delay expec ed om LSST
This me hod was p oposed o he use in cosmology by [5] and [6]. The
echnique equi ed o use he line con amina ion o he LSST bands which
depends on he chosen line and he sou ce edshi . We pe o med
simula ions o such lag eco e y o he MS and DDF ield, o expec ed
cadence [7]. The examples o he ime delay eco e y is illus a ed below.
The esul s e en om he MS a e sa is ac o y o b igh AGN.
The de e mina ion o he ime delay allows o di ec es s o he
nonlinea pa o he Uni e se expansion. We pe o med cosmological
es s a he basis o he ime delays cu en ly measu ed in Halpha,
Hbe a, Mg II and CIV lines [8[. The cons ain s a e no s ong and
oughly consis en wi h he s anda d ΛCDM model since he da a we e
no uni o m, and he la ges sample con ained only jus o e 100 ime
delay measu emen s. Wi h hugely imp o ed s a is ics he cons ain s
should be signi ican .
P obabili y
densi y
